The soil moisture active passive (SMAP) satellite mission distributes a product of CO2 flux estimates (SPL4CMDL) derived from a terrestrial carbon flux model, in which SMAP brightness temperatures are assimilated to update soil moisture (SM) and constrain the carbon cyclemodeling. While the SPL4CMDL product has demonstrated promising performance across the continental USA and Australia, a detailed assessment over the arctic and subarctic zones (ASZ) is still missing. In this study, SPL4CMDL net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (R-E) are evaluated against measurements from 37 eddy covariance towers deployed over the ASZ, spanning from 2015 to 2022. The assessment indicates that the NEE unbiased root-mean-square error falls within the targeted accuracy of 1.6 gC.m(-2).d(-1), as defined for the SPL4CMDL product. However, modeled GPP and R-E are overestimated at the beginning of the growing season over evergreen needleleaf forests and shrublands, while being underestimated over grasslands. Discrepancies are also found in the annual net CO2 budgets. SM appears to have a minimal influence on the GPP and R-E modeling, suggesting that ASZ vegetation is rarely subjected to hydric stress, which contradicts some recent studies. These results highlight the need for further carbon cycle process understanding and model refinements to improve the SPL4CMDL CO2 flux estimatesover the ASZ.

研究地表植被GPP时空变化特征及其对气候变化的响应，对深入理解陆地碳循环、评价陆地生态系统的环境质量以及预估未来气候变化的生态效应等具有重大意义。目前青藏高原GPP时空变化研究大多时序较短且未深入分析其时空变化趋势及特征。因此，本研究采用线性趋势探测方法研究青藏高原地区GPP在2001～2019年间的变化特征，并分析该特征对地形和地物类型的响应，同时探索了GPP与气温、降水和积雪的关系。结果表明：青藏高原GPP年际趋势呈现西北低东南高的分布特征，最大值为0.23 g C·m-2·d-1，最小值为-0.125 g C·m-2·d-1。各月年际趋势中从10月到3月，绝大部分区域GPP年际变化趋势较小，7月GPP的年际变化趋势和空间异质性最大，从-0.384-0.303 g C·m-2·d-1,8～10月又逐渐减小。GPP年际趋势随高程的增加逐渐减小；30°N以南GPP年际趋势随纬度的增加迅速减小，30°N以北GPP年际趋势随纬度的增加缓慢增大；农田植被混合类型...

研究地表植被GPP时空变化特征及其对气候变化的响应，对深入理解陆地碳循环、评价陆地生态系统的环境质量以及预估未来气候变化的生态效应等具有重大意义。目前青藏高原GPP时空变化研究大多时序较短且未深入分析其时空变化趋势及特征。因此，本研究采用线性趋势探测方法研究青藏高原地区GPP在2001～2019年间的变化特征，并分析该特征对地形和地物类型的响应，同时探索了GPP与气温、降水和积雪的关系。结果表明：青藏高原GPP年际趋势呈现西北低东南高的分布特征，最大值为0.23 g C·m-2·d-1，最小值为-0.125 g C·m-2·d-1。各月年际趋势中从10月到3月，绝大部分区域GPP年际变化趋势较小，7月GPP的年际变化趋势和空间异质性最大，从-0.384-0.303 g C·m-2·d-1,8～10月又逐渐减小。GPP年际趋势随高程的增加逐渐减小；30°N以南GPP年际趋势随纬度的增加迅速减小，30°N以北GPP年际趋势随纬度的增加缓慢增大；农田植被混合类型...

研究地表植被GPP时空变化特征及其对气候变化的响应，对深入理解陆地碳循环、评价陆地生态系统的环境质量以及预估未来气候变化的生态效应等具有重大意义。目前青藏高原GPP时空变化研究大多时序较短且未深入分析其时空变化趋势及特征。因此，本研究采用线性趋势探测方法研究青藏高原地区GPP在2001～2019年间的变化特征，并分析该特征对地形和地物类型的响应，同时探索了GPP与气温、降水和积雪的关系。结果表明：青藏高原GPP年际趋势呈现西北低东南高的分布特征，最大值为0.23 g C·m-2·d-1，最小值为-0.125 g C·m-2·d-1。各月年际趋势中从10月到3月，绝大部分区域GPP年际变化趋势较小，7月GPP的年际变化趋势和空间异质性最大，从-0.384-0.303 g C·m-2·d-1,8～10月又逐渐减小。GPP年际趋势随高程的增加逐渐减小；30°N以南GPP年际趋势随纬度的增加迅速减小，30°N以北GPP年际趋势随纬度的增加缓慢增大；农田植被混合类型...

The dendroecology of larch (Larix gmelinii Rupr.) in the world's northernmost forest provided insight into the complex relationship of tree growth, forest stand establishment, and changing eco-climatic factors. The Ary-Mas forest in the northern Siberia (72 & DEG; + NL) is an ecological island, surrounded by tundra. We hypothesized that the environmental constraints that limit larch growth in this harsh habitat include soil moisture and winter winds as well as low air temperature. We constructed and analyzed the larch growth index (GI) chronology from the eighteenth century until 2019. We found that the larch GI depended on the air temperature, soil moisture anomalies, and winter wind speed, and that dependence was significantly different before and after the 2000s. Larch GI responded to the onset of climatic warming in the 1970s by a minor GI increase followed by a GI decrease until the end of 1990. Increased air temperature early in the growing season favored increased GI, whereas elevated winter wind speed negatively influenced larch growth. After warming in the 2000s, the length of the growing season increased by 15 days, and larch GI was sensitive to air temperature both early and late in the growing season. The adverse influence of winter winds has gradually decreased since the 1970s, becoming a minor factor in the 2000s. Soil moisture in wet, cold soils negatively influenced larch growth. Meanwhile, decreased soil moisture in the northern lowlands favored increased larch growth. We found that larch growth increases were strongly correlated with GPP and NPP (gross and net primary productivity) within the Ary-Mas site and for the central Siberian Arctic. We infer that this Arctic region continues to be a carbon sink.