Can the resistance and resilience of trees to drought be increased through thinning to adapt forests to climate change?

最近和预测的极端干燥和炎热的夏季的增加强调了造林方法的必要性，以提高现有森林的耐旱性在短期内，通过物种变化的适应可能之前。我们的目标是调查是否在干旱期间的阻力，以及恢复干旱事件（恢复力），可以通过分配更多的生长空间，以个别树木通过间伐增加。间伐增加了促进树木获得土壤储存的水，只要这是可用的。然而，这些树木也可能是不利的，通过较高的蒸腾表面，或增加邻里竞争的地面植被。为了评估不同生长空间的树木是否具有不同的耐旱性，将使用樟子松和花旗松林间伐试验的树盘和树芯来检查在以前的干旱期间的蒸腾压力和生长减少以及随后的恢复。树木生态学和稳定同位素的碳和氧的树木年轮将被用来量化同化率和气孔导度是如何改变通过间伐。研究结果将为制定短期造林适应战略，使森林生态系统适应气候变化提供重要信息。此外，这项研究将提高我们对树木在极端胁迫事件中的抵抗力和恢复力之间关系的理解。

Recent and predicted increases in extremely dry and hot summers emphasise the need for silvicultural approaches to increase the drought tolerance of existing forests in the short-term, before adaptation through species changes may be possible. We aim to investigate whether resistance during droughts, as well as the recovery following drought events (resilience), can be increased by allocating more growing space to individual trees through thinning. Thinning increases access of promoted trees to soil stored water, as long as this is available. However, these trees may also be disadvantaged through a higher transpirational surface, or the increased neighbourhood competition by ground vegetation. To assess whether trees with different growing space differ in drought tolerance, tree discs and cores from thinning experiments of Pinus sylvestris and Pseudotsuga menziesii stands will be used to examine transpirational stress and growth reduction during previous droughts as well as their subsequent recovery. Dendroecology and stable isotopes of carbon and oxygen in tree-rings will be used to quantify how assimilation rate and stomatal conductance were altered through thinning. The results will provide crucial information for the development of short-term silvicultural adaptation strategies to adapt forest ecosystems to climate change. In addition, this study will improve our understanding of the relationship between resistance and resilience of trees in relation to extreme stress events.