Environmental controls on the increasing GPP of terrestrial vegetation across northern Eurasia

[摘要] Terrestrial ecosystems of northern Eurasia are demonstrating an increasinggross primary productivity (GPP), yet few studies have provided definitiveattribution for the changes. While prior studies point to increasingtemperatures as the principle environmental control, influences from moistureand other factors are less clear. We assess how changes in temperature,precipitation, cloudiness, and forest fires individually contribute to changesin GPP derived from satellite data across northern Eurasia using a light-use-efficiency-based model, for the period 1982–2010. We find that annualsatellite-derived GPP is most sensitive to the temperature, precipitation andcloudiness of summer, which is the peak of the growing season and also theperiod of the year when the GPP trend is maximum. Considering the regionalmedian, the summer temperature explains as much as 37.7 % of thevariation in annual GPP, while precipitation and cloudiness explain 20.7 and19.3 %. Warming over the period analysed, even without a sustainedincrease in precipitation, led to a significant positive impact on GPP for61.7 % of the region. However, a significant negative impact on GPPwas also found, for 2.4 % of the region, primarily the dryergrasslands in the south-west of the study area. For this region,precipitation positively correlates with GPP, as does cloudiness. This showsthat the south-western part of northern Eurasia is relatively more vulnerableto drought than other areas. While our results further advance the notionthat air temperature is the dominant environmental control for recent GPPincreases across northern Eurasia, the role of precipitation and cloudinesscan not be ignored.

[学科分类] 地球化学与岩石