Spatial and temporal of variations of alpine vegetation cover in the source regions of the Yangtze and Yellow Rivers of the Tibetan Plateau from 1982 to 2001
Tóm tắt
Spatial and temporal variations in alpine vegetation cover have been analyzed between 1982 and 2001 in the source regions of the Yangtze and Yellow Rivers on the Tibetan Plateau. The analysis was done using a calibrated-NDVI (Normalized Difference Vegetative Index) temporal series from NOAA-AVHRR images. The spatial and temporal resolutions of images are 8 km and 10 days, respectively. In general, there was no significant trend in alpine vegetation over this time period, although it continued to degrade severely in certain local areas around Zhaling and Eling Lakes, in areas north of these lakes, along the northern foot of Bayankala Mountain in the headwaters of the Yellow River, in small areas in the Geladandong region, in a few places between TuoTuohe and WuDaoliang, and in the QuMalai and Zhiduo belts in the headwaters of the Yangtze River. Degradation behaves as vegetation coverage reduced, soil was uncovered in local areas, and over-ground biomass decreased in grassland. The extent of degradation ranges from 0 to 20%. Areas of 3×3 pixels centered on Wudaoliang, TuoTuohe, QuMalai, MaDuo, and DaRi meteorological stations were selected for statistical analysis. The authors obtained simple correlations between air temperature, precipitation, ground temperature and NDVI in these areas and constructed multivariate statistical models, including and excluding the effect of ground temperature. The results show that vegetation cover is sensitive to variations in temperature, and especially in the ground temperature at depths of ∼40 cm. Permafrost is distributed widely in the study area. The resulting freezing and thawing are related to ground temperature change, and also affect the soil moisture content. Thus, degradation of permafrost directly influences alpine vegetation growth in the study area.
Tài liệu tham khảo
Bradley N-L, Leopold A-C, Ross J, Wellington H (1999) Phenological changes reflect climate change in Wisconsin. Proc Natl Acad Sci USA, 96:9701–9704
Cao M-K, Prince S-D, Li K-P, Small J, Shao X (2003) Response of terrestrial carbon uptake to climate interannual variability in China. Global Change Biol 9:536–546
Ciais P, Peylin P, Bousquet P (2000) Regional biospheric carbon fluxes as inferred from atmospheric CO2 measurements. Ecol Appl 10:1574–1589
Ding Y, Yang J, Liu S, Chen R, Wang G, Shen Y, Wang J, Xie C, Zheng S (2003) Eco-environment range in the source regions of the Yangtze and Yellow Rivers, J Geograph Sci 13(2):178–180
Environment& Ecology Scientific Data Center of Western China, National Natural Science Foundation of China. http://www.westdc.westgis.ac.cn
Fang J-Y, Chen A-P, Peng C-H, Zhao S-Q, Ci L-J (2001) Changes in forest biomass carbon storage in China between 1949 and 1998. Science 292:2320–2322
Fang J, Piao S, He J, Ma W (2003) Increasing terrestrial vegetation activity in China, 1982–1999 (in Chinese). Sci China (Ser C) 33(6):554–565
Holben B-N. (1986) Characteristics of maximum-value composite images for temporal AVHRR data. Int J Remote Sens 7:1435–1445
Keeling C-D, Chin J-F-S, Whorf T-P (1996) Increased activity of northern vegetation in inferred from atmospheric CO2 measurements. Nature 382:146–149
Levenberg K-A (1944) Method for the solution of certain nonlinear problems in least squares. Q Appl Math 2:164–168
Loumagne C, Chkir N, Normand M. (1996) Introduction of the soil/vegetation/atmosphere continuum in a conceptual rainfall/runoff model. Hydrol Sci J 41(6):889–902
Melillo J-M, McGuire A-D, Kicklighter D-W, Moore B, Vörösmarty C-J, Schloss A-L (1993) Global climate change and terrestrial net primary production. Nature 363:234–240
Menzel A, Fabian P (1999) Growing season extended in Europe. Nature 397:659
Nash J-E, Sutcliffe J-V. (1970) River flow forecasting through conceptual models, 1, A discussion of principles. J Hydrol 10:282–290
Pacala S-W (2001) Consistent land-and atmosphere-based U.S. carbon sink estimates. Science 292:2316–2320
Rouse J-W, Haas R-H, Schell J-A, Deering D-W Harlan J-C (1974) Monitoring the vernal advancements and retrogradation (Greenwave effect) of nature vegetation. NASA/GSFC Final Report, NASA, Greenbelt, MD, pp 371
Schimel D, Melillo J, Tian H-Q, McGuire A-D, Kicklighter D, Kittel T, Rosenbloom N, Running S, Thornton P, Ojima D, Parton W, Kelly R, Sykes M, Neilson R, Rizzo B (2000) Contribution of increasing CO2 and climate to carbon storage by ecosystems in the United States. Science 287:2004–2006
Wang G, Ding Y, Wang J, Liu S (2004) Land ecological changes and evolutional patterns in the source regions of the Yangtze and Yellow Rivers in recent 15 years (in Chinese). Acta Geographica Sinica 59(2):163–173
Zhang G, Li L, Wang Q, Li X, Xu W, Dong L (1999) Effects of climatic changes of south Qinghai Plateau on the alpine meadow (in Chinese) (A reference is in the third row of the fourth page). Acta Prataculturae Sinica 8(3):1–10