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In a 10-year (1996-2005) biodiversity experiment, the mechanisms underlying the increasingly positive effect of biodiversity on plant biomass production shifted from sampling to complementarity over time. The effect of diversity on plant biomass was associated primarily with the accumulation of higher total plant nitrogen pools (N g m-2) and secondarily(More)
We review approaches to predicting carbon and nitrogen allocation in forest models in terms of their underlying assumptions and their resulting strengths and limitations. Empirical and allometric methods are easily developed and computationally efficient, but lack the power of evolution-based approaches to explain and predict multifaceted effects of(More)
An 11-year competition experiment among combinations of six prairie perennial plant species showed that resource competition theory generally predicted the long-term outcome of competition. We grew each species in replicated monocultures to determine its requirements for soil nitrate (R*) and light (I*). In six pairwise combinations, the species with the(More)
We present a model that scales from the physiological and structural traits of individual trees competing for light and nitrogen across a gradient of soil nitrogen to their community-level consequences. The model predicts the most competitive (i.e., the evolutionarily stable strategy [ESS]) allocations to foliage, wood, and fine roots for canopy and(More)
Almost all models of plant resource limitation are grounded in either one or both of two simple conceptual models: Liebig's Minimum Hypothesis (LMH), the idea that plants are limited by the resource in shortest supply, and the Multiple Limitation Hypothesis (MLH), the idea that plants should adjust to their environment so that all essential resources are(More)
Most explanations for the positive effect of plant species diversity on productivity have focused on the efficiency of resource use, implicitly assuming that resource supply is constant. To test this assumption, we grew seedlings of Echinacea purpurea in soil collected beneath 10-year-old, experimental plant communities containing one, two, four, eight, or(More)
Many plant communities are recruitment limited, which may occur because there are either too few seeds to fill available microsites, too few available microsites, or both. In a recruitment-limited, Minnesota, USA old field, we tested among these alternatives in a three-phase study. In phase 1, we estimated the production of late-successional forb and C4(More)
Numerous observational studies have documented conspecific negative density-dependence that is consistent with the Janzen–Connell Hypothesis (JCH) of diversity maintenance. However, there have been few experimental tests of a central prediction of the JCH: that removing host-specific enemies should lead to greater increases in per capita recruitment in(More)
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