Effects of precipitation timing on aboveground net primary productivity in inner mongolia temperate steppe
Aboveground net primary productivity (ANPP) of grassland ecosystems is one of critical processes in regional carbon cycle,and is dramatically impacted by concomitant changes in precipitation timing in the context of global climate change.In this study,we firstly acquired ANPP data of the entire Inner Mongolia temperate steppe from 1997 to 2008 with a statistic model,which was derived from linear regression between SPOT-VEG NDVI data in August (from 1997 to 2008)and field ANPP data obtained at 111 specific sites.Secondly,we addressed effects of precipitation timing on ANPP for the entire Inner Mongolia temperate steppe and further for its three main component grassland types (desert steppe,typical steppe,and meadow steppe).Our results demonstrated that,for the entire Inner Mongolia temperate steppe,precipitation periods from February to July was the relatively important periods that affected ANPP during the whole water year (defined here as the 12-month period from September of previous year to August of the current year when the aboveground biomass reaches its peak),while the period from May to July was the most important.In terms of occurrence of monthly rain,rain in July had the greatest effect on ANPP,while rain in August,although still one of the growing months,had the minor effect.With respect to the grassland types,the desert steppe and typical steppe received the greatest impact from the precipitation from May to July,which is in accordance with the observation from the entire temperate steppe,while ANPP of the meadow steppe was relatively little affected by the timing of precipitation,evidenced by not significant (P＞0.05)correlations between precipitation of different periods in most area of meadow steppe.Spatial pattern of most meaningful timing (month,different accumulated periods) of rainfall was consistent with the analysis of correlation coefficients,which showed that precipitation from May to July was the most meaningful accumulated period for ANPP of most of the entire Inner Mongolia temperate steppe.In terms of monthly rain,rain in July was most important in almost 40％ of the area.Also,spatial pattern was grassland type specific.Most part of the desert steppe and typical steppe was affected by precipitation during May to July,while the meadow steppe was mostly affected by rain in current month when ANPP reached its peaks(August) and non-growing season rain of March.
aboveground net primary productivityprecipitation timetemperate steppe
国家科技期刊平台
NSTL
万方数据
维普
