Root-shoot growth responses during interspecific competition quantified using allometric modelling.
Root-shoot growth responses during interspecific competition quantified using allometric modelling.
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DOI：
10.1093/aob/mcq186
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发表时间：
2010-12
期刊：
影响因子：
4.2
通讯作者：
D. Robinson;H. Davidson;Clare J. Trinder;R. Brooker
中科院分区：
文献类型：
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作者：
D. Robinson;H. Davidson;Clare J. Trinder;R. Brooker
背景与目的植物竞争研究受到竞争对手根系量化困难的制约。分析通常仅限于地上的特征。本文提出了一种解决这一问题的新方法。方法竞争植株根系质量可由以下公式估计：竞争植株茎部质量；竞争对手的组合根权；离体植株根重对茎重的n-回归斜率（标度指数，α）和截距（异速生长系数，β）。如果竞争对根、芽生长没有影响，则竞争植株和分离植株的α和β值相等。各竞争植株的根重之和与各竞争植株的茎重估算值异速相等。组合根权可以直接在竞争对手之间进行分配。如果竞争改变了根和梢的相对生长，竞争对手的根重总和将不等于异速估测的根重，不能直接划分。然而，如果调整分离植株的α和β值，直到估算的竞争对手的联合根重与测量的联合根重相匹配，后者可以使用它们的新α和β值在竞争对手之间进行划分。该方法以两种草本植物，鸭蹄草和车前草为例。异速生长模型显示，在竞争过程中，车前草的根冠比显著且持续增加，而车前草则没有。这与达克利的全株干重增加有关，其最终比车前草的干重增加2.5倍。根据异速生长模型推断，羊蹄草对车前草的全株生长优势比单靠茎部数据推断的要早14-24 d。结论在合理的假设下，异速生长模型可以分析任何物种混合中的竞争相互作用，并克服了竞争研究中一个长期存在的问题。
BACKGROUND AND AIMS Plant competition studies are restricted by the difficulty of quantifying root systems of competitors. Analyses are usually limited to above-ground traits. Here, a new approach to address this issue is reported. METHODS Root system weights of competing plants can be estimated from: shoot weights of competitors; combined root weights of competitors; and slopes (scaling exponents, α) and intercepts (allometric coefficients, β) of ln-regressions of root weight on shoot weight of isolated plants. If competition induces no change in root : shoot growth, α and β values of competing and isolated plants will be equal. Measured combined root weight of competitors will equal that estimated allometrically from measured shoot weights of each competing plant. Combined root weights can be partitioned directly among competitors. If, as will be more usual, competition changes relative root and shoot growth, the competitors' combined root weight will not equal that estimated allometrically and cannot be partitioned directly. However, if the isolated-plant α and β values are adjusted until the estimated combined root weight of competitors matches the measured combined root weight, the latter can be partitioned among competitors using their new α and β values. The approach is illustrated using two herbaceous species, Dactylis glomerata and Plantago lanceolata. KEY RESULTS Allometric modelling revealed a large and continuous increase in the root : shoot ratio by Dactylis, but not Plantago, during competition. This was associated with a superior whole-plant dry weight increase in Dactylis, which was ultimately 2·5-fold greater than that of Plantago. Whole-plant growth dominance of Dactylis over Plantago, as deduced from allometric modelling, occurred 14-24 d earlier than suggested by shoot data alone. CONCLUSION Given reasonable assumptions, allometric modelling can analyse competitive interactions in any species mixture, and overcomes a long-standing problem in studies of competition.