Data from: Applying community ecological theory to maximize productivity of cultivated biocrusts

Degraded rangelands around the world may benefit from the reestablishment of lost biological soil crusts (biocrusts, soil surface cryptogamic-microbial communities). Cultivation of biocrust organisms is the first step in this process, and may benefit from harnessing species interactions. Species interactions are a dominant force structuring ecological communities. One key element of community structure, species richness, is itself important because it can promote the productivity of the entire community. Here, we use biological soil crusts as a model to test the effects of species interactions on production of biocrust materials for use in ecosystem rehabilitation. We screened eight different moss and lichen species from semi-arid rangelands of Montana, USA, for growth potential under two watering regimes. Mosses generally grew well, but we were unable to cultivate the selected lichen species. We produced a >400% increase in the biomass of one species (Ceratodon purpureus). We tested whether a parasite-host relationship between two lichens could be used to enhance productivity of the parasite species, but this also resulted in no net gain of lichen productivity. Finally, we constructed all possible community combinations from a pool of five moss species to test for overyielding (community productivity exceeding that expected from the growth of community members in monoculture), and to determine both if, and the mode in which, species richness increases productivity. Polycultures yielded more than would be expected based upon the production of community constituents in monoculture. Using structural equation models we determined that there was a modest effect of species richness on community productivity (r = 0.24-0.25), which was independent of a stronger effect of the identity of species in the community (r = 0.41-0.50). These results will contribute to the optimization of biocrust cultivation, promoting the development of this emerging ecological rehabilitation technology.

全球退化牧场或可通过恢复已消失的生物土壤结皮（biological soil crusts，biocrusts，即土壤表面隐花植物-微生物群落）获益。培育生物土壤结皮生物是该修复流程的首要步骤，而利用物种相互作用或可提升培育成效。物种相互作用是构建生态群落的主导性驱动力。群落结构的关键要素之一——物种丰富度本身意义重大，因其可提升整个群落的生产力。本研究以生物土壤结皮为模型，探究物种相互作用对用于生态修复的生物土壤结皮材料产出的影响。我们从美国蒙大拿州半干旱牧场中筛选出8种苔藓与地衣物种，在两种供水模式下测试其生长潜力。结果显示，苔藓普遍生长良好，但未能成功培育所选的地衣物种。我们使单一物种——紫萼藓（Ceratodon purpureus）的生物量提升了400%以上。我们还测试了能否利用两种地衣间的寄生关系提升寄生物种的生产力，但同样未实现地衣生产力的净增长。最后，我们从5种苔藓的物种库中构建所有可能的群落组合，以检验超产效应（overyielding，即群落生产力超出单培养群落成员生长预期的现象），并探究物种丰富度是否以及通过何种途径提升群落生产力。多物种群落的产出高于基于单培养群落组分预期的产量。通过结构方程模型（structural equation models）分析，我们发现物种丰富度对群落生产力存在适度影响（相关系数r=0.24~0.25），该效应独立于群落物种组成所产生的更强影响（相关系数r=0.41~0.50）。本研究结果将助力优化生物土壤结皮的培育流程，推动这一新兴生态修复技术的发展。