title: 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.
abstract: Anthropogenic changes in land use/cover have altered the vegetation, soil, and carbon (C) cycling on the Qinghai-Tibetan Plateau (QTP) over the last ~50years. As a result, the Grain for Green Program (GfGP) has been widely implemented over the last 10years to mitigate the impacts of cultivation. To quantify the effects of the GfGP on C partitioning and turnover rates at the ecosystem scale, an in situ (13)C pulse labeling experiment was conducted on natural and GfGP grasslands in an agro-pastoral ecotone in the Lake Qinghai region on the QTP. We found that there were significant differences in the C stocks of all the considered pools in both the natural and GfGP grasslands, with higher CO2 uptake rates in the GfGP grassland than that in the natural grassland. Partitioning of photoassimilate (% of recovered (13)C) in C pools of both grasslands was similar 25days after labeling, except in the roots of the 0-15 and 5-15cm soil layer. Soil organic C (SOC) sequestration rate in the GfGP grassland was 11.59±1.89gCm(-2)yr(-1) significantly greater than that in the natural grassland. The results confirmed that the GfGP is an efficient approach for grassland restoration and C sequestration. However, it will take more than a century (119.19±20.26yr) to restore the SOC stock from the current cropland baseline level to the approximate level of natural grassland. We suggest that additional measures are needed in the selection of suitable plant species for vegetation restoration, and in reasonable grazing management.
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Chen
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Education of Qinghai Province, Xining 810008, Qinghai, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Yang
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China.
authors.forename: Shixiao
authors.initials: S
authors.lastname: Xu
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 10041, Sichuan, China. Electronic address: xqzhao@nwipb.cas.cn.
authors.forename: Xinquan
authors.initials: X
authors.lastname: Zhao
keywords: Carbon cycle; Carbon partitioning; Land use/cover change; Qinghai–Tibetan Plateau; Restoration time; Turnover rate