不同生态系统CO2通量和浓度特征分析研究

本文利用1993～1994年日本国家农业环境研究所与中国科学院沙漠研究所合作在内蒙古奈曼地区实测的7种不同生态系统（沙丘、轻度放牧草原、中度放牧草原、重度放牧草原、无放牧草原、玉米田和大豆田）的净辐射、土壤热通量、两个高度的CO2浓度、温度、湿度和风速等资料，采用空气动力学方法，计算了CO2通量及其与环境和人为干扰因子的关系，并分析了不同下垫面的光合作用特征. 结果表明：各种下垫面CO2通量的共同特点是：在白天，CO2通量和梯度的输送方向是从大气向植被，在中午（11～13时）输送达到负的最大值； 在夜间，CO2通量和梯度输送方向与白天相反，是从植被向大气，在早晨（3～5时）达到正的最大值. 植被覆盖率及生物量不同的下垫面光合作用强度有明显差异，天气状况对光合作用也有一定影响.     

Study of Aerodynamic Parameters on Different Underling Surfaces

Aerodynamic parameters including the zero-plane displacement (d), roughness length (20), and friction velocity (u*) on the different underlying surfaces of heavy-grazing site, medium-grazing site, light-grazing site, no-grazing site, dune, inter-dune, grassland, rice paddy site, wheat site, soybean site, and maize site have been computed based on the Monin-Obukhov similarity theory by utilizing the micrometeorologically observed data of dune and vegetation in the semi-arid area at Naiman, Inner Mongolia of China, conducted jointly by the Institute of Desert Research, Chinese Academy of Sciences and the National Institute of Agro-Environmental Sciences of Japan in 1990-1994. And their relationships between wind speed and Richardson number are analyzed. The aerodynamic characteristics of different man-made disturbed grassland ecosystems are also compared. Result shows that the vegetation coverage and the above-ground biomass decrease with the increase in man-made stress of the grassland. The roughness length for different underlying surfaces is closely related to vegetation height, above-ground biomass, and ground surface undulation, and Richardson number Ri is also its influencing factor. The friction velocity varies largely on different underlying surfaces, and it is positively proportional to wind speed and roughness length. The aerodynamic parameters of various times on the same underlying surface are different, too. Above results indicate that grassland and vegetation are of significance in preventing desertification, especially in the arid and semi-arid land ecosystems. And the results of this paper are also important for constructing the land surface physical process as well as regional climate model.     

Monitoring vegetation dynamics in semi-arid African rangelands: Use and limitations of Earth observation data to characterize vegetation structure

Vegetation community structure is a key indicator of long-term vegetation change in semi-arid ecosystems. This study uses ground-based spectral measurements and a canopy reflectance model to investigate the potential of Earth observation data to characterize variations in vegetation structure along a grazing gradient in the eastern Kalahari, Botswana. Despite differences in the bidirectional reflectances of soil, plant litter, bush and grass canopies towards the end of a dry season, it is unlikely that Earth observation data can be used to estimate vegetation structure at this time. This is due to an ambiguity in the relationship between spectral reflectance and vegetation structure caused primarily by the limited dimensionality of reflectance data. Variations in canopy architecture cause differences in the level of inter-canopy shadowing but the net effect—lower reflectance with an increase in bush cover—parallels the darkening effects of any vegetation cover on relatively bright sandy soils in semi-arid environments. These results highlight the continued need for long-term ground-based ecological monitoring in conjunction with satellite-based monitoring of changes in vegetation cover.     

First international payment for marine ecosystem services: The case of the Banc d’Arguin National Park,Mauritania

This article investigates whether the European Union-Mauritania fisheries agreement, which allocates part of the Europe's financial contribution to the conservation of marine ecosystems located within the Banc d’Arguin National Park, can be regarded as a payment for ecosystem service. A framework for qualification as such payment scheme was established based on an extensive literature review. The criteria identified for the qualification as a payment to ecosystem service pertain to: (1) the definition of the ecosystem service(s) involved; (2) the mechanism involved by the payment; and (3) the nature of the transaction. Interviews with local beneficiaries and subsequent data analysis led to the conclusion that this mechanism could be regarded as a payment to ecosystem service and so, through the European Union-Mauritania Fisheries agreement, the European Union were investing to protect local fish resources that could be exploited by its fishing fleet. This agreement, involving the first International Payment to Ecosystem Service of this kind, marks an important step towards better consideration of marine conservation in international public policy and foreign fishing policy in particular. However, this payment is small when compared to revenues generated through the exploitation of developing countries’ fishing grounds by fishing countries. Nevertheless it opens the door for more detailed applications of payment to ecosystem service schemes to other ecosystems contexts, and can provide a useful alternative source of financing of marine biodiversity conservation.     

A Linked Physical and Biological Framework to Assess Biogeochemical Dynamics in a Shallow Estuarine Ecosystem

The littoral zone of Chesapeake Bay contains a mosaic of shallow vegetated and nonvegetated habitats with biotic components that are sensitive to changes in biological and physical driving factors. Static and dynamic modelling frameworks provide an integrative way to study complex hydrodynamic and biogeochemical processes in linked estuarine habitats. In this study we describe a spatial simulation model developed and calibrated relative to a specific littoral zone, estuarine ecosystem. The model consisted of four distinct habitats that contained phytoplankton, sediment microalgae, Zostera marina (eelgrass), and Spartina alterniflora. There was tidal exchange of phytoplankton, particulate and dissolved organic carbon and dissolved inorganic nitrogen between the littoral zone ecosystem and the offshore channel. Physical exchange and biogeochemical transformations within the habitats determined water column concentrations in each habitat. Predicted subtidal water column concentrations and Z. marina and S. alterniflora biomass were within the variability of validation data and the predicted annual rates of net primary production were similar to measured rates. Phytoplankton accounted for 17%, sediment microalgae 46%, the Z. marina community 24% and S. alterniflora 13% of the annual littoral zone primary production. The linked habitat model provided insights into producer, habitat and ecosystem carbon and nitrogen properties that might not have been evident with stand-alone models. Although it was an intra-ecosystem sink for particulate carbon, the seagrass habitat was a DOC source and responsible for over 30% of the littoral zone carbon and nitrogen primary production. The model predicted that the Goodwin Islands littoral zone was a sink of channel derived POC, but a source of DOC to the surrounding estuary. The framework created in this study of estuarine ecosystem dynamics is applicable to many different aquatic systems over a range of spatial and temporal scales.     

Regional oceans governance mechanisms: A review

The development of regional governance for the protection of the environment, sustainable use of natural resources and conservation of its biodiversity is unquestionably a cornerstone of international environmental law and policy. With regard to marine and coastal issues, it has mainly been taking place through Regional Seas programmes, Regional Fishery Bodies and Large Marine Ecosystems mechanisms. Based on a similar geographical approach, however, these regional mechanisms raise concerns relating to their coordination and efficiency, and possibly overlap in what they aim to achieve. This paper provides a review of existing regional oceans governance mechanisms, assessing their individual and collective capacities to move towards ecosystem-based management, and highlighting options to make the regional landscape more coherent and effective.     

Ballast water management in Canada: A historical perspective and implications for the future

Non-indigenous species (NIS) can create significant risks when introduced to foreign ecosystems. One of the many vectors facilitating the global transport of NIS is ballast water, and as commercial shipping increases so does the threat of ballast water-mediated introductions. Despite Canadian regulations, consistent with international guidelines put forth by the International Maritime Organization in the early 1990s, ballast water remains a potential vector for the introduction of many NIS to Canadian marine ecosystems: there have been no new introductions in the Laurentian Great Lakes Region since 2006, yet marine ecosystems continue to see the introduction and establishment of NIS. This paper details and analyzes the development of Canadian ballast water management (BWM), in the context of marine ecosystems, and identifies issues therein. BWM in Canada has a number of management gaps that have persisted since large-scale BWM began in the late 1980s. These include BWM exemptions for vessels not exiting the North American continental shelf, and limitations of effectiveness of mid-ocean exchange as the predominant management method in marine ecosystems. In addition, ballast water regulations for the Canadian Arctic may require additional consideration as the Arctic will likely continue to see an increase in both warming and commercial shipping in the future, thereby increasing the potential risk of NIS. In order to adequately protect all Canadian marine ecosystems, it is recommended that the current BWM regime: fill gaps in management to help prevent further introduction and spread of NIS; focus equally on both marine and freshwater regions, and; look to other aggressive BWM strategies such as those being developed by the state of California.     

河流生态系统结构功能整体性概念模型

在完善与整合现有河流生态系统结构功能概念及模型的基础上,提出河流生态系统结构功能整体性概念模型。水文情势、水力条件和地貌景观格局是对河流生态系统结构与功能具有关键影响的3大生境要素,结构功能模型的核心是建立以3大生境要素为构架的生命支持系统与河流生命系统之间的相互作用和相互制约关系,同时考虑由于人类活动引起生境要素变化对于河流生态系统的影响。河流生态系统结构功能整体性概念模型由以下4种模型组成:河流四维连续体模型、水文情势-河流生态过程耦合模型、水力条件-生物生活史特征适宜模型以及地貌景观空间异质性-生物群落多样性关联模型,这4种模型的一体化整合,基本概括了河流生态系统结构功能的整体特征。     

地下水-陆生植被系统研究评述

依赖于地下水的生态系统广泛分布,潜水含水层本身是个生态系统,地下水不仅维持许多水生生态系统,而且是干旱-半干旱地区陆生植被生存的重要水源。研究地下水与植被的相互联系是生态水文地质学的主要组成部分,重点介绍地下水-植被系统的研究方法。植被吸收的地下水量占总蒸腾量的比例是评价植被依赖地下水程度的一个定量指标,蒸腾量比例呈季节性与区域性变化,取决于植被类型、地下水位埋深与动态变化、土壤岩性与气候条件。植被总蒸腾量可以用涡流相关系统测量。地下水的蒸腾量可以用植物茎流计测量,或者用地下水位昼夜变化估算。用同位素混合模型也能估算地下水占总蒸腾量的比例。植被对地下水位下降的响应可能有两种形式,一种是线性比例响应,另一种是临界突变响应,只有通过长期系统观测植被长势与地下水位的变化才能利用统计分析建立两者响应关系。目前,植被-水文模型只能模拟植被冠层截流与蒸腾对土壤水与地下水的影响,或者模拟土壤水-地下水对植被生长的影响,地下水与植被相互作用与反馈的耦合模型还是个空白。     

欧美地下水有机污染调查评价进展

1999年中国地质调查局启动了第一个地下水有机污染调查项目,当时检测指标只有20个(包括11个挥发性有机污染物、8种有机氯农药和1种多环芳烃)。"十一五"的地下水有机污染调查必测项目包含了38项(挥发性指标28项、有机氯农药9项和1种多环芳烃),取得了地下水有机污染的基本资料。但从对国外文献的调研来看,地下水中有机污染的种类远远超过38种。为了更全面地掌握中国地下水的质量,有必要对不同地区或不同类型的地下水中典型的有机污染物的种类进行研究,为后续地下水有机污染调查的增项做准备。通过检索美国环保局(USEPA)、美国地质调查局(USGS)和欧盟(EU)近年来的地下水质量年度报告和相关文献,调研了地下水中典型有机污染物的类型,选出最常检出的有机污染物,形成最常检出的有机污染物的检出率排序表,列出了检出率高的前50个污染物的名单。