Data from: Divergent temporal trends of net biomass change in western Canadian boreal forests

Abstract1. Forests play a strong role in the global carbon cycle by absorbing atmospheric carbon dioxide through increasing forest biomass. Understanding temporal trends of forest net aboveground biomass change (ΔAGB) can help infer how forest carbon sequestration responds to on-going climate changes. Despite wide spatial variation in the long-term average of climate moisture availability (CMIaverage) across forest ecosystems, temporal trends of ΔAGB associated with CMIaverage remains unclear. 2. We tested the hypothesis that the extent of negative impacts of climate change on ΔAGB would decrease with CMIaverage using the data from permanent sample plots of varying ages from 17 to 210 years, monitored from 1958 to 2011 in western boreal forests of Canada. 3. We found that ΔAGB on average increased with CMIaverage. Temporally, ΔAGB declined sharply between 1958 and 2011 in plots with low CMIaverage owing to increased biomass loss from mortality accompanied by little growth gain, whereas ΔAGB changed little in plots with high CMIaverage. The temporal decrease of ΔAGB in drier areas was attributable to its negative responses to warming-induced temporal decreases in climate moisture availability. 4. Synthesis. Our results indicate that large-scale changes in forest carbon functioning associated with climate change depend on the long-term average of climate moisture availability. Our finding suggests a possible retreat of boreal biome at the drier distribution limits with predicted declines in water availability in the 21st century., Usage notesData from: Divergent temporal trends of net biomass change in western Canadian boreal forestsdata.csv

摘要
1. 森林通过增加自身生物量吸收大气二氧化碳，在全球碳循环中发挥关键作用。明晰森林地上净生物量变化（ΔAGB）的时间趋势，有助于推断森林碳固存能力如何响应当前持续发生的气候变化。尽管森林生态系统间的气候水分可利用性长期平均值（CMIaverage）存在广泛的空间异质性，但与CMIaverage相关的ΔAGB时间趋势仍不明晰。
2. 本研究依托1958年至2011年间加拿大西部北方森林内树龄跨度为17至210年的永久样地监测数据，验证了“气候变化对ΔAGB的负面影响程度将随CMIaverage升高而减弱”这一假说。
3. 研究结果显示：ΔAGB整体随CMIaverage升高而增加。从时间维度分析，CMIaverage较低的样地中，因树木死亡引发的生物量损失加剧且生长增益有限，1958年至2011年间ΔAGB出现显著下降；而CMIaverage较高的样地中ΔAGB几乎无明显变化。干旱区域ΔAGB的时间下降趋势，可归因于其对气候变暖导致的气候水分可利用性持续下降的负响应。
4. 综合结论：本研究结果表明，与气候变化相关的森林碳循环功能大规模变化，取决于气候水分可利用性的长期平均值。本研究发现暗示：随着21世纪全球水资源可利用性预计下降，北方森林生物群区在其干旱分布边界处可能出现退缩。

使用说明
数据来源：《加拿大西部北方森林净生物量变化的差异化时间趋势》配套data.csv文件