Ecological characteristics of Chamaecyparis pisifera and its stand maintenance mechanism

研究了云杉Chamaecyparis pisifera(S.et Z.)在老林中有封闭树冠(封闭林分)和有树冠空隙(林隙林分)的林分中，调查了幼树斑块(最高叶梢高度大于或等于1.3米的斑块)和幼龄斑块(具有树冠高度大于等于1.3米的斑块)。1.3m)，林隙中斑块数量较多，斑块大小呈倒J形分布，较小斑块数量较多，幼龄斑块的分布较为典型。林隙林分幼林斑块的平均大小显著大于林隙林分，而林隙林分的幼林斑块出现的频率较大，这些斑块出现在各种基质上，且在无凋落物的地面上出现的频率更高，包括岩石。郁闭林落叶阔叶树树冠下斑块数量较多，林隙中斑块数量较多。在光照不足条件下，斑块水平伸展，在较强光照条件下，斑块可获得高度生长。林隙的形成提高了下层日照水平，对杉木无性系更新起着重要作用

The occurrence pattern and size structure of clonal patches of Chamaecyparis pisifera (S.et Z.) ENDL., together with the substratum on which the patches were located, were investigated in a stand with a closed canopy (closed stand) and that with a canopy gap (gap stand) in an old-growth C.pisifera forest.Both sapling patches (patches with the height of the tallest foliage shoots <greater than or equal> 1.3m) and juvenile patches (those with that of <1.3m) occurred in both stands, and more abundant patches occurred in the gaps than in the closed stands.Size distributions of these patches were inverse J-shaped with more abundant smaller patches, and this was more typical for juvenile patches. Mean size of juvenile patches was significantly larger in the closed than in the gap stands, whereas larger sapling patches occurred more frequently in the gap stands.These patches occurred on various kinds of substrata and were more frequently on ground without litter, including rocks, in both stands. Patches occurred more abundantly under crowns of deciduous broadleaved trees in the closed stand, and in canopy gaps in the gap stands.They may expand horizontally by layning under insufficient sunlight conditions and may attain height growth under relatively strong sunlight conditions.Canopy gap formation that raises the sunlight level in the lower story plays an important role for the regeneration of C.pisifera from the clonal