摘要
于 1 998～ 2 0 0 0年夏季 ,运用 GPS定位系统确定了 1 2块面积范围为 6.5～ 1 1 2 .8hm2 的彼此隔离的森林斑块 ,比较了斑块面积和栖息地质量对繁殖鸟类群落结构的影响。结果表明 :不同面积斑块中繁殖鸟类的群落结构有所差异 ,各斑块所容纳的繁殖鸟类的物种数从 4种到 2 6种不等 ,鸟类物种数随着斑块面积的增大而增多。不同鸟类对斑块面积的反应并不相同 ,耐边缘种偏爱面积较小的斑块 ,而非边缘种偏爱在大面积的斑块中繁殖。斑块栖息地质量也是影响鸟类群落结构的重要因素 ,质量好的斑块包容的鸟类物种较多。鸟类物种丰富度与斑块质量的相关性 ( R2 =0 .67)小于与斑块面积的相关性 ( R2 =0 .88)。各斑块中的鸟类群落结构在不同年份间比较相似。栖息地破碎化不但缩小了栖息地面积 ,同时也不同程度地降低了栖息地的质量 。
We investigated breeding bird communities of forest fragments (6\^5～112\^8hm\+2) in Zuojia Nature Protection Area and Tumenling mountains during three summers (1998～2000) to compare the influence of area and habitat on community structure. Birds were surveyed with the Point\|count technique. Number of census points increased with fragment area, and were distributed to sample the range of habitats present. Each point was censused at least three times during the breeding season. We plotted accumulated species totals against total number of observation periods for each fragment, forming species accumulation curves. These curves were visually inspected to determine if a plateau in the number of species recorded was reached. Species abundances were calculated for each fragment as the sum of the highest number of individuals recorded from each point divided by the number of observation points. We categorized species by migratory status and preferred breeding habitat and examined the effects of area and habitat variables on them. In addition, we sampled vegetation in one 0\^04hm\+2 circle centered on each observation point and within a second circle located 50m from the first. \;We collected data of tree height, dbh, density, shrub height, shrub density etc. within each circle. Data from all points within a fragment were combined to compare habitat structure among fragments. We performed a Bray\|Curtis analysis (BCA) on importance values of dominant tree species to determine which tree species contributed most to differences among fragments and used principal components analysis (PCA) to describe gradients in structural components of the vegetation among fragments. We used stepwise multiple regression to evaluate the influence of area and habitat on the components of the bird communities. \;We recorded 22 species of trees from all fragments combined. The first three components of BCA accounted for 89% of variation in tree species composition among fragments. The first three principal components accounted for 76% of variation in habitat structure among fragments. Several aspects of the vegetation correlated weakly with area: mean basal area of trees, R 2=0 332, P >0 05;closure of tree crown, R 2=0 304, P >0 05;shrub density, R 2=0 296, P >0 05. Fragments supported from 6 to 39 species and composition was relatively constant among years. Between\|year similarity of species occurrence was high (average similarity: 1998～1999, 89%; 1999～2000, 90%; 2000～2001, 86%). Examination of species accumulation curves indicated that species composition of fragments was adequately determined. Similarly, differences between observed and predicted values were slight and did not affect species\|area regression results. Woodlot area accounted for a large proportion of variance in total species richness each year: R 2=0\^8913, 0\^9016, and 0\^8246, in 1998, 1999, and 2000. Species\|area relationships did not differ among years and data from all years were combined. Ecological generalists dominated small fragments, while more specialized species increased in importance with area. Neither habitat nor fragment isolation explained significant additional variation in total species richness after area. Abundance of more than 30% of species examined correlated with habitat variables, but a greater proportion (60%) were influenced more strongly by fragment area. Inclusion of variables for habitat structure, habitat heterogeneity, tree species distribution, and forest isolation in a multiple regression analysis did not improve the simple regression between total number of species and patch areas.
出处
《生态学报》
CAS
CSCD
北大核心
2003年第6期1087-1094,共8页
Acta Ecologica Sinica
关键词
斑块面积
斑块质量
群落结构
鸟类物种
patch sizes
patch quality
bird communities community structure
