Abstract Thinning is a forestry technique that can improve growth in the remaining trees and make them less vulnerable to water stress, buffering the imminent climatic changes. However, thinning effects have not been thoroughly explored using high-resolution measurements of stem-diameter variation in natural ecosystems, which can provide valuable information on secondary tree growth, relations to climatic variables, and possible water-stress events. In this study, a gradient of thinning intensity was applied on a Pinus halepensis Mill. afforestation in the semiarid SE of the Iberian Peninsula to ascertain the effects on the daily, monthly, annual, and total cumulative growth as well as the relationships between climatic variables and tree-growth parameters (climate-growth sensitivity). The thinning treatments, applied in 2005, consisted of reductions of 75% in the mean basal area (T75), 60% (T60), 48% (T48), and an unthinned control (T0). Digital dendrometers were installed in 2010, 5 years after thinning, to characterize secondary tree growth—i.e. daily-stem variation (DSV), cumulative growth (CG), and the maximum daily shrinkage (MDS), but also the number of days of growth over a 3-year period. Thinning treatments affected the onset and end of growth, making the growing season longer after more intense thinning treatments. Also, the total cumulative growth of the stem diameter increased over the study period following the gradient of thinning intensity. From correlations among climatic variables and DSV, MDS, and CG, we conclude that thinned trees showed better climatic sensitivity and efficiency in the resources use and therefore a stronger adaptation to the environment and greater resilience to perturbations, despite that tree monitoring started 5 years after thinning. In view of these results, we recommend thinning as a tool to adapt forest ecosystems to climate change in Mediterranean areas.

中文翻译：

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在变薄的阿勒颇松树梯度上使用茎直径变化来检测和量化生长以及与气候变量的关系

摘要 间伐是一种林业技术，可以促进剩余树木的生长，使其不易受到水分胁迫，缓冲即将到来的气候变化。然而，还没有使用对自然生态系统中茎直径变化的高分辨率测量来彻底探索变薄效应，这可以提供关于次生树生长、与气候变量的关系以及可能的水分胁迫事件的宝贵信息。在这项研究中，在黑松磨坊上应用了稀释强度梯度。在伊比利亚半岛半干旱东南部造林，以确定对日、月、年和总累积生长的影响，以及气候变量与树木生长参数（气候生长敏感性）之间的关系。2005 年应用的细化处理，包括平均基底面积减少 75% (T75)、60% (T60)、48% (T48) 和未稀释对照 (T0)。数字测树仪于 2010 年安装，即间伐后 5 年，以表征次生树的生长——即每日茎干变异 (DSV)、累积生长 (CG) 和最大日收缩 (MDS)，以及生长天数超过 3 年。间伐处理影响生长的开始和结束，在更强烈的间伐处理后使生长季节更长。此外，茎直径的总累积增长在研究期间随着变薄强度的梯度而增加。从气候变量与 DSV、MDS 和 CG 之间的相关性，我们得出的结论是，尽管树木监测是在间伐后 5 年开始的，但间伐树木在资源利用方面表现出更好的气候敏感性和效率，因此对环境的适应能力更强，对扰动的适应能力更强。鉴于这些结果，我们建议将间伐作为使森林生态系统适应地中海地区气候变化的一种工具。