State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing, China; Department of Estuarine and Delta Systems, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, Yerseke, the Netherlands.
Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China; Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China.
Sci Total Environ. 2021 Jul 15;778:146119. doi: 10.1016/j.scitotenv.2021.146119. Epub 2021 Mar 1.
Habitat fragmentaion into small patches is regarded as a vital cause of biodiversity loss. Fragmentationof habitat-forming species is especially harmful, as patchiness of such species often controls ecosystem stability and resilience by density and patch size-dependent self-reinforcing feedbacks. Although fragmentation are expected to weaken or even break such feedbacks, it remains unclear how the resulting patchiness of habitat-forming species affect ecosystem resilience to environmental stresses. Here, using Spartian alterniflora, the habitat-forming species in saltmarshes as a model, we investigate how patch size, plant density, and shell aggregation interactively control the persistence of a degrading salt marsh that suffered from erosion induced by hydrodynamics. Our results demonstrate that large patches can trap more shells along the patch edge than the smaller ones, therefore significantly facilitating plant re-growth within the patch. Shell removal experiments further reveal that large patches trapping more shells along patch edges reinforce their own persistence by decreasing erosion and thus facilitating plant recovery. By contrast, small patches with lesser plants cannot persist as they trap less shells along patch edges but are able to accumulate more shells at interior locations where they hinder plant re-growth, indicating a critical threshold of patch size ~20 m below which ecosystem collapses. The current study highlights the importance to identify critical threshold of stress-resistant patch sizes in transition-prone ecosystems as early-warning to alert undesired ecosystem collapse and restoration practice.
生境破碎化为小斑块被认为是生物多样性丧失的一个重要原因。生境形成物种的破碎化尤其有害，因为这些物种的斑块性常常通过密度和斑块大小依赖的自我强化反馈来控制生态系统的稳定性和恢复力。尽管人们预计破碎化会削弱甚至打破这种反馈，但仍不清楚生境形成物种的这种斑块性如何影响生态系统对环境压力的恢复力。在这里，我们以盐沼中的生境形成物种 Spartian alterniflora 为模型，研究了斑块大小、植物密度和贝壳聚集如何相互作用来控制遭受水动力侵蚀的退化盐沼的持久性。我们的研究结果表明，大斑块可以在斑块边缘捕获比小斑块更多的贝壳，从而显著促进斑块内植物的再生。贝壳移除实验进一步表明，大斑块通过减少侵蚀来增强自身的持久性，从而促进植物的恢复，在斑块边缘捕获更多的贝壳。相比之下，植物较少的小斑块由于在斑块边缘捕获的贝壳较少而无法持续存在，但能够在阻碍植物再生的内部位置积累更多的贝壳，这表明斑块大小存在一个关键阈值，低于该阈值，生态系统就会崩溃。本研究强调了在易发生变化的生态系统中识别具有抗压力的斑块大小的关键阈值的重要性，这是一种预警，以警示不希望发生的生态系统崩溃，并指导恢复实践。
