Theme 1: Grassland Ecology
Description
Livestock grazing is a major disturbance affecting plant diversity and abundance in terrestrial ecosystems. The intermediate disturbance hypothesis (IDH) predicts that moderate-intensity grazing should produce the highest species diversity, while the Milchunas-Sala-Lauenroth (MSL) model posits that the IDH is valid only for mesic areas. However, it remains unclear how grazing affects soil seed bank and whether or not the IDH or MSL models are valid for soil seed bank communities. Here, we presented a global meta-analysis synthesizing 483 observations: we found that grazing had a negative effect on soil seed bank abundance, but did not alter seed bank richness. Further refining the analysis, light-intensity grazing was found to increase seed bank richness, while moderate-intensity grazing had no effect, and heavy-intensity grazing had a negative effect. Additionally, for both arid and mesic areas, soil seed bank richness declined with grazing intensity increased. Overall, grazing effects on soil seed banks differed from expectations set by studies of aboveground vegetation. Our study provides key insights for policy-makers managing livestock grazing and grassland conservation.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Grazing Effects on Soil Seed Banks: A Global Synthesis
Livestock grazing is a major disturbance affecting plant diversity and abundance in terrestrial ecosystems. The intermediate disturbance hypothesis (IDH) predicts that moderate-intensity grazing should produce the highest species diversity, while the Milchunas-Sala-Lauenroth (MSL) model posits that the IDH is valid only for mesic areas. However, it remains unclear how grazing affects soil seed bank and whether or not the IDH or MSL models are valid for soil seed bank communities. Here, we presented a global meta-analysis synthesizing 483 observations: we found that grazing had a negative effect on soil seed bank abundance, but did not alter seed bank richness. Further refining the analysis, light-intensity grazing was found to increase seed bank richness, while moderate-intensity grazing had no effect, and heavy-intensity grazing had a negative effect. Additionally, for both arid and mesic areas, soil seed bank richness declined with grazing intensity increased. Overall, grazing effects on soil seed banks differed from expectations set by studies of aboveground vegetation. Our study provides key insights for policy-makers managing livestock grazing and grassland conservation.
