4.3 Implications for management practices
Ecosystem organic carbon and nitrogen stocks in grasslands are
determined by soil, plants, and their interactions. Although there was a
decrease in ecosystem nitrogen stock, GE significantly increased the
ecosystem organic carbon stock and improved its distribution in the
aboveground soil and roots and enhanced plant productivity, as compared
to those observed after implementing the grazing methods in this region
(Table 2). This suggests that long-term GE is an effective way to
improve ecological health and resilience in karst grasslands, regardless
of livestock grazing. Although the ecosystem organic carbon and nitrogen
stocks were not significantly different
among grazing methods, we found that
the EOCs and ETNs of MG and RG increased by 16.31% and 7.76%,
respectively, while MG increased the EOCs by 22.29% and slightly
decreased the ETNs compared with CG (Table 2), indicating that grazing
could partly improve the ecosystem C and N stocks. Similar results were
found in other studies (Chen et al., 2021; Wen Li et al., 2017). RG can
substantially increase livestock stocking levels while improving
vegetation, soil carbon, and water infiltration functions (Mosier et
al., 2021). According to the moderate disturbance hypothesis, reasonable
grazing or mowing causes an increase in grassland productivity and
improve soil physicochemical properties, thus maintaining a continuous
supply capacity of nutrients and enabling the ecosystem to stay in a
healthy and stable condition (T. D. Mipam, Zhong, Liu, Miehe, & Tian,
2019; G. Zhou et al., 2017). Previous studies also found that RG
increased SOC and TN stocks (0-1 m) by 13% and 9%, respectively,
compared with continuous grazing (Mosier et al., 2021). Mowing
significantly increased the SOC and TN stocks in the topsoil layer
(0–30 cm) (Chen et al., 2021). Overall,
GE is a viable approach to
significantly improve vegetation resilience and soil carbon storage,
whereas RG should be considered under the condition of pasturing
utilisation in karst grasslands (regardless of GE).