Grazing enhances species diversity in grassland communities

Abstract

In grassland studies, an intermediate level of grazing often results in the highest species diversity. Although a few hypotheses have been proposed to explain this unimodal response of species diversity to grazing intensity, no convincing explanation has been provided. Here, we build a lattice model of a grassland community comprising multiple species with various levels of grazing. We analyze the relationship between grazing and plant diversity in grasslands under variable intensities of grazing pressure. The highest species diversity is observed at an intermediate grazing intensity. Grazers suppress domination by the most superior species in birth rate, resulting in the coexistence of inferior species. This unimodal grazing effect disappears with the introduction of a small amount of nongrazing natural mortality. Unimodal patterns of species diversity may be limited to the case where grazers are the principal source of natural mortality.

Assessing the Effects of Desertification Control Projects from the Farmers’ Perspective: A Case Study of Yanchi County, Northern China

“…For example, most farmers (97.0% and 89.4%) reported that the grassland vegetation coverage increased after the DCPs, but not a great proportion of the farmers (48.5% and 63.8%) thought that the species richness was higher than before ( Table 2). The present finding is consistent with the findings of Pulungan et al, who claimed that an intermediate grazing intensity instead of no grazing often resulted in the highest species diversity [41]. Moreover, the complete grazing ban forced sheep to be only bred in sheep pens.…”

Pastoralism in the highest peaks: Role of the traditional grazing systems in maintaining biodiversity and ecosystem function in the alpine Himalaya

“…Negative effects of grazing have been attributed to high grazing intensity owing to overgrazing and high stocking rates or to low grazing intensity including the abandonment of grazing [ 2 , 21 , 22 , 64 , 65 , 96 ]. The general consensus is that a light to medium grazing intensity is most beneficial [ 2 , 64 , 66 ]. This study demonstrates that the pastures in Lachen valley have benefitted from grazing of various livestock suggesting the stocking rates are within or below “carrying capacity”.…”

“…Studies from around the world show varied effects of grazing on vegetation [2,21,22,[64][65][66]. A meta-analysis of sixty-one studies from the Tibetan plateau showed grazing mediated increase in species diversity but a decrease in above ground biomass [67].…”

Livestock‐exclusion duration required for restoring grassland in semiarid, loess region in China: Estimate based on species composition measured from small‐scale vegetation patterns

“…In the past studies surveyed in various regions, although some results showed that the exclusion enhances the species richness and diversity, many other results showed that no statistical difference between grazing and excluding in species richness and diversity. The results are likely to depend on the growing environment such as water condition, soil fertility, productivity and so on (e.g., Listopad, Köbel, Príncipe, & Gonçalves, 2018; Pulungan et al, 2019; Pykälä, 2005; Schultz, Morgan, & Lunt, 2011). We determined the species that are most able to dominate during the grazing, recovery, and recovered stages in this area (Table 4).…”