Drylands are ecosystems, where lack of rains imposes harsh conditions for the survival of organisms. These ecosystems are also susceptible to degradation and desertification. Their conservation depends on the understanding of the ecological functioning of vegetation and soil. In drylands, the vegetation is spatially structured as a mosaic of patches (vegetation) and interpatches (bare soil). This structure is a consequence of plant-plant interactions (facilitation and competition). Empirical data and modeling approaches reinforce the role of ecological facilitation for the maintenance of all organisms in drylands. However, the true range of facilitation is still poorly known. Here, we explored data of meso- and microarthropods living in soil, as bioindicators, to infer the range of facilitation provided by plants to soil. As dependent variables, we regard data of abundances and species richness collected in random patches (independent samples) and bare soil places. Data from patch size and distances between bare soil and patches were arranged in a single chute. Thus, one may consider a one-dimensional coordinate system, where zero is the border; negative coordinates are distances between bare soil and the border, while positive coordinates represent patch sizes. Discrete portions of this system are taken to calculate averages and variances of abundance and species richness. With these statistics, we investigate how soil communities vary across the patch border. Techniques of data transformation and signal analysis allowed us to reduce the data noise, reveal a continuous mean behavior, and fit a logistic function. Our findings indicate that soil communities change suddenly from simple patterns to numerous and diverse communities in bare soil regions. This abrupt change of fauna quantities, around 0.35 and 0.5 m outside the patch border, means that the facilitation of vegetation on soil goes beyond the patch border. However, the abundance and richness of soil communities in bare soil are small in comparison to overall quantities of soil arthropods. Consequently, variations in quantities of arthropods on bare soil do not necessarily reflect the main role of these soil arthropods for soil functions, which mainly occurs under the patches. Also, we found a minimum patch size (radius ≈ 0.5 m) able to maintain high diverse communities in soil. Accordingly, our results reveal information that can be interpreted in terms of soil amelioration, and, therefore, it indicates the range of plant facilitation, and the minimum patch size able to produce soil amelioration. These findings provide objective values that can be employed to update the general understanding of the ecological dynamics of drylands,as well as to better plan restoration and conservation actions.

旱地是生态系统，缺乏降雨为生物的生存带来了恶劣条件。这些生态系统也容易退化和荒漠化。它们的保护取决于对植被和土壤的生态功能的理解。在干旱地区，植被的空间结构为斑块（植被）和斑块（裸土）的马赛克。这种结构是植物与植物相互作用（促进和竞争）的结果。经验数据和建模方法加强了生态便利化对维持旱地所有生物的作用。但是，促进的真正范围仍然知之甚少。在这里，我们探索了生活在土壤中的中节肢动物和微型节肢动物的数据，作为生物指示剂，以推断植物对土壤的促进作用范围。作为因变量，我们考虑在随机斑块（独立样本）和裸露的土壤中收集的丰度和物种丰富度数据。来自斑块大小和裸露土壤与斑块之间距离的数据在单个滑槽中排列。因此，可以考虑一维坐标系，其中边界为零；边界为零。负坐标是裸土与边界之间的距离，正坐标表示斑块的大小。该系统的离散部分用于计算丰度和物种丰富度的平均值和方差。利用这些统计数据，我们研究了斑块边界上土壤群落的变化。数据转换和信号分析技术使我们能够减少数据噪声，揭示连续的平均行为并拟合逻辑函数。我们的发现表明，在裸露的土壤区域中，土壤群落突然从简单的模式变为众多多样的社区。动物区系数量的突然变化，在斑块边界外约0.35和0.5 m，这意味着对土壤上植被的促进作用超出了斑块边界。然而，与土壤节肢动物的总量相比，裸露土壤中土壤群落的丰富度和丰富度很小。因此，节肢动物在裸露土壤上的数量变化并不一定反映这些节肢动物对土壤功能的主要作用，而这种作用主要发生在斑块下。此外，我们发现了最小的斑块尺寸（半径≈0.5 m）能够维持土壤中高度多样的群落。因此，我们的结果揭示了可以根据土壤改良来解释的信息，因此，它指示了植物促进作用的范围，以及能够改善土壤的最小斑块尺寸。这些发现提供了可用于更新对旱地生态动态的一般理解以及更好地计划恢复和保护行动的客观价值。