农业生态系统中生物多样性的功能--兼论其保护途径与今后研究方向

重点论述了农业生态系统中生物多样性的功能 ,其功能主要表现在害虫控制、土壤侵蚀防治、退化环境恢复、消除污染和促进养分循环等方面。探讨了农业生态系统中生物多样性的保护途径及今后应开展的研究重点。     

Effects of litter removal on plant species diversity: a case study in tropical Eucalyptus forest ecosystems in South China

The removal of litterfall in the Eucalyptus plantations in South China affected the plant biodiversity in these ecosystems was found based on the field observation and lab analysis.The protection times of species diversity of three Eucalyptus communities were different (Community Ⅰ with no protection,Community Ⅱ with 7-year-protection,Community Ⅲ with 35-year-protection).The total numbers of species in these communities(from Community Ⅰ to Ⅱ to Ⅲ)are 1,6,and 17,respectively.The tesults showed that the protection of litterfall from being taken out of the ecosystem is important and can increase plant species diversity.This study ombined biomass data,the chemical and physical properties of the soil,and the diversity of microbes in the communities.It is concluded that the mechanism of the effects of litter removal on biodiversity includes three factors:removing the suitable habitat of microbe and animal,decreasing the soil mutrient, and changing the special habitat for the germination and growth of invading plants.These results should have important implications for managing these Eucalyptus forest ecosystems in South China.     

Dominating Chemical Factors in Mine Water Induced Impoverishment of the Invertebrate Fauna of Two Streams in the Durham Coalfield, Uk

Mine water pollution is causing increasing concern in the UK as some of the world's largest and longest-worked coalfields are abandoned and flooded. Many of the resulting polluting discharges are typified by higher mineral acidity (low pH), and high concentrations of iron and sulphate. Two streams, receiving mine water discharges in the Durham coalfield in northern England, have been studied to identify the major chemical factors affecting the welfare of benthic invertebrates. One of the discharges is strongly acidic (pH 3.9), and the second is marginally acidic (pH 5.3). Simultaneous analyses of hydrochemistry and invertebrate diversity and abundance demonstrate serious faunal impoverishment downstream of minewater discharges. Pathway analysis has been applied to ascertain statistically the dominating chemical factors in this faunal impoverishment. in both cases, total acidity (acidity to pH 8.3 = 612 mg 1^-1 as CaCO³; pH 3.9) and iron concentration (up to 112.5 mg 1^-1) account for nearly all of the faunal impoverishment. Other metals, sulphate and pH (in isolation from mineral acidity) are of lesser importance. Persistence of the detrimental effects of high acidity downstream of the discharges is ascribed to a slow recovery of the carbonate buffering system. These findings assist in the implementation of long-term management and remediation strategies for mine water pollution.     

Anthropogenic threats to evolutionary heritage of angiosperms in the Netherlands through an increase in high-competition environments

Present biodiversity comprises the evolutionary heritage of Earth's epochs. Lineages from particular epochs are often found in particular habitats, but whether current habitat decline threatens the heritage from particular epochs is unknown. We hypothesized that within a given region, humans threaten specifically habitats that harbor lineages from a particular geological epoch. We expect so because humans threaten environments that dominated and lineages that diversified during these epochs. We devised a new approach to quantify, per habitat type, diversification of lineages from different epochs. For Netherlands, one of the floristically and ecologically best-studied regions, we quantified the decline of habitat types and species in the past century. We defined habitat types based on vegetation classification and used existing ranking of decline of vegetation classes and species. Currently, most declining habitat types and the group of red-listed species are characterized by increased diversification of lineages dating back to Paleogene, specifically to Paleocene-Eocene and Oligocene. Among vulnerable habitat types with large representation of lineages from these epochs were sublittoral and eulittoral zones of temperate seas and 2 types of nutrient-poor, open habitats. These losses of evolutionary heritage would go unnoticed with classical measures of evolutionary diversity. Loss of heritage from Paleocene-Eocene became unrelated to decline once low competition, shade tolerance, and low proportion of non-Apiaceae were accounted for, suggesting that these variables explain the loss of heritage from Paleocene-Eocene. Losses of heritage from Oligocene were partly explained by decline of habitat types occupied by weak competitors and shade-tolerant species. Our results suggest a so-far unappreciated human threat to evolutionary heritage: habitat decline threatens descendants from particular epochs. If the trends persist into the future uncontrolled, there may be no habitats within the region for many descendants of evolutionary ancient epochs, such as Paleogene.     

The 2010 Biodiversity Indicators: Challenges for Science and Policy

Abstract:  The 2010 biodiversity target adopted globally and in Europe is an important political commitment for improved biodiversity conservation and management. Whether or not it is achieved will be judged by a set of biodiversity indicators now under development. We reviewed the development of these indicators in Europe and globally, paying particular attention to the need to make the indicators relevant to the purpose; to distinguish between measures of pressure, state, and response; to design and validate the indicators in context; to ensure effective communication with relevant audiences; to turn lists of measures into simple or composite indicators; and to maximize the cost-effectiveness of the indicator process. We conclude that urgent steps are needed to complete the indicator set, reduce and refine the agreed measures, ensure that work is started soon so that reliable reporting occurs in 2010, and start soon on planning for subsequent assessments.     

Ecological Effectiveness of Agri-Environment Schemes in Different Agricultural Landscapes in The Netherlands

Abstract:  Agri-environment schemes are an instrument used by western European countries to counteract the negative effects of contemporary agriculture on biodiversity, but not much is known about their effectiveness. We investigated the ecological effects of Dutch agri-environment schemes aimed at promoting botanical diversity or meadow birds, and we tested whether the effectiveness of the schemes depends on landscape type or structure. In three different types of landscape, we surveyed plants, birds, bees, and hover flies on 78 paired fields that either had agri-environment schemes or were managed conventionally, and we collected data on a range of different environmental variables. Neither plant species richness nor abundance of meadow birds was higher on fields with agri-environment schemes. Landscape type had a significant effect on both species groups, but the effects of the schemes were independent of landscape type. Neither the diversity of plants nor the abundance of birds was related to any of the environmental variables. Agri-environment schemes designed to promote plant species richness or bird abundance did have positive side-effects because they enhanced the species richness of bees and hover flies, irrespective of the type of landscape. Furthermore, landscape type, groundwater level (hover flies), and area of wooded edges (bees) significantly affected both species groups. The failure of the schemes to promote the target species may be related to the high intensity of land use in The Netherlands. Simple conservation measures taken by farmers may not be sufficient to counteract the impact of factors that are often controlled at the landscape level (e.g., hydrology). Similar studies in other countries are needed to place the results of our study into a European context.     

Avian Diversity and Functional Insectivory on North-Central Florida Farmlands

Abstract:  We studied the potential for native birds to control insect pests on farms. We assessed habitat factors correlated with diversity, distribution, and insect-foraging activity of native birds on farms in north-central Florida and then characterized common bird species that consumed insect biomass in crops as "functional insectivores" (birds most likely to contribute to pest control). Analyses of point-count survey data and foraging observations collected over 2 years on paired organic and conventional farm sites indicated that (1) farms supported most (82–96%) land birds known to breed in the region; (2) bird species richness and abundance varied significantly with matrix habitat and field border type (but not with year or farm management type); (3) the highest bird abundances were associated with mixed crop plantings, field borders, and adjacent matrix composed of forest and hedge; and (4) abundances of 10 species identified as functional insectivores were primarily influenced by crop type (mixed crops attracted significantly more insect foragers into fields than monocrops). We documented birds eating pest insects in crops and did not observe substantive crop damage by birds during growing-season observations. We advocate use of the term functional insectivore to emphasize the potential positive role of avian insectivory on farms during the growing season.