Savanna resilience to droughts increases with the proportion of browsing wild herbivores and plant functional diversity

Irob, Katja; Blaum, Niels; Weiss‐Aparicio, Alex; Hauptfleisch, Morgan; Hering, Robert; Uiseb, Kenneth; Tietjen, Britta

doi:10.1111/1365-2664.14351

Cited by 10 publications

(12 citation statements)

References 72 publications

(81 reference statements)

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“…In the results and discussion section, we assess the outcomes by employing the principles of resilience and stability. In accordance with Irob, Blaum, Weiss-Aparicio, et al (2023), resilience refers to the ecological system's capacity to endure disturbances without undergoing significant shifts in its state. This endurance is realized through either resistance to disturbances or the system's ability to recover from stressors.…”

Section: Discussionmentioning

confidence: 99%

“…We employed the EcoHyD model, an ecohydrological and spatially explicit model for dryland systems (Irob, Blaum, Weiss-Aparicio, et al, 2023;Irob et al, 2022;Lohmann et al, 2012;Tietjen et al, 2010), to simulate an area of 2.25 ha, which consists of 900 grid cells with a resolution of 5 × 5 m 2 per cell. This model has been…”

Section: Model Descriptionmentioning

confidence: 99%

“…previously used and validated in different dryland ecosystems(Irob, Blaum, Weiss-Aparicio, et al, 2023; Appendix A5;Lohmann et al, 2012;Tietjen et al, 2010).TheEcoHyD model is a spatially explicit, process-based model that simulates the dynamics of vegetation and hydrology in dryland ecosystems. It consists of two submodels: a vegetation submodel and a hydrological submodel.…”

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confidence: 99%

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

Irob,

Blaum,

Tietjen

2024

Journal of Applied Ecology

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Savannas are characterized by water scarcity and degradation, making them highly vulnerable to increased uncertainties in water availability resulting from climate change. This poses a significant threat to ecosystem services and rural livelihoods that depend on them. In addition, the lack of consensus among climate models on precipitation change makes it difficult for land managers to plan for the future. Therefore, Savanna rangeland management needs to develop strategies that can sustain Savanna resilience and avoid tipping points under an uncertain future climate. Our study aims to analyse the impacts of climate change and rangeland management on degradation in Savanna ecosystems of southern Africa, providing insights for the management of semi‐arid Savannas under uncertain conditions worldwide. To achieve this, we simulated the effects of projected changes in temperature and precipitation, as predicted by 10 global climate models, on water resources and vegetation (cover, functional diversity, tipping points (transition from grass‐dominated to shrub‐dominated vegetation)). We simulated three different rangeland management options (herbivore communities dominated by grazers, by browser and by mixed feeders), each with low and high animal densities, using the ecohydrological model EcoHyD. Our results identified intensive grazing as the primary contributor to the increased risk of degradation in response to changing climatic conditions across all climate change scenarios. This degradation encompassed a reduction in available water for plant growth within the context of predicted climate change. It also entails a decline in the overall vegetation cover, the loss of functionally important plant species and the inefficient utilization of available water resources, leading to earlier tipping points. Synthesis and applications. Our findings underscore that, in the face of climate uncertainty, farmers' most effective strategy for securing their livelihoods and ecosystem stability is to integrate browsers and apply management of mixed herbivore communities. This management approach not only significantly delays or averts tipping points but also maintained greater plant functional diversity, fostering a more robust and resilient ecosystem that acts as a vital buffer against adverse climatic conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

mentioning

confidence: 99%

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

Irob,

Blaum,

Tietjen

2024

Journal of Applied Ecology

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“…A lower dominance would reduce the impact of the loss of a single species on ecosystem functioning (Hillebrand et al, 2008). In addition, high diversity of functional groups can also improve the overall resilience of a grassland ecosystem (Symstad & Tilman, 2001; de la Riva et al, 2017; Irob et al, 2023) for example by a more efficient use of resources, as mentioned above.…”

Section: Discussionmentioning

confidence: 99%

Rangeland resilience to droughts: Changes across an intensification gradient

Tommasino

Lezama

Gallego

et al. 2023

Applied Vegetation Science

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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.

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“…A diverse assemblage of wild herbivores, including both grazers and browsers, acts as a resilience insurance that makes savannas more resistant to droughts (Irob et al, 2023; Li, Buitenwerf, Munk, Amoke, et al, 2020). This is ever more important, as climate change is expected to increase the frequency and intensity of droughts across Africa (Dai, 2013; IPCC, 2022).…”

Section: Discussionmentioning

confidence: 99%

Rotational grazing with cattle‐free zones supports the coexistence of cattle and wild herbivores in African rangelands

Herrik,

Mogensen,

Svenning

et al. 2023

Journal of Applied Ecology

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African wildlife populations are declining at an alarming rate. To stop further population declines and restore ecosystems, more areas for wildlife are needed. Community‐based conservation with wildlife‐livestock coexistence in the vast rangelands of Africa presents a major opportunity. However, the efficacy of wildlife conservation in mixed land‐use areas remains an outstanding question. To assess the ecological outcomes of land‐sharing between regulated livestock herds and wildlife populations in African savannas, we test how rotational cattle grazing affects spatiotemporal dynamics of 15 large herbivore species in the Maasai Mara, Kenya. First, we tested how wild herbivore distributions across the Greater Mara Ecosystem (the Mara, ~2600 km2) are related to cattle density and environmental variables using 584,561 observations of wild herbivores (ecosystem scale). In a second analysis, we tested how rotational cattle grazing affects wild herbivore distributions in a 300 km2 subsection of the Mara using 30,583 observations (landscape scale). Finally, we tested how functional traits of wild herbivores affect species‐level spatiotemporal responses to cattle grazing. At the ecosystem scale, the presence of five wild herbivore species was positively correlated with cattle density, while cattle effects on wild herbivore abundances were species‐dependent with both increases and decreases. At the landscape scale, rotational cattle grazing strongly impacted the spatiotemporal habitat selection of wild herbivores, resulting in distinct lag periods with which different species are attracted to areas previously grazed by cattle. These lag periods were linked to functional traits, with body mass and herd size explaining 35% of the interspecific differences. Small to medium‐sized herbivores with large herds select areas recently grazed by cattle, whereas large species with large herd sizes and small species with small herd sizes avoid recently grazed areas. Synthesis and applications: Our results revealed that the effect of cattle on wild herbivores varies considerably among species, suggesting that cattle‐wildlife interactions range from facilitation to competition. To maintain species that strongly avoid cattle, designated livestock‐free zones remain essential, also in rotational grazing systems. Rotational grazing systems with regulated livestock densities present an important opportunity to better manage wildlife‐livestock coexistence and thus improve wildlife conservation in African rangelands.

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Savanna resilience to droughts increases with the proportion of browsing wild herbivores and plant functional diversity

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 10 publications

References 72 publications

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

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

Rangeland resilience to droughts: Changes across an intensification gradient

Rotational grazing with cattle‐free zones supports the coexistence of cattle and wild herbivores in African rangelands

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