Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Temperate forests regrowing from historical land use and land cover change in the eastern US serve as carbon (C) sinks. Environmental drivers have been significantly altered (e.g. rising atmospheric CO2concentration, warmer temperature,... more
Temperate forests regrowing from historical land use and land cover change in the eastern US serve as carbon (C) sinks. Environmental drivers have been significantly altered (e.g. rising atmospheric CO2concentration, warmer temperature, and elevated nitrogen (N) deposition) and will have a wide range of impacts on future forest C sinks. However, the interactions among these environmental drivers are unclear and their effects are subject to uncertainty. We assessed the combined and interactive effects of rising CO2concentration, climate change (temperature, precipitation), and N deposition on forest aboveground net primary production (ANPP) and their relative contribution to ANPP changes of a temperate forest in the eastern US. We used a process-based ecosystem model PnET-day to simulate coupled cycles of C, water, and N of forest ecosystems. We found that (1) climate change exerted negative effects on ANPP (−0.250 kg C m−2yr−1) whereas rising CO2and N deposition enhanced ANPP (+0.25...
Research Interests:
Research Interests:
Most temperate forests in U.S. are recovering from heavy exploitation and are in intermediate successional stages where partial tree harvest is the primary disturbance. Changes in regional forest composition in response to climate change... more
Most temperate forests in U.S. are recovering from heavy exploitation and are in intermediate successional stages where partial tree harvest is the primary disturbance. Changes in regional forest composition in response to climate change are often predicted for plant functional types using biophysical process models. These models usually simplify the simulation of succession and harvest and may not consider important species‐specific demographic processes driving forests changes. We determined the relative importance of succession, harvest, and climate change to forest composition changes in a 125‐million ha area of the Central Hardwood Forest Region of U.S. We used a forest landscape modeling approach to project changes in density and basal area of 23 tree species due to succession, harvest, and four climate scenarios from 2000 to 2300. On average, succession, harvest, and climate change explained 78, 17, and 1% of the variation in species importance values (IV) at 2050, respective...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Forest landscape models (FLMs) are an important tool for assessing the long-term cumulative effects of harvest over large spatial extents. However, they have not been commonly used to guide forest management planning and on-the-ground... more
Forest landscape models (FLMs) are an important tool for assessing the long-term cumulative effects of harvest over large spatial extents. However, they have not been commonly used to guide forest management planning and on-the-ground operations. This is largely because FLMs track relatively simplistic vegetation information such as age cohort presence/absence, forest type, and biomass that are incompatible with tree density and size on which most harvest prescriptions are based. We describe and demonstrate the newly developed harvest module of the LANDIS PRO FLM, which tracks density, size, basal area, and stocking by species age cohorts for each site (cell). With this quantitative information, the module can simulate basal area controlled harvest, stocking-level controlled harvest, and group selection harvest. Through user-specified harvest year (frequency), stand ranking, and species and age preference, the new module can simulate a wide variety of harvest prescriptions such as t...
Research Interests:
The Ozark highlands of Missouri and Arkansas are dominated by highly stocked oak-hickory forests. Oak decline and escalating mortality have become a concern as upland oak-hickory forests mature. Based on annual FIA plot data from 1999 to... more
The Ozark highlands of Missouri and Arkansas are dominated by highly stocked oak-hickory forests. Oak decline and escalating mortality have become a concern as upland oak-hickory forests mature. Based on annual FIA plot data from 1999 to 2006 we explored oak decline and mortality trends for major oak species (groups) in this region. Oak decline has elevated cumulative mortality of
Research Interests:
Research Interests:
Research Interests:
Forest swamps are widely distributed in cold temperate regions, with important landscape and ecological functions. They are prone to conversion caused by complex factors. Forest swamp conversions involve forest swamping, meadow swamping,... more
Forest swamps are widely distributed in cold temperate regions, with important landscape and ecological functions. They are prone to conversion caused by complex factors. Forest swamp conversions involve forest swamping, meadow swamping, water body swamping, and conversion to farmland. An understanding of the landscape characteristics and primary environmental factors driving forest swamp conversions is imperative for exploring the mechanism of forest swamp conversions. We investigated the landscape characteristics of forest swamp conversions and quantified the relative importance of environmental factors driving these conversions for the period from 1990 to 2015 in the Great Xing'an Mountains of China. We found that forest swamping displayed high patch numbers (34,916) and density (8.51/100 ha), commonly occurring at the edge of large areas of forests. Meadow swamping was localized with low patch numbers (3613) and density (0.88/100 ha) due to lack of water recharge from ground...
Research Interests:
Research Interests:
Research Interests: Landscape Ecology, Earth Sciences, Reproduction, Risk, Fire, and 15 moreLandscape, Biological Sciences, Environmental Sciences, Models, Forest Management, Forests, Forest succession, Fire Risk, Management Strategy, Low Risk, Fire Resistance, Perturbation, Recreational Activity, Model simulation, and High risk
Research Interests: Environmental Science, Forest Ecology And Management, Forest Ecology, Biological Sciences, Environmental Sciences, and 14 moreUnited States, Oak, Fire Suppression, Oak Decline, Fire Hazard, Oak forest, Windthrow, Long Term Effect, Fire Resistance, Fire regime, Spatial Model, Tree Species, Pine Forest, and Landscape Dynamic
Treeline responses to environmental changes describe an important phenomenon in global change research. Often conflicting results and generally too short observations are, however, still challenging our understanding of climate-induced... more
Treeline responses to environmental changes describe an important phenomenon in global change research. Often conflicting results and generally too short observations are, however, still challenging our understanding of climate-induced treeline dynamics. Here, we use a state-of-the-art dendroecological approach to reconstruct long-term changes in the position of the alpine treeline in relation to air temperature at two sides in the Changbai Mountains in northeast China. Over the past 160 years, the treeline increased by around 80 m, a process that can be divided into three phases of different rates and drives. The first phase was mainly influenced by vegetation recovery after an eruption of the Tianchi volcano in 1702. The slowly upward shift in the second phase was consistent with the slowly increasing temperature. The last phase coincided with rapid warming since 1985, and shows with 33 m per 1°C, the most intense upward shift. The spatial distribution and age structure of trees b...
Research Interests:
The spatial pattern of forest fire locations is important in the study of the dynamics of fire disturbance. In this article we used a spatial point process modeling approach to quantitatively study the effects of land cover, topography,... more
The spatial pattern of forest fire locations is important in the study of the dynamics of fire disturbance. In this article we used a spatial point process modeling approach to quantitatively study the effects of land cover, topography, roads, municipalities, ownership, and population density on fire occurrence reported between 1970 and 2002 in the Missouri Ozark Highland forests, where more than 90% of fires are human-caused. We used the AIC (Akaike information criterion) method to select an appropriate inhomogeneous Poisson process model to best fit to the data. The fitted model was diagnosed using residual analysis as well. Our results showed that fire locations were spatially clustered, and high fire occurrence probability was found in areas that (1) were public land, (2) within 6 km to 17 km of municipalities, and (3) <500 m from roads where forests are accessible to humans. In addition, fire occurrence probability was higher in pine-oak forests on moderate (<25 degree) s...
Research Interests:
Research Interests: IEEE and Age Structure
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Water consumption ensures crop production and grain security, and is influenced by many factors. Analyzing the impact factors of water consumption during crop production will be beneficial to the full use of water resources and crop... more
Water consumption ensures crop production and grain security, and is influenced by many factors. Analyzing the impact factors of water consumption during crop production will be beneficial to the full use of water resources and crop growth. Jilin Province is one of the major crop production areas in China and is facing water shortages. Using the water footprint as an indicator, this study evaluated the water consumption of crop production in Jilin Province during 2000–2016, explored the impacts of climatic and agricultural input factors on the water consumption of crop production, and identified the most influential factors in years under different levels of rainfall. The results indicate that the crop water footprint exhibited a decreasing trend during 2000–2016, and the most influential factors of the crop water footprint changed over the years with different levels of rainfall. Precipitation and the effective irrigation area were the most influential factors in the drought year, ...
Research Interests:
Climate change and human activities are important factors driving changes in wetland ecosystems. It is therefore crucial to quantitatively characterize the relative importance of these stressors in wetlands. Previous such analyses have... more
Climate change and human activities are important factors driving changes in wetland ecosystems. It is therefore crucial to quantitatively characterize the relative importance of these stressors in wetlands. Previous such analyses have generally not distinguished between wetland types, or have focused on individual wetland types. In this study, three representative wetland areas of the upper, middle and lower reaches of the Heilongjiang River Basin (HRB) were selected as the study area. An object-based classification was used with Landsat TM data to extract the spatial distribution of wetland in 1990, 2000 and 2010. We then quantified the relative importance of climate change and human activities on the wetlands by using the R package “relaimpo” package. The results indicated that: (1) the effects of human activities on wetland changes were greater (contribution rate of 63.57%) than climate change in the HRB. Specifically, there were differences in the relative importance of climate...