Herbivore regulation of plant abundance in aquatic ecosystems

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small‐scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta‐analysis of the outcomes of plant–herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between‐taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore–plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with greater reductions in plant abundance compared with invasive herbivores and invasive plants, native herbivores and invasive plants, native herbivores and mixed‐nativeness plants, and native herbivores and native plants. By contrast, assemblages comprised of native herbivores and invasive plants were associated with lower reductions in plant abundance compared with both mixed‐nativeness herbivores and native plants, and native herbivores and native plants. However, the effects of herbivore–plant nativeness on changes in plant abundance were reduced at high herbivore densities. Our mean reductions in aquatic plant abundance are greater than those reported in the literature for terrestrial plants, but lower than aquatic algae. Our findings highlight the need for a substantial shift in how biologists incorporate plant–herbivore interactions into theories of aquatic ecosystem structure and functioning. Currently, the failure to incorporate top‐down effects continues to hinder our capacity to understand and manage the ecological dynamics of habitats that contain aquatic plants.     

辽宁省菜田生态系统组分优势值与系统优势度分析

辽宁省菜田生态系统组分优势值与系统优势度分析周宝利，葛晓光李宁义（沈阳农业大学园艺系，１１０１６１）（沈阳市城建中专，１１００１３）ＡｎａｌｙｓｉｓｏｎＳｕｐｅｒｉｏｒｉｔｙＶａｌｕｅａｎｄＤｏｍｉｎａｎｃｅＤｅｇｒｅｅｏｆＶａｒｉｏｕｓＣｏｍｐｏｎ...     

Evaluation method for coalmining-based cities ecosystem based on attribute mathematical model with Huainan City as an example

Attributive recognition model of coalmining-based cities ecosystem classification is developed in terms of attributive mathematical theory. Based on the analysis of main causes of coalmining-based cities ecosystem, the city vitality, city structure strength, city resilience ability, service functions and health status are chosen as the criterion indicators of coalmining-based cities ecosystem classification; the attributive measurement functions are constructed to compute the attributive measurement of single indicator and multi-indicator; and the synthetic attributive measurement is calculated by the AHP; the health classification of cities ecosystem are recognized by the confidence criterion. An empirical analysis is made by the proposed model and method, the synthetic evaluation results are better than fuzzy comprehensive evaluation method which validates the proposed model feasible, effective and reliable in coalmining-based cities ecosystem classification. As attributive recognition theory can success fully resolve certain issues with a number of fuzzy attribution in comprehensive evaluation, its confidence criterion is established on the basis of the ordered evaluation sets, consequently it will make the evaluation results more reliable.     

Evaluating regional water security through a freshwater ecosystem service flow model: A case study in Beijing-Tianjian-Hebei region,China

Freshwater ecosystem service is essential to human’s survival and development. Many studies have documented the spatial differences in the supply and demand of ecosystem services and proposed the concept of ecosystem services flows. However, few studies characterize freshwater ecosystem service flow quantitatively. Therefore, our paper aims to quantify the effects of freshwater ecosystem service flow on downstream areas. We developed a freshwater ecosystem service flow model and applied it in the Beijing–Tianjin–Hebei (BTH) region, China, for the year of 2000, 2005, and 2010. We assessed the regional water security with an improved freshwater security index by integrating freshwater service provision, consumption and flow; and found that most areas of the BTH region (69.2%) were affected by upstream freshwater flows. The areas achieving water security in the region also expanded to 66.9%, 66.1%, and 71.3%, which were 6.4%, 6.8% and 5.7% increments compared to no-flow situation, in 2000, 2005 and 2010, respectively. Setting quota for human water consumption is suggested to further improve water security. These results highlight the need to fully understand the connections between distant freshwater ecosystem service provision and local freshwater ecosystem service consumption. This approach may also help managers to choose more sustainable strategies for critical freshwater resource management across different regions.     

Mismatches between supply and demand in wildlife tourism: Insights for assessing cultural ecosystem services

Assessing cultural ecosystem services provided by biodiversity requires a combination of ecological and social approaches. In this study, we investigated the capacity of large African mammal species to provide the cultural ecosystem service of wildlife tourism by using a supply and demand framework. First, we tested the relationship between supply and demand for large mammal species in wildlife tourism. Second, we tested whether the trophic level and body size of mammals influenced the mismatch between supply and demand, and whether the patterns of mismatches were consistent among four protected areas (PAs) in three Southern African countries. To quantify supply of species, we counted large mammals along 196 five km road transects within the four PAs; to estimate demand, we gathered 651 face-to-face questionnaires of wildlife tourists and distinguished between their expectation and hope to see specific species. Results show that a higher supply of large mammal species increased the expectation to see a species (linear regression slope β = 0.28, p < 0.01), whereas supply did not affect the hopes to see a specific species (β = −0.04, p = 0.63). Analyses of mismatches revealed that predator species were more demanded in relation to their supply than ungulates. Finally, we found that the demands of wildlife tourists for mammal species in relation to their supply were consistent across the four PAs. Supply-demand analyses reveal that species’ traits, in particular trophic level, shape the hopes of wildlife tourists to see specific mammal species. We propose that the quantification of supply-demand mismatches can be used to identify charismatic species and relevant species’ traits, and can be applied for wildlife tourism assessments within as well as across regions. Supply-demand analyses provide a useful framework and deliver indicators for better assessing cultural ecosystem services involving wildlife and nature-based tourism, and can be used for conservation management.     

江西高天岩自然保护区生态系统服务功能价值评估

高天岩自然保护区位于江西省莲花县,为当地人提供了多项生态服务功能。根据高天岩自然保护区生态与社会经济系统的特征,构建其生态系统服务功能价值评估指标体系,并以2014年数据为基础,综合运用成本替代、市场价值、影子工程、造林成本、成果参数和旅行费用等定量分析方法,评估其生态系统的经济价值。结果表明:2014年,高天岩自然保护区生态系统服务总经济价值为7.20×10~8元,其中,土壤保持和固碳释氧的经济价值居前两位,分别为4.39×10~8元和1.16×10~8元,各占服务总经济价值的60.89%和16.11%。9项服务指标按评估的经济价值大小排序为:土壤保持固碳释氧产品供给生物多样性保护环境净化气候调节旅游休憩调洪蓄水社会保障。直观的经济数字反映了高天岩自然保护区生态系统对人类社会的重要贡献,一方面有利于强化管理者和公众保护高天岩自然保护区的意识,另一方面为政府制定高天岩自然保护区生态系统补偿标准提供数据支撑。     

海洋可持续发展目标与海洋和滨海生态系统管理

海洋和海岸带可以为人类提供多种生态系统服务,保护与持续利用海洋资源以促进海洋和海岸带可持续发展已被正式纳入联合国可持续发展目标。实施海洋可持续发展目标面临几大挑战,包括如何减小陆基人类活动的影响、加强海岸带的综合管理、提高海洋资源效率、适应气候变化和提高沿海居民的人类福祉等。为应对这些挑战,需要将海洋和海岸带融合为一个大型生态系统,利用基于生态系统的管理方法,综合考虑各个部门和多种胁迫因素的累积影响,通过建立综合的海洋观测体系,合理划分海洋功能区,按照海洋环境承载力限制陆基人类活动,合理配置并有效利用海洋资源,提升海洋和海岸带生态系统的整体服务功能,从而进一步推进实施海洋可持续发展目标。     

Tropical terrestrial invertebrates—Where to from here?

There are over one million described invertebrate species on Earth, the majority of which are likely to inhabit the highly biodiverse rain forests around the equator. These are some of the most vulnerable ecosystems on Earth due to the pressures of deforestation and climate change with many of their inhabitants at risk of extinction. Invertebrates play a major role in ecosystem functioning from decomposition and nutrient cycling to herbivory and pollination; however, while our understanding of these roles is improving, we are far from being able to predict the consequences of further deforestation, climate change, and biodiversity loss due to the lack of comparative data and the high proportion of species which remain to be discovered. As we move into an era of increased pressure on old-growth habitats and biodiversity, it is imperative that we understand how changes to invertebrate communities, and the extinction of species, affect ecosystems. Innovative and comprehensive methods that approach these issues are needed. Here, we highlight priorities for future tropical terrestrial invertebrate research such as the efficiency of sustainable land management, exploration of innovative methods for better understanding of invertebrate ecology and behavior, and quantifying the role of invertebrates in ecosystem functioning.