Joe Walker

EPN6201R-991005 May 2000 EVALUATION GUIDELINES FOR ECOLOGICAL INDICATORS Edited by Laura E. Jackson Janis C. Kurtz William S. Fisher US Environmental Protection Agency Office of Research and Development Research Triangle Park, NC 2771 I @ Printed ...

Ecological Applications, 4(2), 1994, pp. 313-321 © 1994 by the Ecological Society of America REGIONAL-SCALE RELATIONSHIPS OF LEAF AREA INDEX TO SPECIFIC LEAF AREA AND LEAF NITROGEN CONTENT1 Lars L. Pierce and Steven W. Running School of Forestry, ...

This chapter looks at how indicators can be used to assess agricultural sustainability. Indicators are biophysical, economic and social attributes that can be measured and used to assess the condition and sustainability of the land from the farm to the regional level. Reliable indicators provide signals about the current status of natural resources and how they are likely to change. They can be used to confirm that current farming practices and land-use systems are effective in maintaining the resource base or economic status, identify problems and high- light potential risks. Indicators provide useful information for initiating change or deciding on future on-ground investments.

1. Succession is a key ecological process that underpins much ecological restoration. 2. Restoration is a practical implementation of succession concepts that in-volves operational and field management control to decide where, what, how, and when to apply management actions to restore ...

... produce five plots with 500 trees ha-1 (natural density), two with 125 ha-1, two with 25 ha-1 and four with zero ha-1, with ... (i) The point locations for all individuals in the woodland were expressed as cartesian coordinates, and a fixed grid of 1 mx 1 m elements superimposed over ...

ABSTRACT The sandmass at Cooloola comprises a series of overlapping aeolian dune systems that extend in age from the present back more than 100 000 years. Podzols are the dominant soils, forming a sequence from rudimentary through to giant forms, according to age. The lignotuber morphology of Eucalyptus signata and E. intermedia was examined within each dune system across the chronosequence, at sites in which most factors affecting plant growth (available soil water status, drainage, light, temperature, fire regimes, exposure to wind and/or salt spray) other than a declining soil nutrient supply were similar. Three lignotuber morphologies were identified: (1) a single-stemmed (SS) form; (2) a multi-stemmed (MS) form with stems originating from a lignotuber only slightly larger than a main stem; and (3) a multi-stemmed plate-like form (MSP) with individual stems separated and growing from a plate-like lignotuber. Multi-stemmed forms of the two eucalypts occur along the coastal margin and on the most nutrient- poor dunes; at all other sites single-stemmed forms are dominant. The most nutrient-poor site had only MS and MSP forms, whilst in sheltered areas the coastal margin had SS individuals. We conclude that in the Cooloola sandmass the development of multi-stemmed forms in both E. signata and E. intermedia may be induced by a variety of factors, including very low nutrient status, but the multi-stemmed plate-like form of E. intermedia is most likely a response to an exceptionally low nutrient supply.

ABSTRACT The crown-gap ratio C is defined as the mean distance between adjacent crowns divided by the mean crown diameter. Previous field studies have established that for a limited range of vegetation stands crown cover is related to C by a general function, viz. crown cover = k/(1 + C)2, where k is a constant. In the present study we investigated the general derivation of the function which relates crown cover to C. The function was then used to determine values for k, a range of point distributions being simulated from semi-regular to clumped, with mixtures of crown sizes.The relationship between crown cover and 1/(1 + C)2 was linear in all cases tested (R2= 1.0). The value of k was shown to depend on the sampling technique used, the degree of clumping, and the range in crown sizes permitted.The variation in k was reduced by using a specific sampling method and limiting the range of spatial distributions and crown sizes considered.The constraints imposed were:1Sampling followed a zig-zag transect (Delaunay two-sided model).2Point distributions were not overly clumped.3The range of crown diameters approximated a Gaussian distribution with a relative range of 1–4.Given these constraints the value of k was determined to be 0.806 with a variance of less than 2%. A table is given to convert values for C into crown cover percentages and, if required, to calculate foliage cover per cent.The constraints imposed are considered to be within conditions normally encountered in the field, making the use of C an accurate and simple method by which to estimate crown or foliage cover per cent.

To include competitive interactions in a physiologically-based model of mixed growth-form plant communities presents a major methodological problem. This paper outlines a two-step solution: (1) a spatial framework for calculating a continuous surface that depicts the magnitude of influences of crowns, roots, and stems on resource availability, termed ECOLOGICAL FIELD THEORY (EFT), and (2) a mathematical technique for coupling water, light, and nutrients into a single growth equation using a physiologically-based continuous-time Markov approach, termed the CTM METHOD. Assumptions, limitations, and an application of the methodology to plant growth in a semiarid woodland community in Australia are presented.

ABSTRACT Parna is a wind-blown clay, mobilised from inland Australia as the result of a series of intermittent high wind events during the Quaternary. Parna can be recognised on the basis of colour, texture, distributional patterns, and pedology. Parna deposits have been recorded across a wide area of south eastern Australia and have influenced the local pedology and hydrology. In some cases parna has increased soil sodicity and the potential for dryland salinisation. Predicting its spatial distribution is useful when considering agricultural potential and in assessing the risk and spatial spread of dryland salinity. Here we present the results of modelling to predict its local distribution in an area covering 291 km2 in the Young district of NSW. Two conceptual models of parna deposition and subsequent redistribution were used to develop a current parna distribution map: (a) deposition = f(topography, aspect) after assuming that interactions of rainfall, vegetation, and wind speed were relatively the same at the local scale; (b) removal or retention = f (slope angle, catchment size, slope length) as a representation of the erosive energy of gravity. Five landscape variables, elevation, aspect, slope, flow accumulation, and flow length, were derived from a 20 m digital elevation model (DEM). A training set of parna deposits was established using air photos and field survey from limited exposures in the Young district of NSW. These areas were digitised and converted to a grid of areas of parna and no-parna. This training set for parna and the 5 landscape variable grids were processed in the IDRISI for WINDOWS Geographic Information System (GIS). Spatial relationships between the parna and no-parna deposits and the 5 landscape variables were extracted from this training set. This information was imported into an inductive learning program called KnowledgeSEEKER. A decision tree was built by recursive partitioning of the data set using Chi-squares to categorise variables, and an F test for continuous variables to best replicate the training data classification of ‘parna’ and ‘no-parna’. The rules derived from this process were applied to the study area to predict the occurrence of parna in the broader landscape. Predictions were field checked and the rules adjusted until they best represented the occurrence of parna in the field. The final model showed predictions of parna deposits as follows: (i) higher elevations in the Young landscape were the dominant sites of parna deposits; (ii) thicker deposits of parna occurred on the windward south-west and north-west; (iii) thinner deposits occurred on the leeward side of a central ridge feature; (iv) because the training set concentrated around the major central ridge feature, poorer predictions were obtained on gently undulating country.

ABSTRACT Community awareness of the sustainable use of land, water and vegetation resources is increasing. The sustainable use of these resources is pivotal to sustainable farming systems. However, techniques for monitoring the sustainable management of these resources are poorly understood and untested. We propose a framework to benchmark and monitor resources in the grains industry. Eight steps are listed below to achieve these objectives: (i) define industry issues; (ii) identify the issues through growers, stakeholder and community consultation; (iii) identify indicators (measurable attributes, properties or characteristics) of sustainability through consultation with growers, stakeholders, experts and community members, relating to: crop productivity; resource maintenance/enhancement; biodiversity; economic viability; community viability; and institutional structure; (iv) develop and use selection criteria to select indicators that consider: responsiveness to change; ease of capture; community acceptance and involvement; interpretation; measurement error; stability, frequency and cost of measurement; spatial scale issues; and mapping capability in space and through time. The appropriateness of indicators can be evaluated using a decision making system such as a multiobjective decision support system (MO-DSS, a method to assist in decision making from multiple and conflicting objectives); (v) involve stakeholders and the community in the definition of goals and setting benchmarking and monitoring targets for sustainable farming; (vi) take preventive and corrective/remedial action; (vii) evaluate effectiveness of actions taken; and (viii) revise indicators as part of a continual improvement principle designed to achieve best management practice for sustainable farming systems. The major recommendations are to: (i) implement the framework for resources (land, water and vegetation, economic, community and institution) benchmarking and monitoring, and integrate this process with current activities so that awareness, implementation and evolution of sustainable resource management practices become normal practice in the grains industry; (ii) empower the grains industry to take the lead by using relevant sustainability indicators to benchmark and monitor resources; (iii) adopt a collaborative approach by involving various industry, community, catchment management and government agency groups to minimise implementation time. Monitoring programs such as Waterwatch, Soilcheck, Grasscheck and Topcrop should be utilised; (iv) encourage the adoption of a decision making system by growers and industry representatives as a participatory decision and evaluation process. Widespread use of sustainability indicators would assist in validating and refining these indicators and evaluating sustainable farming systems. The indicators could also assist in evaluating best management practices for the grains industry.

Abstract Fire has been present during the evolution of poplar box communities and the flora is well adapted to fire. Broad fire regions are recognised on the basis of bioclimatic data and the effects of different fire regimcs on plant species and communities arc dis-cussed in ...

A model for simulating the combined effects of water, light and nutrients on tree, shrub and grass growth in a semi-arid woodland is described. Continuous-time Markov (CTM) assumptions are used to derive a plant growth model based on general resource availability. Physiological ...

ABSTRACT The effects of a range of tree densities on native herbage (mainly Aristida ramosa, Bothriochloa decipiens and Themeda australis biomass in a Eucalyptus crebra woodland near Kingaroy, Queensland, were investigated between March 1977 and July 1981. Rainfall in this area averages 750 mm year−1. Initial tree density was 640 trees ha−1 and this was manipulated using arboricide chemicals to leave plots containing 640, 320, 160, 80 and nil live trees ha−1. Fires were excluded from the whole area, and half the plots were grazed by cattle. The largest increase in herbage biomass was recorded in the ‘all trees killed’ treatment (nil trees ha−1), closely followed by the ‘scattered tree’ treatment (80 trees ha−1). The relationship between tree density and herbage biomass was linear. Recruitment of grass and forb plants, as reflected by changes in density, varied according to treatment. Increased grass recruitment was correlated with cattle grazing, whilst forb recruitment was influenced mainly by tree density.

ABSTRACT Solodic soils within a semi-arid poplar box (Eucalyptus populnea) woodland at Wycanna, in southern Queensland, have been subjected to impacts from sheep and cattle grazing for at least 100 years. The micromorphology of the surface of two soils, a gradational texture profile (Gn 3.13, Paleustalf) and a duplex profile (Db 1.23, Paleustalf) showed that compaction had occurred. Recovery of the soil surfaces following removal of animal grazing was measured in terms of porosity, presence of illuvial layers, surface soil strength, some chemical properties and water infiltration rates. The grazing impact was greatest on the Gn 3.13 soil and visual signs of the grazing impact were still evident 16 years following sheep removal. Reduced soil organic matter and increased surface soil hardness as a result of grazing, rather than surface crusting or changes in water infiltration rates are suggested as the mechanisms controlling the observed increases in woody plant populations in these semi-arid woodlands.

The Loess Plateau is being redeveloped to achieve a healthy ecosystem. Taking a small watershed as an example, this study used an analytic hierarchy process to identify different land uses, soil characteristics, crop yield and income for assessment of ecosystem rehabilitation. Various ...