Effects of grazing exclusion on soil infiltrability and preferential flow in savannah livestock grazing systems

Abstract

Although the establishment of grazing exclosures is often considered an important strategy of reducing soil degradation, their effect on hydrological functions is still poorly understood, particularly in dry‐hot savanna systems with heavy livestock grazing. In addition, the different roles played by the herb roots and the niche differentiation of woody plant roots induced by the grazing and exclosure in soil hydrological functions are still unclear. This study aimed to evaluate the effect of exclosure management on hydrological functions and services and assess the role of different functional vegetation types in improving these functions and services. The experiments were conducted in the continuous grazing areas and exclosure areas in a savanna ecosystem in Yuanjiang, southwest China. The root biomass of herb and woody plants, soil physical properties, water infiltration, and preferential water flow were measured in each study site. The results showed a significant improvement in soil physical properties with more termite holes, lower soil bulk density, and higher total and non‐capillary soil porosity in exclosure areas compared with grazing ones. As a result, the initial and average water infiltration, and preferential flow significantly increased by 132.76%, 185.31%, and 30.29%, respectively, in exclosure areas compared with the grazing ones. The results also showed that the exclosure significantly improved the soil surface water content by increasing the root biomass of herb and woody plants in the shallow soil layers. Herb plants probably improved water infiltration and insulated evaporation, while woody plants improved lateral preferential water flow paths and accelerated the water exchange between vertical and horizontal soil layers, thereby improving the water availability for different plants. This study demonstrated that the exclosure‐induced restoration and niche differentiation of herb and woody plants, coupled with improved soil structure in exclosures, could promote hydrological function and services and improve water management in savanna systems. Therefore, the grazing exclosures could be expanded periodically and cautiously to prevent soil degradation in the present savanna systems.

Are syntropic agroforestry systems microclimatically similar to tropical forests?

“…The current challenge of agricultural systems is to produce food to meet society's demands, utilizing ecologically planned and designed agroecosystems, thereby reviving traditional practices while integrating interdisciplinary scienti c knowledge to enhance production, landscape, and ecosystem In this context, developing agricultural systems capable of combining food production with other ecosystem services becomes an increasingly pressing demand in scienti c discussions. Studies demonstrate alternative food production methods that can reduce the impacts of agriculture on ecosystems and thus enhance productive capacity over time, strengthening ecosystem services (Chen et al 2022; Puech e Starkb 2023). Based on an environmentally sustainable approach, with a focus on food security, human health, and social and economic well-being ( Building upon this approach, studies show that the use of shade trees in agroforestry systems offers the possibility to mitigate extremes in terms of temperature, humidity, and other microclimatic variables (Lin 20007;Glazle et al 2021;Wang et al 2022).…”