Ueda Masafumi, Shibata Ei'ichi
Nara Forest Research Institute, Takatori, Nara 635-0133, Japan.
Tree Physiol. 2004 Jun;24(6):701-6. doi: 10.1093/treephys/24.6.701.
We examined the water status of Hinoki cypress, Chamaecyparis obtusa (Siebold & Zucc.) Endl., trees after a severe typhoon to determine possible causes of the decline and dieback that can occur in what appear, at first, to be healthy trees in typhoon-damaged forest stands. We found that in apparently healthy trees in a storm-damaged stand, the water conducting area of the trunk cross section was greatly reduced compared with that of similarly sized trees in a nearby undamaged stand. Although leaf specific hydraulic resistance (Wl) from soil to leaf and from trunk to leaf was higher in trees from the storm-damaged than the undamaged stand, Wl values from soil to root were similar. Diurnal patterns in the rates of change in trunk diameter differed between trees in the damaged and the undamaged stand. We conclude that increased aboveground hydraulic resistance caused by a reduction in trunk water conducting area could be a major reason for the decline and dieback of apparently healthy trees in typhoon-damaged stands.
我们研究了日本扁柏（Chamaecyparis obtusa (Siebold & Zucc.) Endl.）在遭受严重台风后的水分状况，以确定在台风受损林分中最初看似健康的树木出现衰退和枯死的可能原因。我们发现，在风暴受损林分中看似健康的树木，其树干横截面的导水面积与附近未受损林分中大小相似的树木相比大幅减少。尽管来自风暴受损林分的树木从土壤到叶片以及从树干到叶片的叶比水力阻力（Wl）高于未受损林分的树木，但从土壤到根系的Wl值相似。受损林分和未受损林分中树木的树干直径变化率的日变化模式有所不同。我们得出结论，树干导水面积减少导致的地上水力阻力增加可能是台风受损林分中看似健康的树木衰退和枯死的主要原因。
