NET PRIMARY PRODUCTIVITY
; INDUCED LAND DEGRADATION
; GREEN-UP DATES
; CLIMATE-CHANGE
; ABOVEGROUND BIOMASS
; INNER-MONGOLIA
; RAINFALL VARIABILITY
; TEMPERATE GRASSLAND
; SEMIARID GRASSLAND
; USE EFFICIENCY
WOS学科分类:
Remote Sensing
WOS研究方向:
Remote Sensing
英文摘要:
The timing regimes of precipitation can exert profound impacts on grassland ecosystems. However, it is still unclear how the peak aboveground biomass (AGB(peak)) of alpine grasslands responds to the temporal variability of growing season precipitation (GSP) on the northern Tibetan Plateau. Here, the temporal variability of precipitation was defined as the number and intensity of precipitation events as well as the time interval between consecutive precipitation events. We conducted annual field measurements of AGB(peak) between 2009 and 2016 at four sites that were representative of alpine meadow, meadow-steppe, alpine steppe, and desert-steppe. Thus, an empirical model was established with the time series of the field-measured AGB(peak) and the corresponding enhanced vegetation index (EVI) (R-2 = 0.78), which was used to estimate grassland AGB(peak) at the regional scale. The relative importance of the three indices of the temporal variability of precipitation, events, intensity, and time interval on grassland AGB(peak) was quantified by principal component regression and shown in a red-green-blue (RGB) composition map. The standardized importance values were used to calculate the vegetation sensitivity index to the temporal variability of precipitation (VSIP). Our results showed that the standardized VSIP was larger than 60 for only 15% of alpine grassland pixels and that AGB(peak) did not change significantly for more than 60% of alpine grassland pixels over the past decades, which was likely due to the nonsignificant changes in the temporal variability of precipitation in most pixels. However, a U-shaped relationship was found between VSIP and GSP across the four representative grassland types, indicating that the sensitivity of grassland AGB(peak) to precipitation was dependent on the types of grassland communities. Moreover, we found that the temporal variability of precipitation explained more of the field-measured AGB(peak) variance than did the total amount of precipitation alone at the site scale, which implies that the mechanisms underlying how the temporal variability of precipitation controls the AGB(peak) of alpine grasslands should be better understood at the local scale. We hypothesize that alpine grassland plants promptly respond to the temporal variability of precipitation to keep community biomass production more stable over time, but this conclusion should be further tested. Finally, we call for a long-term experimental study that includes multiple natural and anthropogenic factors together, such as warming, nitrogen deposition, and grazing and fencing, to better understand the mechanisms of alpine grassland stability on the Tibetan Plateau.
1.Chinese Acad Sci, Lhasa Natl Ecol Res Stn, Key Lab Ecosyst Network Observat & Modelling, Inst Geog Sci & Nat Resources Res, Beijing 100101, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 3.Free Univ Berlin, Inst Biol, Biodivers Theoret Ecol, D-14195 Berlin, Germany 4.Chinese Acad Sci, Nanjing Inst Geog & Limnol, Key Lab Watershed Geog Sci, Nanjing 210008, Jiangsu, Peoples R China 5.Univ Padua, Dept Land Environm Agr & Forestry, I-35020 Legnaro, PD, Italy 6.Berlin Brandenburg Inst Adv Biodivers Res BBIB, D-14195 Berlin, Germany
Recommended Citation:
Li, Meng,Wu, Jianshuang,Song, Chunqiao,et al. Temporal Variability of Precipitation and Biomass of Alpine Grasslands on the Northern Tibetan Plateau[J]. REMOTE SENSING,2019-01-01,11(3)