Three dimensional tree and gap architecture affected by forest managemen t- A comparison of different forest types in the Pacific North West, USA based on terrestrial laser scanning

直到1993年西北森林计划生效，美国的原始森林面积一直在以惊人的速度减少。花旗松（Pseudotzuga menziesii（Mirbel）Franco）是西北太平洋地区重要的经济树种之一，是在皆伐和单种同龄林取代原始林后发展起来的。今天，美国的造林学正在经历管理范式的变化。已提出了替代性造林制度，以建立类似于古老特征的林分结构，据信这些林分结构可提供生态系统服务和功能，如生境多样性、娱乐美学，并可增强生态系统的复原力和稳定性。然而，沿着森林水平和垂直结构的日益复杂，树木的生长条件变得更加异质。拟议研究的第一部分将评估所应用的管理做法是否实际上导致了更复杂的空间结构，类似于古老森林的空间复杂性。这个问题将回答在老的增长和年轻的管理站的树/冠结构的比较。地面激光扫描将用于对表征森林复杂性的全面空间方面的结构参数进行三维评估。将对原始森林、传统的面向生产的林分和明确为增加结构多样性而进行管理的人工林进行对比，以确定其空间结构的差异，例如树冠的垂直分层和个别树木的树冠轮廓。研究的第二部分旨在比较边缘与林分内部树木的树/冠结构。将调查改变的森林结构和生长条件是否会导致树木习性、树冠剖面和相关木材质量属性（如分枝度）发生重大变化。由于林隙在空间复杂性管理中发挥着重要作用，因此林隙的大小和形状具有特殊的意义。 林隙将在所有三个维度上使用地面激光扫描测量，并将与树木和树冠形状和木材质量的外部属性的相邻trees.The拟议的研究的主要目标是测试人工林隙的适用性，旨在模拟人工林中的古老森林的空间结构。此外，它将定性地描述复杂性管理如何影响剩余树木的木材质量的形状和外部属性。最后，研究将得出建议，如何设计造林措施，可能会平衡两个可能不同的管理目标：结构多样性和高质量的木材生产。

Until the Northwest Forest Plan came into effect in 1993 the US area covered by old-growth forests has been decreasing in an alarming rate. Douglas-fir (Pseudotzuga menziesii (Mirbel) Franco) as one of the economically most important tree species of the Pacific North West was planted after clear-cutting and monospecific even-aged stands replaced the ancient forests. Today, silviculture in the US is undergoing a change in the management paradigm. Alternative silvicultural regimes have been proposed in order to create stand structures resembling old-growth features which are believed to provide ecosystem services and functions, such as habitat diversity, aesthetics for recreation purposes and may enhance ecosystem resilience and stability. However, along with increasing complexity in horizontal and vertical structures of forests the growing conditions of trees become more heterogeneous. The first part of the proposed study will evaluate whether or not the applied management practices actually resulted in more complex spatial structures which resembles the spatial complexity of old-growth forests. This question will be answered by a comparison of tree/crown structures in old-growth and young managed stands. Terrestrial laser scanning will be used for a three-dimensional assessment of structural parameters that characterize the comprehensive spatial aspects of complexity in forests. Old-growth forests, traditional production oriented stands and plantations which had explicitly been managed towards more structural diversity will be contrasted in order to identify differences in their spatial structure, e.g. vertical layering of the canopy and crown profiles of individual trees. The second part of the study aims at comparing tree/crown structures in edge versus stand interior trees. It will be investigated if altered forest structure and growing conditions result in significant changes in tree habitus, crown profiles, and related wood quality attributes such as branchiness. As gaps play an important role in the management for spatial complexity, the size and shape of gaps are of special interest. Gaps will be measured in all three dimensions using terrestrial laser scanning and will be related to the tree and crown shape and external attributes of wood quality of adjacent trees.The main goal of the proposed study is to test the suitability of artificial gaps aiming at resembling the spatial structure of old-growth forests in plantations. Furthermore, it will be qualitatively described how management for complexity affects the shape and external attributes of wood quality of the remaining trees. Finally, the study will derive suggestions on how to design silvicultural measures which may balance the two possibly diverging management goals: structural diversity and high quality timber production.