Biodiversity or biological diversity, is defined as the variety of species and the variability of living or-ganisms, their habitats and the biological ecosystems, encompassing the ecological and evolutionary proc-esses of the natural environment. Biodiversity is the wealth of species ecosystems and ecological proc-esses that help make possible the economic and envi-ronmental systems. Mankind depends on earth抯 bio-diversity for food, fiber, medicines and new products. The loss of biodiversity is one of the major threats to the world抯 ecosystems in the 21st century. Eco-system processes are strongly affected by biodiversity, but the functional relationship between the two de-pends on the system considered<1, 2>. In all cases, however, processes must be maintained so that the ecosystem can continue to exist in either a constant or a changing environment. Functional redundancy of similar species may stabilize ecosystem processes during occasional species extinctions<3>, but this abil-ity appears to be limited<4>. Changes in ecosystem processes may themselves lead to a decline in biodi-versity and thus to further reductions in ecosystem function. Terrestrial ecologists has always given at least of the soil. But only recently have they begun to un-derstand that soil biodiversity is a crucial factor in regulating how ecosystems function. Over the past few years, ecologists have realized that many of the most important interactions between plants take place below ground, particularly in the third of the world抯 soils that are poor in nutrients. In such soils, the dynamic interactions between plant roots, animals and microbial processes seem to de-termine what grows where and how. As ecologists have begun to pick up their shovels, they have been faced with a huge challenge: a single cubic metre of temperate grassland soil contains thousands of species of microorganisms and inverte-brates whose identities and activities are largely un-known. There is ecology that is as complex as any of the community and ecosystem ecology that has been studied above ground. Studies<5> show that plant species richness and plant functional diversity have a positive influence on overall catabolic activity and catabolic diversity of the culturable bacterial community in the bulk soil in an experimental grassland ecosystem. Although these bacterial represent only a small fraction of taxa pre-sent in the soil, there are a useful indicator group for measuring the effects of the autotrophic plant com-ponents on the bacterial decomposers in such a sys-tem. The increased oxidation of the C sources sup-plied reflects an increased bacterial density<6> while the increase in catabolic diversity reflects the use of different carbon-oxidation pathways and therefore functional diversity<7>. It is unlikely that a single genotype or low-level taxonomic unit could express so much plasticity in C-source utilization, and this functional diversity is therefore probably related to taxonomic diversity<6~8>. However, plants show re-dundancy among taxa within functional groups, and a similar situation may exist within bacterial communi-ties, so that functional diversity would provide a minimum estimate of taxonomic diversity. Catabolic activity and catabolic diversity of cul-turable soil bacteria increased linearly with the loga-rithm of plant species number and with the number of plant functional groups<5>. These effects may have material and energy flows to the soil. They may also have been mediated by increased diversity of soil mi-crohabitats via a stimulation of the soil fauna. Earth-worms are decomposes of dead plant material. They and other macrofauna mix organic material in the soil, reduce the size of the detritus particles and made them available to microbes. Micro- and mesofauna feed on microbes and thereby increase microbial turnover and plant nutrient availability. A reduction in plant biomass caused by a loss in plant diversity is expected to have strong effects
More abstracts about the 植物多样性对土壤微生物的影响(英文)