Grazing exclusion alters ecosystem carbon pools in Alxa desert steppe

Abstract

The Alxa desert steppe has been strongly degraded by overgrazing, contributing c. 22% of the total springtime dust originating from Asia. Previous work in this region has focused on the impacts of grazer exclusion on restoration of vegetation and soil fertility, yet carbon dynamics are not well known. The effects of 7 years of grazer exclusion on carbon dynamics were studied and related to changes in vegetation and soil properties. Removal of grazing resulted in a significantly greater plant cover and aboveground plant biomass compared with areas that had been subject to grazing, but this had no effects on belowground plant biomass. Removal of grazing resulted in significantly decreased soil bulk density in the 0Á10 cm layer, increased soil water content (7% cf. 40%) and greater soil microbial biomass C (6% cf. 73%) compared with soils in the grazed area. Soil organic carbon (SOC) pools were lower and soil inorganic carbon (SIC) pools were higher in areas that were excluded from grazing. After 7 years of grazer exclusion, the total C pool in the plantÁsoil system was 10% greater (primarily due to 21% greater in SIC) than that in the area that had been grazed over that time period.

Effects of grazing exclusion on soil carbon and nitrogen storage in semi-arid grassland in Inner Mongolia, China

“…Besides the aboveground biomass, removal of grazing also resulted in an increase of belowground biomass at our three experiment sites, which is consistent with other studies (Cheng et al, 2011;Qiu et al, 2013). However, some studies reported that grazing exclusion had insignificant or even negative effects on belowground biomass (Reeder et al, 2004;Niu et al, 2011). The inconsistency of these results might be due to complicated factors, such as the degree of degradation before grazing exclusion, the soil and vegetation types, the duration of grazing exclusion and the regional climatic conditions (Pineiro et al, 2009;Wu et al, 2009;Cheng et al, 2011).…”

Awassi sheep keeping in the Arabic steppe in relation to nitrous oxide emission from soil

“…The rising demand for Awassi products means that increasing numbers of sheep will be bred, thus leading to an overuse of the steppe. For instance, Niu et al (2011) stated that the Alxa desert in China has been strongly depleted by overgrazing. Providing feed is the biggest problem for sheep keepers in Syria.…”

Effects of Grazing Exclusion on Soil Properties in Maqin Alpine Meadow, Tibetan Plateau, China

“…However, studies on the effectiveness of grazing exclusion have had many inconsistent results. Several researchers [8,9] found that grazing exclusion could strongly increase soil fertility and carbon storage. Others [10] reported that soil carbon storage decreased at non-grazed sites compared with adjacent grazed sites.…”