Effect of Localized Placement of Nutrients on Root Competition in Self-thinning Populations
Effect of Localized Placement of Nutrients on Root Competition in Self-thinning Populations
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DOI：
10.1006/anbo.1996.0130
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发表时间：
1996-09
期刊：
影响因子：
4.2
通讯作者：
E. Morris
中科院分区：
文献类型：
--
作者：
E. Morris
摘要利用局部营养物质的配置来增加根系竞争，从而降低植物种群自疏线的斜率和/或截距。如果平均根间距减小，并且养分供应有限，养分的局部放置将导致根系竞争增加。据此预测，高密度、营养有限的罗勒种群是一个重要的生态系统。与非局部对照相比，用营养物的局部放置生长的植物将沿着沿着较低的生物量密度线自减薄。这是测试在两个肥力水平上的土壤为基础的盆栽介质实验1，并在一个肥力水平上洗砂实验2。实验2中，营养物的局部放置显著降低了地上部和根生物量的自疏线的高度（截距）。在实验1中，在较高的肥力水平，本地化放置的养分没有显着的影响，在较低的肥力水平，本地化没有显着的影响，地上部生物量的稀疏线，并导致了零斜率的根生物量的稀疏线。基于冠层的自疏模型未能解释实验2中观察到的稀疏线截距的减少。在这两个实验中，局部放置的养分导致更高比例的总根长位于本地化区域，这将导致在平均根间距离的减少。这将加剧养分限制条件下的根系竞争。实验2的结果支持了根系竞争加剧会降低自疏线的假设。
Abstract The hypothesis that increased root competition can lower the slope and/or intercept of the self-thinning line traversed by plant populations was tested using localized placement of nutrients to increase root competition. Localized placement of nutrients will result in increased root competition, if average inter-root distances are reduced, and if nutrients are in limiting supply. It was predicted that high-density, nutrient-limited populations of Ocimum basilicum L. grown with localized placement of nutrients would self-thin along a lower biomass–density line than non-localized controls. This was tested at two fertility levels on a soil-based potting medium in expt 1, and at one fertility level on washed sand in expt 2. Localized placement of nutrients significantly reduced the elevation (intercept) of the self-thinning line for both shoot and root biomass in expt 2. In expt 1, at the higher-fertility level, localized placement of nutrients had no significant effect; at the lower fertility level, localization had no significant effect on thinning lines for shoot biomass, and resulted in a zero slope of the thinning line for root biomass. Canopy-based models of self-thinning failed to account for the reduction in the thinning-line intercept observed in expt 2. In both experiments, localized placement of nutrients resulted in a higher proportion of total root length being located in the localization zone, which would result in a reduction in the average inter-root distance. This would intensify root competition under conditions of nutrient limitation. The hypothesis that intensified root competition would lower the self-thinning line is supported by the results of expt 2.