Cranston Benjamin M, Powers Breanna F, Macinnis-Ng Cate
School of Biological Sciences The University of Auckland Private Bag 92019 Auckland Mail Center Auckland 1142 New Zealand.
School of the Environment The University of Auckland Private Bag 92019 Auckland Mail Center Auckland 1142 New Zealand.
Appl Plant Sci. 2020 Feb 14;8(2):e11325. doi: 10.1002/aps3.11325. eCollection 2020 Feb.
Drought-induced tree mortality is an emergent threat to forests worldwide, particularly to large trees. Drought-manipulation experiments involving throughfall exclusion (TFE) tend to focus on large plots that can be expensive to establish and maintain and may be unsuitable for large trees or indigenous forests. We set out to establish a relatively inexpensive TFE method in a natural forest with large trees.
We designed a novel TFE method and installed it in the Waitākere Range of West Auckland, New Zealand, to study the southern conifer kauri () under long-term simulated drought. We measured fluxes of water (sap flow) and carbon (stem increment and litterfall) as indicators of drought effects.
Throughfall was cut off to a 22.25-m area around individual boles, causing reduced soil moisture and reduced sap flow in droughted trees.
Our new TFE method centered on individual, large trees in native forest and is highly customizable to fit other forest and species types. It can be used to assess physiological responses to drought of individual trees independent of stem size.
干旱导致的树木死亡是全球森林面临的一个新出现的威胁，对大树尤其如此。涉及截留降水排除（TFE）的干旱控制实验往往侧重于大型地块，这些地块的建立和维护成本高昂，可能不适用于大树或原生森林。我们着手在有大树的天然林中建立一种相对廉价的TFE方法。
我们设计了一种新颖的TFE方法，并将其安装在新西兰奥克兰西部的怀塔克雷山脉，以研究南方针叶树贝壳杉（）在长期模拟干旱条件下的情况。我们测量了水（液流）和碳（树干生长量和凋落物）的通量，作为干旱影响的指标。
在每棵树干周围22.25平方米的区域内截留了降水，导致干旱树木的土壤湿度降低和液流减少。
我们新的TFE方法以原生森林中的单株大树为中心，高度可定制，以适应其他森林和物种类型。它可用于评估单株树木对干旱的生理反应，而不受树干大小的影响。
