文章基本信息

标题：Global variability in belowground autotrophic respiration in terrestrial ecosystems
本地全文：下载
作者：Tang, Xiaolu ; Fan, Shaohui ; Zhang, Wenjie 等
期刊名称：Earth System Science Data Discussions
电子版ISSN：1866-3591
出版年度：2019
卷号：11
期号：4
页码：1839-1852
DOI：10.5194/essd-11-1839-2019
语种：English
出版社：Copernicus Publications
摘要：Abstract. Belowground autotrophic respiration (RA) is one of the largest but most highlyuncertain carbon flux components in terrestrial ecosystems. However, RA hasnot been explored globally before and still acts as a “black box” inglobal carbon cycling currently. Such progress and uncertainty motivate thedevelopment of a global RA dataset and understanding its spatial and temporalpatterns, causes, and responses to future climate change. We applied the randomforest (RF) algorithm to upscale an updated dataset from the Global SoilRespiration Database (v4) – covering all major ecosystem types and climatezones with 449 field observations, using globally gridded temperature,precipitation, soil and other environmental variables. We used a 10-foldcross validation to evaluate the performance of RF in predicting the spatialand temporal pattern of RA. Finally, a globally gridded RA dataset from 1980to 2012 was produced with a spatial resolution of 0.5∘ × 0.5∘ (longitude × latitude) and a temporal resolution of 1 year (expressed in g C m−2 yr−1; grams of carbon per square meter per year). Globally, mean RA was 43.8±0.4 Pg C yr−1, with a temporallyincreasing trend of 0.025±0.006 Pg C yr−2 from 1980 to 2012.Such an incremental trend was widespread, representing 58 % of global land. Foreach 1 ∘C increase in annual mean temperature, global RA increased by 0.85±0.13 Pg C yr−2, and it was 0.17±0.03 Pg C yr−2for a 10 mm increase in annual mean precipitation, indicating positivefeedback of RA to future climate change. Precipitation was the main dominantclimatic driver controlling RA, accounting for 56 % of global land,and was the most widely spread globally, particularly in dry or semi-arid areas, followedby shortwave radiation (25 %) and temperature (19 %). Different temporalpatterns for varying climate zones and biomes indicated uneven responses ofRA to future climate change, challenging the perspective that the parametersof global carbon stimulation are independent of climate zones and biomes. Thedeveloped RA dataset, the missing carbon flux component that is notconstrained and validated in terrestrial ecosystem models and Earth systemmodels, will provide insights into understanding mechanisms underlying thespatial and temporal variability in belowground vegetation carbon dynamics.The developed RA dataset also has great potential to serve as a benchmarkfor future data–model comparisons. The developed RA dataset in a commonNetCDF format is freely available at https://doi.org/10.6084/m9.figshare.7636193 (Tang et al., 2019).