Positive interactions can increase size inequality in plant populations
Positive interactions can increase size inequality in plant populations
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积极的相互作用可以增加植物种群的大小不平等
DOI：
10.1111/j.1365-2745.2009.01562.x
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发表时间：
2009-11-01
影响因子：
5.5
通讯作者：
Wang, Gang
中科院分区：
文献类型：
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作者：
Chu, Cheng-Jin;Weiner, Jacob;Wang, Gang
1.个体大小的巨大变异是自然植物种群的普遍特征。 虽然竞争在产生这种变化中的作用已被广泛研究，但植物之间的正相互作用的潜在影响，这在高应力环境中是常见的，还没有被调查。2.使用基于个体的“影响区”模型，我们调查了竞争，非生物应力和促进作用对植物单作中大小不平等的影响。 在该模型中，胁迫降低了植物的生长速率，而易化作用改善了胁迫的影响。促进和竞争都发生在重叠的影响区。我们使用高山草甸中的克隆草Escherichus nutans.3的田间实验来测试模型的一些预测。当没有密度依赖的死亡率时，易化增加了模型种群的大小不平等。 这种影响随着密度的增加而降低，因为竞争压倒了促进作用。4.当模型中包括密度依赖死亡率时，压力通过降低生长率延迟了死亡率的发生并降低了死亡率，因此在任何时间点，生存者的数量在恶劣条件下都高于更良性的条件下。 易化增加了自我精简过程中的大小不平等。我们的研究结果表明，促进与非生物胁迫和竞争相互作用，影响植物种群的大小不平等的程度。促进作用增加了低至中等密度和自疏过程中的大小不平等。
1. Large variation in the size of individuals is a ubiquitous feature of natural plant populations. While the role of competition in generating this variation has been studied extensively, the potential effects of positive interactions among plants, which are common in high‐stress environments, have not been investigated.2. Using an individual‐based ‘zone‐of‐influence’ model, we investigate the effects of competition, abiotic stress and facilitation on size inequality in plant monocultures. In the model, stress reduces the growth rate of plants, and facilitation ameliorates the effects of stress. Both facilitation and competition occur in overlapping zones of influence. We tested some of the model’s predictions with a field experiment using the clonal grassElymus nutansin an alpine meadow.3. Facilitation increased the size inequality of model populations when there was no density‐dependent mortality. This effect decreased with density as competition overwhelmed facilitation. The lowest size inequality was found at intermediate densities both with the model and in the field.4. When density‐dependent mortality was included in the model, stress delayed its onset and reduced its rate by reducing growth rates, so the number of survivors at any point in time was higher under harsh than under more benign conditions. Facilitation increased size inequality during self‐thinning.5.Synthesis. Our results demonstrate that facilitation interacts with abiotic stress and competition to influence the degree of size inequality in plant populations. Facilitation increased size inequality at low to intermediate densities and during self‐thinning.