Influences of grazing and exclosure on carbon sequestration in degraded sandy grassland, Inner Mongolia, north China

Abstract

Livestock grazing is recognised as one of the main causes of vegetation and soil degradation/desertification in the semi-arid Horqin sandy steppe of northern China. In this paper, soilplant system carbon (C) in a representative degraded sandy grassland in the Horqin sandy steppe (42°58' N, 120°42'E altitude c. 360 m a.s.l.) was measured. Three situations: long-term continuous grazing (CG), exclosure for 5 years (5EX), and exclosure for 10 years (10EX), were compared to assess the effect of grazing management on C sequestration. Ground cover increased from the CG (35%) to the 5EX (63%) and to the 10EX (81%), and accordingly soil organic C at 0-15 cm depth and total plant components C increased from the CG (492 and 98 g m -2 ) to the 5EX (524and 134 g m -2) and to the 10EX (584 and 317 g m -2 ). The results suggested that continuous grazing in the erosion-prone sandy grassland is very detrimental to vegetation and soil. Under exclosure conditions, vegetation restoration and litter accumulation significantly increased plantsoil system C storage, and thus sequestration of atmospheric C. It was concluded that the degraded sandy grassland could contribute to significant C sequestration with the implementation of protective practices.

Field <sup>13</sup>CO<sub>2</sub> pulse labeling reveals differential partitioning patterns of photoassimilated carbon in response to livestock exclosure in a <i>Kobresia</i> meadow

“…Some field studies have proposed exclosure as an effective approach for restoring vegetation and improving C storage of the grassland Su et al, 2003), while others demonstrated that exclosure has had negative effects on C sequestration in grasslands (Reeder and Schuman, 2002). This apparent contradiction can be explained by the different evolutionary processes, degrees of degradation and grazing history in these grassland communities.…”

“…Livestock exclosures have a potential value in assessing the effects of grazing upon vegetation and C sequestration in the grasslands (Bock et al, 1984;Cheng et al, 2011;He et al, 2011;Li et al, 2012;Su et al, 2003). Exclosures appear to favor higher community diversity and productivity compared with grazing in the arid grasslands (Bock et al, 1984;Cheng et al, 2011).…”

“…Exclosures appear to favor higher community diversity and productivity compared with grazing in the arid grasslands (Bock et al, 1984;Cheng et al, 2011). Furthermore, grazing exclosures are widely used as a management practice to restore degraded grasslands Su et al, 2003). However, recent studies on a fenced Leymus chinensis grassland in northern China demonstrated that the outcomes from exclosure were related to the community types of the grasslands, with responses to litter accumulation dependent on plant density (He et al, 2011).…”

“…However, recent studies on a fenced Leymus chinensis grassland in northern China demonstrated that the outcomes from exclosure were related to the community types of the grasslands, with responses to litter accumulation dependent on plant density (He et al, 2011). Generally, there were cascade effects on C sequestration in the plant-soil system from variations of the community structure and other factors related to exclosure Su et al, 2003). Many studies demonstrated that plant diversity and the interactions among different species or plant functional groups had major effects on C sequestration (Fornara and Tilman, 2008;Steinbeiss et al, 2008).…”

Effects of land‐use regimes on carbon sequestration in the Loess Plateau, northern China

“…For the two grasslands, continuous grazing resulted in a significant increase in soil BD (Su et al 2003) in upper soil layers (0-40 cm); this may result from livestock tramping. For the cropland, long-term intensive farming led to a decrease of Bd in surface soil layers, except for the plough pan.…”