A pertinent debate in plant ecology centers around the generality of the self‐thinning rule. However, studies focused on highly simplified settings such as even‐aged monospecific populations or optimal conditions. This neglects the fact that most natural communities, to which the classical self‐thinning slope is often applied, are age‐structured, composed of multiple species and exposed to various types of abiotic stress. With the help of an individual‐based model, we relax these simplified assumptions and systematically test for changes in the biomass–density relationships of uneven‐aged, functionally diverse plant communities across a complete stress gradient, using excessive to insufficient soil water as a case study. We show that frequent recruitment, which resulted in an uneven‐aged community, and stress intensity caused predictable changes in the entire biomass–density trajectory. Increasing stress resulted in steeper (more negative) slopes and increased the intercept in the classical self‐thinning section irrespective of excessive or insufficient soil water as a stress type. Recruitment steepened the slope, too and enabled a novel section in the biomass–density trajectory. This novel section represented a quasi‐steady state of the density‐dependent dynamics of new generations which occurred locally within patches of recruitment. At the community level, the slope of the biomass–density relationship at quasi‐steady state had a significantly flatter slope of −1.1 under optimal soil water conditions. Functional diversity showed little impact on density‐dependent mortality. Namely, it resulted in an earlier onset of mortality but not in changes in the values of the slope and intercept. We conclude that the classical −3/2 slope is not useful to describe the biomass–density relationship in natural and semi‐natural plant communities. The magnitude and direction of variation in the slope are related to the age‐structure and abiotic stress intensity in the plant community.

中文翻译：

---

由于年龄结构和非生物胁迫，植物群落的生物量与密度之间的关系偏离了自瘦规则。

有关植物生态学的辩论围绕自我稀疏规则的普遍性展开。但是，研究的重点是高度简化的环境，例如偶数年龄的单特异性种群或最佳条件。这忽略了一个事实，即通常采用经典的自瘦坡的大多数自然群落具有年龄结构，由多种物种组成，并遭受各种非生物胁迫。在基于个体的模型的帮助下，我们放宽了这些简化的假设，并系统地测试了在整个应力梯度下年龄不等，功能不同的植物群落的生物量-密度关系的变化，其中使用了过量或不足的土壤水研究。我们显示，频繁招募导致社区年龄不均，应力强度导致整个生物质-密度轨迹发生可预测的变化。应力的增加导致陡峭的（更负的）斜率，并且在经典的自稀化段中增加了截距，而与作为应力类型的土壤水过多或不足无关。招募也使坡度变陡，并在生物质-密度轨迹中实现了新的切面。这个新颖的部分代表了新生代密度依赖性动力学的准稳态，这种动力学局部发生在征募片内。在群落水平上，在最佳土壤水条件下，准稳态生物量-密度关系的斜率具有显着平坦的-1.1斜率。功能多样性对密度依赖性死亡率影响不大。即 它导致了较早的死亡，但没有改变斜率和截距的值。我们得出结论，经典的−3/2斜率对于描述自然和半自然植物群落中的生物量-密度关系没有用。坡度变化的大小和方向与植物群落的年龄结构和非生物胁迫强度有关。