长白山红松阔叶混交林森林天然更新条件的研究

Natural regeneration condition in Pinus koraiensis broad-leaved mixed forest

研究长白山红松阔叶混交林森林天然更新的变化规律及其条件。红松阔叶混交林是长白山主要的森林类型 ,保存不多 ,对于研究以前森林经营环境具有重要意义。研究的目的在于揭示红松天然更新规律及其与森林组成结构的关系。研究结果表明 ,红松阔叶混交林天然更新与森林群落类型 ,海拔 ,森林植物条件及人类活动等干扰有极大关系。一般在陡坡或山脊上胡枝子柞树红松林中 ,那里林冠郁闭度达到 80 %～ 90 %或更大 ,林分中红松组成也更大 ,红松天然更新良好。每公顷有红松幼苗和小幼树万株以上。但是在郁闭的红松林冠下 ,很少能长大。在大部分的阔叶红松混交林中 ,除了林冠比较郁闭的地方外 ,针叶树包括红松在内的天然更新通常稀少 ,每公顷仅有幼苗幼树数千株 ,其中大部是阔叶树。随着海拔上升到一定范围 ,在更新中云冷杉的成分增加。老择伐迹地由于林下植被密 ,常常缺乏更新。74 .2 %耐荫树种的幼苗幼树是在林冠下观查到 ,它们 70 %以上分布于离立木 2 .5 m以内 ,这正好等于林木平均冠幅的半径。所以 。

The Korean pine (Pinus koraiensis) broadleaved mixed forest was one of the dominant vegetation types in Changbai Mountain Forests,now it is a rare remnant ecosystem with an irreplaceable reference for understanding the pre logging environment of the region. Primary objective of this study was to examine the natural regeneration of Korean pine in the forest and its relation to the forest composition and structure. Our results indicated that natural regeneration was closely related to forest community composition, structure and human disturbances such as pine seeds harvesting. Natural regeneration of the Korean pine was moderate in the Mongolian oak Korean pine forest on steep slopes, where the canopy density reaches 80%～90% or more and the proportion of Korean pine in the forest was high. Over ten thousand seedlings and small saplings of Korean pine per hectare were observed, but they rarely grew up under close canopies. In Korean pine broadleaved mixed forests there is no much natural regeneration of conifer trees including Korean pine, except in the relatively close canopies. In the Korean pine broadleaved mixed forests the natural regeneration is largely of hardwood trees, especially seedlings and saplings of Fraxinus mandshurica, which sometimes reach more than 13000 plants per hectare. At higher elevations the amount of spruce and fire seedlings and saplings increases. A significant low density of seedlings at the old partially cutting sites was observed, which suggested that partial removals of canopy trees strongly influenced regeneration. Our results also showed that seventy four per cent of the seedlings and saplings of shade tolerant species was recorded under the canopy. Interestingly, more than 70% of total natural regeneration of Korean pine was found within 2.5 m from the standing live trees, which is the average radius of crown projection. Therefore, the best seedling regeneration environment of Korean pine and the shade tolerant species is under the close canopies.