Responses of carbon transfer, partitioning, and residence time to land use in the plant–soil system of an alpine meadow on the Qinghai-Tibetan Plateau

More than a century of Grain for Green Program is expected to restore soil carbon stock on alpine grassland revealed by field 13 C pulse labeling

“…Although it was not directly estimated, and 13 C allocated in soil layers below 15 cm and SOC leaching were not considered, shoot respiration also played an important role, and was responsible for the release of 14.81 and 21.68% of recovered 13 C into the atmosphere in the natural and GfGP grasslands, respectively. Shoot and soil respiration released m E ( 13 CO 2 ) accounted for up to 40.28 and 45.06% of recovered 13 C in the natural and GfGP grasslands, respectively, and was within the range (31.6-58.4%) reported in previous studies (Gao et al, 2015;Hafner et al, 2012;Ingrisch et al, 2015;Wu et al, 2010;Zhao et al, 2015).…”

“…The MRT 1 corresponded to the rapid TR 1 that represents shoot respiration losses and the reallocation of assimilated m E ( 13 C) to belowground, while MRT 2 corresponded to the slow TR 2 that represents partitioning to storage, structural growth, and defense compounds (Epron et al, 2012). The MRT 2 of the shoot m E ( 13 C) in the natural grassland (159 days) was higher than that in the GfGP grassland (73 days), indicating that more C was partitioned to stable pools of transiently stored and structural C because of the higher proportion of perennial species in the natural grassland, as reported by Zhao et al (2015). The greater shoot respiration and related soil respiration (Fig.…”

“…In terrestrial ecosystems, the size of the C reservoir for the whole ecosystem equals the C stocks in the vegetation and soil (Carvalhais et al, 2014), and is an ecosystem property that indicates C sequestration capability of an ecosystem (Zhao et al, 2015). This was represented by the C stocks in the shoots, roots, and soil in the present study.…”

“…The 13 C pulse labeling made it possible to explore the fate of newly assimilated C, including its partitioning within plants and to the soil, its storage within ecosystems and losses into the atmosphere in the natural and GfGP grasslands under in situ conditions (Gao et al, 2015;Hafner et al, 2012;Ingrisch et al, 2015;Street et al, 2013;Wu et al, 2010;Zhao et al, 2015;Zou et al, 2014). The results indicated that, although the 13 CO 2 uptake rate was greater in the GfGP grassland than in the natural grassland (Figs.…”

“…13 C pulse labeling can be used to explore the SOC sequestration rate, i.e., newly assimilated C partitioned into SOC, under in situ conditions (Gao et al, 2015;Hafner et al, 2012;Ingrisch et al, 2015;Street et al, 2013;Wu et al, 2010;Zhao et al, 2015;Zou et al, 2014). Using the method from Street et al (2013) that is based on the robust positive linear relationship between gross primary productivity (GPP) and annual net primary productivity (ANPP) reported by Litton et al (2007), the product of GPP and % of recovered 13 C in the soil provides estimates of the SOC sequestration rate and total photosynthesized C partitioned into the soil (Litton et al, 2007;Roper et al, 2013;Street et al, 2013).…”