Effect of sheep grazing on seed circulation on the Loess Plateau

Abstract

The soil seed bank (SSB) is the basis for the natural regeneration of vegetation, especially in severely eroded or degraded ecosystems (Baskin & Baskin, 1978). In rangelands, the degree of heterogeneity among SSBs is strongly influenced by livestock pressure through selective grazing and grazing-related environmental impacts (Kassahun et al., 2009;Solomon et al., 2006). The diversity of seeds in disturbed habitats is determined by the original plant populations, propagule production, and soil seed reserves (Grime, 1979), all of which are affected by ecological perturbations. The quality of the SSB declines as a function of time as vegetation is destroyed (Bakker et al., 1996). Therefore, the SSBs of arid and semiarid ecosystems are highly variable over space and time, and are linked to factors that influence seed production, mortality, and spatial distribution (Kemp, 1989). Drought cycles (Msangi, 2004) and overgrazing (Klintenberg & Seely, 2004) are the primary drivers of dryland degradation, and together can result in broad-scale restructuring of vegetation and

Higher dung seedling density increases livestock dung greenhouse gas emissions in an alpine meadow

“… and ) in the faeces being absorbed by the dung seedlings (Yu, 2010), there was a significant negative correlation between dung seedling density and dung GHG fluxes (Table S5). That is to say, the germination of dung seeds and subsequent growth of the resulting seedlings stimulate the decomposition of faeces (Wang et al, 2021; Figure S1), which further demonstrates that dung is the hot spot for material flow as well as transformation in grassland ecosystems (Yang et al, 2019). As compared to measuring GHG emissions, dung seed germination is easier to detect.…”

“…Nutrient release from livestock dung into soil involves complex processes subject to biological degradation (Wang et al, 2021; Yang et al, 2019). During these processes, the decomposers (i.e.…”

“…On the one hand, livestock faeces constitute the dung seed bank of the grassland; that is, mature plant seeds are sometimes consumed by livestock while foraging, and some seeds survive passage through the digestive tract and are ultimately deposited in dung (referred to as endozoochorous seed dispersal). These viable seeds within large-herbivore faeces form the dung seed bank (Wang et al, 2019(Wang et al, , 2021Wang & Hou, 2021a). Dung seed banks are ubiquitous in grazing ecosystems, especially during the season in which seeds ripen and are important drivers of vegetation renewal and a vital supplement to the soil seed bank (Wang et al, 2021).…”

“…These viable seeds within large-herbivore faeces form the dung seed bank (Wang et al, 2019(Wang et al, , 2021Wang & Hou, 2021a). Dung seed banks are ubiquitous in grazing ecosystems, especially during the season in which seeds ripen and are important drivers of vegetation renewal and a vital supplement to the soil seed bank (Wang et al, 2021). The germination of dung seeds and the growth of dung seedlings occur at the same time as the process of faeces decomposition.…”

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

“…Seed dispersal through endozoochory is an important source of vegetation renewal and a supplement to the soil seed bank (SSB; Wang et al, 2021). Moreover, the nutrients and organic matter in livestock dung promote seedling emergence and growth (Nchanji & Plumptre, 2003;Traveset et al, 2001;Woldu & Saleem, 2000).…”