Impact of 25 years of grazing exclusion and shrub removal on plant community structure and soil characteristics in a xerophytic rangeland

Abstract

Aim of study: We tested the hypothesis that long periods of grazing exclusion in areas with a history of high grazing intensity will have a positive impact on soil nutrient conditions and favor soil infiltration, increase biomass and lead to a recovery in vegetation.Area of study: Noria de Guadalupe, Zacatecas, Mexico.Material and methods: We analyzed the impact of grazing exclusion on biomass, species richness, evenness, soil nutrient content and soil water infiltration after 25 years of exclusion during each of the four seasons by  excluding two 15 × 15 m plots of grazing and compared with two control plots.Main results: Exclusion management did not lead to biomass increases; however, it did lead to an important recovery in the plant community. Moreover, soil nutrient content was more affected by the seasonality of rainfall in the study site than by 25 years of exclusion. The elimination of dominant shrubs in the excluded area led to a faster recovery in palatable shrubs and shortgrass vegetation, which was improved by better infiltration values during the end of spring and summer explaining some of the differences in nutrient avaibility.Research highlights: In our study, exclusion management can lead to an important recovery in vegetation without affecting the growth of Atriplex canescens, a valuable source of fodder. Although biomass presented a higher dependence on seasonality and was not related to the treatment, the impact on the forage quality is evident by the different plant communities established after 25 years of exclusion.