秦皇岛白桦人工林群落结构特征研究

Community Structure of Betula platyphylla Plantation in Qinhuangdao City

采用随机样地调查方法,以40年人工毛白杨林为对照,对秦皇岛海滨林场20年生白桦人工林的群落层次结构、物种组成、多样性和乔木层径阶结构、树高结构进行了比较分析。结果表明:(1)白桦林和毛白杨林群落层次结构差异较大。白桦林处于幼龄林向中龄林过渡阶段,群落层次简单,由乔木层和草本层组成,灌木层缺乏。毛白杨林处于成过熟林状态,层次结构复杂,由主林层、次林层、灌木层和草本层4个层次组成,形成了复层异龄混交林。(2)白桦林和毛白杨林群落物种多样性不同。白桦林物种数量(24科29属32种)比毛白杨林(12科15属17种)更丰富,但不同层次物种组成差异较大,白桦林乔木层物种单一(1科1属1种),灌木层缺乏,毛白杨林乔木层(2科3属5种)和灌木层(5科5属6种)比白桦林种类丰富,白桦林草本层种类丰富(19科24属27种),远高于毛白杨林(10科12属12种);群落物种多样性[Shannon-Weiner指数(H)、Simpson指数(D)和群落均匀度指数(J)]白桦林草本层>毛白杨林草本层>毛白杨林灌木层>毛白杨林乔木层>白桦林乔木层;两个群落整体及乔灌草各层次之间种类组成存在较大差异,物种相似性水平较低。(3)白桦林和毛白杨林径阶结构和树高结构特征不同,白桦林径阶结构和树高结构均呈单峰型曲线,径阶和树高分布较为集中,胸径和树高变动系数小,个体分化不明显,呈现出典型的同龄林结构特征。毛白杨林径阶结构呈倒"J"型分布,树高结构呈双峰型曲线,个体分化明显,呈现出异龄林结构特征。(4)白桦林虽然在研究区秦皇岛海滨平原区正常生长,但其生长环境具有一定的特殊性,在其他平原地区造林需对环境进行认真筛选。

Taking 40-year-old Populus tomentosa plantation as a control,the community structure,species composition,diversity,tree layer diameter and tree height structure of 20-year-old Betula platyphylla plantation in Qinhuangdao Seaside Forest Farm were compared and analyzed through random sample plot survey method.The results showed that:(1)The hierarchical structures of B.platyphylla forest and P.tomentosa forest were different.B.platyphylla forest was in the transitional stage from young forest to middle-aged forest,it’s community level was simple,composed of arbor layer and herb layer,and the shrub layer was lacking.P.tomentosa forest was in the state of over-ripe forest,with complex hierarchical structures of four layers:main forest layer,secondary forest layer,shrub layer and herb layer,forming a mixed layer of mixed forests;(2)Species diversity had significant difference between B.platyphylla forest and P.tomentosa ones.The species in B.platyphylla forest(24 families,29 genera and 32 species)were more abundant than that of P.tomentosa ones(12 families,15 genera and 17 species),but the species composition of different levels is quite different,The B.platyphylla forest had 1 species(1 family,1 genera and 1 species)in arbor layer and the shrub layer was lack,the species composition of it was lower than P.tomentosa forest in arbor layer(2 families,3 genera and 5 species)and shrub layer(5 families,5 genera and 6 species),but the herb layer(19 families,24 genera and 27 species)of it was much higher than that of P.tomentosa(12 species,12 genera and 12 species);Ordination of community species diversity(Shannon-Weiner index(H),Simpson index(D)and community uniformity index(J))was:herb layer of B.platyphylla forest>herb layer of P.tomentosa forest>shrub layer of P.tomentosa forest>arbor layer of P.tomentosa forest>arbor layer of B.platyphylla forest;Species similarity was lower in the two communities as a whole and in the layer of trees,shrubs and grasses;(3)B.platyphylla forest and P.tomentosa forest have different structures of diameter and height.B.platyphylla forest had a single peak curve in the structure of diameter and height,the distribution of diameter and height was relatively concentrated,the coefficient of change of DBH and height was small,and the individual differentiation was not obvious,which indicated a typical structural characteristics of young and middle aged forest of the same age.The diameter structure of P.tomentosa forest was inverted"J"type distribution,tree height structure was double peak curve,individual differentiation is obvious,showing the structural characteristics of different age forest;(4)Although B.platyphylla forest grew normally in the coastal plain of Qinhuangdao in the study area,its growth environment had certain particularity,and afforestation in other plain areas need to be carefully screened of the environment.