[1] Alexandrov G A, Oikawa T, Esser G, 1999. Estimating terrestrial NPP:what the data say and how they may be interpreted? Ecological Modelling, 117(2-3):361-369. doi: 10.1016/s0304-3800(99)00019-8
[2] Barford C C, Wofsy S C, Goulden M L et al., 2001. Factors con-trolling long-and short-term sequestration of atmospheric CO2 in a mid-latitude forest. Science, 294(5547):1688-1691. doi: 10.1126/science.1062962
[3] Beer C, Reichstein M, Tomelleri E et al., 2010. Terrestrial gross carbon dioxide uptake:global distribution and covariation with climate. Science, 329(5993):834-838. doi:10.1126/science. 1184984
[4] Bolin B, 1977. Changes of land biota and their importance for the carbon cycle. Science, 196(4290):613-615. doi: 10.1126/science.196.4290.613
[5] Chen L Y, Li H, Zhang P J et al., 2015. Climate and native grass-land vegetation as drivers of the community structures of shrub-encroached grasslands in Inner Mongolia, China. Land-scape Ecology, 30(9):1627-1641. doi: 10.1007/s10980-014-0044-9
[6] Chen T, van der Werf G R, de Jeu R A M et al., 2013. A global analysis of the impact of drought on net primary productivity. Hydrology and Earth System Sciences, 17(10):3885-3894. doi: 10.5194/hessd-10-2429-2013
[7] Chen Y Z, Mu S J, Sun Z G et al., 2016. Grassland carbon se-questration ability in China:a new perspective from terrestrial aridity zones. Rangeland Ecology & Management, 69(1):84-94. doi: 10.1016/j.rama.2015.09.003
[8] Chen Y Z, Li J L, Ju W M et al., 2017. Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient. PLoS One, 12(7):e0179875. doi: 10.1371/journal.pone.0179875
[9] Chen Zhenghua, Ma Qingyuan, Wang Jian et al., 2008. Estimation of Heihe Basin net primary productivity using the CASA model. Journal of Natural Resources, 23(4):263-273. (in Chinese)
[10] DeLucia E H, Drake J E, Thomas R B et al., 2007. Forest carbon use efficiency:is respiration a constant fraction of gross primary production? Global Change Biology, 13(6):1157-1167. doi: 10.1111/j.1365-2486.2007.01365.x
[11] Dong J R, Kaufmann R K, Myneni R B et al., 2003. Remote sensing estimates of boreal and temperate forest woody bio-mass:carbon pools, sources, and sinks. Remote Sensing of En-vironment, 84(3):393-410. doi:10.1016/s0034-4257(02) 00130-x
[12] Field C B, Randerson J T, Malmström C M, 1995. Global net primary production:combining ecology and remote sensing. Remote Sensing of Environment, 51(1):74-88. doi: 10.1016/0034-4257(94)00066-v
[13] Gang C, Zhou W, Wang Z et al., 2015. Comparative assessment of grassland NPP dynamics in response to climate change in China, North America, Europe and Australia from 1981 to 2010. Journal of Agronomy and Crop Science, 201(1):57-68. doi: 10.1111/jac.12088
[14] Gang C, Wang Z, Zhou W et al., 2016b. Assessing the spatiotem-poral dynamic of global grassland water use efficiency in re-sponse to climate change from 2000 to 2013. Journal of Agronomy and Crop Science, 202(5):343-354. doi: 10.1111/jac.12137
[15] Gang C C, Wang Z Q, Chen Y Z et al., 2016a. Drought-induced dynamics of carbon and water use efficiency of global grass-lands from 2000 to 2011. Ecological Indicators, 67:788-797. doi: 10.1016/j.ecolind.2016.03.049
[16] Gang C C, Zhao W, Zhao T et al., 2018. The impacts of land conversion and management measures on the grassland net primary productivity over the Loess Plateau, Northern China. Science of the Total Environment, 645:827-836. doi: 10.1016/j.scitotenv.2018.07.161
[17] Gao Q Z, Schwartz M W, Zhu W Q et al., 2016. Changes in global grassland productivity during 1982 to 2011 attributable to climatic factors. Remote Sensing, 8(5):384. doi: 10.3390/rs8050384
[18] Grace J, José J S, Meir P et al., 2006. Productivity and carbon fluxes of tropical savannas. Journal of Biogeography, 33(3):387-400. doi: 10.1111/j.1365-2699.2005.01448.x
[19] Hicke J A, Asner G P, Randerson J T et al., 2002. Trends in North American net primary productivity derived from satellite ob-servations, 1982-1998. Global Biogeochemical Cycles, 16(2):2-1-2-14. doi: 10.1029/2001gb001550
[20] Hilker T, Lyapustin A I, Tucker C J et al., 2014. Vegetation dynam-ics and rainfall sensitivity of the Amazon. Proceedings of the National Academy of Sciences of the United States of America, 111(45):16041-16046. doi: 10.1073/pnas.1404870111
[21] Joos F, Prentice I C, Sitch S et al., 2001. Global warming feed-backs on terrestrial carbon uptake under the Intergovernmental Panel on Climate Change (IPCC) Emission Scenarios. Global Biogeochemical Cycles, 15(4):891-907. doi: 10.1029/2000gb001375
[22] Keenan T F, Baker I, Barr A et al., 2012. Terrestrial biosphere model performance for inter-annual variability of land-atmosphere CO2 exchange. Global Change Biology, 18(6):1971-1987. doi: 10.1111/j.1365-2486.2012.02678.x
[23] Khalifa M, Elagib N A, Ribbe L et al., 2018. Spatio-temporal variations in climate, primary productivity and efficiency of water and carbon use of the land cover types in Sudan and Ethiopia. Science of the Total Environment, 624:790-806. doi: 10.1016/j.scitotenv.2017.12.090
[24] Knutson T R, Delworth T L, Dixon K W et al., 1999. Model as-sessment of regional surface temperature trends (1949-1997). Journal of Geophysical Research:Atmospheres, 104(D24):30981-30996. doi: 10.1029/1999jd900965
[25] Liang W, Yang Y T, Fan D M et al., 2015. Analysis of spatial and temporal patterns of net primary production and their climate controls in China from 1982 to 2010. Agricultural and Forest Meteorology, 204:22-36. doi:10.1016/j.agrformet.2015.01. 015
[26] Lieth H, 1975. Modeling the primary productivity of the world. In:Lieth H, Whittaker R H (eds). Primary Productivity of the Biosphere. Berlin, Heidelberg:Springer, 237-263. doi: 10.1007/978-3-642-80913-2_12
[27] Lin X H, Han P F, Zhang W et al., 2017. Sensitivity of alpine grassland carbon balance to interannual variability in climate and atmospheric CO2 on the Tibetan Plateau during the last century. Global and Planetary Change, 154:23-32. doi: 10.1016/j.gloplacha.2017.05.008
[28] Ling H, He B, Chen A F et al., 2016. Drought dominates the in-terannual variability in global terrestrial net primary production by controlling semi-arid ecosystems. Scientific Reports, 6:24639. doi: 10.1038/srep24639
[29] Liu J, Chen J M, Cihlar J et al., 2002. Net primary productivity mapped for Canada at 1-km resolution. Global Ecology and Biogeography, 11(2):115-129. doi:10.1046/j.1466-822x. 2002.00278.x
[30] Liu Y Y, Wang Q, Zhang Z Y et al., 2019a. Grassland dynamics in responses to climate variation and human activities in China from 2000 to 2013. Science of the Total Environment, 690:27-39. doi: 10.1016/j.scitotenv.2019.06.503
[31] Liu Y Y, Yang Y, Wang Q et al., 2019b. Evaluating the responses of net primary productivity and carbon use efficiency of global grassland to climate variability along an aridity gradient. Science of the Total Environment, 652:671-682. doi: 10.1016/j.scitotenv.2018.10.295
[32] Liu Y Y, Zhang Z Y, Tong L J et al., 2019c. Assessing the effects of climate variation and human activities on grassland degra-dation and restoration across the globe. Ecological Indicators, 106:105504. doi: 10.1016/j.ecolind.2019.105504
[33] Mao D H, Wang Z M, Li L et al., 2014. Spatiotemporal dynamics of grassland aboveground net primary productivity and its as-sociation with climatic pattern and changes in Northern China. Ecological Indicators, 41:40-48. doi:10.1016/j.ecolind.2014. 01.020
[34] Melillo J M, McGuire A D, Kicklighter D W et al., 1993. Global climate change and terrestrial net primary production. Nature, 363(6426):234-240. doi: 10.1038/363234a0
[35] Nemani R R, Keeling C D, Hashimoto H et al., 2003. Cli-mate-driven increases in global terrestrial net primary produc-tion from 1982 to 1999. Science, 300(5625):1560-1563. doi: 10.1126/science.1082750
[36] Potter C, Klooster S, Genovese V, 2012. Net primary production of terrestrial ecosystems from 2000 to 2009. Climatic Change, 115(2):365-378. doi: 10.1007/s10584-012-0460-2
[37] Potter C S, Randerson J T, Field C B et al., 1993. Terrestrial eco-system production:a process model based on global satellite and surface data. Global Biogeochem. Cycles, 7:811-841.
[38] Raich J W, Rastetter E B, Melillo J M et al., 1991. Potential net primary productivity in South America:application of a global model. Ecological Applications, 1(4):399-429. doi: 10.2307/1941899
[39] Schimel D S, House J I, Hibbard K A et al., 2001. Recent patterns and mechanisms of carbon exchange by terrestrial ecosystems. Nature, 414(6860):169-172. doi: 10.1038/35102500
[40] Scurlock J M O, Johnson K, Olson R J, 2002. Estimating net primary productivity from grassland biomass dynamics meas-urements. Global Change Biology, 8(8):736-753. doi: 10.1046/j.1365-2486.2002.00512.x
[41] Toms J D, Lesperance M L, 2003. Piecewise regression:a tool for identifying ecological thresholds. Ecology, 84(8):2034-2041. doi: 10.1890/02-0472
[42] Uchijima Z, Seino H, 1985. Agroclimatic Evaluation of net primary productivity of natural vegetations:(1) chikugo model for eval-uating net primary productivity. Journal of Agricultural Meteor-ology, 40(4):343-352. doi: 10.2480/agrmet.40.343
[43] Xia J Z, Liu S G, Liang S L et al., 2014. Spatio-temporal patterns and climate variables controlling of biomass carbon stock of global grassland ecosystems from 1982 to 2006. Remote Sensing, 6(3):1783-1802. doi: 10.3390/rs6031783
[44] Xing Xiaoxu, Xu Xingliang, Zhang Xianzhou et al., 2010. Simu-lating net primary production of grasslands in northeastern Asia using MODIS data from 2000 to 2005. Journal of Geo-graphical Sciences, 20(2):193-204. doi: 10.1007/s11442-010-0193-y
[45] Xu H J, Wang X P, Zhang X X, 2016. Alpine grasslands response to climatic factors and anthropogenic activities on the Tibetan Plateau from 2000 to 2012. Ecological Engineering, 92:251-259. doi: 10.1016/j.ecoleng.2016.04.005
[46] Yang Y, Wang Z Q, Li J L et al., 2017. Assessing the spatiotem-poral dynamic of global grassland carbon use efficiency in re-sponse to climate change from 2000 to 2013. Acta Oecologica, 81:22-31. doi: 10.1016/j.actao.2017.04.004
[47] Yang Y H, Fang J Y, Ma W H et al., 2008. Relationship between variability in aboveground net primary production and precip-itation in global grasslands. Geophysical Research Letters, 35(23):L23710. doi: 10.1029/2008gl035408
[48] Zeng B, Yang T B, 2008. Impacts of climate warming on vegeta-tion in Qaidam Area from 1990 to 2003. Environmental Mon-itoring and Assessment, 144(1-3):403-417. doi: 10.1007/s10661-007-0003-x
[49] Zhang Y, Zhang C B, Wang Z Q et al., 2016. Vegetation dynamics and its driving forces from climate change and human activities in the Three-River Source Region, China from 1982 to 2012. Science of the Total Environment, 563-564:210-220. doi: 10.1016/j.scitotenv.2016.03.223
[50] Zhao M S, Running S W, 2010. Drought-induced reduction in global terrestrial net primary production from 2000 through 2009. Science, 329(5994):940-943. doi:10.1126/science. 1192666
[51] Zheng Zhong, Qi Yuan, Pan Xiaoduo et al., 2013. Estimating the grassland NPP in Qinghai Lake Basin based on WRF model data and CASA model. Journal of Glaciology and Geocryolo-gy, 35(2):465-474. (in Chinese)
[52] Zhou W, Yang H, Huang L et al., 2017. Grassland degradation remote sensing monitoring and driving factors quantitative as-sessment in China from 1982 to 2010. Ecological Indicators, 83:303-313. doi: 10.1016/j.ecolind.2017.08.019
[53] Zhou W, Yang H, Zhou L et al., 2018. Dynamics of grassland carbon sequestration and its coupling relation with hydrothermal factor of Inner Mongolia. Ecological Indicators, 95:1-11. doi: 10.1016/j.ecolind.2018.07.008