Long-term disadvantages of selective root placement: root proliferation and shoot biomass of two perennial grass species in a 2-year experiment
Long-term disadvantages of selective root placement: root proliferation and shoot biomass of two perennial grass species in a 2-year experiment
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DOI：
10.1046/j.0022-0477.2001.00589.x
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发表时间：
2001-10-01
影响因子：
5.5
通讯作者：
De Kroon, H
中科院分区：
文献类型：
--
作者：
Fransen, B;De Kroon, H
1.在异质环境中根系觅食的长期效益尚不清楚。许多以前的研究持续时间短，可能忽略了补丁耗尽和根周转的影响，这可能会限制多年生植物的根觅食的长期回报。2根觅食的好处进行了调查，为Holcus lanatus和Nardus stricta在两个生长季节。拍摄每个物种的生物量进行了测量，在均匀的营养丰富和营养贫乏的治疗和在一个异质的治疗组成的营养丰富和营养贫乏的一方，在高和低的整体水平的营养物质的可用性在相同的补丁对比。土壤类型之间的土壤溶液中的硝酸盐浓度的初始差异消失，使几个月后，硝酸盐水平低，在所有的土壤类型。3在异质处理，Holcus能够增殖的根在营养丰富的方面相比，营养贫乏的一面，但只有在高的整体水平的养分供应。Nardus没有选择性地将根放置在异质处理的营养丰富的一侧，无论是在任何营养水平。4根寿命，由微型电子管观察确定，揭示了Holcus的根往往比Nardus的根寿命更短，在营养贫乏的土壤中寿命更长。5最初，Holcus在异质处理中产生更多的芽生物量，在营养可用性的总体水平，结果表明，在相同的处理条件下，地上部生物量比预期的要少，但在第一个生长季节结束时，这种优势消失了，2年后，非均匀处理的地上部生物量比预期的要少得多。在高的整体水平的养分供应，Holcus拍摄生物量并不显着大于在同质营养不良的治疗。相比之下，Nardus在异质处理的地上部生物量与预期值相似，在第一和第二生长季节之后。6对于Holcus，快速的根增殖和可能的高营养吸收导致短期内地上部生物量增加，但由于根寿命有限，这随后被快速的斑块耗尽和高损失所限制。我们讨论的长期回报的根增殖多年生物种的异质环境的影响。
1 The long-term benefits of root foraging in heterogeneous environments are unclear. The short duration of many previous studies may have overlooked the effects of patch depletion and root turnover, which may limit the long-term rewards of root foraging for perennial plants.2 The benefits of root foraging were investigated for Holcus lanatus and Nardus stricta over two growing seasons. Shoot biomass of each species was measured in homogeneous nutrient-rich and nutrient-poor treatments and in a heterogeneous treatment consisting of a nutrient-rich and a nutrient-poor side, at a high and a low overall level of nutrient availability at the same patch contrast. Large initial differences in nitrate concentrations in the soil solution between the soil types disappeared so that, after several months, nitrate levels were low in all soil types.3 In heterogeneous treatments, Holcus was able to proliferate roots in the nutrient-rich side compared with the nutrient-poor side, but only at the high overall level of nutrient availability. Nardus did not selectively place roots in the nutrient-rich side of the heterogeneous treatment at either nutrient level.4 Root longevity, as determined by minirhizotron observations, revealed that roots of Holcus tended to be shorter lived than those of Nardus, and to live longer in nutrient-poor soils.5 Initially, Holcus produced more shoot biomass in the heterogeneous treatments, at both overall levels of nutrient availability, than expected from values in the homogeneous treatments, but this advantage disappeared by the end of the first growing season and, after 2 years, shoot biomass in the heterogeneous treatments was much less than expected. At the high overall level of nutrient availability, Holcus shoot biomass was not significantly greater than that produced in the homogeneous nutrient-poor treatment. In contrast, shoot biomass of Nardus in the heterogeneous treatment was similar to the expected value, both after the first and second growing seasons.6 For Holcus, fast root proliferation and presumably a high nutrient uptake resulted in increased shoot biomass in the short term, but this was then curtailed by rapid patch depletion and high losses due to a limited root life span. We discuss the implications for the long-term rewards of root proliferation in perennial species of heterogeneous environments.