秦皇岛市陆地植被与大气碳平衡研究

地球的碳循环已成为全球气候变化的一个热点,陆地植被是地球破循环中的一个重要贮存库。本文在分析秦皇岛市陆地植被状况的基础上,对CO_2排放量和吸收量进行了估算,结果表明,陆地植被吸收CO_2的数量占排放量的79％。结合秦皇岛市的实际,提出有利于大气碳平衡的对策。     

塔河上游地区阿拉尔段天然退化生态系统植物群落物种多样性特征分析及恢复途径

通过对塔河上游阿拉尔地区天然植被的物种多样性的特征分析,并结合实际情况,得出了该地区天然植被生态系统在人类干扰下普遍存在退化现象,尤其在绿洲—荒漠过渡带,这种现象更为严重。应采取有效措施对天然植被特别是过渡带的植被进行生态恢复。另外还讨论了本地区植被恢复与重建的对策。     

Testing the Stochastic Dynamic Methodology (StDM) as a management tool in a shallow temperate estuary of south Europe (Mondego, Portugal)

A long-term monitoring program has been carried out since the early 1990s in the Mondego estuary, on Portugal's west coast, which is presently under heavy human pressure. In this shallow warm-temperate estuary, a significant macroalgal proliferation has been observed, which is a clear sign of nutrient enrichment. As a result of competition with algae, the extension of the seagrass meadows (mainly Zostera noltii) has been reduced. The present paper examined the applicability of a holistic Stochastic Dynamic Methodology (StDM) in predicting the tendencies of trophic key-components (macrophytes, macroalgae, benthic macroinvertebrate and wading birds) as a response to the changes in estuarine environmental conditions. The StDM is a sequential modelling process developed in order to predict the ecological status of changed ecosystems, from which management strategies can be designed. The data used in the dynamic model construction included true gradients of environmental changes and was sampled from January 1993 to September 1995 and from December 1998 to December 2005. The dynamic model developed was preceded by a conventional multivariate statistical procedure performed to discriminate the significant relationships between the selected ecological components. The model validation was based on independent data collected from January 1996 to January 1997 and from February 1999 to April 2000 for all the state variables considered. Overall, the simulation results are encouraging since they seem to demonstrate the StDM reliability in capturing the trophic dynamics of the studied estuary, by predicting the behavioural pattern for the most part of the components selected, with a focus on the Zostera noltii meadows recovery after the implementation of important management measures.     

The Future of Scattered Trees in Agricultural Landscapes

Abstract: Mature trees scattered throughout agricultural landscapes are critical habitat for some biota and provide a range of ecosystem services. These trees are declining in intensively managed agricultural landscapes globally. We developed a simulation model to predict the rates at which these trees are declining, identified the key variables that can be manipulated to mitigate this decline, and compared alternative management proposals. We used the initial numbers of trees in the stand, the predicted ages of these trees, their rate of growth, the number of recruits established, the frequency of recruitment, and the rate of tree mortality to simulate the dynamics of scattered trees in agricultural landscapes. We applied this simulation model to case studies from Spain, United States, Australia, and Costa Rica. We predicted that mature trees would be lost from these landscapes in 90–180 years under current management. Existing management recommendations for these landscapes—which focus on increasing recruitment—would not reverse this trend. The loss of scattered mature trees was most sensitive to tree mortality, stand age, number of recruits, and frequency of recruitment. We predicted that perpetuating mature trees in agricultural landscapes at or above existing densities requires a strategy that keeps mortality among established trees below around 0.5% per year, recruits new trees at a rate that is higher than the number of existing trees, and recruits new trees at a frequency in years equivalent to around 15% of the maximum life expectancy of trees. Numbers of mature trees in landscapes represented by the case studies will decline before they increase, even if strategies of this type are implemented immediately. This decline will be greater if a management response is delayed.     

陆地生态系统净第一性生产力过程模型研究综述

陆地生态系统净第一性生产力的模拟已从统计模型发展到过程模型时代。过程模型从机理上对植物的生物物理过程以及影响因子进行分析和模拟,理论框架完整,结构严谨。论文从植物器官、个体、冠层、景观以及区域等不同尺度对过程模型进行分析。近年来,由于遥感和GIS技术的支持,使得遥感过程模型融合了遥感及时、准确、宏观、多尺度的优势而成为当前生产力模型的主攻方向。遥感过程模型可实现生态系统NPP的及时模拟和动态监测,便捷、准确地反映NPP的时空变化格局。而在NPP建模过程中,尺度转换是所面临的一个重要问题。不同尺度模型间扩展时,需要采取相应的数学手段进行尺度转换,同时遥感和GIS技术提供了尺度转换的有力工具。综观我国NPP研究的发展,起步晚、发展快是其特点。虽然取得了大量的研究成果,但过程模型的建模方面还很不足,这是一个亟待解决的问题。     

Trophic state, ecosystem efficiency and biodiversity of transitional aquatic ecosystems: analysis of environmental quality based on different benthic indicators

Estuaries and coastal lagoons are characterized by a strong spatial and temporal variability of physicochemical characteristics and productivity patterns. In these environments, the magnitude and direction of the ecological responses to inorganic nutrient increase (i.e. eutrophication) are difficult to predict. In the framework of the project, New Indicators of Trophic state and environmental quality of marine coastal ecosystems and transitional environments (NITIDA), we analysed benthic indicators of trophic state, ecosystem efficiency, and environmental quality in four different transitional environments. The trophic state of the sediments was assessed in terms of quantity and bioavailability of sediment organic C pools; ecosystem efficiency was determined in terms of the prokaryote efficiency in exploiting enzymatycally degraded organic C; environmental quality was determined in terms of meiofaunal diversity. Here, we provide a synopsis of the results obtained and a meta-analysis of the scores assessments obtained using the different ecological indicators of environmental quality and demonstrate that trophic state, ecosystem efficiency, and biodiversity in transitional ecosystems are closely linked. We conclude that the assessment of the environmental quality of transitional ecosystems should be based upon a battery of trophic state indicators and 'sensors' of ecosystem functioning, efficiency, and quality.     

Effect-Directed Analysis of Key Toxicants in European River Basins. A Review (9 pp)

Background, Aim and Scope Extensive monitoring programs on chemical contamination are run in many European river basins. With respect to the implementation of the European Union (EU) Water Framework Directive (WFD), these programs are increasingly accompanied by monitoring the ecological status of the river basins. Assuming an impact of chemical contamination on the ecological status, the assignment of effects in aquatic ecosystems to those stressors that cause the effects is a prerequisite for taking political or technical measures to achieve the goals of the WFD. Thus, one focus of present European research is on toxicant identification in European river basins in order to allow for a reduction of toxic pressure on aquatic ecosystems according to the WFD. Main Features: An overview is presented on studies that were performed to link chemical pollution in European river basins to measurable ecotoxic effects. This includes correlation-based approaches as well as investigations that apply effect-directed analysis (EDA) integrating toxicity testing, fractionation and non-target chemical analysis. Effect-based key toxicants that were identified in European surface waters are compiled and compared to EU priority pollutants. Further needs for research are identified. Results: Studies on the identification of effect-based key toxicants focused on mutagenicity, aryl hydrocarbon receptor-mediated effects, endocrine disruption, green algae, and invertebrates. The identified pollutants include priority pollutants and other well-known environmental pollutants such as polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins, furans, and biphenyls, nonylphenol, some pesticides and tributyltin, but also other compounds that were neither considered as environmental pollutants before nor regulated such as substituted phenols, natural or synthetic estrogens and androgens, dinaphthofurans, 2-(2-naphthalenyl)benzothiophene, and N-phenyl-2-naphthylamine. Discussion: Individual studies at specific sites in a European river basin demonstrated the power of combined biological and chemical analytical approaches and, particularly, of effect-directed analysis. However, the available information on effect-based key toxicants is very limited with respect to the entirety of rivers possibly at risk due to chemical contamination and with respect to toxicological endpoints considered at a specific site. A relatively broad basis of information exists only for estrogenicity and aryl hydrocarbon, receptor-mediated effects. Conclusions: The development of tools and strategies for an identification of key toxicants on a broader scale are a challenging task for the next years. Since investigations dealing with toxicant identification are too labor and cost-intensive for monitoring purposes, they have to be focused on the key sites in a river basin. These should include hot spots of contamination, particularly if there is evidence that they might pose a risk for downstream areas, but may also involve accumulation zones in the lower reach of a river in order to get an integrated picture on the contamination of the basin. Perspectives: While EDA is almost exclusively based on measurable effects in in vitro and in vivo biotests to date, an increasing focus in the future should be on the integration of EDA into Ecological Risk Assessment and on the development of tools to confirm EDA-determined key toxicants as stressors in populations, communities and ecosystems. Considering these requirements and applied in a focused way, toxicant identification may significantly help to implement the Water Framework Directive by providing evidence on the main stressors and possible mitigation measures in order to improve the ecological status of a river ecosystem.     

Stability of Isolated Populations of Terrestrial Mammals Inhabiting the Islands of the Peter the Great Bay,Sea of Japan

A comparative analysis of the dynamics of insular populations of terrestrial animals was performed. The stability of insular populations and the relationship between their viability and the type of dynamics are discussed.     

Overview of case studies on recovery of aquatic systems from disturbance

An extensive review of the published literature identified more than 150 case studies in which some aspect of resilience in freshwater systems was reported. Approximately 79% of systems studied were lotic and the remainder lentic. Most of the stressor types were chemical with DDT (N=29) and rotenone (N=15) the most common. The most common nonchemical stressors were logging activity (N=16), flooding (N=8), dredging (N=3), and drought (N=7). The variety of endpoints to which recovery could be measured ranged from sparse data for phytoplankton (N=13), periphyton (N=6), and macrophytes (N=8) to relatively more data for fish (N=412) and macroinvertebrates (N=698). Unfortunately the same characteristics were rarely measured consistently among sites. For example, with respect to fish, more than 30 different species were studied and recovery was measured in many ways, most commonly on the basis of: (1) first reappearance of the species, (2) return time of predisturbance densities, and (3) return time of predisturbance average individual size. Based on these criteria, all systems in these studies seem to be resilient to most disturbances with most recovery times being less than three years. Exceptions included when (1) the disturbance resulted in physical alteration of the existing habitat, (2) residual pollutants remained in the system, or (3) the system was isolated and recolonization was suppressed.