黄土高原马栏林区辽东栎林种内、种间竞争研究

Intraspecific and Interspecific Competition of Quercus liaotungensis in Malan Forest Region of Loess Plateau

利用Hegyi的单木竞争指数模型对黄土高原马栏林区辽东栎(Quercus liaotungensis)的种内和种间竞争强度进行了定量分析.结果显示:(1)辽东栎种内竞争强度与种间竞争强度的总和大致相等,其种内及种间竞争强度均随对象木胸径的增大而逐渐减小,其关系服从幂函数规律,竞争主要发生在胸径小于15 cm的幼树阶段.(2)各组成树种对辽东栎影响程度(竞争指数)的大小顺序为:辽东栎>油松(Pinus tabulaeformis)>白桦(Betulaplatyphylla)>山杨(Populus davidiana)>杜梨(Pyrus betulaefolia)>湖北山楂(Crataegus hupehensis)>茶条槭(Acer ginnala)>陕西鹅耳枥(Carpinus shensiensis)>葛萝槭(A.grosseri).(3)油松是该地区的次优势种,对辽东栎有较大的竞争压力,在群落发展中可能会形成以油松占优势的混交林.(4)辽东栎胸径小于15 cm时,种内种间竞争是导致大量个体死亡的主要原因;胸径超过15 cm时,人为砍伐可能是个体死亡的主要原因.研究结果认为马栏林区混交林油松的密度不宜过大,尤其是在与未成熟辽东栎种群混交时密度应合理,应对该林区的混交林进行人工抚育,及时择伐密度过大的油松,而在辽东栎胸径达到15 cm之前择伐长势较差的植株,以促使森林群落尽快趋于稳定.

The intraspecific and interspecific competition intensity of Quercus liaotungensis in Malan forest region of Loess Plateau were quantitatively analyzed using Hegyi＇s single tree competition index model. The results showed. （1） The intensity of the intraspecific competition in Q. liaotungensis population and interspecific competition of all associated species were approximately equal. They both decreased gradually with the increase of Diameter Breast Height （DBH） of objective tree and obeyed power function rule with DBH. Such competition mostly happened when the DBH of Q. liaotungensis was less than 15 centimeters; （2） The influence degree （competition intensity） of every species was descending as Q. liaotungensis, Pinus tabulae f orrnis , Betula plat yph ylla , Populus davidiana , P yrus betulae f olia , Crataegus hupehensis , Acer ginnala ,Carpinus shensiensis and A. grosseri; （3） P. tabulaeforrnis,the subdominant species in this region,given the maximal competition pressure to Q. liaotungensis in interspecific relationship. There was a possibility that this forest would become a mixed forest that Pinus tabulaeformis at the dominant status; （4） Intraspecific and interspecific competition was the main reason to make the death of Q. liaotungensis with DBH less than 15 centimeters. Felling would be the reason for the death of Q. liaotungensis when its DBH exceeded 15 centimeters. We suggested that P. tabulaeformis should be at a proper density in mixed forest,especially when it mixed with an immature Q. liaotungensis population that has many young trees. To nurture the mixed forest at a proper density and make it stable as soon as possible, P. tabulaeformis that superabundant and Q. liaotungensis that are ill growing should be picked to cut down.