兴安落叶松老龄林落叶松林木死亡格局以及倒木对更新的影响

对兴安落叶松老龄林落叶松林木死亡格局和死亡木对更新的影响进行了研究 .结果表明 ,丛桦落叶松林和杜香落叶松林的枯立木以中径木占多数 ,赤杨落叶松林主要为中、大径木 ,草类落叶松林主要是中、小径木 .落叶松枯立木主要因火烧、受压和老死而形成 .丛桦落叶松林和赤杨落叶松林掘根倒木较多 .杜香落叶松林和草类落叶松林的倒木以风折为主 .地形、山体走向和盛行风向对树倒方向影响很大 .丛桦落叶松林倒木方向杂乱 ,赤杨落叶松林林木均向东倒下 ,杜香落叶松林和草类落叶松林的掘根木分别向南、东北方倒下 ,两者的风折木倒向随机性较大 .草类落叶松和赤杨落叶松老龄林内 ,倒木更新为 1 8和 40株·m- 2 ,远远高于矿物土基质上 2株·m- 2 的水平 .丛桦落叶松林内倒木和林地上更新均相当好 ,约为 2 8株·m- 2 .杜香落叶松林倒木更新效果不突出 .

Mortality patterns of Larix gmelini and effect of fallen dead wood on regeneration of old Larixgmeliniforest.

The study shows that the snags of L.gmelini are resulted from fire, suppression, or ageing. There are more medium diameter snags in L.gmelini Betula fruticosa and L.gmelini Ledum palustre forests, more medium and large diameter snags in L.gmelini Herbae forest, and more medium and small diameter snags in L.gmelini Alnus mandshurica forest. For dead trees, the uprooted trees are dominant in L.gmelini Betula fruticosa and L.gmelini Alnus mandshurica forest, snapped trees are dominant in L.gmelini Ledum palustre and L.gmelini Herbae forests. The treefall direction is chiefly affected by topography, run of mountain, and direction of dominant wind, which is random in L.gmelini Betula fruticosa forest, east in L.gmelini Alnus mandshurica forest, south and northeast for uprooted trees in L.gmelini Ledum palustre and L.gmelini Herbae forests, respectively, and random for snapped trees in both forests. In L.gmelini Herbae and L.gmelini Alnus mandshurica forests, the density of seedlings and saplings on fallen dead wood (18 and 40 individuals per m 2, respectively) is greater than that on mineral soil (2 individuals per m 2).The regeneration of seedlings and saplings is quite good (28 individuals per m 2) on dead logs and on forest floor in L.gmelini Betula fruticosa forest. The effect of dead logs on regeneration is not clear in L.gmelini Ledum palustre forest.