An explanation of patterns of breeding bird species richness and density following clearcutting in northeastern USA forests
An explanation of patterns of breeding bird species richness and density following clearcutting in northeastern USA forests
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DOI：
10.1016/s0378-1127(02)00074-9
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发表时间：
2003-02-17
影响因子：
3.7
通讯作者：
Smith, CR
中科院分区：
文献类型：
--
作者：
Keller, JK;Richmond, ME;Smith, CR
本文对纽约中部地区23个年龄在2 ~ 120岁的林龄均匀的演替林分进行了平均4年的种鸟调查，观察了采伐后种鸟丰富度和密度的变化。从采伐后的第2-6年开始，丰富度和密度急剧增加，到第25年急剧下降。三次函数最适合这一结果（P < 0.0007），其次，在第25年至第120年间，丰富度和密度的增减幅度较小（P < 0.03）。丰富度和密度的快速增加与叶面积高度相关，在采伐前大量放养的样地，叶面积在第6年或第7年恢复到采伐前的水平。6年生林分的物种丰富度是任何成熟林分的2倍以上。同样，6年龄林分的平均鸟类密度为501只/40公顷，是任何成熟林分（184只/40公顷）的2.5倍以上。从第7年到第25年，鸟类数量的下降伴随着树冠的关闭，可能与地面附近觅食和筑巢地点的丧失有关。第二，从25年到100年，鸟类丰富度和密度的增加不太明显，这与(1)树木死亡造成的冠层间隙的大小和持续时间的增加导致树叶向森林所有垂直层的重新分布有关；(2)树洞的大小和树皮的复杂性增加，为觅食和筑巢提供了新的基质。总体而言，鸟类演替趋势似乎是由适合特定鸟类种群的植被斑块类型的兴衰决定的。研究表明，东北森林在早期演替阶段，由于叶片和昆虫的高生产力以及水平结构复杂性的增加，虽然缺乏垂直异质性和孔洞相关基质，但却显著支持较高的鸟类丰富度和密度。通过伐林而认真实施的年龄均匀的林分管理，有可能增加森林景观的物种丰富度，并为早期演替的新热带迁徙者提供重要的栖息地，同时有效地满足对可销售木材的需求。(C) 2002 Elsevier Science B.V.版权所有
We surveyed breeding birds for an average of 4 years on 23 primarily even-aged successional stands ranging from 2 to 120 years old to observe changes in species richness and density following clearcutting in central New York. An initial sharp increase in richness and density from post-cut years 2-6 preceded a steep decline by year 25. Cubic functions best fit this (P < 0.0007) and a second, smaller increase and decline in richness and density between years 25 and 120 (P < 0.03). The rapid initial increases in richness and density were highly correlated with leaf area which, on plots that were heavily stocked prior to cutting, returned to precut levels by year 6 or 7. Species richness on 6-year-old clearcuts was more than twice that of any mature stand sampled. Similarly, 6-year-old clearcuts exhibited a mean avian density (501 pr/40 ha), more than 2.5 times that of any mature stand (184 pr/40 ha). The decline in avian populations from years 7 to 25 accompanied canopy closure and was likely associated with the loss of foraging and nesting sites near ground level. The second, less pronounced increase in avian richness and density from years 25 to 100 was associated with (1) the redistribution of foliage to all vertical layers of the forest resulting from the increasing size and duration of canopy gaps caused by tree deaths; and (2) the increasing size and bark complexity of tree holes, which provided new foraging and nesting substrates. Overall, avian successional trends appear to be determined by the development and decline of vegetation patch types appropriate to specific guilds of birds. We suggest that, while lacking the vertical heterogeneity and bole-related substrates traditionally cited as correlates of avian richness and density in older forests, early successional stages of northeastern forests support significantly higher avifaunal richness and density due to a combination of high productivity of leaves and insects along with increased horizontal structural complexity. Even-aged stand management, carefully implemented through clearcutting, has the potential to increase the species richness of forested landscapes and provide important habitat for early successional Neotropical migrants, while effectively meeting demands for marketable timber. (C) 2002 Elsevier Science B.V. All rights reserved.