Precipitation regulates the livestock dung seed bank through above ground vegetation productivity in the Qaidam basin

Abstract

AbstractThe livestock dung seed bank (DSB) plays an important role in the regeneration and sustainability of grasslands in grazing ecosystems. As global precipitation patterns change, the productivity of the above ground vegetation (AGV) in semiarid and arid regions may be substantially affected, as will both the size and composition of the livestock DSB. However, the effects of altered precipitation patterns remain to be determined. Dung was collected for three consecutive years (2018–2020) from horses, cattle and sheep in the desert region of the Qaidam basin, China. The seedling emergence method was used to examine species richness and seed density in the DSB, and the structure and composition of the DSB and the AGV were also investigated. Combined with precipitation data, a structural equation model was used to explore how precipitation affects the livestock DSB by quantifying changes in the AGV in the basin. The results showed that horses [seedling density 5.32 (2018), 6.30 (2019) and 7.44 (2020) g−1 dung] had greater seed dispersal potential than cattle (3.91, 5.08 and 6.42 g−1 dung) or sheep (0.88, 1.32 and 2.96 g−1 dung), indicating that horse dung contributes the most to the AGV in the Qaidam basin. Furthermore, the seed composition of the DSB differed substantially from species of the AGV, implying that the DSB can promote the diversification of grasslands. An increase in precipitation increased both the productivity of the AGV (and hence livestock forage) and the size and composition of the DSB. These results highlight that the DSB is an essential driver of the development of grasslands in arid areas and that the indirect effect of precipitation on the livestock DSB for the regeneration and conservation of grasslands should be considered in arid regions.