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• An ecosystem process model-based NEP was predicted under varying climate scenarios. • Alpine grasslands were projected to play an important part in carbon sink contributions in Qinghai Province in the 21st century. • An earlier peak and faster decreasing NEP projected for a warmer climate scenario (RCP 8.5). • A more stable carbon sink was projected under a less warm, stable precipitation scenario (RCP 4.5). The alpine grasslands of the Qinghai-Tibetan Plateau play an important role in multiple ecosystem functions, all of which are key in regulating regional climate influences and providing pristine headwaters for millions of people downstream from this basin. Alpine grasslands act as a carbon sink, storing carbon dioxide and keeping heat-trapping greenhouse gases out of the atmosphere, but it is not clear how this will change in a warming climate in the future. In this paper, the net ecosystem productivity (NEP) of alpine grasslands in Qinghai province, on the Qinghai-Tibetan Plateau, was predicted for the period from 2010 to 2099. Trends and stability were analyzed under two climate scenarios, Representative Concentration Pathway 4.5 (RCP4.5) and 8.5 (RCP8.5) representing the lower and higher emission scenarios for greenhouse gases. The results suggest that grasslands will continue to contribute as a carbon sink, with a positive NEP through this century. Almost the same magnitude (38 Tg C a-1, 1 T g = 1012 g) of contribution was projected under both scenarios. Grasslands are projected to be the major contributor to NEP in Qinghai province, with more than 89% of NEP in the future. The carbon sink function will increase over more than 69% of the grasslands and peak around 2069 (RCP4.5) or 2066 (RCP8.5). Then the carbon sink function will begin to decrease and it will decrease more quickly and become more variable under the RCP8.5 than the RCP4.5. The impacts of temperature and precipitation changes were analyzed and NEP was found to be more sensitive to temperature than precipitation change. The trend of increasing contribution to NEP is driven by a warming climate, while the stability of NEP is mainly influenced by the precipitation, which results in an upward trend before the peak and a decline due to stresses from limits in available water in a continued warming climate. [ABSTRACT FROM AUTHOR]

GLO-PEM is driven by soil moisture data of AMSR-E and PAR (Photosynthetically active radiation) which is retrieved from MODIS atmospheric data product in this paper. Using remote sensing data can overcome uncertainty brought from interpolation of precipitation and PAR. Comparing with observed radiation data, PAR retrieved by remote sensing is in high accuracy in this study. RMSE is 9 and 19.68 W m and R is 0.89 and 0.67 respectively. As a result of GLO-PEM, annual total amount of NPP of Qinghai-Tibet Plateau is 0.37 Pg C a in 2005-2008. There is a significant linear relationship between field and simulated NPP. Determination coefficient reached 0.93. NPP is decrease from southeast to northwest in the Qinghai-Tibet Plateau. NPP changes from 0 to 1500 g C m a. There is different limit factors of vegetation growth in west and east plateau. In the west of 450 mm rainfall line, the limit factors is precipitation. In the east of 450 mm rainfall line, temperature is the dominated factor of vegetation growth. [ABSTRACT FROM AUTHOR]

The maintenance and improvement of ecosystem services on the Tibet Plateau are critical for national ecological security in China and are core objectives of ecological conservation in this region. In this paper, ecosystem service benefits of the Tibet Ecological Conservation Project were comprehensively assessed by estimating and mapping the spatiotemporal variation patterns of critical ecosystem services on the Tibet Plateau from 2000 to 2015. Furthermore, we linked the benefit assessment to the sustainable spatial planning of future ecological conservation strategies. Comparing the 8 years before and after the project, the water retention and carbon sink services of the forest, grassland and wetland ecosystems were slightly increased after the project, and the ecosystem sand fixation service has been steadily enhanced. The increasing forage supply service of grassland significantly reduced the grassland carrying pressure and eased the conflict between grassland and livestock. However, enhanced rainfall erosivity occurred due to increased rainfall, and root-layer soils could not recover in a short period of time, both factors have led to a decline in soil conservation service. The warm and humid climate is beneficial for the restoration of ecosystems on the Tibet Plateau, and the implementation of the Tibet Ecological Conservation Project has had a positive effect on the local improvement of ecosystem services. A new spatial planning strategy for ecological conservation was introduced and aims to establish a comprehensive, nationwide system to protect important natural ecosystems and wildlife, and to promote the sustainable use of natural resources. [ABSTRACT FROM AUTHOR]

Alpine ecosystems play an important role in the global carbon cycle, yet the long-term response of in situ ground-based observations of carbon fluxes to climate change remains not fully understood. Here, we analyzed the continuous net ecosystem CO 2 exchange (NEE) measured with the eddy covariance technique over an alpine Potentilla fruticosa shrubland on the northeastern Qinghai-Tibetan Plateau from 2003 to 2012. The shrubland acted as a net CO 2 sink with a negative NEE (−74.4 ± 12.7 g C m −2 year −1 , Mean ± S.E.). The mean annual gross primary productivity (GPP) and annual ecosystem respiration (RES) were 511.8 ± 11.3 and 437.4 ± 17.8 g C m −2 year −1 , respectively. The classification and regression trees (CART) analysis showed that aggregated growing season degree days (GDD) was the predominant determinant on variations in monthly NEE and monthly GPP, including its effect on leaf area index (LAI, satellite-retrieved data). However, variations in monthly RES were determined much more strongly by LAI. Non-growing season soil temperature (T s ) and growing season length (GSL) accounted for 59% and 42% of variations in annual GPP and annual NEE, respectively. Growing season soil water content (SWC) exerted a positive linear influence on variations in annual RES ( r 2 = 0.40, p = 0.03). The thermal conditions and soil water status during the onset of the growing season are crucial for inter-annual variations of carbon fluxes. Our results suggested that an extended growing season and warmer non-growing season would enhance carbon assimilation capacity in the alpine shrubland. [ABSTRACT FROM AUTHOR]