Rangeland resilience to droughts: Changes across an intensification gradient

Abstract

The intensification of livestock systems generates structural and functional changes in native grassland, which alter their capacity to respond to disturbances. Our objective was to evaluate the resilience to an extraordinary consecutive droughts event, across an intensification gradient of pastoral systems. Our prediction is that sites with more intensive management (less diverse) will have lower resilience (as resistance and/or recovery) to drought. LocationSouth-central region of Uruguay. MethodsWe evaluated the resilience (as resistance and recovery) to consecutive droughts, across an intensification gradient of pastoral systems. We analyzed the effect of diversity on resilience at two scales: 1. regional, where we compared the resilience of three systems with an increasing level of intensification that determine changes in diversity, 2. patch, we carried out a manipulative experiment with different grazing management systems (different level of defoliation, and fertilization). In both experiments the response variables, resistance and recovery, were calculated from the Normalized Difference Vegetation Index, a remotely sensed proxy of aerial net primary productivity. ResultsOur results showed that sown pastures (the less diverse) had significantly lower resistance, than native grassland and overseed grassland. Also, sown pastures showed the lowest recovery rate, although differences were only significant with overseed grassland. Grazing treatments at the plot level (manipulative experiment) did not show clear differences among treatments neither for resistance nor recovery. However, resistance of the individual plots showed a positive significant association with evenness and diversity of functional groups. ConclusionThis study showed that the different grazing managements studied were resilient, in terms of their ANPP, to a major drought disturbance event. Differences in resilience was expressed in resistance rather than recovery. These results support our prediction, both at the regional and plot scales, that the least rich and diverse situations showed the lowest resilience, at least in terms of resistance.

Navigating uncertainty: Managing herbivore communities enhances Savanna ecosystem resilience under climate change

“…However, by maintaining adequate vegetation cover and leaf area index, water loss through evapotranspiration is minimized, leading to increased water availability for ecosystem services, other purposes and the restoration of degraded ecosystems (Irob, Blaum, Weiss-Aparicio, et al, 2023;Tommasino et al, 2023).…”

“…However, the extent of change required can vary based on the specific system and location, necessitating either incremental adjustments or more transformative step changes in management strategies. For instance, rangeland managers could consider measures such as preventing shrub encroachment, actively maintaining biodiversity, optimizing grazing practices and fostering resilient vegetation cover (Higgins et al, 2007;Tommasino et al, 2023;Wangai et al, 2016). These approaches should be evaluated within the context of their economic viability and potential benefits for sustaining ecosystem health and services.…”

Hybrid modeling for grassland productivity prediction: A parametric and machine learning technique for grazing management with applicability to digital twin decision systems

“…Such drought periods have a significant impact on forage production and, hence, on livestock productivity, including a drastic reduction in reproductive performance that causes lag effects on Net Secondary Productivity (Gutierrez et al 2020). It has been recently reported that areas with a greater diversity of perennial forage resources (native grasslands, intersown grasslands or pasture based on exotic pastures) are more resilient to droughts events (Tommasino et al 2023).…”