疏伐是對?地內樹木的密?、品質或分佈進?部分的砍伐移除，對於森?結構、物化環境可以造成?即的變化。這些微環境的改變，會造成原本森?結構的改變，往往有?於種子發芽、幼苗生長。此外，疏伐亦會打開原本被佔據的空間，讓其他樹種能有進駐的機會。樹種?新過程中，種子是否能到達，到達後是否能發芽長大，生長及存活，均會影響該樹種能否順??新。本計畫主要目標即在研究?同疏伐處?對原生樹種?新及?育的影響，以?解?同原生樹種?新之瓶頸及困境。前期計畫已於人工?永久樣區內設置 108 個種子網及324 個小苗樣區，並已收集疏伐前植物物候、種子產?及小苗??的基本資?。本期計畫將持續定期收集種子及監測小苗生長存活?況，以瞭解?同疏伐強?處?後，原生樹種小苗在人工?內分布及隨時間及疏伐強?變化的情形。此外，種子雨在空間及時間上分布?況及變?情形，亦是本研究計畫關心的另一重點。?同疏伐強?處?的樣區，是否有?同程?的種子傳播限制(seed dispersal limitation)及新增上的限制 (recruitment limitation)；而負密?制約效應(negative density-dependent effect)是否也隨?同疏伐強?而有所?同也將是研究的另一重點。 Thinning is a management practice to remove certain portion of trees in a plantation area, thus it will creates changes in forest structures and microenvironment immediately. This in turn, will provide suitable conditions for seed germination and seedling establishment. Furthermore, thinning will open up spaces which were unavailable to other species before. There are many crucial stages involved in tree regeneration processes. These stages include arrival of seeds to potential site, successful seed germination in suitable habitat, and successful seedling survive through adult stage. The goal of this project is to understand the effect of thinning on the regeneration processes of native tree species and to understand the crucial stage in their recruitment processes. In the previous project, we have established 108 seed traps and 324 seedling plots in the 12 one ha plot in Cryptomeria japonica plantation forest. In this project, we will continue collecting seed traps and monitoring seedling survival and growth to understand the spatial pattern of seed rain and the pattern of seedling survival after thinning. We will also investigate the effect of different thinning intensity on seed dispersal limitation and recruitment limitation. In addition, we will test whether negative density-dependent effect decrease as the thinning intensity increase.
