Mixed stands of spruce and beech under drought stress and stress recovery. From pattern to process.

干旱胁迫和胁迫恢复下的云杉和山毛榉混合林。

• 批准号: 426363208
• 负责人: Professor Dr. Hans Pretzsch
• 金额: --
• 依托单位: Lehrstuhl für Waldwachstumskunde
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/426363208?language=en
• 关键词: Mixed; stands; spruce; beech; under

Norway spruce (Picea abies (L.) Karst.) and European beech (Fagus sylvatica L.) dominate Central European forests. The effects of drought stress on the growth of these two species are significant, while the mechanisms behind are not yet fully understood, particularly when they grow in mixed stands. Our aim within the joint project KROOF is to understand the processes of tree and stand growth in monocultures and mixtures of Norway spruce and European beech under drought stress and stress recovery. The common base of all partners of the KROOF project is a throughfall-exclusion-experiment (TEE) and a series of plots along a precipitation gradient across Bavaria (PGR), which both offer the unique opportunity to study the interactions between soil processes (e.g. soil water, nutrient availability), resource availability (e.g. light, water, nutrients) and tree and stand growth. After analyzing the drought experiments and their effects on tree and stand growth within the first funding term our null hypotheses for the second funding term are: (1) Norway spruce and European beech react similarly to annual and extended drought periods, (2) both, Norway spruce and European beech do not show different growth responses to drought in intra- and inter-specific neighbourhood, (3) the water use efficiency of Norway spruce and European does neither differ in annual and extended drought periods nor in intra- and inter-specific neighbourhood, (4) drought does not modify stem and crown allometry, (5) growth recovery is similar on dry and moist sites along the PGR for Norway spruce and European beech, and in intra- and interspecific environments, (6) growth recovery is independent of tree size and competitive status, similarly for Norway spruce and European beech, in intra- and interspecific environments, (7) drought stress is independent of the relative size of trees within the population, (8) wood density as well as the relationship between tree ring width and wood density is equal under drought and control conditions and does not differ between mixed-species stands and monocultures and (9) overyielding in mixed stands compared to monocultures is equal along the PGR and independent of the respective growth limiting resource (water, nutrient, light). Consequently, our work plan aims at six objectives, i.e. the retrospective analyses of the drought reactions documented in the time series of growth and resource measurements on TEE and PGR (O1), the analysis of the growth recovery from the 2015 drought stress along the PGR (O2), the analysis of the growth recovery from extreme drought stress at the TEE site (O3), the modification of growth partitioning among trees of different sizes within a population under drought stress (O4), the analysis of the effects of drought and mixing both tree species on their wood density (O5), and the scrutiny of light, water, and nutrient supply as potential causes of overyielding in mixed-species stands versus monocultures (O6).

挪威云杉（Picea abies（L.）喀斯特。）和欧洲山毛榉（Fagus sylvatica L.）在中欧的森林中肆虐。干旱胁迫对这两个物种的生长的影响是显着的，而背后的机制尚未完全理解，特别是当它们生长在混合林。我们在KROOF联合项目中的目标是了解挪威云杉和欧洲山毛榉在干旱胁迫和胁迫恢复下的单一栽培和混合栽培中树木和林分生长的过程。KROOF项目的所有合作伙伴的共同基础是穿透雨排除实验（TEE）和一系列沿着巴伐利亚降水梯度的地块（PGR），这两者都提供了研究土壤过程（例如土壤水分，养分可用性），资源可用性（例如光，水，养分）以及树木和林分生长之间相互作用的独特机会。在分析了第一个资助期内的干旱实验及其对树木和林分生长的影响后，我们对第二个资助期的零假设是：（1）挪威云杉和欧洲山毛榉对年干旱期和长期干旱期的反应相似。（2）挪威云杉和欧洲山毛榉在种内和种间对干旱的反应没有差异。（3）挪威云杉和欧洲山毛榉的水分利用效率在年度和长期干旱期以及种内和种间邻近度上没有差异，（4）干旱不会改变树干和树冠的异速生长，（5）挪威云杉和欧洲山毛榉在PGR沿着干燥和潮湿地点的生长恢复相似，在种内和种间环境中，（6）生长恢复与树木大小和竞争状态无关，挪威云杉和欧洲山毛榉在种内和种间环境中也是如此，（7）干旱胁迫与种群内树木的相对大小无关，（8）木材密度以及树木年轮宽度与木材密度的关系在干旱和对照条件下是相等的，并且在混交林和单作林之间没有差异;与单作林相比，混交林的丰产性在PGR沿线沿着是相等的，并且与各自的生长限制资源（水、养分、光）无关。因此，我们的工作计划针对六个目标，即对TEE和PGR（O 1）上生长和资源测量时间序列中记录的干旱反应进行回顾性分析，分析PGR（O2）从2015年干旱胁迫沿着的生长恢复，分析TEE站点（O3）从极端干旱胁迫的生长恢复，在干旱胁迫（O 4）下，群体内不同大小树木之间生长分配的改变，干旱和两个树种混合对其木材密度（O 5）的影响的分析，以及光，水，和养分供应作为潜在的原因，在混合种林与单一栽培（O 6）。