Root allocation and foraging precision in heterogeneous soils

Root growth patterns respond to small-scale resource heterogeneity and the presence of roots of neighboring plants, but how a plant integrates its responses to these cues is not well understood. In the presence of neighbors, plants may shift allocation to roots as a consequence of plant size and root:shoot allometry, as a response to resource depletion by neighbors, or through a direct response to neighbor presence. The same response pathways also have the potential to alter proliferation in resource-rich patches in soil.
Four species of grassland plants were grown in the greenhouse as single plants, monocultures, and mixtures. Root length allocation as a function of shoot mass was examined for background soil and fertilized patches. Plants grown with same-species neighbors followed the same allometric trajectory as single plants for root length in background soil, so any change in root allocation was due only to reduced plant size. Root proliferation in patches declined with neighbors,...

根系生长模式会对小规模资源异质性（small-scale resource heterogeneity）及邻近植物根系的存在做出响应，但植物如何整合其对这些信号的响应尚不清楚。在存在邻近植物的情况下，植物可能通过以下方式改变向根系的资源分配：植株大小与根冠异速生长（root:shoot allometry）的影响、对邻近植物资源消耗的响应，或对邻近植物存在的直接响应。相同的响应通路也可能改变土壤中资源丰富斑块内的根系增殖。

四种草原植物在温室中以单株、单种栽培（monocultures）和混合栽培（mixtures）的方式生长。研究分析了背景土壤与施肥斑块中，根系长度分配随地上生物量变化的规律。在背景土壤中，与同种邻近植物共生的植株，其根系长度遵循与单株一致的异速生长轨迹，因此根系分配的任何变化均仅源于植株大小的减小。斑块中的根系增殖随邻近植物的存在而下降……