Interannual NPP variation and trend of Picea schrenkiana forests under changing climate conditions in the Tianshan Mountains, Xinjiang, China

Abstract

AbstractThe interannual net primary production variation and trends of a Picea schrenkiana forest were investigated in the context of historical changes in climate and increased atmospheric CO2 concentration at four sites in the Tianshan Mountain range, China. Historical changes in climate and atmospheric CO2 concentration were used as Biome–BGC model drivers to evaluate the spatial patterns and temporal trends of net primary production (NPP). The temporal dynamics of NPP of P. schrenkiana forests were different in the western, middle and eastern sites of Tianshan, which showed substantial interannual variation. Climate changes would result in increased NPP at all study sites, but only the change in NPP in the western forest (3.186 gC m−2 year−1, P < 0.05) was statistically significant. Our study also showed a higher increase in the air temperature, precipitation and NPP during 1987–2000 than 1961–1986. Statistical analysis indicates that changes in NPP are positively correlated with annual precipitation (R = 0.77–0.92) but that NPP was less sensitive to changes in air temperature. According to the simulation, increases in atmospheric CO2 increased NPP by improving the water use efficiency. The results of this study show that the Tianshan Mount boreal forest ecosystem is sensitive to historical changes in climate and increasing atmospheric CO2. The relative impacts of these variations on NPP interact in complex ways and are spatially variable, depending on local conditions and climate gradients.