Institut National de l'Information Géographique et Forestière, Laboratoire d'Inventaire Forestier, 14 rue Girardet, 54000 Nancy, France.
Institut National de l'Information Géographique et Forestière, Laboratoire d'Inventaire Forestier, 14 rue Girardet, 54000 Nancy, France.
Sci Total Environ. 2020 Nov 10;742:140453. doi: 10.1016/j.scitotenv.2020.140453. Epub 2020 Jun 23.
Tree growing conditions are changing rapidly in the face of climate change. Capturing tree-growth response to such changes across environmental contexts and tree species calls for a continuous forest monitoring over space. Based on >10,000 tree-ring measurements sampled across the systematic grid of the continuous French national forest inventory (NFI) over the 2006-2016 period, we evaluated the radial growth trends of eight conifer tree species prevalent in European forests across their native and introduced ranges and various bioclimatic contexts (n = 16 forest systems). For each forest system, radial increments were filtered out from tree, plot, soil and climatic normal influences to isolate environment-driven growth signals and quantify residual time-series. Associated growth trends across forest systems were then confronted against environmental variables (e.g. short-term averages and trends in seasonal climate). Trends for a given species were systematically more positive in cooler contexts (higher elevations or northern distribution margins) than in warmer contexts (plains). Decreases and increases in precipitation regimes were found to be associated with negative and positive tree growth trends, respectively. Remarkably, positive growth trends were mainly observed for native forest systems (7/9) and negative trends for introduced systems (5/7). Native forests showed a more heterogeneous forest structure as compared to introduced forests that, in line with observed positive dependence of tree growth trends onto both water availability and forest heterogeneity, appears to modulate the competitive pressure on water resource with ongoing summer maximum temperature increase. Over a short annually-resolved study period, we were able to capture tree growth responses coherent with climate change across diverse forest ecosystems. With ongoing accumulation of data, the continuous French NFI hence arises as powerful support to monitoring climate change effects on forests.
面对气候变化，树木的生长条件正在迅速发生变化。要捕捉树木对这种变化的生长反应，需要在空间上对其进行持续的森林监测。基于 2006 年至 2016 年期间在法国国家森林清查（NFI）系统网格中对 10,000 多个树木年轮测量值的采样，我们评估了在其原生和引入范围以及各种生物气候背景下，欧洲森林中八种常见针叶树的径向生长趋势（n = 16 个森林系统）。对于每个森林系统，从树木、林分、土壤和气候的正常影响中筛选出径向增量，以隔离受环境驱动的生长信号并量化剩余时间序列。然后，将跨森林系统的相关生长趋势与环境变量（例如短期平均和季节性气候趋势）进行对比。在较凉爽的环境（较高海拔或北部分布边缘），给定物种的趋势通常更为积极，而在较温暖的环境（平原）中则相反。发现降水格局的减少和增加分别与树木生长的负趋势和正趋势相关。值得注意的是，原生森林系统（7/9）的生长趋势主要为正，而引入系统（5/7）的生长趋势则为负。与观察到的树木生长趋势对水的可用性和森林异质性的积极依赖一致，原生森林表现出比引入森林更为多样的森林结构，这似乎调节了随着夏季最高温度的升高，对水资源的竞争压力。在一个短期的年度分辨率研究期间，我们能够捕捉到与气候变化相一致的不同森林生态系统中的树木生长反应。随着数据的不断积累，持续的法国 NFI 为监测气候变化对森林的影响提供了有力支持。
