IFER - Institute of Forest Ecosystem Research, Cs. armády 655, 254 01 Jílové u Prahy, Czech Republic.
Institute of Botany of The Czech Academy of Sciences, Zámek 1, 252 43 Průhonice, Czech Republic.
Sci Total Environ. 2018 Apr 1;619-620:1637-1647. doi: 10.1016/j.scitotenv.2017.10.138. Epub 2017 Nov 7.
Tree growth response to recent environmental changes is of key interest for forest ecology. This study addressed the following questions with respect to Norway spruce (Picea abies, L. Karst.) in Central Europe: Has tree growth accelerated during the last five decades? What are the main environmental drivers of the observed tree radial stem growth and how much variability can be explained by them? Using a nationwide dendrochronological sampling of Norway spruce in the Czech Republic (1246 trees, 266 plots), novel regional tree-ring width chronologies for 40(±10)- and 60(±10)-year old trees were assembled, averaged across three elevation zones (break points at 500 and 700m). Correspondingly averaged drivers, including temperature, precipitation, nitrogen (N) deposition and ambient CO concentration, were used in a general linear model (GLM) to analyze the contribution of these in explaining tree ring width variability for the period from 1961 to 2013. Spruce tree radial stem growth responded strongly to the changing environment in Central Europe during the period, with a mean tree ring width increase of 24 and 32% for the 40- and 60-year old trees, respectively. The indicative General Linear Model analysis identified CO, precipitation during the vegetation season, spring air temperature (March-May) and N-deposition as the significant covariates of growth, with the latter including interactions with elevation zones. The regression models explained 57% and 55% of the variability in the two tree ring width chronologies, respectively. Growth response to N-deposition showed the highest variability along the elevation gradient with growth stimulation/limitation at sites below/above 700m. A strong sensitivity of stem growth to CO was also indicated, suggesting that the effect of rising ambient CO concentration (direct or indirect by increased water use efficiency) should be considered in analyses of long-term growth together with climatic factors and N-deposition.
树木对近期环境变化的生长响应是森林生态学的研究重点。本研究针对中欧的挪威云杉（Picea abies，L. Karst.）提出了以下问题：在过去的五十年中，树木的生长是否加速了？观测到的树木径向茎生长的主要环境驱动因素是什么？它们能解释多少变异性？利用捷克全国范围内的挪威云杉树木年代学采样（1246 棵树，266 个样地），组装了 40（±10）年和 60（±10）年生树木的新的区域树木年轮宽度年表，在三个海拔带（500 和 700m 处的断点）上进行了平均。相应地，在广义线性模型（GLM）中使用包括温度、降水、氮（N）沉积和环境 CO2 浓度在内的平均驱动因素，分析了这些因素对 1961 年至 2013 年期间树木年轮宽度变异性的解释贡献。在这一时期，中欧不断变化的环境对云杉径向茎生长产生了强烈影响，40 年和 60 年生树木的平均年轮宽度分别增加了 24%和 32%。指示性的广义线性模型分析确定 CO2、植被生长季节的降水、春季气温（3 月至 5 月）和 N 沉积是生长的重要协变量，其中包括与海拔带的相互作用。回归模型分别解释了两个树木年轮宽度年表变异性的 57%和 55%。N 沉积的生长响应显示出沿海拔梯度的最大变异性，在 700m 以下/以上的地点表现出生长刺激/限制。树木生长对 CO2 的敏感性也很强，这表明在分析长期生长时，应考虑不断上升的环境 CO2 浓度的影响（直接或间接通过增加水分利用效率），与气候因素和 N 沉积一起。
