Sun Jingyao, Yu Kailiang, Rietkerk Max, Chen Ning, Zhang Hongxia, Song Guang, Li Xinrong
Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
Proc Natl Acad Sci U S A. 2025 Jul 29;122(30):e2424836122. doi: 10.1073/pnas.2424836122. Epub 2025 Jul 21.
Biota could be ecosystem engineers in generating an intrinsic heterogeneous landscape through scale-dependent feedbacks. Thereby, they can form resource-enriched patchiness or islands of fertility, comprising self-organizing spatial patterns. Research so far has largely focused on the self-organized spatial patterns of plant communities in drylands. It, however, remains unclear whether and how biocrusts having distinct morphology and life history from plant communities could self-organize themselves and form unique spatial patterns. Here, we conducted field observations of biocrusts across successional stages and employed a probabilistic cellular automaton model to investigate the distinct self-organized spatial patterns exhibited by mosaic patches of mosses and lichens with different patch size distributions (PSDs). Our study demonstrates that short-range positive feedbacks initially promote the development of patches, featured with a heavy-tailed PSD, while long-range negative feedbacks subsequently curtail further expansion of big patches, thereby establishing a characteristic patch scale with regular PSDs. Strikingly, only lichens reverted back to the heavy-tailed PSD in the late succession stage, presumably implying self-organized critical fragmentation of lichen patches. Field measurements of biocrust performance at the center and edge of patches of varying sizes along succession stages further support the classic scale-dependent feedback mechanism for Turing pattern formation. Collectively, our results clearly demonstrate the capability of the biocrust communities to self-organize themselves to form distinct spatial patterns governed by the spatial and temporal scale-dependent feedbacks, potentially impacting dryland ecosystem functions and resilience.
生物群可以通过尺度依赖的反馈成为生态系统工程师，从而生成内在的异质景观。因此，它们可以形成资源丰富的斑块或肥沃岛屿，包括自组织空间格局。到目前为止，研究主要集中在旱地植物群落的自组织空间格局上。然而，与植物群落具有不同形态和生活史的生物土壤结皮是否以及如何能够自我组织并形成独特的空间格局仍不清楚。在这里，我们对生物土壤结皮在不同演替阶段进行了实地观察，并采用概率细胞自动机模型来研究具有不同斑块大小分布（PSD）的苔藓和地衣镶嵌斑块所呈现的独特自组织空间格局。我们的研究表明，短程正反馈最初促进了具有重尾PSD特征的斑块的发展，而长程负反馈随后抑制了大斑块的进一步扩张，从而建立了具有规则PSD的特征斑块尺度。引人注目的是，只有地衣在演替后期恢复到重尾PSD，这可能意味着地衣斑块的自组织临界破碎。沿着演替阶段对不同大小斑块中心和边缘的生物土壤结皮性能进行实地测量，进一步支持了图灵模式形成的经典尺度依赖反馈机制。总体而言，我们的结果清楚地证明了生物土壤结皮群落能够自我组织形成由时空尺度依赖反馈控制的独特空间格局，这可能会影响旱地生态系统功能和恢复力。
