CN115720819A - A Vegetation Restoration Method in High Altitude Hydropower Development Area - Google Patents

Abstract

The invention discloses a vegetation recovery method for a high-altitude hydropower development area, which provides a slag field artificial grassland and fruit forest planting technology, a subalpine soil farm grass-shrub-forest artificial vegetation recovery technology, a alpine region soil farm turf transplantation and artificial grassland planting technology based on the ecological conditions of much gravel and drought climate of dry valley of the southeast Tibetan region. The method disclosed by the invention finds out the current situation of natural environment elements, simulates construction situations, monitors the dynamic change characteristics of regional environment elements, develops the plateau high mountain canyon regional vegetation recovery research under the hydropower development disturbance, integrates monitoring and situation simulation, forms a targeted and scientific recovery technology and mode, and fills up the relevant blank in the field of high and cold regions.

Description

A Vegetation Restoration Method in High Altitude Hydropower Development Area

technical field

The invention belongs to the technical field of vegetation restoration of waste slag fields of hydropower stations, and relates to a vegetation restoration method in high-altitude hydropower development areas.

Background technique

Since the completion and operation of the Three Gorges Hydropower Station, there has been a climax of hydropower construction, but the research on the restoration of ecological problems caused by hydropower projects has just started. At present, the ecological restoration technology in the hydropower development area is mostly focused on the research on the ecological restoration technology in low-altitude areas, drier and hot valley spoil areas and reservoir water-fluctuation zones. The Three Gorges Reservoir area has been the most researched on vegetation restoration and soil erosion control in the water-fluctuating zone of the reservoir area, and more achievements have been made. In the water-fluctuation zone of the Three Gorges reservoir area, a monitoring and early warning system for ecological environment problems in the water-fluctuation zone based on 3S technology was established, and functional areas were divided, land use policies were optimized, and rural industries were adjusted to rationally use the water-fluctuation zone area. The layer substrate spraying vegetation slope protection technology is used to stabilize the slope. The vegetation restoration adopts different elevations to restore different vegetation types, and adopts a reasonable combination of trees, shrubs, grasses, and rattans for vegetation restoration. At the same time, slope greening technology is used to control non-point source pollution.

Most of the research on vegetation restoration of hydropower station waste dumps in my country focuses on the vegetation restoration technology of dregs in low-altitude dry-hot valleys. Since most hydropower stations are located in low-altitude areas with sufficient temperature, the vegetation can be restored to a certain extent through the natural succession of plants. Chinese scholar Zhang Xinbao et al. (1996) believed that serious water and soil loss in rock-soil slag field, exposed rock mass or thin soil quality are the important limiting factors affecting its vegetation restoration, and proposed that the vegetation restoration model of rock-soil slag field should be based on rock-soil type, combined with climate, Soil and terrain conditions are used to determine the restoration strategy, and the selection of suitable plant species is given priority. Lu Weili et al. (2011) investigated the waste residue site of the Jinsha River dry-hot valley hydropower station and found that after 5 years of recovery, there were 49 plant species belonging to 23 families and 45 genera, and the plant community was in the primary stage of secondary succession. Mu Jun et al. (2010) researched on the vegetation restoration technology of the waste residue field of the Jinsha River dry-hot valley hydropower station.

All in all, since most of the current hydropower projects in my country are located in low-altitude areas with sufficient temperature, the project areas have been slightly artificially transformed, and the vegetation can be restored to a certain extent through natural succession. However, for the development of hydropower at high altitudes and with multiple altitude gradients, there are still many ecological restoration technical problems that need further research and tackling.

Contents of the invention

The technical problem solved by the present invention is to provide a vegetation recovery method in high-altitude hydropower development areas, and propose artificial grassland in slag field and economic fruit forest planting technology, grass-shrub-forest artificial vegetation restoration technology in sub-alpine soil material field and soil material in alpine region Field turf transplantation and artificial grassland planting technology to speed up the vegetation recovery of hydropower station slag fields in ecologically fragile areas.

The present invention is achieved through the following technical solutions:

A vegetation restoration method in a high-altitude hydropower development area, characterized in that it includes dry and warm valley vegetation restoration, sub-alpine vegetation restoration, and alpine meadow restoration adapted to different altitude gradients in southeast Tibet, specifically including the following operations:

1) For dry and warm valleys at an altitude of 2000-3000m, artificial grassland construction and fruit forest construction are used for vegetation restoration; among them:

The construction of artificial grassland is: level the area to be repaired and lay agricultural film for anti-seepage treatment, then cover the soil layer with a thickness of 20-30cm and add cattle and sheep manure to improve the soil, using oats and/or alfalfa as grass seeds , Carry out furrow sowing in the way of deep seeding and simple explanation; timely irrigation after sowing;

The construction of the fruit forest is: digging planting holes and laying agricultural film on the bottom for anti-seepage, then covering the soil with a thickness of 40-50cm, adding cow manure to improve the soil, and then covering 30-40cm of soil, and finally using agricultural plastic film. Bedding; before planting, soak the roots of the saplings in rooting powder solution or dip them in mud, and spread the rooting powder on the roots when planting; plant the seedlings in the middle of the well-built pit, and plant them firmly while returning to the soil, and plant them after covering the soil Sow alfalfa in holes, and then cover with film; build soil ridges after planting, 10-20cm above the ground level; irrigate after planting and conduct field management;

2) Arbors, shrubs and subalpine meadows are used for vegetation restoration in the subalpine area at an altitude of 3400-4000m; among them, the subalpine meadow area needs to be covered with surface guest soil with a thickness of 30-50cm, and Elymus chinensis and old Single sowing or mixed sowing of awn wheat and/or alfalfa grass seeds; when sowing, use deep seeds and shallow out, sowing depth 3-5cm; compact on the same day of sowing, cover with plastic film after sowing, and then cover with gravel and gravel with a particle size of 5-10cm The proportion of the area accounts for 40% of the surface soil. After the emergence of the seedlings, the plastic film is uncovered and watered in time to keep the gravel;

Trees/shrubs are transplanted or planted, keep the root system of the shrub seedlings and tree seedlings to be transplanted moist, then dip the root system in mud or water-retaining agent and put it into the seedling bucket. Seedling cultivation; level the surface of the planting hole after planting, and cover the topsoil with a thickness of 20-25cm; within one week after the completion of the cultivation, step on the seedlings;

4) Alpine meadows with an altitude above 4000m are used for vegetation restoration by means of turf transplantation or planting, among which:

Sod transplantation is to achieve vegetation restoration through turf stripping, stockpiling and maintenance, and replanting;

The planting uses old mangosteen and Elymus as the grass species for vegetation restoration, and the vegetation restoration is carried out by artificially planting grassland;

When the turf is transplanted, the longest side of the original turf cutting area should be no more than 50cm, and the shortest side should be no less than 25cm. A certain space should be reserved when the turf is transported and stacked; The replanting is smooth, so that the roots of the turf and the soil are seamlessly connected; after the turf is replanted, the grass gap is filled with humus, and the turf is lightly patted firmly; after the turf is replanted, its original growth environment is restored in time;

When artificially planting grassland, after stripping the surface soil, adopt block land preparation method, ditch and leave a row distance of 15cm to 20cm, single or mixed grass seed sowing, deep seeding and superficial planting in furrow seeding; timely compaction after sowing, Field management shall be carried out in time after sowing; the turf shall be covered after the grass leaves turn yellow.

Compared with the prior art, the present invention has the following beneficial technical effects:

Based on the ecological conditions of dry and warm river valleys in southeast Tibet with many gravels and arid climate, the present invention proposes artificial grassland in slag field and fruit forest establishment technology, grass-shrub-forest artificial vegetation restoration technology in sub-alpine soil field, and turf transplantation in soil field in alpine region and artificial grassland planting technology. The present invention finds out the status quo of natural environmental elements, simulates construction scenarios, monitors the dynamic change characteristics of regional environmental elements, conducts research on vegetation restoration in plateau, alpine, and canyon regions under the disturbance of hydropower development, and integrates monitoring, test platforms and scenario simulations to form a pertinence , scientific restoration techniques and models, to fill the relevant gaps in this field in alpine regions.

In dry and warm valleys, the present invention utilizes film covering to help maintain soil moisture and prevent water seepage and loss from slag crevices. The film can gradually degrade over time without polluting the environment; and alfalfa are planted plants; oats grow fast, have a large biomass, and can also bear fruit, which is conducive to increasing the income of local herdsmen; alfalfa is a leguminous plant, which can fix nitrogen itself and improve the soil, and alfalfa has relatively high feeding value; The mixture of plant species is conducive to improving the efficiency of vegetation restoration and increasing the income of local herdsmen. The combination of alfalfa and oats is selected for the artificial grassland of the present invention, the survival rate is relatively high, and the current coverage reaches more than 90%; the walnut is selected to be planted through the fruit forest, and the survival rate is all above 90%; the established fruit forest can also be harvested Fruits generate direct economic income.

The present invention selects Elymus and alfalfa as artificial grassland building plant species in subalpine mountainous areas, or selects Elymus and old awn wheat as single sowing grass seeds, and the results show that the artificial grass grows well, and the coverage reaches 80 It is further suggested that gravel be placed on the upper layer of the overburdened surface soil, which is conducive to soil heat preservation, water retention and fertilizer retention, and then promotes the growth of plant roots; the present invention promotes plant growth by exploring artificial grass planting and its proportion matching, and gravel After three years of continuous monitoring, a good vegetation recovery plan has been constructed: after two growing seasons of maintenance The survival rate of spruce species is close to 100%, which shows that spruce, as a local native species, has a strong ability to adapt to the environment and is an ideal tree for future vegetation restoration.

The turf transplantation and artificial grassland planting method in the alpine meadow area provided by the present invention fully considers the particularity of the alpine meadow turf field, and pays attention to the relationship between the size and thickness of the alpine meadow turf block when cutting and the viability It is suggested that the longest side of the cutting area should not be greater than 50cm, and the shortest side should not be less than 25cm, so as to prevent the turf from dying due to cutting off the root system of the plant if the division is too small, while too large is not conducive to handling and affects the adhesion of the turf to the ground after resurfacing, thereby reducing the turf. Survival rate; and when replanting and stacking, the bottom of the turf needs to be in full contact with the soil, so that the turf can survive the winter exercise and completely turn green; at the same time, the stacking space should meet the requirements of not overlapping the turf, so as to avoid watering. In time, the turf died due to lack of air between the turf blocks. The invention overcomes the technical prejudice in the turf transplantation process, ensures the overwintering of the turf transplantation in the soil field in the alpine region, and realizes its survival in the harsh environment.

Description of drawings

Figure 1 shows the volumetric water content of soil with different cover soil thicknesses and with or without anti-seepage measures;

Figure 2 shows the aboveground biomass of different grass species combinations in the artificial grassland;

Fig. 3 is the survival rate of walnut saplings with or without anti-seepage measures in different covering soil thicknesses;

Figure 4 shows the volumetric water content of soil with different cover soil thicknesses and with or without anti-seepage measures;

Figure 5-1 and Figure 5-2 are the display pictures of the root system "wrapping" the growth of gravel;

Figure 6-1 shows the impact of gravel placement layers on soil temperature;

Figure 6-2 shows the impact of gravel placement levels on soil moisture;

Figures 7-1 to 7-3 show the effects of gravel placement layers on the greening of Elymus tachycarpa in spring, respectively, the gravel covers the surface layer, the gravel is placed in the middle layer, and the gravel is placed in the lower layer;

Figure 8 is a schematic diagram of the alpine artificial grass seed screening test;

Figure 9 shows the effects of density and fertilization on the first-year biomass distribution of Elymus chinensis.

Detailed ways

The present invention will be further described in detail below in conjunction with the examples, which are explanations of the present invention rather than limitations.

A method of vegetation restoration in high-altitude hydropower development areas, specifically using Rongqu slag field, Lawu 1# and Lawushan soil field vegetation restoration test sites to illustrate the technology of artificial grassland and fruit forest establishment in slag field, subalpine soil Grass-shrub-forest artificial vegetation restoration technology in the material field and turf transplantation and artificial grassland establishment technology in the alpine area.

Mount Lawu Test Site: Facilities such as fences, signboards, and simple board houses have been set up. Tall fescue, purple fescue, ryegrass and bluegrass have been selected as plant species for artificial grass. Keep warm again, and the grass seeds can still turn green in the coming year, with a coverage of more than 80%. The turf transplanting area adopts single-layer transplanting, and all turf has survived, and the survival rate is close to 100%.

Rawu 1# test site: Fences, reservoirs, runoff fields, signs, simple board houses and other facilities have been set up, and they are all in normal operation at present. The test site selects Elymus and alfalfa as artificial grass construction plants species, the status quo is growing well, with a coverage of more than 80%. In addition, the spruce planting experiment was carried out in this test site. After two growing seasons of maintenance, the survival rate of spruce species is close to 100%. Currently, the spruce species in the site are still alive.

Rongqugou Test Site: Fences, signs and other facilities have been set up, and they are currently well preserved. The combination of alfalfa and oats for artificial grassland planting has a high survival rate, and the current coverage is over 90%. In addition, according to local conditions, apples, walnuts, peach trees and other fruit trees are selected for planting, and the survival rate is over 90%. The entire test area is basically covered with vegetation, and the control effect is good.

Embodiment 1 dry warm valley artificial grassland vegetation recovery

Specifically, the vegetation restoration of the dry and warm valley slag field at an altitude of 2000-3000m will be described. The dry and warm valley slag field (Rongqu slag field) has typical geological conditions in southeast Tibet, and the ecological environment is fragile. The slag field area is mainly formed by the accumulation of waste slag. Restoration is difficult, and its vegetation restoration technology can be extended to related engineering disturbance areas at an altitude of 2000-3000m.

In order to screen the restoration models of artificial grasslands with both ecological and economic benefits, artificial grassland establishment models were screened through soil improvement, anti-seepage treatment, covering soil thickness, grass species combination treatment and restoration effect monitoring.

1. Ground improvement and anti-seepage treatment

Soil improvement: Since there will be a considerable probability of gravel exposure in the slag yard, gravel with a diameter of 10cm to 40cm is selected for mixing, and the thickness of the laying is 30cm to 40cm to simulate the slag yard scenario;

In the leveled slag field, add 2kg/ ^m2 of cow manure to improve the soil; cow and sheep manure is an organic fertilizer, which can improve the soil texture and provide effective nutrients for plant growth, which is beneficial to plant growth.

Anti-seepage treatment and covering soil thickness: The thickness of the soil layer determines the water holding capacity of the soil, and the covering soil thickness is 10cm, 20cm, 30cm and 40cm for screening;

Anti-seepage treatment: Choose a film of 0.05-0.07mm for bedding. The covering of the film is conducive to maintaining soil moisture and preventing water seepage and loss from the gaps in the debris; the film can gradually degrade over time without polluting the environment.

After the above treatments, soil moisture, temperature and plant growth conditions were monitored simultaneously.

The results of soil volumetric water content with different cover soil thicknesses and with or without anti-seepage measures are shown in Figure 1; the results show that the water content at the depth of 10 cm in the soil is relatively low. High, strong sunshine, so the soil water evaporates quickly, resulting in low surface soil volume water content.

There is a big difference in the volume water content of the soil with the anti-seepage layer and without the anti-seepage layer. In the treatment without the anti-seepage layer (15cm-CK, 30cm-CK), the volume water content of the soil at 15cm is higher. The soil volume water content at 30cm (30cm-CK) is the lowest, which may be due to the fact that the bottom is all slag and poor water retention, so the soil volume water content is low; the water content at 15cm is relatively high, which may be due to the soil texture. skin, resulting in reduced water evapotranspiration and water uptake by capillary action, which may have contributed to the higher volumetric water content at 15 cm of the soil. In the treatment with anti-seepage layer (15cm-FS, 30cm-FS), there is no big difference in soil water content at 15cm and 30cm in the soil, indicating that the soil water retention is maintained.

The contents of soil organic matter, total nitrogen, available phosphorus, available potassium alkali-hydrolyzable nitrogen and cation exchange capacity increased with the increase of covering soil thickness, which indicated that the increase of covering soil thickness was beneficial to increase the growth of plants. Moreover, when the covering soil is 20cm, the anti-seepage layer can increase the content of organic matter, total nitrogen, available phosphorus, and available potassium, but when the covering soil is 30cm, the anti-seepage layer has no significant impact on soil nutrients.

After covering 10cm of soil, the vegetation can recover naturally. But aboveground biomass is not as high as that of artificial grassland. The aboveground biomass of 20cm and 30cm of covering soil was higher than that of 10cm of covering soil. There is no significant difference in aboveground biomass between 20cm and 30cm of soil with anti-seepage measures and without anti-seepage measures. Underground biomass was higher in the 10cm covering soil, and there was no significant difference in the underground biomass between the 20cm and 30cm covering soil with anti-seepage measures and no anti-seepage measures. From the above research results, it can be seen that covering 10cm of soil can also restore vegetation, but the biomass is low, and increasing the thickness of covering soil can increase the biomass.

Therefore, choosing a soil layer thickness of 20-30 cm and performing anti-seepage treatment can maintain soil water content and ensure the survival of plants in the case of large evaporation in dry and warm valleys.

2. Grass selection:

The survey of plant diversity was carried out in this dry and warm valley (2000-3000m above sea level).

Using the investigation method of flora and flora, four species of Elymus, awnmass, alfalfa and oats were preliminarily selected as candidate grass species.

Then establish an artificial grassland for further screening: when sowing 20g seeds per square meter, when planted alone, the above-ground biomass of oats is the largest, while the above-ground biomass of elymus and old awn wheat is the smallest when planted alone;

When the two plants were planted together, the biomass of alfalfa and oats was the largest, while the biomass of Elymus and old mans wheat were the smallest;

When the three plants were combined, the shoot biomass of the alfalfa, oat, old mans wheat combination was the largest, and the aboveground biomass of the alfalfa elymus and old mans wheat combination was smaller;

When the combination of four species was planted, the aboveground biomass of the four species was not as high as that of one or two plants.

The screening results are shown in Figure 2, which shows that due to the large biomass and fast growth of oats, alfalfa can fix nitrogen and increase soil nitrogen, while old awn wheat and Elymus can survive, but their biomass is small, so they are not suitable for growing in velvet. Therefore, it is more appropriate to choose the combination of alfalfa and oats for the establishment of artificial grassland in Rongqu slag field.

Further, the analysis of nutrient element content of oat and alfalfa leaves with different soil thickness and anti-seepage measures. The total nitrogen, total carbon and total phosphorus content of oats increased with the increase of soil cover thickness, but there was no significant difference.

The total nitrogen, total carbon and total phosphorus content of alfalfa leaves increased with the increase of soil cover thickness, but there was no significant difference. The total nitrogen content of alfalfa leaves was significantly higher than that of oat leaves, because alfalfa was a nitrogen-fixing plant, so the total nitrogen content of leaves was higher.

To sum up, the combination of oats and alfalfa can be used for the establishment of artificial grassland in the Rongqu slag field. Although the vegetation can be restored by covering 10cm of soil, the aboveground biomass is low. By analyzing the change trend of soil water content, it is suggested that the thickness of the artificial grassland in the slag field should be 20cm-30cm, which can ensure the normal growth of herbaceous plants, and take anti-seepage measures, which is conducive to ensuring the better growth of plants.

The specific restoration measures for this dry warm valley grassland are given below

1) Artificial grass planting

A site preparation

In the leveled slag yard, choose a film of 0.05-0.07mm for bedding. The covering of the film is conducive to maintaining soil moisture and preventing water seepage and loss from the gaps in the debris. The 0.05-0.07mm film can gradually degrade over time without polluting the environment.

B covered with soil

The soil cover thickness is 20-30cm. The thickness of the soil layer determines the water holding capacity of the soil. The thickness of the 20-30cm soil layer can maintain the soil water content and ensure the survival of plants in the case of large evaporation in dry and warm valleys.

C soil improvement

Add 1000-1300kg/mu of cattle and sheep manure to improve the soil. Cattle and sheep manure is an organic fertilizer, which can improve the soil texture and provide effective nutrients for plant growth, which is beneficial to plant growth.

D artificial grass planting

The planted seeds meet the national seed classification standards, the purity and clarity are not less than 95%, the germination rate is not less than 90%, and the seeds are not allowed to carry quarantine objects. Oats grow fast, have large biomass, and can bear fruit, which is conducive to increasing the income of local herdsmen; alfalfa is a leguminous plant that can fix nitrogen by itself and improve the soil, and alfalfa has a relatively high feed value; the mixture of the two plants is conducive to improving Vegetation restoration efficiency and increased income of local pastoralists.

E sowing depth

In view of the severe spring drought in Tibet, easy to lose moisture, and difficult to protect seedlings, it is necessary to adopt measures to protect seedlings that are deeply planted and simple. For the improved soil, dig a trench with a depth of 10-15cm and a width of 10-15cm. Choose oat and alfalfa seed mixed sowing ratio 0.8:1.2～1:1; 10～13kg/mu for furrow sowing.

F Field Management

After sowing, level the ground and then irrigate.

Irrigate oats at the three-leaf stage, five-to-six-leaf stage (the time is about 15 days after the three-leaf stage), late jointing stage to flowering stage and milk ripening stage, which is the guarantee of high oat yield.

In dry and warm valleys, due to the large amount of evaporation and less rainfall from May to August, the frequency of irrigation should be increased, irrigated once every 10 days. At the same time, prevent excessive soil moisture, causing oats to lodging.

Embodiment 2 Dry and warm valley through fruit forest vegetation recovery

In view of the ecological conditions of dry and warm valleys, walnuts were selected for the planting of simulated slag field fruit trees, and the selection of walnut fruit tree planting models was carried out through simulated slag field scenarios, anti-seepage treatment, soil thickness treatment and restoration effect monitoring:

Lay a mixture of gravel with a thickness of 30cm-40cm and a diameter of 10cm-40cm in the planting hole to simulate the scene of the slag field; the thickness of the covering soil in the planting hole is 50-60cm, 70-80cm and 90-100cm respectively and anti-seepage treatment; add 4-5kg of cow manure .m ^-2 holes were used for soil improvement; walnuts with a tree diameter of 3 cm to 4 cm were selected for planting, and the roots of the walnut trees were soaked in 100 mg.kg ^-1 rooting powder solution; 10 walnut saplings were planted for each treatment, and the soil moisture and plant survival rate were monitored at the same time.

Different cover soil thicknesses and with or without anti-seepage measures walnut sapling survival rate as shown in Figure 3, different cover soil thicknesses and with or without anti-seepage measures soil volume water content as shown in Figure 4; This is because the location of the Rongqu slag field is a dry and warm valley with high temperature and strong sunshine, so the soil water evaporates quickly, resulting in low surface soil volumetric water content;

There is a big difference in the soil volumetric water content with the anti-seepage layer and without the anti-seepage layer. In the treatment without the anti-seepage layer (60cm-CK, 80cm-CK), the soil volumetric water content is at the soil depth of 60cm and 80cm It is similar to the volume water content at 15cm of the soil, which may be due to the fact that the bottom is all slag and has poor water retention, so the volume water content in the soil is low, and the water content will change greatly with time;

In the treatment with anti-seepage layer (60cm-FS, 80cm-FS), there is no big difference in soil water content at the soil depth of 60cm and 80cm, indicating that the water retention of the soil is maintained. There was no significant difference in soil volume water content between infiltration measures.

In summary, according to the survival rate of walnut saplings, the change of soil volume water content and the economic cost of covering soil thickness, it is recommended that the covering soil thickness be 70-80 cm in the process of planting walnut fruit forests in slag yards, and certain anti-seepage measures should be taken at the same time (via The fruit forest is planted by laying film anti-seepage in the planting hole, and the covering soil is 80cm), which can maintain soil moisture and nutrients. According to the monitoring of soil moisture, in the dry and warm valley climate, pay attention to irrigation in winter and spring, and irrigate once a week, which is conducive to the survival of fruit trees.

Embodiment 3 sub-alpine vegetation recovery

Vegetation restoration is carried out in the alpine/subalpine region (Wushan 1# soil field area, which belongs to the Three Parallel Rivers area in the west of Hengduan Mountains) ecological environment has characteristics of sensitivity, fragility, and variability. The area where the Rumei dam site is located has a deep valley, and the climate and ecological environment of the valley and the mountain tops on both sides are very different. The local soil resources are scarce, especially the cultivated land resources are very precious.

By simulating excavation, artificial grass planting, tree and shrub transplanting, nutrient control, field monitoring and other test methods, the present invention explores artificial grass planting and its ratio matching, placement technology of gravel to promote plant growth, and optimal topsoil coverage thickness The scheme, the transplantation and maintenance methods of trees and shrubs, and the transplantation of Miscanthus turf are described below.

3.1) Screening of Elymus chinensis, old awn wheat and alfalfa as artificial grassland construction plant species

According to the biomass of the grass species after trial planting shown in Table 1, and analyzed from the perspectives of existing biomass and grazing tolerance, it is recommended that the 1# soil material field of Laoshan Mountain should choose Elymus pachycarpa and old awn wheat It is more suitable as a single sowing grass seed.

Table 1 Biomass of sowing methods of different grass species

If it is necessary to comprehensively consider the nitrogen fixation effect of leguminous plants in the later stage of ecological restoration, it is recommended to choose Elymus echinensis, old awn wheat and alfalfa mixed sowing; According to separate statistics, the existing aboveground biomass is about 245g/m ² . When choosing grass species, a certain amount of grazing resistance is considered, and the above combinations are strong in grazing resistance.

3.2) Optimizing the best plan for the growth of artificial grass under different topsoil cover thicknesses

Covering the topsoil with a thickness of 30 cm is a more favorable and more profitable recovery method for the growth of mixed grass seeds. This program can make the canopy biomass, root system 0-25 cm and root system 25-50 cm reach 111.47, 139.47 and 51.87 g/ m ² ; while in 2016 they reached 86.67, 99.53, and 27.07g/m ² respectively (as shown in Table 2).

Table 2 Effect of sieving topsoil thickness (including gravel ratio) on the biomass of mixed grass seeds

Note: Different lowercase letters represent significant differences (P=0.05)

Table 3 The effect of sieving topsoil thickness (gravel ratio) on the biomass of alfalfa

Note: Different lowercase letters represent significant differences (P=0.05)

Covering the topsoil with a thickness of 50 cm is a more favorable and cost-effective recovery method for alfalfa growth. This program can make the canopy biomass, root system 0-25 cm and root system 25-50 cm reach 16.53, 44.80 and 19.20 g/m2 in 2015, respectively , and reached 61.33, 104.73, and 26.73g/m2 respectively in 2016 (as shown in Table 3).

Covering the topsoil with a thickness of 40cm is a more favorable and cost-effective restoration method for the growth of Elymus tachycarpa. This scheme can make the canopy biomass, root system 0-25cm and root system 25-50cm reach 62.93, 125.33 and 33.33g/m respectively ² (as shown in Table 3).

Table 3 The effect of unscreened topsoil thickness (gravel ratio) on the biomass of Elymus tachycarpa

Note: Different lowercase letters represent significant differences (P=0.05)

Generally speaking, the thickness of topsoil is too thin and the proportion of gravel is large, which is good for heat preservation in winter, but not good for water retention; the topsoil is too thick and lacks the heat preservation effect of gravel, so the soil temperature is low in winter, but the porosity of the soil layer is small, which is good for water retention.

Soil cover thickness had no significant effect on 0-10cm soil pH, organic matter and total nitrogen. The thinner topsoil cover (20-30cm) in the alfalfa sample plot has higher soil total phosphorus and available phosphorus content, while the highest value of soil total phosphorus and organic phosphorus is located in the deep topsoil cover (40-50cm) where mixed grass seeds are planted. Look like. The highest value of available nitrogen was located in the plot covered with 20cm topsoil planted with alfalfa, which may be related to the certain nitrogen fixation ability of leguminous plants. The contents of total nitrogen, available phosphorus and available nitrogen in the subsoil (10-20cm) were not significantly different among different species and topsoil thickness, while the highest value of total phosphorus was located in the plot covered with alfalfa 30cm topsoil.

A low level of compound fertilizer (20g/m ² ) can effectively improve soil nutrient content.

3.3) Soil gravel placement technology to promote plant root growth

In the subalpine region of Mount Lau 1#, placing gravel in the surface layer (0-10cm), middle layer (20-30cm) and lower layer (40-50cm) will significantly promote the growth of plant roots in this layer. Compared with gravel placed in the lower layer, gravel placed on the surface can increase the total biomass by 76-100% (2015) and 43-61% (2016). What is interesting is that the plant root system shows the characteristics of "wrapped" gravel growth (as shown in Figure 5-1 and Figure 5-2). Due to the low precipitation and strong evaporation in this area, the water in the soil is not easy to preserve. The gravel in the soil has certain pores and has a certain water absorption performance, which plays a role in preserving water. Therefore, the existence of the gravel layer is conducive to the growth of plant roots. This promotion effect is more obvious when the gravel is placed in the surface and middle plots.

Covering the soil surface with gravel is also beneficial to heat preservation in winter, and the average temperature can be increased by 4°C (as shown in Figure 6-1 and Figure 6-2). In addition, the level of gravel placement has a significant impact on soil fertility, and gravel covering the soil surface is conducive to maintaining soil fertility and preventing fertilizer from being washed away by rain.

Therefore, in the vegetation restoration test of the Laoshan 1# soil material field, a certain proportion of gravel was properly mixed into the recovered topsoil, especially if the gravel was placed on the soil surface, it was beneficial to the growth of plant roots. In addition, studies have found that the gravel covering the surface can intercept snowfall and reduce soil evaporation (the amount of evaporation is small due to the reduction of snowfall, which is good for heat preservation), which is conducive to the germination and greening of plants in spring (the effect of temperature is greater than that of water when herbs overwinter in subalpine mountains. greater coincidence, as shown in Figure 7-1, Figure 7-2, and Figure 7-3).

3.4) Optimizing the plan of artificial pasture growth under different topsoil cover thicknesses on slopes

The topsoil cover thickness of 30cm and 40cm is the restoration method with the highest ecological benefit for the old awn wheat. This scheme can make the canopy biomass, root biomass and total biomass reach the highest. Considering the cost of topsoil covering, it is recommended to cover the slope with a thickness of 30cm.

3.5) Miscanthus turf transplantation and maintenance techniques

After a year of observation, it was found that the seeds of Miscanthus spp. were difficult to germinate. It can be concluded that Miscanthus spp. does not reproduce by seeds, but by root tillers. It is suggested that Miscanthus spp. should focus on the overall protection of the turf. The turf of Miscanthus turf protected in situ can basically survive. However, due to changes in environmental factors such as altitude, terrain, and climate in ex-situ conservation, after maintenance, there is still a small part of the mortality rate, and most turf can survive.

3.6) Spruce planting in different places

One is the field test, the survival rate is more than 90%. The second is that the street trees from Mangkang County to Rumei Town have chosen spruce, the overall survival rate is relatively high, and the growth is good;

After two growing seasons of maintenance, the survival rate of spruce species is close to 100%, which shows that spruce, as a local native species, has a strong ability to adapt to the environment and is an ideal tree for vegetation restoration in the future.

Transplantation methods and techniques of juniper and alpine oak

The transplanted area was transplanted in the subsoil (simulated borrow pit), and the survival rate of backfilling topsoil and backfilling subsoil was low. Juniper has been observed for two growing seasons, less than 10%. The survival rate of Alpine oak transplantation is less than 50%.

Embodiment 4 sub-alpine vegetation restoration comprises the following operations:

1) Artificial grassland establishment

A site preparation

Before sowing in spring, cover the surface layer of guest soil in the area without topsoil: if the artificial grassland is a mixed grass seed (mixed with Elymus and alfalfa at a mass ratio of 1:1, or at a ratio of 1:1 of old awn wheat and alfalfa ), the thickness of the covering soil layer on the bottom surface of the grassland is 30cm; if the artificial grassland is single-sowed Elymus pachycarpa, the thickness of the covering soil layer on the bottom surface of the grassland is 40cm; if the artificial grassland is single-sowing alfalfa, the thickness of the covering soil layer 50cm; if the artificial grass is unicast old awn wheat on the slope, the thickness of the covering soil layer is 30cm;

After the covering soil layer is overturned, rake and level it. After site preparation, apply compound fertilizer 30g/m ² , and the ratio of nitrogen, phosphorus and potassium in the compound fertilizer is 1:0.5:1.5; use manual or agricultural machinery to fully mix the soil and fertilizer, and rake the soil finely.

Irrigation before sowing is the key to the germination, growth and survival of Elymus chinensis seeds. On the basis of plowing the ground in spring, furrows and ridges were constructed for irrigation. Irrigation before sowing must improve the irrigation technology, ensure the quality of irrigation water, prevent leaking irrigation and water accumulation in depressions, so as not to affect the sowing period.

B sowing

The suitable sowing period is from May 1st to May 30th. Utilize machinery or human and animal power to ditch and drill, row spacing: 20-30cm, artificially spread evenly, seeding rate: 300kg/hm ² .

In view of the severe spring drought, difficulty in moisture conservation and seedling preservation in the dry and warm valleys of Tibet, it is necessary to adopt deep planting and shallow seedling preservation measures, and the suitable sowing depth is 3-5cm.

After sowing, it is necessary to suppress in time, so that it can be suppressed on the same day of sowing to prevent moisture loss. After sowing, covering the mulch can play a role in heat preservation and water retention. The film is surrounded by stones and soil compaction to avoid being blown away by the wind until the seedlings emerge. After emergence, the mulch can be uncovered. After sowing, cover the gravel with a particle size of 5 to 10 cm, which can play a role in heat preservation and water retention until the seedlings emerge. After emergence, the gravel remains.

C Field management

The seedling stage of Elymus chinensis grows slowly. In the year of sowing, attention should be paid to removing impurities and prohibiting grazing. Within one month after emergence, water once a week to ensure the growth of Elymus chinensis. Later irrigation can be watered according to the actual rainfall situation, and if drought is found, it should be irrigated 1 to 2 times in time, and at the same time prevent excessive soil moisture, causing the Elymus acarina to fall.

2) Spruce planting

A site preparation

Except when the soil freezes in winter, the land can be prepared in other seasons (where there is little rainfall and drought in winter and spring, the land preparation must be carried out before the rainy season). For spring cultivation, the soil should be prepared before the rainy season of the previous year, and the soil should be prepared in the autumn of the previous year at the latest. On the mature cultivated land with deep and fertile soil and the newly harvested land with moist soil and low weed coverage, it is not necessary to prepare the land in advance, and plant it as it is prepared.

Artificial pits and horizontal trenches are used for windy, low rainfall, broken terrain, medium-thick soil layers, and no water accumulation. The specifications are width × depth: 50cm × 30cm, and the plant spacing is determined according to the cultivation density. The planting density should be determined according to the local site conditions and business value orientation, generally 3330 plants/hm ² to 5000 plants hm ² .

Cultivation

To keep the root system moist, the seedlings are transported to the cultivation site and loaded into barrels, and the seedlings are planted in the barrels for cultivation.

During transportation, avoid heavy pressure and sun exposure, pay attention to moisturizing and prevent covering (use triangular support to prevent heavy pressure, and set up non-woven fabric cover for sun protection, strengthen initial watering management and pay attention to moisturizing).

False plant on the spot, put it into a seedling bucket before planting (inject the water soaked in the roots of the seedlings or dip it in a water-retaining agent, the water-retaining agent is Aisen water-retaining agent), and carry the bucket for cultivation.

The planting time is preferably when the soil thawing depth reaches or exceeds the root length of the seedlings by 20cm to 25cm, and it is generally carried out at the end of April and the beginning of May. When pruning injured roots, abnormally developed partial roots, excessively long main roots and lateral roots. Dip the root system in a thin and suitable mud or water retaining agent.

Open the slit upright at the seedling setting point, push forward and pull back repeatedly with the shovel inserted, and the slit width is about 3cm to 5cm. Deep feeding and shallow lifting, stretching the root system (1cm to 2cm in the depth of the buried foundation), stepping on the seedlings. Shovel down vertically about 5cm away from the seedlings, first pull and then push, squeeze the roots of the seedlings, repeat once, and finally half of the shovel blocks the shovel gap. The surface of the hole is leveled, and the thickness of the covering surface is 25cm. Within a week of the end of the cultivation, the seedlings will be stepped on, and the seedlings will be replanted and stepped on again after thawing in the spring of the next year.

C management

Due to the slow growth of spruce seedlings, regular impurity removal management is required every year. Except for the weeds about 5cm around the root system of the seedlings, all the rest are cut off, and the cut grasses and shrubs are cleared out of the woodland.

In the present invention, through the exploration of artificial grass planting and its ratio matching, the placement technology of gravel to promote plant growth, the optimal plan of surface soil covering thickness, the transplantation and maintenance of trees and shrubs, and the transplantation of Miscanthus turf, etc., through three consecutive years Continuous monitoring has established a good vegetation recovery plan: after two growing seasons of conservation, the survival rate of spruce species is close to 100%.

Embodiment 5 alpine vegetation recovery

Specifically, Mount Lawu is used for illustration; it is located on the west side of Mangkang County, about 7Km away from Mangkang County in a straight line, longitude: 98.5234669°, latitude: 29.7027983°. The main climate characteristics of this area are high altitude, large temperature difference, low precipitation, and large evaporation. Vegetation restoration needs to overcome high altitude, low precipitation, large temperature difference and other problems. In addition, the region is an ecologically fragile area, the stability of the ecosystem structure is poor, and the self-repair ability is weak. Once the ecosystem degrades, it is difficult to recover.

In view of the destruction of the original vegetation in the high-altitude area of the plateau with an altitude of about 4000m or more, due to the fragile ecosystem, the self-recovery ability is low, and there is no seed bank in the soil. At the same time, through continuous observation, it was found that after the topsoil in this area was stripped, pioneer species rarely appeared, and only a few Artemisia plants and 1 bluegrass plant appeared in 3 years. Therefore, it is difficult to restore ecological functions in a short period of time by establishing a species framework through the establishment of pioneer species, so the restoration of vegetation in this area requires manual intervention.

Vegetation replanting mainly refers to stripping the turf in the original area and transplanting the shrubs. After the area is used, the turf and shrubs are transplanted back to the original area; the replanting is to repurchase vegetation species to restore the vegetation in the disturbed area. Replanting makes full use of the tree and grass species resources in the original area, but the transplanting site needs to be considered. It is difficult to guarantee the survival rate of multiple transplants in alpine regions; the transplanting site does not need to be considered for planting, but the protection of the original vegetation is not enough, and the planting needs to be considered Vegetation purchase, transportation and other expenses.

The following is an explanation of the vegetation restoration and model of the soil material field in Laowu Mountain.

5.1) Artificial grassland establishment and overwintering

By selecting the artificial grassland, planting it for one year (as shown in Figure 8), and experiencing nearly 6 months of winter exercise (if it has not passed the winter test, it is not clear whether it will survive the second year, and the long-term recovery effect cannot be evaluated), The results show that alfalfa and oats without awns are not suitable for the area at an altitude of about 4200m. They grow well in the first year, but after a winter, they fail to survive and turn green in the second year; oats without awns are annual grasses, although they grow well. But it is not suitable for long-term restoration of borrow pits (annual is not suitable for long-term).

Elymus and old manswort are more suitable for growth in areas around 4200m above sea level. Both Elymus and old manswort belong to the genus Elymus. It can safely survive the winter in areas with ℃ ℃, and the growth period is 4-5 years, so it can grow better in this area.

Tall fescue, red fescue, ryegrass and bluegrass mixed grass species did not turn green and survive the second year after a winter of hardening. But take certain measures to keep warm—that is, cover with a layer of straw, and these kinds of grasses can grow better in the coming year.

Therefore, the selected species that are suitable for this area are Elymus chinensis and Old Miscanthus, and their classification is shown in Table 1.

Table 1 Species suitable for vegetation restoration in Wulashan

Species Chinese name old awn wheat Elymus Species Latin name Elymus sibiricus Linn Elymus nutans Griseb. boundary plant kingdom plant kingdom Door Angiosperm Angiosperm outlining Monocots Monocots head Gramineae Gramineae division Poaceae Poaceae Subfamily Poaaceae Poaaceae family wheat family wheat family belongs to Elymus Elymus

5.2) Sod layer stripping, maintenance and replanting technology

Soil improvement in the disturbed area: clear the construction waste in the backfilled area before backfilling the topsoil, fill the pits and fill in the depressions for ground repair, and after the repair is completed, the slope is generally covered with artificial soil with a thickness of 10-20cm, and the flat area is covered with mechanical soil with a thickness of 30cm.

Part of the turf stripped from the soil material field was replanted on the soil in the improved disturbed area (with organic fertilizer 2kg/m ² ) or chemical fertilizer (30g/m ² ) or no treatment, and part was still stacked in the stacking area.

After stripping and replanting in July 2015, after nearly a year of maintenance, especially after 6 months of winter (November to April) exercise, it was observed in June 2016 that the turf had basically turned green survive.

In the process of stripping and replanting, we noticed the correlation between the size and thickness of alpine meadow turf blocks when cutting and the survival, and proposed that the longest side of the cutting area should not be greater than 50cm, and the shortest side should not be less than 25cm, so as to prevent the blocks from being too small Cutting off the plant root system will cause the turf to die, and too large is not conducive to handling and affects the viability of the turf; therefore, the size and thickness of the alpine meadow turf should be paid attention to when cutting.

The present invention proposes the following implementation methods of turf block cutting: the side length of the turf block is controlled between 30cm and 50cm. According to the results of repeated tests, the block can be basically controlled according to the above side length during excavation, and the hoe can be manually used to divide the block. Blocks and blocks do not need to be very specific.

At the same time, the turf blocks should not be stacked on top of each other, so as to avoid the death of the turf due to the lack of air between the turf blocks and the turf blocks due to untimely watering.

When replanting and stacking, pay attention to the complete contact between the bottom and the soil: carry out site preparation, trim the terrain, cover the soil field level, and fill the grass gaps with humus; lightly pat the turf to prevent warping and bulging. When planting and stacking, the bottom is in full contact with the soil. In this way, the turf blocks can survive the winter exercise and completely turn green. The specific replanting adopts machinery, manual transportation, and manual replanting, and the funds come from the estimated budget of soil and water conservation to ensure the replanting work.

5.3) Artificial grassland establishment

Grass species selection for artificial grassland, alfalfa, awnless oats, elymus, old awn wheat, tall fescue, red fescue, ryegrass and bluegrass mixed grass species were selected, planted for 1 year and experienced nearly 6 months winter workout.

The results showed that alfalfa and awnless oats were not suitable for the area around 4200m above sea level. They grew well in the first year, but failed to survive and turn green in the second year after a winter. This may be due to the fact that the optimum temperature for the growth of alfalfa is 15-25°C. Above 30°C, the growth slows down or rest grazing occurs. Below 5°C, the growth of the shoot stagnates, and below -2.2°C, the aboveground part dies. In the Mount Lau area, the winter temperature is significantly lower than -2.2°C; from December to early March, the soil surface temperature is between -0.05°C and 2.53°C, and the water content is also very low, indicating that the soil is very dry. Therefore, even if certain heat preservation measures (covering with straw) are taken, they cannot survive and grow.

Although awnless oats are annual grasses, although they grow well, they are not suitable for long-term restoration of borrow pits. Elymus and old awn wheat are more suitable for growing in areas with an altitude of about 4200m. This may be due to the fact that Elymus and old manswheat belong to the genus Elymus and are dry grasses with wide adaptability, special cold resistance and drought resistance, and can safely survive the winter in areas with a temperature of -41°C in winter. The growth period is 4-5 years. Therefore, it can grow well in this area.

Tall fescue, red fescue, ryegrass and bluegrass mixed grass species did not turn green and survive the second year after a winter of hardening. But take certain measures to keep warm—that is, cover with a layer of straw (the plants have withered in winter, and the covering is mainly for heat preservation to ensure that they can turn green in the second year), and these types of grasses can grow better in the coming year.

According to the one-year observation and analysis of the succession of plant communities, the altitude of the Laoshan test site is about 4200m, and the species of Elymus, old awn wheat, alfalfa, awnless oats, tall fescue, red fescue, and ryegrass were selected. Mixed grass species with bluegrass and other grass species. The results show that Elymus and old awn wheat are suitable for planting in Mount Lauu area; but alfalfa and awnless oats are not suitable; tall fescue, black fescue, ryegrass and bluegrass mixed grass species will not survive the winter if there is no overwintering measures. In the coming year, it will not be able to turn green and survive.

After more than a year of growth, the old awn wheat and Elymus pranicum in the experimental area of the Laowu mountain soil material field are growing well, and the plant height can reach about 80-90cm; It needs to be replanted the following year; alfalfa is almost impossible to survive.

Therefore, it is advisable to choose Elymus and awnless oats for the establishment of artificial grassland in the soil material field of Laowu Mountain. However, from an economic point of view, it is recommended to choose Elymus.

5.4) Effects of grass seed density and fertilization on the biomass of Elymus spp.

Through the analysis of density and fertilization and their interaction, it was found that both density and fertilization had a significant impact on biomass. Density tests of 30g/m ² , 40g/m ² and 50g/m ² were carried out, and it was found that the aboveground biomass of 30g/m ² planting density was significantly greater than that of other densities under any fertilization conditions. Except for the underground biomass with a density of 30g/ ^m2 being significantly greater than that at other densities when farmyard manure was added, there was no significant difference in the underground biomass at other densities or under other fertilization conditions; the results are shown in Figure 9 Show.

The results are inconsistent with the theoretical assumptions. It is generally believed that the theoretical seeding rate is the optimum density, that is, the high yield can be achieved at 40g/m ² . However, the test results found that the aboveground biomass and underground biomass (under the condition of farmyard manure) with a low density of 30g/m ² were the highest, while there was no significant difference between the aboveground biomass and underground biomass of 40g/m ² and 50g/m ² . This shows that the theoretical sowing rate of 40g/ ^m2 is not the optimum density in this area, but the sowing density is too high, which makes the average resource space occupied by each individual plant small, hinders the individual growth, and fails to obtain the expected higher biomass. Therefore the present invention thinks that 30g/m ² is optimum sowing density

In the first year of fertilization, farmyard manure or compound fertilizer can significantly increase the aboveground biomass, but only the application of farmyard manure showed higher belowground biomass. Alkaline nitrogen after application of farmyard manure and compound fertilizer was significantly higher than that of no fertilization, while available phosphorus was significantly higher after application of compound fertilizer than that of farmyard manure and no fertilization.

In the second year of fertilization, compound fertilizer or farmyard manure made the biomass of Elymus (including aboveground biomass, underground biomass, total biomass and root-to-shoot ratio) significantly higher than that of no fertilization, and the effect of compound fertilizer on biomass was obvious higher than farmyard manure.

Embodiment 6 alpine vegetation restoration comprises the following operations:

6.1) Stripping, stacking and replanting of alpine meadow turf

A sod stripping

The thickness of the original turf (including the root system) needs to be about 15-30cm, and the thickness of the lower humus soil needs to be about 10-20cm, so as to meet the stripping conditions. Attention should be paid to the selection of seasons for stripping. Try to choose a season with abundant rainfall and humid climate, generally between June and August every year. In this season, the alpine meadow is in the growth period, and the plants have strong vitality. At the same time, the climate Warm, moist, plants are easy to survive.

The turf and humus within the disturbed area are manually stripped by machinery. In order to facilitate transportation and storage, the stripped turf should be divided into blocks, and the side length should be controlled between 30cm and 50cm to prevent the root system from being cut off by too small a block. Sod dies. After the turf is stripped, the humus soil in the lower layer is very important for the survival of the turf replanting, and it should be stacked together for use when replanting the turf.

B. Temporary stacking of turf

Flat storage: If the stacking space is relatively ample, it can be stored flat. When storing, the humus soil is stacked in the lower part, the thickness of the stack is 30-40cm, and the turf is laid on the upper part in a single layer, leaving a space of 3-5cm between the turf and covering the space with humus, which is convenient for turf growth and later transplantation.

Stacked storage: If the stacking space is limited and the construction time is short, and the storage time of the stripped turf is basically not too long (no more than 3 months), you can choose to stack it. Stacked storage has a certain impact on the turf, but if the management and protection are strengthened after transplanting, the vegetation can still be restored in a relatively short period of time after re-laying. When stacking and storing turf, the lower part is piled with humus, and the turf is stacked on the surface layer by layer (3 to 5 layers can be stacked). When stacking and storing, a certain cross space should be left for ventilation and water seepage. The height of the humus mound is 1.0-1.5m. The turf storage area is protected by a meadow block retaining wall, which adopts a trapezoidal section, and the meadow block is stacked.

C Temporary stacking and maintenance of turf

When the turf is temporarily stored, try to choose the leeward side and flat terrain. If possible, the surface of the turf can be covered with a windproof and breathable dense mesh to prevent the strong wind from taking away the stored moisture and ensure the survival of the turf. The surface of the topsoil pile is fully covered with rainproof cloth to avoid wind blowing sand. Sprinkle water in the temporary storage area of turf to keep the soil moist and ensure the water demand of the turf. At the same time, the temporary storage area of turf should be set in a higher area. If there is no condition, a ditch should be set up around the storage area to drain excess precipitation during heavy rains in time to avoid turf rot and death due to long-term submersion.

D turf replanting

Before the disturbance of the soil material, the topsoil needs to be stripped. The organic soil comes from the topsoil stripped in the previous stage, and the gravel is covered to prevent 10cm below the topsoil, and the gap is backfilled with soil. When replanting the turf, first backfill the organic soil layer and ensure smooth replanting so that the roots of the turf are seamlessly connected with the soil;

After the turf is replanted, the gaps in the grass are filled with humus; both replanting and caulking are manual operations, and the turf can be gently patted to prevent warping and bulging.

E turf maintenance after replanting

According to the actual environmental conditions and the seasonal needs of the replanted turf growth and development, fertilization, watering and maintenance should be carried out in a timely manner (fertilization is once a quarter on average, and the number of watering is variable according to the weather of the year, and the average is once a month. Fertilization amount: compound fertilizer The dosage is 500kg/hm ² , the organic fertilizer is 20000kg/hm ² . The water consumption is 3m ³ /100m ² .) to meet the needs of vegetation for nutrition and water. The replanted turf is relatively fragile, and it will take a while to combine with the underlying soil. Therefore, within 10 days after the turf is replanted, try to minimize artificial or external disturbance to the replanted turf area, and the area with poor turf recovery should be extended accordingly maintenance period to restore growth. After the turf is replanted, the humus soil sprinkled on the lower native vegetation should be removed in time to restore its original growth environment and prompt it to turn green in time.

Overwintering with non-woven thatch cover insulation.

6.2) Artificial grassland establishment

A site preparation

After stripping the surface soil, according to the slope of the terrain, adopt the block land preparation method, use machinery to plow, loosen the soil, and then use nail-toothed rakes to level the land. Rake to a depth of 4-10cm, apply farmyard manure, break up soil clods, level the ground, bury the fertilizer, and blend the soil and fertilizer. Combining with plowed land, apply farmyard manure (cow manure or sheep manure) 2kg/m ² , spread evenly and then prepare the land once, plow to a depth of 18-20cm to fully mix the soil and fertilizer, and rake the soil finely.

B planting

Unicast or Mixed. The main choice is Elymus pachycarpa, and it can also be mixed with grass species such as old awn wheat. According to the actual situation, scientifically and reasonably match the mixing ratio (grass seeds are mixed according to 1:1, and then sowed after mixing, the amount of seeds used is 200-300kg/hm ² ). The suitable sowing period is from late May to early June. Drill sowing or sowing is mainly based on drill sowing, using machinery or manpower to open trenches, with a row spacing of 15cm to 20cm, artificial evenly sowing, and a seeding rate of 300kg/hm ² . Compact immediately after sowing. In view of the characteristics of gravel on the ground and less soil in the study area, seedling preservation measures should be adopted (suitable sowing depth is 3-5cm), and the suitable sowing depth is 3-5cm. After sowing, it should be irrigated in time and watered thoroughly so that the seeds can fully contact with water, soil and fertilizer.

C Field management

Elymus is a perennial herbage, which grows slowly at the seedling stage. In the year of sowing, attention should be paid to prohibiting grazing.

The turf replanted or replanted by the present invention has good growth at present, and the survival rate is above 90%.

The above-mentioned embodiments are preferred examples for realizing the present invention, and the present invention is not limited to the above-mentioned embodiments. Any non-essential additions and substitutions made by those skilled in the art according to the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims (9)

1. A vegetation recovery method for high-altitude hydropower development areas is characterized by comprising the steps of dry and warm valley vegetation recovery, subalpine vegetation recovery and alpine meadow recovery which are suitable for different elevation gradients in the southeast of the Tibetan province, and specifically comprises the following operations:

1) Carrying out vegetation recovery on dry and warm valley with the altitude of 2000 to 3000m by adopting artificial grassland construction and fruit forest construction; wherein:

the artificial grassland construction comprises the following steps: leveling an area to be repaired, paving an agricultural film for anti-seepage treatment, then covering a soil layer with the thickness of 20-30cm, adding cattle and sheep manure for soil improvement, and performing furrow sowing in a deep-seed and shallow-seed mode by taking oat and/or alfalfa as grass seeds; irrigating in time after sowing;

the construction of the fruit forest comprises the following steps: digging a planting hole, paving an agricultural film at the bottom for seepage prevention, then covering soil with the thickness of 40-50cm, adding cow dung to improve the soil, covering the soil with the thickness of 30-40 cm, and finally paving an agricultural plastic film; before planting, soaking the root of the tree seedling in rooting powder solution or dipping the root in slurry, and spreading rooting powder on the root during planting; digging a pit for planting the nursery stock in the middle of the prepared pit, compacting while returning soil during planting, sowing alfalfa in a planting hole after covering soil, and then coating a film; building a soil ridge after planting, wherein the height of the soil ridge is 10-20cm higher than the ground level; irrigating and performing field management after planting;

2) Carrying out vegetation recovery by adopting arbor, bush and subalpine meadow in a subalpine area with the altitude of 3400-4000 m; wherein, the subalpine meadow area needs to cover surface covering soil with the thickness of 30 to 50cm, and the elymus nutans, the old awn wheat and/or the alfalfa grass are selected to be sown in a unicast mode or a mixed mode; deep seed shallow sowing is adopted during sowing, and the sowing depth is 3-5 cm; compacting the seeds on the same day of sowing, covering a mulching film after sowing, covering gravels with the particle size of 5-10 cm, wherein the area proportion of the gravels accounts for 40% of the surface soil, uncovering the mulching film after seedling emergence, watering in time and keeping the gravels;

transplanting or planting arbors/bushes, keeping the root systems of shrub seedlings and arbors seedlings to be transplanted wet, dipping the root systems with slurry or a water-retaining agent, filling the root systems into a seedling planting barrel, injecting water soaked with the roots of the seedlings into the seedling planting barrel, lifting the barrel, planting the seedlings and cultivating; after planting, flattening the surface of the planting hole, and covering the surface soil with the thickness of 20 to 25cm; within one week after the cultivation, the nursery stock is held and stepped;

3) The alpine meadow is in the alpine region of elevation more than 4000m, adopts the mode of turf transplantation or planting to carry out vegetation restoration, wherein:

the turf transplantation realizes vegetation restoration through turf stripping, stocking maintenance and replanting;

the planting is implemented by taking old awn wheat and elymus as vegetation recovery grass seeds and adopting an artificial grassland planting mode to carry out vegetation recovery;

when the turf is transplanted, the longest edge of the cutting area of the original turf is not more than 50cm, the shortest edge is not less than 25cm, and a certain space is reserved when the turf is transported and stacked; when the turf is replanted, firstly backfilling an organic soil layer, placing gravels under 10cm, and ensuring smooth replanting so that the root of the turf is seamlessly connected with soil; after the turf is replanted, filling and compacting the grass gaps with humus, and lightly compacting the turf; the original growing environment of the turf is recovered in time after the turf is replanted;

when the grassland is artificially built and planted, the surface soil is peeled off, the soil is prepared by adopting a block soil preparation mode, furrows are opened, the row spacing is kept between 15cm and 20cm, the grass seeds are sowed in a single way or in a mixed way, and deep seeds are shallow when the grass seeds are sowed in the furrows; compacting in time after sowing, and performing field management in time after sowing; the grass is covered after the grass leaves are withered and yellow.

2. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 1, wherein the construction of the artificial grassland in the dry and warm valley specifically comprises the following operations:

1) Land preparation: leveling the slag field, and paving an agricultural film with the thickness of 0.05-0.07 mm for anti-seepage treatment;

2) And (3) covering soil: covering soil on the film, wherein the covering thickness of the soil layer is 20-30 cm;

3) Soil improvement: adding cattle and sheep manure with the addition amount of 1000-1300 kg/mu to improve the soil;

4) Planting artificial grassland: the deep-planting and shallow-emergence furrow sowing mode is adopted, the seed purity and the purity are not lower than 95%, and the germination rate is not lower than 90%;

digging a ditch with the depth of 10-15 cm and the width of 10-15 cm during furrow sowing, and sowing oat and alfalfa in a mixed mode, wherein the mass ratio of the oat to the alfalfa is 0.8 to 1;

5) Leveling the land after sowing, and then irrigating;

irrigating water in the three-leaf stage, five-six-leaf stage, late jointing stage to flowering stage and milk stage of oat.

3. A vegetation recovery method in a high-altitude hydropower development area as claimed in claim 1, wherein the establishment of the dry and warm valley through fruit forests specifically comprises the following operations:

1) Land preparation: digging planting holes of 80cm multiplied by 80cm and row spacing of 3m multiplied by 3m in a leveled slag field;

2) Planting hole arrangement: laying an agricultural film with the thickness of 0.05mm at the bottom of the planting hole for seepage prevention, and covering soil with the thickness of 40-50 cm; adding 4-5 kg/hole of cow dung to improve soil, and covering 30-40 cm of soil; finally, a film with the thickness of 0.05-0.07 mm is used for covering;

3) Planting in a fruit forest: selecting walnut seedlings with the tree diameter of 3 cm-4 cm for planting in 2-3 months in the planting period; cutting out damaged and rotten root of seedling before field planting, and applying 100mg ^-1 Soaking ABT rooting powder solution for 1 day, or dipping the root with slurry; during planting, root-growing powder is scattered at the root;

then digging a pit in the middle of the prepared pit for field planting, and treading while returning soil during field planting to ensure that the seedlings are normal and root systems are stretched;

after covering soil, sowing alfalfa in the planting holes to prevent soil moisture from evaporating and increase nitrogen fixation effect, and then covering a film and preserving water;

then building a soil ridge which is 20cm higher than the ground level;

4) Management and fertilization: fertilizing four times before germination, after flower falling, in the hard core period of fruits in the last 7 months and before land freezing; mixing and applying animal manure and green manure with compound fertilizer, wherein 100-200 kg of animal manure or green manure is needed for each adult tree;

irrigation: irrigation is carried out in winter and spring, and irrigation is carried out once every two weeks.

4. The method for vegetation restoration in a high-altitude hydropower development area as claimed in claim 1, wherein the vegetation restoration in the subalpine meadow comprises the following operations:

a, soil preparation:

covering surface soil in a grassland planning area before sowing in spring, wherein the thickness is 30 to 50cm; after covering soil, turning over the soil, raking finely and dragging flatly; then applying compound fertilizer, fully mixing the soil and the fertilizer, and then raking, finely raking, ridging and ridging;

b, sowing:

the sowing period is 5 months and 1 day to 5 months and 30 days, ditching and drilling are carried out, and the row spacing is 20 to 30cm; unicasting or mixed sowing elymus nutans, old aweto and/or alfalfa seeds, wherein the sowing amount is 30 g/m; deep seed shallow sowing is adopted during sowing, and the sowing depth is 3-5 cm; compacting on the same day as sowing, covering a mulching film after sowing, and covering gravels with the particle size of 5-10 cm, wherein the area ratio of the gravels accounts for 40% of the surface soil; uncovering the mulching film after seedling emergence, and reserving gravels;

c, field management:

watering once a week within one month after seedling emergence; watering in the later period in combination with the actual rainfall condition.

5. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 4, wherein if the artificial grassland is a mixed-seeded grass seed, the thickness of the soil covering layer on the bottom surface of the grassland is 30cm;

if the artificial grassland is the unicast elymus nutans, the thickness of the soil layer covered on the bottom surface of the grassland is 40cm;

if the artificial grassland is the single-broadcast alfalfa, the thickness of the soil covering layer on the bottom surface of the grassland is 50cm;

if the artificial grassland is a slope unicast old awn wheat, the thickness of the covering soil layer is 30cm.

6. The method for recovering vegetation in a high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery of trees and shrubs in the sub-high mountain area comprises the following operations:

a, soil preparation:

preparing the soil before the premise of rainy season; the method is characterized in that the method is used for cultivating new cut lands with deep and fertile soil layers and wet soil and low weed coverage rate;

the cultivation density is 3330-5000 hm; the specification of the hole planting pits is 50cm multiplied by 30cm with the width multiplied by the depth, and the planting distance is determined according to the planting density;

b, cultivation:

keeping the root systems of shrub seedlings and arbor seedlings to be transplanted wet, and trimming injured root systems, abnormally developed partial roots, overlong main roots and lateral roots after the shrub seedlings and arbor seedlings are transported to a cultivation field; then dipping the root system with slurry or water-retaining agent, loading into a seedling planting barrel, injecting water soaked with the root into the seedling planting barrel, lifting the barrel, planting seedlings and cultivating;

the planting time is carried out at the end of 4 months and the beginning of 5 months, and the soil thawing depth reaches or exceeds the seedling root length by 20 cm-25 cm;

vertically slotting at a final singling point, repeatedly pushing and pulling an insertion spade, and enabling the width of a slot to be 3-5 cm; deep lifting and shallow lifting, stretching root systems, deeply burying the foundation at the diameter position of 1-2 cm, and treading for final singling; vertically lowering the spade 5cm away from the seedling, pulling and pushing the spade, compacting the seedling root, repeating the steps once, and finally blocking the spade seam by a half spade; leveling the cave surface, and covering the surface layer with the depth of 20-25 cm;

within one week after the cultivation, the seedlings are subjected to supporting treading, and after the seedlings are unfrozen in the spring of the next year, the seedlings are subjected to Miao Mufu planting and supporting treading again;

c, management:

and (4) carrying out impurity removal management every year at regular intervals, cutting off all the weeds except for keeping 5cm of weeds around the root system of the seedling, and cleaning the cut weeds to the outside of the forest land.

7. The method for recovering vegetation in the high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery of the alpine meadow adopts turf replanting and comprises the following operations:

a, peeling off turf:

the stripping time is 6-8 months per year, and stripping conditions are met when the original turf thickness and root system grow to 15-30 cm and the lower layer humus thickness is 10-20cm;

the peeled turf is divided into blocks, and the side length is controlled to be between 30cm and 50cm; after the turf is peeled off, collecting and stacking the lower-layer humus soil;

b, stacking the turf:

laying and storing: when the turf is stored, the humus soil is piled at the lower part, the piling thickness is 30-40 cm, the turf is flatly paved at the upper part in a single layer, 3-5 cm intervals are reserved among the turf, and the collected humus soil is covered among the intervals;

stacking and storing: when the greensward is stacked and stored, humus soil is stacked at the lower part, the greensward is stacked and stored in a shape of Chinese character 'pin' by 3-5 layers, and the height of the greensward and the humus soil is 1.0-1.5 m; the turf storage area is kept and protected by a meadow soil block retaining wall, the meadow soil block retaining wall is of a trapezoid cross section, and meadow soil blocks are stacked and placed;

c, stacking and maintaining turf:

selecting a leeward, high-terrain and flat section when the turf is temporarily stocked;

the surface of the surface soil pile is covered and shielded completely by waterproof cloth; sprinkling water in the temporary turf storage area to keep the soil moist;

d, turf replanting:

when the turf is replanted, firstly, an organic soil layer is backfilled, and the replanting is smooth, so that the root of the turf is seamlessly connected with the soil; after the turf is replanted, the grass gaps are tightly filled with humus soil, the turf is lightly compacted, and the raised corners and bulges are prevented;

e, maintaining the grass after replanting:

artificial or external force disturbance to the replanted turf area is reduced as much as possible within 10 days after the turf is replanted, and the maintenance period of the poorly restored turf area is prolonged correspondingly to enable the poorly restored turf area to restore the growth;

after the turf is replanted, the humus soil scattered on the lower native vegetation is removed in time, the original growth environment is restored, and the turf is promoted to turn green in time.

8. A method of vegetation restoration in a high altitude hydroelectric development area as claimed in claim 7 wherein the longest edge of the turf cutting area is no more than 50cm and the shortest edge is no less than 25cm during replanting; during excavation, basically controlling the block division according to the side length, controlling the side length to be 30cm to 50cm, and manually adopting a hoe for block division;

the stacking space is required to meet the requirement that the turf blocks are not overlapped to be stacked, and a distance of 10cm to 20cm is reserved;

the bottom of the turf is in full contact with the soil during replanting: after the land is replanted and prepared, the terrain is trimmed, the earth covering field is flat, and the grass gaps are tightly filled with humus; the turf is lightly compacted to prevent the upwarp and bulge, and the bottom is ensured to be completely contacted with the soil during replanting and stacking.

9. The method for recovering vegetation in the high-altitude hydropower development area as claimed in claim 1, wherein the vegetation recovery in the alpine meadow area is artificially established and comprises the following operations:

a, soil preparation:

stripping surface soil, ploughing by using a machine in a block soil preparation mode, loosening the soil, and leveling the soil by using a rake; harrowing the soil 4-10 cm deep, applying farmyard manure, crushing soil blocks, leveling the ground, burying the manure to enable the soil manure to be melted;

ploughing twice, applying farmyard manure of 2kg/m, uniformly spreading and then carrying out land preparation for 1 time, wherein the ploughing depth is 18-20 cm, so that the soil and the manure are fully mixed, and raking and harrowing the fine soil;

b, planting:

the sowing period is 5 late months to 6 early months, and the grass seeds are sowed in a single way or in a mixed way;

the sowing mode is broadcast sowing or drill sowing, ditching is carried out mechanically or manually, the row spacing is 15-20 cm, manual uniform sowing is carried out, the sowing quantity is 200-300kg/hm, deep sowing is shallow, the sowing depth is 3-5 cm, and timely compaction is carried out after sowing;

irrigating in time after sowing, and watering thoroughly to make seeds fully contact with water, soil and fertilizer;

c, field management:

the elymus nutans is perennial pasture, and the grazing should be forbidden in the current year of sowing.

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