Climatic Legacies Drive Spatial Aggregation of Plants in Drylands

In drylands, vegetation is spatially aggregated in patches separated by bare soil areas. So far, research on vegetation spatial patterns mainly focused on the effect of current climates and herbivory pressure. Yet, past climates might leave traces (called legacies) that affect present-day spatial vegetation patterns. Here, we joined two datasets on plant spatial patterns and information about past climates during the mid-Holocene and the last glacial maximum to investigate the effects of past and current climates on plant spatial patterns. We show that past climates have effects of similar magnitude as current climate on the vegetation cover, but have a remarkably stronger imprint on the spatial aggregation of vegetation in drylands. Furthermore, we found that climate legacies on plant spatial patterns might relate to climate long-lasting effects on soil multifunctionality and sand content. Climate legacies detected here emphasize the contrasting time scales of processes involved in vegetation patterning, which we should account for when assessing dryland functioning and resilience from these patterns. This study opens perspectives to assess legacies from human activities and past climate on ecosystems.