Craine Joseph M, Fargione Joseph, Sugita Shinya
Environmental Studies, Dartmouth College, Hanover, NH 03755, USA.
New Phytol. 2005 Jun;166(3):933-40. doi: 10.1111/j.1469-8137.2005.01386.x.
Concentration reduction theory is the leading theory regarding the mechanism of competition for nutrients in soils among plants, yet it has not been rigorously tested. Here we used a spatially explicit, fine-scale grid-based model that simulated diffusion and plant uptake of nutrients by plants in soil to test whether concentration reduction theory was appropriate for terrestrial plant competition for nutrients. In the absence of competition, increasing the rate of diffusion allows a plant to maintain positive growth rates below the lowest average concentration to which it can reduce nutrients in soil solution (R*). As such, differences among plants in the reduction of soil moisture, which here primarily affects nutrient diffusion, can cause R* to predict competitive success incorrectly. The stronger competitor for nutrients captures the largest proportion of the nutrient supply by ensuring nutrients contact its roots before those of a competitor. Although the metric derived from concentration reduction theory, R*, might have predictive power for competitive outcomes in terrestrial ecosystems, this evidence suggests that plants outcompete other plants for nutrients by pre-empting the supply, not reducing the average concentration.
浓度降低理论是关于植物间土壤养分竞争机制的主导理论，但尚未得到严格验证。在此，我们使用了一个基于空间明确、精细尺度网格的模型，该模型模拟了土壤中养分的扩散以及植物对养分的吸收，以检验浓度降低理论是否适用于陆生植物对养分的竞争。在没有竞争的情况下，提高扩散速率能使植物在低于其能将土壤溶液中养分降低到的最低平均浓度（R*）时仍保持正生长速率。因此，植物在降低土壤湿度方面的差异（此处主要影响养分扩散）可能导致R对竞争成功的预测出现错误。更强的养分竞争者通过确保养分在竞争者之前接触到其根系，从而获取了最大比例的养分供应。尽管从浓度降低理论得出的指标R可能对陆地生态系统中的竞争结果具有预测能力，但这一证据表明，植物通过抢先获取养分供应而非降低平均浓度来在养分竞争中胜过其他植物。
