Climate change has exposed desert ecosystems to frequent extreme disturbances, including wet-dry cycles and freeze-thaw events, which accelerate desertification on a global scale. The limited nutrient availability characteristic of these ecosystems may constrain microbial survival and growth, making them more vulnerable to environmental perturbations and stressors. However, how nutrient availability modulates the stability of soil ecological communities and functions in desert ecosystems remains poorly understood. In this study, we examined how nutrient addition, applied either before or after disturbances, affects the resistance of bacterial communities and multifunctionality to drought and freeze events in desert ecosystems. Our findings revealed that freeze-thaw events, rather than drought, significantly reduced bacterial diversity, with all disturbances altering the community structure. Pre-disturbance nutrient addition notably improved the resistance of soil bacterial diversity and community composition to disturbances, which played a critical role in maintaining multifunctionality in desert ecosystems. This enhanced bacterial resistance was strongly associated with increased bacterial network complexity and the enrichment of disturbance-tolerant taxa. Our results highlight the pivotal role of nutrient availability in stabilising soil bacterial communities and multifunctionality under extreme climatic conditions in desert ecosystems. These findings offer valuable insights and practical strategies for the ecological protection and management of desertification.

The change in nutrient availability in the soil can affect key functions of forest ecosystems, such as insect herbivory. Although insect herbivory is particularly relevant because it can impact on the growth and mortality of forest plant species, the evidence of the impacts of fertilizers addition on herbivory patterns is limited. In this study, we specifically evaluated how herbivory frequency on the timber species Nothofagus antarctica is affected by the addition of nitrogen (N), phosphorus (P), potassium (K) and their combinations to the soil, using a long term full-factorial field experiment in a North-Patagonian Forest (Argentina). Our study investigated the effects of fertilizers (N, P, and K) on herbivory frequency and leaf nutrient concentrations of the studied species. We found that the addition of fertilizers to the soil increased herbivory frequency, which was mediated by increases in leaf nutrient concentrations. Furthermore, we observed that interactions between fertilizers in leaf nutrient concentrations generally produced increases in herbivory, both in the amount of leaf consumed and in the foliar damage percentage. These findings suggest that fertilization can have complex effects on plant-herbivore interactions, and that the specific effects may depend on the identity of the nutrients that combined, the plant species, and the level of nutrient availability. Our results provide evidence that changes in soil nutrient availability are important in forest ecosystems, and that should be considered to develop effective management strategies for the sustainable use of natural resources in Patagonian forests.