西北干旱区荒漠生态系统通量贡献区模型研究

涡度相关仪通量值所代表的通量贡献区范围,对于通量观测塔的选址、仪器安装高度的确定以及通量观测数据的质量控制等具有重要的指导意义。利用通量贡献区模型对位于古尔班通古特沙漠试验场通量观测资料的空间代表性进行初步分析。结果表明：该荒漠区在大气稳定条件下90%的通量贡献区最远可以达到686.40 m,通量贡献函数最大点的位置在162.50 m;大气稳定时各风向的通量贡献区范围在生长末期均达到最大,生长初期和中期的源区变化因受到各风向风速和植被下垫面的影响而有差异;大气不稳定时不同生长时期各风向通量贡献区没有固定变化规律;通量源区大约有58.71%的信息来自于荒漠区通量观测塔西南至西北方,整个生长季生长末期通量贡献最多,所占比例为40.16%。由FSAM模型测得的通量贡献区范围可以较准确地反映荒漠生态系统下垫面的通量信息。     

传统农林复合系统:一种全球重要文化遗产类型(英文)

作为一种土地利用活动,传统农林复合系统已经经历了成百上千年的历史,并且依然发挥着重要的作用在世界上,特别是热带和亚热带地区。在全球变化和粮食安全等危机的时代背景下,传统农林复合系统受到越来越多政府和非政府组织的重视,因为传统农林复合系统具有重要的经济、生态和社会文化效益。这与全球重要农业文化遗产要求的特征也相一致,目前为止,已经有5个国家4个典型的传统农林复合系统被列为全球重要农业文化遗产。这些传统农林复合系统具有丰富的农业生物多样性,多重的生态系统服务功能,重要的社会文化价值,无论在区域还是全球水平上。目前传统农林复合系统面临一些威胁和挑战,如人口迁移、市场冲击、气候变化等,但是只要政府和非政府组织、社区、农民之间采取多种方式紧密合作,在未来的全球土地利用活动中,传统农林复合系统必将得到有效保护和推广。     

Influences of alpine ecosystem degradation on soil temperature in the freezing-thawing process on Qinghai–Tibet Plateau

The alpine ecosystem is very sensitive to environmental change due to global and local disturbances. The alpine ecosystem degradation, characterized by reducing vegetation coverage or biomass, has been occurring in the Qinghai–Tibet Plateau, which alters local energy balance, and water and biochemical cycles. However, detailed characterization of the ecosystem degradation effect is lack in literature. In this study, the impact of alpine ecosystem degradation on soil temperature for seasonal frozen soil and permafrost are examined. The vegetation coverage is used to indicate the degree of ecosystems degradation. Daily soil temperature is monitored at different depths for different vegetation coverage, for both permafrost and seasonal frozen soils. Results show that under the insulating effort of the vegetation, the freezing and thawing process become quicker and steeper, and the start of the freezing and thawing process moves up due to the insulating effort of the vegetation. The influence of vegetation coverage on the freezing process is more evident than the thawing process; with the decrease of vegetation coverage, the integral of frozen depth increases for seasonal frozen soil, but is vice versa for permafrost.     

草地生态系统土壤有机碳库对人为干扰和全球变化的响应研究进展

草地土壤碳库碳储量及其变化与调控机制是草地碳循环研究的核心.草地生态系统正经受着越来越严重的人为与自然因素干扰,如土地利用变化、大气氮沉降增加、施肥及大气CO2浓度与温度升高.因此,加强人为干扰和全球变化背景下草地土壤有机碳库的响应研究有重要意义.总结了放牧、草地开垦及外来氮素输入等3种主要的人类活动对土壤有机碳总量和活性碳组分的影响及其对全球变化的响应与适应,在此基础上指出了目前草地生态系统土壤有机碳库研究的薄弱环节及今后的重点研究领域.     

亚洲通量观测网建立的回顾与展望

1IntroductionTheelucidationofthebudgetsofcarbon,waterandothermassesatvariouslandecosystemshasbecomeanimportantsubjectintheglobalwarmingissue.Forthisstudy,thedatafrompreciseandlong-termobservationsofcarbondioxide,watervapor,andheatfluxtakeninvariouslandsur…     

Tidal exposure or microhabitats: what determines sandy‐beach nematode zonation? a case study of a macrotidal ridge‐and‐runnel sandy beach in Belgium

Lately, across‐shore zonation has been found to be more important in structuring the nematode community of a tropical macrotidal sandy beach than microhabitat heterogeneity. To evaluate whether this zonation pattern applies to a temperate beach, a macrotidal ridge‐and‐runnels sandy beach in the North Sea was studied. We investigated whether a similar zonation occurs in sandbar and runnel microhabitats, and whether the runnels harbour a different community from the subtidal. Our results indicate that nematode communities from runnel and sandbar habitats are significantly different. In addition, horizontal zonation patterns for nematode communities differ between both habitats. Nematode assemblages from sandbars are divided to lower, middle and upper beach while upper and middle runnels cluster together. The subtidal and upper runnels showed dissimilar nematode assemblages, although runnels showed the same dominant species (Daptonema normandicum), which increases its abundance towards the upper runnels. This study illustrates the importance of microhabitat heterogeneity, which resulted in different zonation patterns across the sandy beach examined. The divergent zonation between sandbars and runnels in the macrotidal temperate sandy beach, compared with the pattern observed for a subtropical sandy beach with similar morphodynamics, indicates that generalizations about nematode distribution patterns should be made with caution.     

Assessing the ecosystem effects of the abalone Haliotis midae from its diet and foraging behaviour

The South African abalone Haliotis midae is commercially exploited and seriously threatened by overfishing. This not only affects the species itself but potentially the functioning of the ecosystem because of associated changes in community structure. The nature of effects that can follow the loss or reduction of a species depends in part on its position in the foodweb and its feeding behaviour. To assess the ecosystem effects of the adults and subadults of this previously abundant herbivore on the south-west coast of South Africa, we studied their diet and mode of food procurement by (a) in-field observations of adult and subadult abalone, (b) analysis of the gut contents of adults, (c) comparison of diet with the availability of algae, and (d) a mesocosm experiment on subadult feeding behaviour. Both field and dietary studies showed that adults subsist mainly by trapping drift kelp, but also occasionally graze on attached algae such as Plocamium spp., and feed in a manner that is highly selective, with drift kelp constituting 95–98% of the diet, and several species of common algae being avoided. In the mesocosm experiment, subadults preferentially fed on drift kelp, but emerged at night to a greater extent to graze on microflora if no drift material was available. Their propensity to emerge was, however, reduced if the rock lobster Jasus lalandii was present. Collectively, this evidence indicates that any ecosystem effects that subadults and adults of H. midae have as grazers will be weak because they feed mainly by trapping drift material, and the frequency of grazing and the incidence of consumption of attached algae are low.     

Mussel reefs on soft sediments: a severely reduced but important habitat for macroinvertebrates and fishes in New Zealand

Green-lipped mussels (Perna canaliculus) formed extensive reefs on soft sediments in sheltered embayments around northern New Zealand until overfishing and/or increased sediment input caused their virtual disappearance by 1980. To determine the role of mussel reefs as habitat for other animals, we located remnant soft-sediment reefs in five locations and compared the density, biomass, productivity and composition of mobile macroinvertebrate communities, and the density of small fishes associated with mussels, with fauna in the surrounding soft sediments. The mussel reefs had a distinct assemblage of macroinvertebrates, which had 3.5 times the density, 3.4 times the biomass and 3.5 times the productivity of surrounding areas. The density of small fishes was 13.7 times higher than in surrounding areas. These results show that soft-sediment mussel reefs support an abundant and productive fauna, highlighting the probable large loss of productivity associated with the historical decline in mussel habitat and the consequent desirability of restoration efforts.     

Rock warming and drying under simulated intertidal conditions,part II: weathering and biological influences on evaporative cooling and near‐surface micro‐climatic conditions as an example of biogeomorphic ecosystem engineering

The way in which rocks and engineering materials heat‐up and dry‐out in the intertidal zone is of relevance to both weathering and ecology. These behaviours can be measured in the laboratory under controlled conditions designed to replicate those occurring in the field. Previous studies have demonstrated differences in thermal behaviours between rock types and through time as a result of soiling in terrestrial environments, but the influence of weathering and colonization on rock behaviours in the intertidal zone has not been previously assessed. We measured the warming and drying of blocks of rock (limestone and granite) and marine concrete during ‘low‐tide’ events simulated in the laboratory, before and after a period of exposure (eight months) on rock platforms in Cornwall, UK. As well as differences between the material types, temperatures of control (unexposed) and field‐exposed blocks differed in the order of 1 to 2 °C. Drying behaviours were also different after field exposure. Differences during the first few hours of exposure to air and heat were attributed to discolouration and albedo effects. Over longer periods of time, changes in the availability of near‐surface pore water as a result of micro‐scale bioerosion of limestone and the development of bio‐chemical crusts on marine concrete [observed using scanning electron microscopy (SEM)] are suggested as mechanisms enhancing and reducing, respectively, the efficiency of evaporative cooling. The retention of moisture by epilithic biofilms may also influence thermal and drying behaviours of granite. These observations represent one of the first examples of cross‐scalar biogeomorphic linkages in the intertidal zone. The significance of the results for the subsequent efficiency of weathering, and near‐surface micro‐climatic conditions experienced by colonizing organisms is discussed. The involvement of microorganisms in the creation of more (or less) ecologically stressful conditions through the alteration of substratum geomorphic properties and behaviours is suggested as an example of ‘biogeomorphic ecosystem engineering’. Copyright © 2011 John Wiley & Sons, Ltd.     

基于PSR模型的滨海湿地生态系统健康评价——以辽河三角洲滨海湿地为例

以PSR评价模型为基础,选取人口、经济、环境、资源开发、政策法规和管理决策等指标,诊断和评估滨海湿地生态系统在湿地开发和环境污染等一系列人类活动干扰下的健康现状,将健康等级分为优、良好、一般、较差和极差等5级.结果表明,辽河三角洲滨海湿地生态系统健康状态一般,由于过度的围垦开发,自然湿地面积在1988～2007年间减少了11 072 hm2,其中,碱蓬湿地减少了75%(2 440 hm2),而水产养殖场增加了182%(9 359 hm2).流域及沿岸的工农业排污致使评价区域内水体污染较严重,COD、TIN、活性磷酸盐和Pb的含量分别达到3.06 mg/dm3、795.45、44.01和6.46μg/dm3,普遍为四类或劣四类水质.环境的恶化,导致碱蓬、芦苇湿地面积萎缩,鸟类种类和数量不断减少,底栖生物多样性降低.并据此提出了辽河三角洲滨海湿地的管理与保护措施.