Department of Biology, University of Montana Western, Dillon, MT, 59725, USA.
Department of Biology, York University, Toronto, ON, Canada.
Sci Rep. 2023 Mar 23;13(1):4803. doi: 10.1038/s41598-023-31967-0.
Biological soil crusts can have strong effects on vascular plant communities which have been inferred from short-term germination and early establishment responses. However, biocrusts are often assumed to function as an "organizing principle" in communities because their effects can "cascade" to interactions among crust-associated plant species. We conducted surveys and experiments to explore these cascades and found that biocrusts were positively associated with large patches (> 10 m diameter) of a dominant shrub Artemisia tridentata. At the smaller scale of individual shrubs and the open matrices between shrubs, biocrusts were negatively associated with Artemisia. Juveniles of Artemisia were found only in biocrusts in intershrub spaces and never under shrubs or in soil without biocrusts. In two-year field experiments, biocrusts increased the growth of Festuca and the photosynthetic rates of Artemisia. Festuca planted under Artemisia were also at least twice as large as those planted in open sites without crusts or where Artemisia were removed. Thus, biocrusts can facilitate vascular plants over long time periods and can contribute to a "realized" cascade with nested negative and positive interactions for a range of species, but unusual among documented cascades in that it includes only autotrophs.
生物土壤结皮对维管植物群落可能有强烈的影响，这可以从短期萌发和早期建立的反应中推断出来。然而，生物结皮通常被认为是群落的“组织原则”，因为它们的作用可以“级联”到与结皮相关的植物物种之间的相互作用。我们进行了调查和实验来探索这些级联效应，发现生物结皮与一种优势灌木三裂叶滨藜（Artemisia tridentata）的大斑块（>10m 直径）呈正相关。在单个灌木和灌木之间的开阔基质的较小尺度上，生物结皮与三裂叶滨藜呈负相关。三裂叶滨藜的幼株仅存在于灌木间的生物结皮中，而不在灌木下或没有生物结皮的土壤中。在两年的野外实验中，生物结皮增加了羊茅的生长和三裂叶滨藜的光合速率。种植在三裂叶滨藜下的羊茅至少是种植在没有结皮的开阔地或去除三裂叶滨藜的地方的两倍大。因此，生物结皮可以在长时间内促进维管植物的生长，并为一系列物种提供“实现”的级联，包括嵌套的负相互作用和正相互作用，但在已记录的级联中，它是不同寻常的，因为它只包括自养生物。
