Biocrusts harbor soil-surface communities composed of autotrophic and heterotrophic microbiota that affect nutrient cycling, plant performance, soil hydrology and stability within drylands. Biocrust community composition is mostly thought to be driven by abiotic factors, but the structure of the bacteria, fungi, protist, and microfauna taxa are rarely documented simultaneously or over time. In this study, we examined the composition, abundance, and diversity of microbes (bacteria and fungi) and microfauna (protists and microscopic microfauna) in three types of biocrusts among two different vegetative habitats in the northern Chihuahuan Desert during three successive seasons. Microbial groups were identified by phospholipid fatty acid analyses (PLFA) and included actinobacteria, other gram-positive bacteria, other gram-negative bacteria, rhizobia arbuscular mycorrhizal fungi, and saprophytic fungi. Microfauna were enumerated via microscopy and included nematodes, tardigrades, rotifers, amoebae, ciliates, and flagellates. We found that microbial communities were most affected by biocrust type, whereas microfaunal communities were more influenced by sampling season. Season was also associated with different indicator taxa. Additionally, microbial communities were related to biocrust chemical properties—which changed with season and surrounding vegetation—while microfaunal communities were not. In cyanolichen-dominated crusts, but not others, the structure of microbial and microfaunal communities were strongly correlated. Our study highlights possible food web interactions and provides evidence that the co-occurring microbial and microfaunal taxa associated with biocrusts are temporally dynamic and structured by different drivers.

生物结皮包含由自养和异养微生物群组成的土壤表面群落，这些微生物群影响旱地内的养分循环、植物性能、土壤水文和稳定性。生物地壳群落组成主要被认为是由非生物因素驱动的，但细菌、真菌、原生生物和微型动物分类群的结构很少同时或随着时间的推移被记录下来。在这项研究中，我们在连续三个季节检查了赤环沙漠北部两个不同植被栖息地的三种生物结皮中微生物（细菌和真菌）和微型动物（原生生物和微观微型动物）的组成、丰度和多样性。通过磷脂脂肪酸分析 (PLFA) 鉴定微生物群，包括放线菌、其他革兰氏阳性菌、其他革兰氏阴性菌、根瘤菌属丛枝菌根真菌和腐生真菌。微型动物通过显微镜计数，包括线虫、缓步动物、轮虫、变形虫、纤毛虫和鞭毛虫。我们发现微生物群落受生物结皮类型的影响最大，而微型动物群落受采样季节的影响更大。季节也与不同的指标类群有关。此外，微生物群落与生物结皮化学特性有关——随着季节和周围植被的变化而变化——而微型动物群落则不然。在以氰化物为主的地壳中，但在其他地壳中，微生物和微动物群落的结构具有很强的相关性。