Gross Katherine L, Peters Andrew, Pregitzer Kurt S
W.K. Kellogg Biological Station and Department of Botany, Plant Pathology and Zoology, Michigan State University, Hickory, 49060, Corners, MI, USA.
Biology Department, Indiana University, 47401, Bloomington, IN, USA.
Oecologia. 1993 Mar;95(1):61-64. doi: 10.1007/BF00649507.
Proliferation of roots in a nutrient patch can occur either as a result of an increase in root length (morphological response) or by a change in root birth or death rates (demographic responses). In this study we attempted to distinguish between these two mechanisms of response to nutrient patches and to compare the responses of four old-field plant species (two annuals, two perennials). For all four species combined, there were significant increases in root numbers and root length in fertilized patches. Root proliferation in fertilized patches was largely due to increased birth (=branching) rates of new roots. However, there was also a significant increase in root death rates in the fertilized patches which reduced the magnitude of the increase in net root numbers. Plots for individual species suggested they differed in the magnitude and timing of root proliferation in fertilized patches due to differences in root birth and death rates. However, because of the limited sample size in this study, there was only a marginally significant difference among species in root birth rates, and no difference in death rates. Further studies are currently underway to better quantify species differences in the demographic mechanism, as well as magnitude, of response to nutrient patches and if this would affect the ability to exploit small-scale heterogeneity in soil resources.
根系在养分斑块中的增殖可能是由于根长增加（形态学响应），也可能是由于根的出生或死亡率变化（种群统计学响应）。在本研究中，我们试图区分这两种对养分斑块的响应机制，并比较四种弃耕地植物物种（两种一年生植物、两种多年生植物）的响应。对于所有四种物种而言，施肥斑块中的根数量和根长均显著增加。施肥斑块中的根系增殖主要是由于新根出生（即分支）率的提高。然而，施肥斑块中的根死亡率也显著增加，这降低了净根数量增加的幅度。单个物种的图表表明，由于根出生和死亡率的差异，它们在施肥斑块中根系增殖的幅度和时间有所不同。然而，由于本研究中的样本量有限，物种间根出生率仅存在微弱的显著差异，死亡率则无差异。目前正在进行进一步的研究，以更好地量化物种在种群统计学机制以及对养分斑块响应的幅度方面的差异，以及这是否会影响利用土壤资源中小尺度异质性的能力。
