Xiubo Yu

Major Ecosystems in China: Dynamics and Challenges for Sustainable Management

Ecosystems, though impacted by global environmental change, can also contribute to the adaptation and mitigation of such large scale changes. Therefore, sustainable ecosystem management is crucial in reaching a sustainable future for the biosphere. Based on the published literature and publicly accessible data, this paper discussed the status and trends of forest, grassland, and wetland ecosystems in China that play important roles in the ecological integrity and human welfare of the nation. Ecological degradation has been observed in these ecosystems at various levels and geographic locations. Biophysical (e.g., climate change) and socioeconomic factors (e.g., intensive human use) are the main reasons for ecosystem degradation with the latter factors serving as the dominant driving forces. The three broad categories of ecosystems in China have partially recovered from degradation thanks to large scale ecological restoration projects implemented in the last few decades. China, as the largest and most populated developing nation, still faces huge challenges regarding ecosystem management in a changing and globalizing world. To further improve ecosystem management in China, four recommendations were proposed, including: (1) advance ecosystem management towards an application-oriented, multidisciplinary science; (2) establish a well-functioning national ecological monitoring and data sharing mechanism; (3) develop impact and effectiveness assessment approaches for policies, plans, and ecological restoration projects; and (4) promote legal and institutional innovations to balance the intrinsic needs of ecological and socioeconomic systems. Any change in China’s ecosystem management approach towards a more sustainable one will benefit the whole world. Therefore, international collaborations on ecological and environmental issues need to be expanded.

Implementing Integrated River Basin Management in China

This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are matched with the advice of the China Council for International Cooperation on Environment and Development task force on integrated river basin management to the national government of China. This article demonstrates that the World Wildlife Fund for Nature uses various strategies of different types to support a transition process towards integrated river basin management. Successful deployment of these strategies for change in environmental policy requires special skills, actions, and attitudes on the part of the policy entrepreneur, especially in China, where the government has a dominant role regarding water management and the position of policy entrepeneurs is delicate.

Freshwater management and climate change adaptation: Experiences from the central Yangtze in China

The Yangtze is the largest river basin in China and home to over 400 million people. In recent history, and especially during 1950s–1970s, extensive lakes and floodplains were reclaimed as polders for agriculture and rural development. Consequently, the flood retention capacity was decreased, many lakes were disconnected from the main channel of the Yangtze by embankments and sluice gates, and eutrophication was common. It is anticipated that there will be a greater frequency of extreme floods and droughts in the basin according to climate change scenarios. WWF commenced a programme in 2002 in partnership with government agencies and local communities to reconnect three lakes (Zhangdu, Hong and Tian-e-zhou) in Hubei Province to the river by opening sluice gates seasonally and improving lake management. The resilience of the lake environment to climate change and the livelihoods of local people were enhanced. The measures assessed here highlight: (a) the need for adaptation programmes to concurrently improve livelihoods and reduce exposure to physical risks; (b) the need to build the capacity of people and institutions; and (c) the value of decentralized adaptation as compared with new infrastructure investments.

Ecosystem services and management strategy in China

Introduction to the Task Forces Work.- Concept of Ecosystem Services and Ecosystem Management.- Status of Major Ecosystems and Management.- Scenario Analysis.- Chinese Case Studies.- International Experience.- Major Findings.- Policy Recommendations.

A comparison of forest fire indices for predicting fire risk in contrasting climates in China

Abstract The relationships between fire danger indices and fire risk have been extensively studied in many regions of the world. This work uses partial effect analysis in semiparametric logistic regression models to assess the nonlinear relationships among location, day, altitude, fire danger indices, normalized difference vegetation index (NDVI), and fire ignition from 1996 to 2008 in four different climatic regions in China. The four regions are North China (NR), Northeast China (NE), Southeast China (SE), and Southwest China (SW). The three main results are as follows: First, different fire danger indices are selected as significant variables dependent on the region. The inter-regional difference could be partially explained by difference in local weather and vegetation conditions. Second, spatial location exerts highly significant effects in all four regions. NDVI values are selected as explained variable for NR, NE, and SE on fire ignitions. On a daily scale, altitude influences fire ignition for NR, SE, and SW. Third, the robustness of the probability models used in NE, SE, and SW is better than that in NR on a daily scale. The semiparametric logistic regression model used in this study is useful for assessing the ability of fire danger indices to estimate probabilities of fire ignition on a daily scale. This study encourages further research on assessing the predictive ability of fire danger indices developed at other temporal and spatial scales in China.

Seasonal variability in baseline δ15N and usage as a nutrient indicator in Lake Poyang, China

Seasonal variation in nitrogen isotope ratios (δ15N) of four baseline candidates belonging to the planktonic and benthic food webs of Lake Poyang, China, was investigated. These baseline candidates were particulate organic matter (POM), sediment organic matter (SOM), a filterer mussel (Corbicula flumine), and a grazer snail (Bellamya aeruginosa). δ15N values of POM and SOM varied significantly among the sampling seasons, while no significant seasonal variation was observed among the δ15N values of the mussels and snails sampled in different seasons. POM δ15N was correlated with lake water PO4-P, while SOM δ15N was correlated with NO3-N. Mussel δ15N and lake water TN, NO3-N, and PO4-P were significantly correlated as were snail δ15N and TN, TP, and NO3-N. SOM and snails were better bioindicators of the water column nutrient concentration of Lake Poyang. The significant correlations between mussel δ15N and POM, as well as between snail δ15N and SOM, indicated the potential use of these baselines in trophic evaluations in planktonic and benthic food webs in this water-level fluctuating lake.

Temporal variation of energy sources in a floodplain lake fish community

We compared the stable isotope ratios of δ 13C and δ 15N of four basal food sources and eight fish species collected in spring and summer from the largest freshwater lake in China, Lake Poyang. The aim was to study the temporal variations in the fishes’ energy sources. The δ 13C and δ 15N ratios of all eight species of fish were higher in summer. Employing the IsoSource mixing model, we identified that the terrestrial plant Carex spp. was the most important primary producer supporting fish biomass in spring when the water level was low; meanwhile, the submerged macrophyte Potamogeton malaianus made consistent contributions to fish. However, in summer, when the water level was high, the submerged macrophyte Ceratophyllum demersum was the most important primary production source for fish. Our study indicated that feeding links in floodplain lakes are complex and modified by hydrologic seasonality.

Probability models of fire risk based on forest fire indices in contrasting climates over China

Abstract: Fire weather indices have been widely applied to predict fire risk in many regions of the world. The objectives of this study were to establish fire risk probability models based on fire indices over different climatic regions in China. We linked the indices adopted in Canadian, US, and Australia with location, time, altitude, vegetation and fire characteristics during 1998–2007 in four regions using semi— parametric logistic (SPL) regression models. Different combinations of fire risk indices were selected as explanatory variables for specific regional probability model. SPL regression models of probability of fire ignition and large fire events were established to describe the non—linear relationship between fire risk indices and fire risk probabilities in the four regions. Graphs of observed versus estimated probabilities, fire risk maps, graphs of numbers of large fire events were produced from the probability models to assess the skill of these models. Fire ignition in all regions showed a significant link with altitude and NDVI. Indices of fuel moisture are important factors influencing fire occurrence in northern China. The fuel indices of organic material are significant indicators of fire risk in southern China. Besides the well skill of predicting fire risk, the probability models are a useful method to assess the utility of the fire risk indices in estimating fire events. The analysis presents some of the dynamics of climate-fire interactions and their value for management systems.

TSUNAGARI: a new interdisciplinary and transdisciplinary study toward conservation and sustainable use of biodiversity and ecosystem services

The expanding economical activities have accelerated losses of biodiversity and ecosystem services, which are especially pronounced in Asia. To find solutions to stop these losses, a group of scientists studying both ecological and social sciences has launched an interdisciplinary research network, entitled TSUNAGARI (Trans-System, UNified Approach for Global and Regional Integration of social-ecological study toward sustainable use of biodiversity and ecosystem services). The project is based on two main perspectives: (1) integrating different disciplines of environmental research across multiple spatial scales, and (2) evaluating the importance of ecosystem connectivity between land and ocean for biodiversity and ecosystem services. The integrative studies have been started as follows: (1) integrating global-scale analyses of biodiversity and economy by developing GIS-based footprint analysis, (2) establishing the link between the studies of local good practices of ecosystem management and life cycle assessment on ecosystem good and services, (3) linking local-scale ecosystem studies to decision making processes for sustainable society by multiple stakeholders, and (4) upscaling local analyses of ecosystem processes to broad-scale analyses of ecosystem patterns. The proposed approaches are considered effective to solve problems that impede conservation of biodiversity and sustainable use of multiple ecosystem services in various situations although we also find some gaps such as regional biases in biodiversity data and involvement of different types of stakeholders. By overcoming the major bottlenecks, we believe the new integrated approaches will promote conservation and sustainable management of biodiversity and ecosystem services research, and contribute to advance decision-making processes from local communities to international levels.

The importance of terrestrial carbon in supporting molluscs in the wetlands of Poyang Lake

Allochthonous organic matter plays an important role in nutrient cycling and energy mobilization in freshwater ecosystems. However, the subsidies of this carbon source in floodplain ecosystems have not yet well understood. We used a Bayesian mixing model and stable isotopes (δ13C and δ15N) of primary food resources and dominant molluscs species, to estimate the relative importance of allochthonous carbon sources for consumers in a representative sub-lake of Poyang Lake during a prolonged dry season. Our study inferred that terrestrial-derived carbon from Carex spp. could be the primary contributor to snails and mussels in Dahuchi Lake. The mean percentage of allochthonous food resources accounted for 35%–50% of the C incorporated by these consumers. Seston was another important energy sources for benthic consumers. However, during the winter and low water-level period, benthic algae and submerged vegetation contributed less carbon to benthic consumers. Our data highlighted the importance of terrestrial organic carbon to benthic consumers in the wetlands of Poyang Lake during the prolonged dry period. Further, our results provided a perspective that linkages between terrestrial and aquatic ecosystems might be facilitated by wintering geese via their droppings.