In temperate arid regions, livestock production and irrigation agriculture are known to alter the taxonomic and functional structure of biocrusts. However, the effect of land use on biocrusts has not been evaluated in tropical semiarid regions. This study evaluated the effect of rainfed agriculture and firewood extraction on the taxonomic and functional structure of biocrusts in a tropical semiarid region of Central Mexico. We collected biocrusts in sites of rainfed agriculture and firewood extraction to identify species by morphology and then, to count the number of species and to estimate the cover of total biocrust, taxonomic groups (cyanobacteria, lichens, and bryophytes), and functional groups (cyanobacteria with and without heterocysts, chlorolichens, cyanolichens, and bryophytes). In addition, we analyzed the relationship between the cover of total biocrust, taxonomic, and functional groups, and vegetation and soil traits of sites of rainfed agriculture and firewood extraction. In sites of rainfed agriculture, biocrusts had 14–18 species, with 50–70% cover, and were dominated by cyanobacteria with heterocysts. Biocrusts were associated with high bare soil cover and compact soil with a high pH. In sites of firewood extraction, biocrusts had 23–29 species, with 70–90% cover, and were dominated by cyanolichens and bryophytes. Biocrusts were associated with soils with high infiltration and nutrient content. These differences suggest that rainfed agriculture has negative effects on biocrusts, similar to the effects of livestock production and irrigation agriculture in temperate arid regions. In comparison to rainfed agriculture, firewood extraction had less detrimental effects on biocrusts.

在温带干旱地区，众所周知，畜牧生产和灌溉农业会改变生物结皮的分类和功能结构。然而，尚未在热带半干旱地区评估土地利用对生物结皮的影响。本研究评估了雨养农业和木柴提取对墨西哥中部热带半干旱地区生物结皮的分类和功能结构的影响。我们在雨养农业和柴火提取现场收集生物结皮，以通过形态识别物种，然后计算物种数量并估计总生物结皮、分类群（蓝细菌、地衣和苔藓植物）和功能群（蓝细菌）的覆盖率有和没有杂囊、绿地衣、蓝藻和苔藓植物）。此外，我们分析了总生物地壳覆盖率、分类学和功能群与雨养农业和柴火采伐地点的植被和土壤特征之间的关系。在雨养农业的地点，生物结壳有 14-18 种，覆盖率 50-70%，并且以带杂囊的蓝藻为主。生物结皮与高裸土覆盖和高 pH 值的致密土壤有关。在采柴场，生物结壳有 23-29 种，覆盖率 70-90%，以蓝藻和苔藓植物为主。生物结皮与高渗透和高养分含量的土壤有关。这些差异表明，雨养农业对生物结皮有负面影响，类似于温带干旱地区的畜牧生产和灌溉农业的影响。与雨养农业相比，