Plant community diversity in the Chobe Enclave, Botswana: Insights for functional habitat heterogeneity for herbivores

Precise vegetation descriptions and maps are essential tools for the management of natural areas, as well as for understanding animal habitat use. The Chobe Enclave (CE), adjacent to the Chobe National Park and the Chobe Forest Reserve, forms a critical dry season range for many large herbivores. As a tool for future management and studies about wildlife habitat use and migration, this study proposed to describe the plant communities in the CE and to study their relationships with microtopography and soils. Plant species were inventoried in 82 sampling plots (40 x 20 m), covering the vegetation diversity recognised by an unsupervised classification (Landsat images, 30-m resolution). A hierarchical clustering classified the inventories in eight plant communities, mapped with a supervised classification. This study was conducted in parallel with a soil study. Soil variations and degree of flooding largely determine community composition. Floodplains along the Linyanti River and dambos (concentrating local run off from rainfall) provide reliable green forage for wildlife during the dry season. Adjacent to floodplains, riverine forests also maintain green browse and grazing well into the dry season. In drylands, vegetation is largely determined by soil texture. Forests dominated by Baikiaea plurijuga occupy the acidic, red sands in the east, while sandveld vegetation grows on deep sands in paleo-river channels. These habitats support dominant grasses, which provide important forage for grazers during the wet season. Finally, woodlands dominated by Colophospermum mopane, characterised by sodium-rich and alkaline soils, enable herbivores to meet their mineral requirements during reproduction. Conservation implications: Our soil and vegetation studies provide important insights into factors determining plant communities. Their diversity and close vicinity play a critical role in enabling herbivores to adapt to seasonal variations in forage quantity and quality. Results will enable researchers to gain insights into animal habitat seasonal use in the Chobe Enclave

Football and social inclusion: evaluating social policy

Sport, particularly football, is increasingly recognized as a means for promoting social inclusion. Yet rigorous evaluations of football-based social inclusion projects are rarely carried out. This paper explains the importance of evaluation and proposes the use of realist evaluation as a framework for developing theory, informing social policy and improving project design. It also aims to develop a workable template for small-scale project evaluation. The paper draws a series of conclusions on how rigorous evaluation of football-based social inclusion projects can benefit participants, practitioners and policy makers, as well as football clubs and the communities they serve

Functional Resource Heterogeneity Increases Livestock and Rangeland Productivity

Most of the world’s rangelands are subject to large spatial and temporal variation in forage quantity and quality, which can have severe consequences for the stability and profitability of livestock production. Adaptive foraging movements between functional seasonal resources can help to ameliorate the destabilizing effects on herbivore body stores of spatial and temporal variability of forage quantity and quality. Functional dry-season habitats (key resources) provide sufficient nutrients and energy to minimize reliance on body stores and are critical for maintaining population stability by buffering the effects of drought. Functional wet-season habitats dominated by short, nutritious grasses facilitate optimal intake of nutrients and energy for lactating females, for optimal calf growth rates and for building body stores. Adaptive foraging responses to high-quality focal patches induced by rainfall and disturbance further facilitate intake of nutrients and energy. In addition, focused grazing impact in high-quality patches helps to prevent grassland maturing and losing quality. In this regard, the design of many rotational grazing systems is conceptually flawed because of their inflexible movement of livestock that does not allow adaptation to spatial and temporal variability in forage quantity and quality or sufficient duration of stay in paddocks for livestock to benefit from self facilitation of grazing. Similarly the fixed intraseasonal resting periods of most rotational grazing systems might not coincide with the key pulses of nitrogen mineralization and rainfall in the growing season, which can reduce their efficiency in providing a functional recovery period for grazed grasses. This might explain why complex rotational grazing systems on average have not outperformed continuous grazing systems. It follows, therefore, that ranchers need to adopt flexible grazing management practices that allow adaptation to spatial and temporal variability in forage quantity and quality, allow facilitation of grazing (season-long grazing), and allow more effective recovery periods (season-long resting)./La mayoría de los pastizales del mundo estásujeta a gran variación espacial y temporal en cantidad y calidad de forraje, lo cual puede tener severas consecuencias con la estabilidad y rentabilidad de la producción de ganado. El movimiento adaptativo del pastoreo entre la funcionalidad temporal de los recursos puede ayudar a reducir el efecto desestabilizador en la reserva corporal de los herbívoros de la variabilidad espacial y temporal de la cantidad y calidad del forraje. Hábitats funcionales de temporada seca (recursos clave) proveen de suficientes nutrientes y energía para minimizar la dependencia de reservas corporales y son criticas para mantener la estabilidad de la población y efecto amortiguador de la sequia. Hábitats funcionales de temporada húmeda dominados por pastos cortos nutritivos facilitan el consume óptimo de nutrientes y energía para hembras lactantes paralas tasas de crecimiento optimo del becerro por la construcción de reservas corporales. La respuesta adaptativa al pastoreo en áreas específicas de alta calidad inducidos por la lluvia y disturbio además facilita el consumo de nutrientes y energía. En suma, focalizando el impacto del pastoreo en parches de alta calidad ayuda a prevenir la maduración del pasto y pérdida de calidad. Eneste contexto, el diseño de varios sistemas de pastoreo tiene la falla conceptual en la nula flexibilidad del movimiento del ganadoque no permite la adaptación espacial y temporal en la variación en la calidad y cantidad del forraje o suficiente tiempo de estancia en el potrero por el ganado para beneficiarse de auto facilitación del pastoreo. De manera similar, los periodos de descanso fijos intratemporales de la mayoría de los sistemas de pastoreo no podrían coincidir con los pulsos claves de lamineralización del nitrógeno y lluvia en la época de crecimiento la cual podría reducir la eficiencia en proveer recuperación funcional del periodo de los pastos pastoreados. Esto podría explicar porque sistemas de pastoreo complejos tienen en promedio un bajo desempeño comparado con el pastoreo continuo. Se desprende por lo tanto, que los rancheros necesitan adopter prácticas de manejo de pastoreo flexible que permita adaptar la variabilidad espacial y temporal de la cantidad y calidad del forraje permitiendo facilitar el pastoreo (temporal-permanente pastoreo) y periodos de recuperación más efectivos (temporal-permanente descanso).The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Productivity_Spp_Comp_Burkepile_et_al_JoE

This file contains data for plant species composition, productivity, and light availability from a herbivore exclusion experiment conducted across a productivity gradient in Kruger National Park, South Afric

Data from: Herbivore size matters for productivity-richness relationships in African savannas

1.Productivity and herbivory often interact to shape plant community composition and species richness with levels of production mediating the impact of herbivory. Yet, differences in herbivore traits such as size, feeding guild, and dietary requirements may result in different impacts of diverse herbivore guilds across productivity gradients. 2.We used size-selective herbivore exclosures to separate the effects of herbivory by larger herbivores, such as elephant, Burchell's zebra, and blue wildebeest from those of medium/smaller herbivores, such as impala and warthog, on herbaceous plant communities. These exclosures were established along a 10-fold productivity gradient, ranging from 90-950 g m−2 of standing plant biomass in the Kruger National Park, South Africa. 3.Exclusion of all herbivores generally increased plant species richness at low productivity but decreased richness at high productivity. Exclusion of medium/smaller herbivores (e.g. impala, warthog) showed stronger effects on plant richness, particularly loss of forbs, at higher productivity rather than at lower productivity. In contrast, exclusion of larger herbivores had stronger effects on plant richness, typically with increasing forb richness, at low rather than high productivity. 4.The change in species richness appeared linked to changes in light availability following herbivore exclusion. Strong increases in shading led to declines in species richness while more moderate increases in shading led in increases in species richness, possibly due to amelioration of heat and water stress by modest increases in shading. 5.Increasing plant dominance, which likely alters multiple mechanisms of plant interactions, was correlated with declines in plant richness following herbivore exclusion. The impact of increasing dominance on plant richness operated independent of productivity, with the exclusion of impala appearing particularly important in driving this relationship. 6.Synthesis. We show that the impact of herbivore losses on plant diversity will be strongly situation dependent and will vary with the herbivores lost (e.g. larger vs. smaller, grazers vs. browsers), plant functional type (e.g. grasses vs. forbs), and environmental context (e.g. productivity). Although larger herbivores are often emphasized for their strong impacts on community dynamics and ecosystem processes, we show that smaller, abundant herbivores can exert strong top-down control on plant communities

Data from: Fire frequency drives habitat selection by a diverse herbivore guild impacting top–down control of plant communities in an African savanna

In areas with diverse herbivore communities such as African savannas, the frequency of disturbance by fire may alter the top–down role of different herbivore species on plant community dynamics. In a seven year experiment in the Kruger National Park, South Africa, we examined the habitat use of nine common herbivore species across annually burned, triennially burned and unburned areas. We also used two types of exclosures (plus open access controls) to examine the impacts of different herbivores on plant community dynamics across fire disturbance regimes. Full exclosures excluded all herbivores > 0.5 kg (e.g. elephant, zebra, impala) while partial exclosures allowed access only to animals with shoulder heights ≤ 0.85 m (e.g. impala, steenbok). Annual burns attracted a diverse suite of herbivores, and exclusion of larger herbivores (e.g. elephant, zebra, wildebeest) increased plant abundance. When smaller species, mainly impala, were also excluded there were declines in plant diversity, likely mediated by a decline in open space available for colonization of uncommon plant species. Unburned areas attracted the least diverse suite of herbivores, dominated by impala. Here, herbivore exclusion, especially of impala, led to strong declines in plant richness and diversity. With no fire disturbance, herbivore exclusion led to competitive exclusion via increases in plant dominance and light limitation. In contrast, on triennial burns, herbivore exclusion had no effect on plant richness or diversity, potentially due to relatively little open space for colonization across exclosure treatments but also little competitive exclusion due to the intermediate fire disturbance. Further, the diverse suite of grazers and browsers on triennial burns may have had a compensating effect of on the diversity of grasses and forbs. Ultimately, our work shows that differential disturbance regimes can result in differential consumer pressure across a landscape and result in heterogeneous patterns in top–down control of community dynamics

Appendix A. Site and herbivore exclosure design information.

Site and herbivore exclosure design information

Appendix B. Plant community response metrics through time.

Plant community response metrics through time

Appendix C. Mechanisms underlying community change.

Mechanisms underlying community change