Root allocation and multiple nutrient limitation in the New Jersey Pinelands

Abstract

Abstract Current understanding of the effects of resource stress on plant communities emphasizes the adaptive integration of multiple limiting factors, but it has been difficult to directly demonstrate the fundamental assumption of the adaptive control of limitation. One model predicts a positive correlation between optimal allocation to the uptake of each resource and growth response to enrichment of that resource. Here we report a test of this prediction by a fertilization experiment in the New Jersey Pinelands Biosphere Reserve where limitation was measured by growth response to nutrient enrichments, and allocation was measured by root proliferation in microsites enriched by those same nutrients. Results suggest that a stand of regenerating Pinus echinata Mill. (shortleaf pine) was jointly limited by nitrogen and potassium, with a possible small effect of phosphorus. Root allocation was proportional to growth response, which supports the assumption of adaptive control of limitation.