林隙对黄土高原马栏林区优势种更新的影响

林隙对森林的结构和动态具有重要的影响。黄土高原马栏林区主要群落类型中,对优势种辽东栎(Quercus liaotungensis)、油松(Pinus tabulaeformis)不同大小林隙内的幼苗和幼树进行统计计算,并与林冠下进行对比分析。结果表明:两个优势种存在不同的更新策略,即辽东栎主要通过高萌发量来维持其种群的更新,而油松则是通过降低幼苗到幼树过程中的死亡率来维持其种群的更新;林隙面积在20~40m²时油松的自然更新情况最好,而辽东栎在不同大小林隙中的自然更新情况较为复杂;适当的林隙干扰总体上促进了该地区优势种的自然更新,林隙对其更新的促进机制各异;在林隙干扰下,辽东栎和油松在各自占优势群落(辽东栎林和油松林)中的优势地位均没有被对方取代的趋势,所以辽东栎林和油松林会作为该地区的顶级群落和亚顶级群落而长期存在。

Effect of Forest Gap on Regeneration of Dominant Species in Malan Forest Area on the Loess Plateau

Forest gap disturbs the forest structure and dynamics of forest. Quercus liaotungensis and Pinus tabulaeformis are the dominant species in the main community types in Malan forest area on the Loess Plateau. In this paper, the seedlings and saplings of these two species in various-sized forest gaps are measured, and the seedlings and saplings in gaps and under the canopies are compared and analyzed. The results show that these two dominant species have different regeneration strategies, that is, Q. liaotungensis regenerates its population by relying on its high germination, while P. tabulaeformis regenerates its population by reducing the mortality rate of its seedlings and saplings. When the gap area is 20-40 m², the natural regeneration of P. tabulaeformis is the best, but the natural regeneration of Q. liaotungensis in various-sized gaps is more complex. Forest gap disturbance can promote the natural regeneration of these two dominant species. In the future, the dominance of the Q. liaotungensis and P. tabulaeformis in the Q. liaotungensis forest and P. tabulaeformis forest will not be replaced each other by forest gap disturbance. So Q. liaotungensis and P. tabulaeformis in the Q. liaotungensis forest and P. tabulaeformis forest will exist for a long period as the succession climax and subclimax in this area.