Multi-year lags between forest browning and soil respiration at high northern latitudes.
Multi-year lags between forest browning and soil respiration at high northern latitudes.
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DOI：
10.1371/journal.pone.0050441
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Thomson AM
中科院分区：
文献类型：
--
作者：
Bond-Lamberty B;Bunn AG;Thomson AM
高纬度北方生态系统正经历着快速的气候变化，由于其土壤碳密度高，干扰状况不断变化，因此是一个巨大的潜在气候反馈。来自这些生态系统的一个重要的碳流是土壤呼吸（RS，由植物根系和土壤动物产生的二氧化碳从土壤表面流向大气），因此，高纬度碳循环的任何变化都可能反映在实地观察到的RS中。本研究使用了两种变体的机器学习算法和最小二乘回归来研究遥感冠层绿度（NDVI），气候和其他变量是如何耦合到年度R S的基础上，从全球数据库中的64个环极站点的105个观测。NDVI的加入使模型的性能大约提高了一倍，表现最好的模型解释了观测到的R S变异性的62%。我们发现，初夏的NDVI从往年一般是最好的单一预测R S，并优于当年的温度或湿度。这意味着这些变量之间存在很大的时间滞后，多年碳库会产生大规模的影响。RS下降的地区在空间上与布朗宁北方森林和温暖的温度，特别是在北美西部。我们认为，在过去的十年里，由于森林压力和死亡率的抑制，环极区的总RS可能已经减慢了1.5%，这反过来又降低了RS。北极苔原可能会表现出明显不同的反应，但很少有数据可以用来测试这一点。如在此所做的那样，将大规模远程观测和小规模实地测量相结合，有可能推断出北方生态系统对气候变化的大规模反应在时间和空间上的复杂性。
High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (R S, the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere), and any change in the high-latitude carbon cycle might thus be reflected in R S observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI), climate, and other variables are coupled to annual R S based on 105 observations from 64 circumpolar sites in a global database. The addition of NDVI roughly doubled model performance, with the best-performing models explaining ∼62% of observed R S variability. We show that early-summer NDVI from previous years is generally the best single predictor of R S, and is better than current-year temperature or moisture. This implies significant temporal lags between these variables, with multi-year carbon pools exerting large-scale effects. Areas of decreasing R S are spatially correlated with browning boreal forests and warmer temperatures, particularly in western North America. We suggest that total circumpolar R S may have slowed by ∼5% over the last decade, depressed by forest stress and mortality, which in turn decrease R S. Arctic tundra may exhibit a significantly different response, but few data are available with which to test this. Combining large-scale remote observations and small-scale field measurements, as done here, has the potential to allow inferences about the temporal and spatial complexity of the large-scale response of northern ecosystems to changing climate.
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影响因子：
5.2
作者：
Bunn, AG;Goetz, SJ;Fiske, GJ
通讯作者：
Fiske, GJ
影响因子：
56.9
作者：
Beer, Christian;Reichstein, Markus;Papale, Dario
通讯作者：
Papale, Dario
影响因子：
11.6
作者：
Carbone, Mariah S.;Czimczik, Claudia I.;Trumbore, Susan E.
通讯作者：
Trumbore, Susan E.
DOI：
10.1073/pnas.0501647102
发表时间：
2005-08-02
影响因子：
11.1
作者：
Angert, A;Biraud, S;Fung, I
通讯作者：
Fung, I
影响因子：
11.6
作者：
Dulamsuren, Choimaa;Hauck, Markus;Leuschner, Christoph
通讯作者：
Leuschner, Christoph