Martorell Carlos, Martínez-Blancas Alejandra
Departamento de Ecología y Recursos Naturales, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad de México, Mexico.
Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA.
Ecology. 2025 Mar;106(3):e70052. doi: 10.1002/ecy.70052.
Plant-soil feedbacks (PSFs) may determine plant-species coexistence. They may stabilize coexistence, but frequently destabilize it by increasing fitness differences between species. Most studies focus on pairwise models in greenhouses. Thus, whether PSFs favor or deter coexistence is still unclear, especially in multispecies field contexts. We analyzed pairwise and multispecies coexistence over a hydric gradient in a semiarid grassland. Using PSF strength estimates between 17 species, we measured stability and fitness differences between all species pairs, and built all possible multispecies communities to test computationally whether they were stabilized by PSFs. We analyzed whether coexistence probability diminishes with species richness, as previously hypothesized. Because PSFs change with environmental conditions, we investigated their contribution to overall diversity maintenance over the hydric gradient. Strong PSF increased fitness differences, hindering pairwise coexistence. As expected, the probability that an assemblage was stable diminished with its richness, with the largest stable community containing 12 of the 17 species. However, all species coexisted with others in at least one assemblage, highlighting the importance of multispecies analyses. Positive PSFs promoted coexistence in pairwise analyses, but were associated with species-poor communities. Contrastingly, negative PSFs predominated in species-rich associations, perhaps due to indirect positive interactions (an "enemy of my enemy is my friend" scenario) that are known to maintain diversity in this grassland. Changes in the density of different species over the hydric gradient predicted from PSF-stabilized communities matched observations in nature. This seems to promote species turnover and thus coexistence along the gradient. As such, the interplay between environmental conditions and PSFs may be an important driver of diversity. Our results emphasize the need to move beyond pairwise coexistence models. In multispecies systems, crucial indirect interactions may arise. The interplay between environment and PSF under field conditions may provide important insights into coexistence in nature.
植物 - 土壤反馈（PSFs）可能决定植物物种的共存。它们可能会稳定共存，但也常常通过增加物种间的适合度差异而破坏共存。大多数研究集中在温室中的成对模型。因此，PSFs是促进还是抑制共存仍不清楚，尤其是在多物种的野外环境中。我们分析了半干旱草原上沿水分梯度的成对和多物种共存情况。利用17个物种之间的PSF强度估计值，我们测量了所有物种对之间的稳定性和适合度差异，并构建了所有可能的多物种群落，以通过计算测试它们是否由PSFs稳定。我们分析了共存概率是否如先前假设的那样随着物种丰富度的增加而降低。由于PSFs会随环境条件变化，我们研究了它们在整个水分梯度上对总体多样性维持的贡献。强烈的PSF增加了适合度差异，阻碍了成对共存。正如预期的那样，一个组合稳定的概率随着其丰富度的增加而降低，最大的稳定群落包含17个物种中的12个。然而，所有物种在至少一个组合中与其他物种共存，这突出了多物种分析的重要性。在成对分析中，正向PSFs促进了共存，但与物种贫乏的群落相关。相反，负向PSFs在物种丰富的组合中占主导地位，这可能是由于已知能维持该草原多样性的间接正向相互作用（“敌人的敌人就是我的朋友”的情况）。从PSF稳定的群落预测的不同物种密度在水分梯度上的变化与自然界中的观察结果相符。这似乎促进了物种更替，从而促进了沿梯度的共存。因此，环境条件和PSFs之间的相互作用可能是多样性的一个重要驱动因素。我们的结果强调了超越成对共存模型的必要性。在多物种系统中，可能会出现关键的间接相互作用。野外条件下环境与PSF之间的相互作用可能为自然界中的共存提供重要见解。
