1. To what extent does the diversity of a community determine (a) "stability," (b) productivity, (c) resistance to invasion or disease, and (d) ability to recover from natural and human impacts? Equally important, how do these factors interact? Do high diversity systems have higher or lower production than systems whose diversity has been impaired? What is the role of biological invasions in altering system production or energy flow?
  2. How good are the estimates of genetic, species, and ecosystem biodiversity, and how do the limitations (i.e., understanding of the scale of error) influence an understanding of biodiversity patterns and of ecosystem structure and function?

Human Impact on Processes Responsible for Biodiversity Change:

  1. What are the direct impacts on biodiversity of human-altered systems? That is, what is the variation in biodiversity over spatial and temporal scales relevant to the critical environmental issues? Examples of specific research questions are:
  • How do human influences on biodiversity differ from those caused by natural processes?
  • To what extent do human effects alter the probability of ecosystem collapse in different systems?
  • To what extent are particular changes in biodiversity due to human activities reversible?
  • Given the often direct impacts on certain target species within a region, are species within functional groups interchangeable within a system?
  • How does the addition or loss of species due to human activities affect community structure and resilience?
  1. What are the indirect impacts on biodiversity of human-altered systems? Examples of specific research questions are:
  • What characteristics of species enhance susceptibility or provide immunity to precipitous declines?
  • In what types of habitats are alternative ecological communities stable?
  • Are threshold processes involved in precipitous declines (and the persistence of these declines) in biodiversity, and, ultimately, in the risk of extinction of individual species?
  • Does genetic or species diversity provide a buffer against irreversible or massive perturbations?
  • What are the long-term effects of species replacements (e.g., exotic species) on ecosystem function?

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