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Interannual variability in aboveground net primary production (ANPP) was assessed with long-term (mean = 12 years) data from 11 Long Term Ecological Research sites across North America. The greatest interannual variability in ANPP occurred in grasslands and old fields, with forests the least variable. At a continental scale, ANPP was strongly correlated(More)
Ecosystem responses to increased variability in rainfall, a prediction of general circulation models, were assessed in native grassland by reducing storm frequency and increasing rainfall quantity per storm during a 4-year experiment. More extreme rainfall patterns, without concurrent changes in total rainfall quantity, increased temporal variability in(More)
Water availability limits plant growth and production in almost all terrestrial ecosystems. However, biomes differ substantially in sensitivity of aboveground net primary production (ANPP) to between-year variation in precipitation. Average rain-use efficiency (RUE; ANPP/precipitation) also varies between biomes, supposedly because of differences in(More)
The invasion paradox describes the co-occurrence of independent lines of support for both a negative and a positive relationship between native biodiversity and the invasions of exotic species. The paradox leaves the implications of native-exotic species richness relationships open to debate: Are rich native communities more or less susceptible to invasion(More)
uman activities have caused dramatic and unprecedented changes in the global chemical and physical environment, including well-documented increases in atmospheric carbon dioxide (CO 2) concentration and mean annual temperature (Karl and Knight 1998, New et al. 2001, IPCC 2007). If greenhouse gas emissions continue to increase at present rates, atmospheric(More)
Climate change forecasts of more frequent climate extremes suggest that such events will become increasingly important drivers of future ecosystem dynamics and function. Because the rarity and unpredictability of naturally occurring climate extremes limits assessment of their ecological impacts, we experimentally imposed extreme drought and a midsummer heat(More)
Articles T he responses of terrestrial ecosystems to global environmental change, and the resulting impacts on the natural resources on which humans depend, are topics of great societal concern and current scientific interest (Vitousek 1994). Anthropogenic emissions of greenhouse gases are expected to raise the mean temperatures of Earth's surface by 1.4°C(More)
Theoretical analyses and experimental studies of synthesized assemblages indicate that under particular circumstances species diversity can enhance community productivity through niche complementarity. It remains unclear whether this process has important effects in mature natural ecosystems where competitive feedbacks and complex environmental influences(More)
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E cology as a science began well over a century ago, when it was based primarily on observational studies (McIntosh 1985). Toward the end of the 20th century, this led to a more experimental, reductionist approach, focused on testing hypotheses and developing theories. Controlled manipulative experiments have shaped our understanding of ecological(More)