Nutrient dependent effects of consumer identity and diversity on freshwater ecosystem function

1. Over the past decade, ecologists have tried to determine how changes in species composition and diversity affect ecosystem structure and function. Until recently, the majority of these studies have been conducted in terrestrial ecosystems and have not taken into account environmental variability. The purpose of this research was to determine how species identity and diversity in the freshwater zooplankton affected biomass of algae and zooplankton at two levels of nutrient enrichment.
2. Several species of cladocerans were grown alone and together in microcosms at both ambient and raised phosphorus concentrations to determine if the effects of consumer identity and diversity were nutrient dependent.
3. Total zooplankton biomass was greater, while algal biomass was lower, in mixed culture than in monoculture. The effects of zooplankton diversity on algal biomass, however, were only observed at raised phosphorus concentrations, suggesting that diversity effects were nutrient dependent. Specifically, diversity effects appeared to be related with biological mechanisms such as complementarity in resource use and/or facilitation.
4. More diverse communities of zooplankton appear to be better able to control algae than single species of zooplankton at high nutrient concentrations; therefore, zooplankton diversity may provide a buffer against eutrophication in freshwater ecosystems.     

试论土壤线虫多样性在生态系统中的作用

土壤线虫的物种多样性和功能群丰富, 不同功能群的土壤线虫取食习惯也不一样, 而土壤线虫取食习惯的多样性以及它们自身的一些属性决定了它们在土壤中与其他生物之间关系的复杂性。土壤中不同生物之间的相互作用决定了土壤食物网的复杂性, 进而影响着土壤生态系统功能。然而, 有关土壤线虫的多样性与土壤生态系统功能之间的关系的研究还很不足。要全面了解土壤线虫在生态系统中的作用, 研究工作必须: (1) 结合室内模拟和野外控制实验; (2) 结合物种多样性调查和不同功能群的功能分析。     

群落水平食物网能流季节演替特征

稳定碳、氮同位素比值分析技术是研究生态系统中物质循环与能量流动的有效技术.δ13C可以用来判断食物网中不同生物的能量来源;δ15N主要用于确定生物在食物网中所处的营养位置.通常用δ13C—δ15N图来表征某一特定时间或空间的食物网结构,但是这种方法在比较不同时间和空间食物网结构中功效较差.同时这种定性描述食物网结构也无法满足食物网复杂变化下的假说验证.应用环形统计方法,以太湖梅梁湾鱼类群落为例,定量评价了群落水平食物网能流季节演替特征.结果表明太湖梅梁湾鱼类营养生态位移动的季节特征明显.进一步物种水平分析结果表明,各种鱼类角度和幅度随季节均有变化.Rayleigh检验结果表明,群落中不同种类在秋冬、冬春和夏秋均有显著的一致的方向变化;而春夏期间不显著.Watson-William检验结果表明,群落水平的鱼类营养生态位移动在秋冬和冬春季节转换中有显著差异.引起鱼类群落水平营养生态位在食物网空间中季节性移动的主要因素为可利用资源稳定同位素的季节变化和不同鱼类种群自身的食性季节性转变.同时,由于梅梁湾食物网鱼类群落杂食性水平高,季节性浮游初级生产力成为食物网能量流动的重要驱动作用.因此,在富营养化生态系统中,食物网群落水平营养生态位季节波动也暗示了系统稳定性的下降.定量评价食物网变化有助于认识和理解食物网结构与功能在生态学和生态系统管理等方面的重要.     

The NSW Environmental Services Scheme: Results for the biodiversity benefits index, lessons learned, and the way forward

Summary   In 2002 the Environmental Services Scheme (ESS) was launched in New South Wales, Australia. Its aim was to pilot a process to provide financial incentives to landholders to undertake changes in land use or land management that improved the status of environmental services (e.g. provision of clean water, healthy soils, biodiversity conservation). To guide the direction of incentive funds, metrics were developed for use by departmental staff to score the benefits of land use or land management changes to a range of environmental services. The purpose of this paper is to (i) report on the development of one of these metrics – the biodiversity benefits index; (ii) present the data generated by field application of the metric to 20 properties contracted to the ESS; and (iii) discuss the lessons learned and recent developments of the metric that aim to make it accessible to a wider range of end-users and applications.     

Biocontrol potential varies with changes in biofuel–crop plant communities and landscape perenniality

We examined the potential local‐ and landscape‐level impacts of different biofuel production systems on biocontrol, an important service provided by arthropod natural enemies. Specifically, we sampled natural enemies with sweep nets and measured predation of sentinel pest eggs in stands of corn, switchgrass and mixed prairie in Michigan and Wisconsin (total n=40 for natural enemy sampling, n=60 for egg predation), relating them to crop type, forb cover and diversity, and the composition and heterogeneity of the surrounding landscape. Grasslands with intermediate levels of forb cover and flower diversity supported two‐orders of magnitude more natural enemy biomass, fourfold more natural enemy families, and threefold greater rates of egg predation than corn. Data suggest this was in part due to a general increase in biomass, richness and predation in perennial grasslands compared with corn, combined with a positive effect of intermediate levels of forb cover and flower diversity. Specifically, natural enemy biomass and family richness showed hump‐shaped relationships to forb cover that peaked in sites with 5–25% forbs, while egg predation increased with floral diversity. At the landscape scale, both natural‐enemy biomass and egg predation increased with the area of forest in the landscape, and egg predation almost doubled as the area of herbaceous, perennial habitats within 1.5 km of study sites increased. Our results suggest that floristically diverse, perennial grasslands support diverse and abundant predator communities that contribute to natural pest suppression. In addition, large‐scale production of biofuel crops could positively or negatively affect biocontrol services in agricultural landscapes through associated changes in the area of perennial habitats. Biofuel landscapes that incorporate perennial grasslands could support a variety of beneficial organisms and ecosystem services in addition to producing biomass.     

生态系统服务的生态学机制研究进展

全面认识和理解生态系统服务的生态学机制是加强生态系统服务功能管理的前提,但目前从生态系统服务的生态学机制研究中提供给管理者的信息还非常有限.针对生态系统服务功能的物质基础(生境、生态系统结构和生态系统过程),目前生态系统服务的生态学机制研究主要集中在3个方面:生物多样性与生态系统服务功能关系;生态系统服务功能的时空尺度特征;气候和土地利用变化对生态系统服务功能的影响机制.在综述上述3方面进展的基础上,提出了今后的研究方向.     

Biodiversity in the context of ecosystem services: the applied need for systems approaches

Recent evidence strongly suggests that biodiversity loss and ecosystem degradation continue. How might a systems approach to ecology help us better understand and address these issues? Systems approaches play a very limited role in the science that underpins traditional biodiversity conservation, but could provide important insights into mechanisms that affect population growth. This potential is illustrated using data from a critically endangered bird population. Although species-specific insights have practical value, the main applied challenge for a systems approach is to help improve our understanding of the role of biodiversity in the context of ecosystem services (ES) and the associated values and benefits people derive from these services. This has profound implications for the way we conceptualize and address ecological problems. Instead of focusing directly on biodiversity, the important response variables become measures of values and benefits, ES or ecosystem processes. We then need to understand the sensitivity of these variables to biodiversity change relative to other abiotic or anthropogenic factors, which includes exploring the role of variability at different levels of biological organization. These issues are discussed using the recent UK National Ecosystems Assessment as a framework.     

陆地生态系统服务与生物多样性研究进展

在生物多样性迅速消失的压力下,人类面临生态系统服务质量严重下降的威胁。为了使生态系统的重要功能更直观的展现在人们面前,许多学者把生态系统服务对人类的惠益进行整理分类,最有影响力的是千年生态系统评估(MA,Millennium Ecosystem Assessment)把生态系统服务分为供给、调节、文化和支持服务四类,服务的核心是生态系统的产品、过程和格局。生态系统服务的识别与分类是生态系统功能的对象化过程,也是以人类需求来审视生态系统的过程。生态系统通过结构-过程-功能这一途径来实现生态系统服务,各种服务的直接动力来源于自然界生物地球化学循环,生物多样性通过生态系统属性和过程来影响生态系统服务形成和维持。生物多样性越高,生态系统功能性状的范围越广,生态系统服务质量就越高、越稳定。全球变化中的土地利用和土地覆盖变化是生物多样性快速下降的主要原因,也是目前影响生态系统服务最广泛、最剧烈的驱动力,而这正是人类活动造成的,人类需求和生态系统有限的服务能力之间在不同尺度表现出严重冲突。要提高生态系统服务质量,要在不同区域进行重点不同的布局,尽可能的扩大生态系统规模和提高生态系统功能,核心是提高生物多样性水平。     

Exclusion of agricultural lands in spatial conservation prioritization strategies: consequences for biodiversity and ecosystem service representation

Agroecosystems have traditionally been considered incompatible with biological conservation goals, and often been excluded from spatial conservation prioritization strategies. The consequences for the representativeness of identified priority areas have been little explored. Here, we evaluate these for biodiversity and carbon storage representation when agricultural land areas are excluded from a spatial prioritization strategy for South America. Comparing different prioritization approaches, we also assess how the spatial overlap of priority areas changes. The exclusion of agricultural lands was detrimental to biodiversity representation, indicating that priority areas for agricultural production overlap with areas of relatively high occurrence of species. By contrast, exclusion of agricultural lands benefits representation of carbon storage within priority areas, as lands of high value for agriculture and carbon storage overlap little. When agricultural lands were included and equally weighted with biodiversity and carbon storage, a balanced representation resulted. Our findings suggest that with appropriate management, South American agroecosystems can significantly contribute to biodiversity conservation.     

土地利用变化对生态系统服务功能的影响——以密云水库流域为例

生态系统服务功能与人类福利息息相关,土地利用变化是生态系统服务功能退化的主要驱动力之一,以人地关系紧张,生态系统服务功能变化剧烈的密云水库流域为对象,分析流域1990-2009年土地利用的变化,采用空间显式的生态系统服务功能评估软件InVEST中的“产水量”、“土壤保持”、“水质净化”模型,研究流域土地利用变化对生态系统服务功能的影响.结果表明1990-2009年密云水库流域土地利用变化剧烈,农田、草地和水体的面积分别减少了30％、48％、61％,林地、建筑用地和裸地的面积增加,增幅分别为30％、230％、282％.随着土地利用变化,生态系统服务功能相应产生着显著变化,研究期内,土壤保持功能和固碳服务分别增加46％和19％,但水资源供给服务和水质净化功能分别减少了3％和25％.农田面积的减少和森林的扩张改善了土壤保持服务,森林面积的增加同时也改善了固碳服务,但会削弱水资源供给服务,建筑用地的扩张会大幅度削弱水质净化功能,为维持和改善流域整体的生态系统服务功能,应加强对森林和建筑用地的控制.其研究为密云水库流域土地利用科学管理决策提供参考.     

What do Israeli high school students understand about biodiversity? An evaluation of the high school biology programme, ‘Nature in a World of Change’

One of the most serious problems facing our planet is the biodiversity crisis. As a solution to this problem, both scientists and educators have emphasised the need for educating people about how to conserve the Earth’s biodiversity. As a small contribution to this effort, we have designed a learning unit about biodiversity, Nature in a world of change, which has recently been implemented with 74 12th-grade Israeli high-school biology students. This unit consists of two components: an introductory module and a collection of three articles adapted from the primary scientific literature. This paper focuses on an in-depth examination with 25 students participating in the programme’s implementation. The evaluation process includes a self-assessment of prior basic ecological knowledge and a post-test focusing on concepts and issues central to the understanding of biodiversity, such as niche and Simpson’s Index. Analysis of perturbations in a food web (by an invasive species) was a special focus of the assessments, reflecting similar concerns prevalent among the scientific community. The results of this evaluation revealed that students with a solid ecological background could successfully deal with the newly acquired concepts presented in the module and the articles.     

Terrestrial models and global change: challenges for the future

A wide variety of models have illustrated the potential importance of terrestrial biological feedbacks on climate and climate change; yet our ability to make precise predictions is severely limited, due to a high degree of uncertainty. In this paper, after briefly reviewing current models, we present challenges for new terrestrial models and introduce a simple mechanistic approach that may complement existing approaches.