Jingsheng Wang

Ecological and Environmental Issues Faced by a Developing Tibet

The Tibetan plateau, covering an area of 2.6 million km 2 with an average elevation of over 4000 m, often called “the third pole of the world”, has fundamental significance to the environment of China, Asia, and the world. The Tibetan plateau is called a “water tower” due to its downstream influence on approximately 40% of the world’s population. It is a region with rich species diversity and a high-altitude plateau biodiversity conservation base site, where some ancient species were preserved and new species evolved under the unique geology development process. In recent years, a series of ecological and environmental issues have emerged due to enhanced anthropogenic disturbances and climatic change. These issues are gradually eroding the capacity of the Tibet plateau to act as an “ecological security barrier” of atmosphere circulation and water sources for China and southern Asia. This study critically reviews several imminent ecological and environmental issues faced by Tibet and has the goal of drawing the attention of governments and international societies. The effects of global warming are more obvious in Tibet than in other areas at similar latitude. The temperature in Tibet has been increasing at a faster rate than other inland areas of China in the past decades. 1 Precipitation exhibited no obvious trend, but has occurred in a more concentrated way during each year. The permafrost soil of Tibet historically covered an area of 1,401,000 km 2 , accounting for 54.3% of Tibetan plateau. 2 In the past 30 years, the lower altitude limit of permafrost in Tibet has moved up on average 50 m. The thickness of the active soil

Object-oriented classification for urban land cover mapping with ASTER imagery

This document demonstrates the potential of using an object‐oriented approach to map urban land cover. One objective of this work was to test the ability of the object‐oriented classification in the generation of urban land cover maps. Anotehr was to produce an updated land cover map for the city of Beijing from Advanced Spaceborne Thermal Emission and Reflecton Radiometer (ASTER) data, with an evaluation of its accuracy.

Light-intensity grazing improves alpine meadow productivity and adaption to climate change on the Tibetan Plateau

To explore grazing effects on carbon fluxes in alpine meadow ecosystems, we used a paired eddy-covariance (EC) system to measure carbon fluxes in adjacent fenced (FM) and grazed (GM) meadows on the Tibetan plateau. Gross primary productivity (GPP) and ecosystem respiration (Re) were greater at GM than FM for the first two years of fencing. In the third year, the productivity at FM increased to a level similar to the GM site. The higher productivity at GM was mainly caused by its higher photosynthetic capacity. Grazing exclusion did not increase carbon sequestration capacity for this alpine grassland system. The higher optimal photosynthetic temperature and the weakened ecosystem response to climatic factors at GM may help to facilitate the adaption of alpine meadow ecosystems to changing climate.

Analysis of forest fires in Northeast China from 2003 to 2011

Wildfires, a common disturbance in ecosystems, can be an immediate and dominant source of interannual carbon variability. In this study, we used an instantaneous Moderate Resolution Imaging Spectroradiometer (MODIS) global disturbance index algorithm to explore continuous spatiotemporal patterns of forest fires in Northeast China. The forest fires that were sensed remotely were then validated by field records. The findings suggest that the disturbance index is effective in locating forest fires in Northeast China, as evidenced by a close match with field fire records. We found that the incidence of forest fires was closely linked to extreme conditions of climate warming and drought, and more fires occurred in dry years than in wet years. Among different forest types, shrublands, mixed forest, and deciduous needleleaf forests were more prone to wildfires because of their fire regime characteristics. The study demonstrates that the algorithm was effective in detecting forest fires from 2003 to 2011 in Northeast China, providing fundamental data for forest inventory and large-scale ecological applications.

Response of Kobresia pygmaea and Stipa purpurea Grassland Communities in Northern Tibet to Nitrogen and Phosphate Addition

Abstract The Tibetan Plateau is of fundamental ecological significance to China, Asia, and the world. In recent years, Tibetan grasslands have suffered from severe degradation due to climate change and anthropogenic disturbance. In this study, nitrogen (N) and phosphate were applied to a moderately degraded Kobresia pygmaea meadow and Stipa purpurea steppe in the arid alpine northern Tibetan Plateau. The results showed that with increasing nitrogenous fertilizer, the height, coverage, biomass, and importance value of the K. pygmaea population decreased whereas the population of S. purpurea exhibited the opposite trend. Application of a mixed fertilizer with the same amount of N and phosphorus (P) (5 g each per m2) doubled the biomass of the K. pygmaea meadow and increased the aboveground biomass of the S. purpurea steppe by 72.3%. The nitrogenous fertilizer increased the total biomass and belowground biomass of the S. purpurea steppe, whereas the mixed fertilizer was beneficial to aboveground grass recovery. Application of 10 g N + 5 g P m−2 fertilizer increased aboveground biomass by 164.8%, whereas the belowground biomass was less than the control by 4.7%. The N and P fertilizer did not affect soil pH, except for some changes in soil N and P contents.

Dynamic assessment of forest resources quality at the provincial level using AHP and cluster analysis

AHP and cluster analysis were integrated to assess the forest resources quality (FQR).Ecological projects have significantly improved the FRQ at provincial and national levels.During 2009-2013, the numbers of provinces scoring at excellent, medium, inferior level were 3, 15, 12 and 1.Forest resources in the 31 provinces during 2009-2013 were grouped into four clusters.The findings provide theoretical and technical references for forest management in China. The aim of this study was to quantitatively assess and analyze the dynamic changes and current problems of Chinese forest resources based on the National Forest Inventory (NFI). In this study, a hierarchical model was established using the analytic hierarchy process to assess forest resources quality (FRQ) at the provincial level. Four criteria were used, including forest quantity, forest productivity, forest structure, and forest health and each criterion was further composed of multiple factors. Among these assessment factors, stock volume per unit area was the most important, while canopy structure was the least important. The ranges of FRQ Indies across China during the 6th NFI (1999-2003), 7th NFI (2004-2008), and 8th NFI (2009-2013) were 0.3031-0.6366, 0.3499-0.7186, and 0.3534-0.7555, respectively. From the 6th to 8th NFI, forest quality improved by different degrees for all provinces, whereas the other three criteria presented an increasing or decreasing trend. In general, the implementation of ecological projects has significantly improved the FRQ at provincial and national levels. During the 8th NFI, the FRQ levels were excellent for 3 provinces, good for 15 provinces, medium for 12 provinces, and only one province exhibited an inferior level of FRQ. Based on cluster analysis, Chinese forest resources during the 8th NFI could be grouped into four clusters according to the provincial administrative region, and each cluster had its own advantages and disadvantages. Stock volume increment and forest calamity were in a very good state, while canopy structure was the key factor limiting the FQR for all the clusters. Some relevant measures were proposed to improve the existing conditions of Chinese forest resources. The results of this study are significant in that they can provide theoretical and technical references for future adjustment and sustainable management of forest resources in China.

Controls of seed quantity and quality on seedling recruitment of smith fir along altitudinal gradient in southeastern Tibetan Plateau

Alpine treeline ecotones are harsh environment for tree establishment due to low temperature. Tree establishment at treelines requires favorable climate, suitable microsites, and viable seeds. But most researches have been addressed treeline microclimate and its effects on tree regeneration, the knowledge of seed quantity and quality and its controls on seedling recruitment were limited. We measured seed rain, soil seed bank, seed germination rate and seedling recruitment in natural forests in combination with seed transplanting manipulation to evaluate the controls of seed quantity and quality on seedling recruitment of Abies georgei var. smithii (smith fir) along altitudinal gradient, with focus on treeline ecotone in the Sygera Mountains, southeastern Tibetan Plateau. Both seed quantity and seed quality of smith fir decreased with increasing altitude and was thereby associated with decline in seed germination rate. Seed quantity and seedling recruitment were better in north-facing slope than in south slope. The treeline ecotone above 4200 m appeared as the threshold altitude to sharply decrease seed quality and seedling recruitment. The emergence and overwintering rates of transplanting seeds from 3600−3800 m also went down remarkably above 4200 m at north-facing slope. It also underpins the fact that treeline ecotone is the bottleneck of seedling recruitment. Our results suggest that seed quantity and quality are the principal limitation of treeline upward advance. This study also provides evidence to support stable treeline position in southeastern Tibetan Plateau.

Ecological Restoration in the Typical Areas

Human activities are strongly regional and targeted, and usually tightly bound to the regional natural resources, the needs of social economic development, and ecological fragility, which cause typical regional ecosystem degradation problems. For serious degradation areas, it is an effective way to carry out regional ecological restoration and construction for restoration ecology study, which is the key to promote sustainable development and ecological security, and also the urgent requirement for the current reality. According to the demand of regional sustainable development, this chapter focused on ecological deterioration, and restoration and construction in typical areas. The chapter specially made thematic discussions on new progression in degradation problems of developing and utilizing the resource, ecological restoration practices, theory, techniques, mode, and management. This chapter was trying to provide experience and lessons, macro guidance and decision-making reference for ecological restoration in typical areas. From the regional cases of this chapter, we can see that regional ecological restoration and construction is intricate. Finally, it is necessary to point out that there are many regional ecological restoration cases, here just introduce several cases in western fragile region. The ecological restoration cases revealed in this chapter are just the first attempt to conclude the past experiences in China, which are initial identification for correlated theories and methods.

Dynamics of soil organic carbon in alpine meadow of Tibetan Plateau with CENTURY model

The estimation of soil organic carbon(SOC) densities and dynamics is necessary to understand terrestrial carbon cycle and carbon budget. The relative research on the Tibetan Plateau was few and uncertainty of the SOC densities and dynamics. The dynamics of soil organic carbon and its fractions, including active, slow and passive pools, were simulated using CENTURY model in alpine meadow at Damxung on Tibetan Plateau. Results showed that the SOC density in surface soil (0–20cm) was approximately 3292.20±15.78g/m2 in alpine meadow. The study simulated the change process of soil organic carbon and its components. Active, slow and passive soil organic carbon were respectively stable in 76.07–100.55g/m2, 1913.05–2008.05g/m2, 1312.47–1320.76g/m2 in equilibrium state. Soil organic carbon decreased in the past 30 years and slightly decreased in the future 100 years using CENTURY model. Results of this study indicated that CENTURY model was applied to alpine meadow ecosystem. This suggest that CENTURY model is a uesful tool for alpine meadow ecosystem study. While our study represents a case study, the results suggest that CENTURY model studies in alpine meadow can help to evaluate the dynamics of SOC and the grassland management.