Population structure, stand-level dieback and recovery ofScalesia pedunculata forest in the Galápagos Islands
Population structure, stand-level dieback and recovery ofScalesia pedunculata forest in the Galápagos Islands
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加拉帕戈斯群岛长柄鳞翅目林种群结构、林分顶枯及恢复
DOI：
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发表时间：
1988
影响因子：
2
通讯作者：
D. Mueller‐Dombois
中科院分区：
文献类型：
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作者：
S. Itow;D. Mueller‐Dombois
有柄扇贝是菊科的一种生长迅速、寿命短的树，在加拉菲帕戈斯群岛的圣克鲁斯岛的中海拔潮湿森林区形成密集的单种林分（Bowman，1961，Itow，1965; Wiggins和Porter，1971）。该物种显然是从一个草本祖先进化而来的。根据一位当地长期居民的观察记录，在1935年至1940年期间，有柄扇贝经历了大规模死亡（Kastdalen，1982）。森林变薄，只有几个分散的残余，直到开花，与20世纪40年代初的干旱期相吻合，森林地区成为密集的同一物种的幼苗。本论文的第一作者对该物种的生态学和行为感兴趣，并于1970年、1978年和1981年访问了Galfipagos，对Scalpeluspedunculata种群的大小分布进行了调查。他收集的数据表明，森林的每个林分由一个或几个同龄的同龄组组成，没有任何年轻的世代，但数据没有公布（其中一部分出现在本文中）。根据他的野外研究，他注意到了S. pedunculata，如（1）它的先锋行为，（2）森林的物种贫乏的宪法，（3）在林分中的年轻的树世代的缺乏，（4）在后成熟的生活阶段的树冠种群的同步崩溃，和（5）一个自我循环或建立和崩溃演替（Itow，1978，1983：Original in Japanese）。哈曼（1979）还报道了该物种的开拓行为和森林的循环更替。1982-1983年的E1 Nifio给加拉菲帕戈斯群岛带来了极高的降雨量，并使S. pedunculata在当时和之后死亡（Hamann，1985; Lawesson，1987）。本文着重研究了我国南方红豆杉的种群结构。pedunculata在1982-83 E1 Nifio之前及其之后的变化，并进一步与其他太平洋岛屿森林的林分水平枯死现象进行比较。研究区域是Los Gemeros，一个海拔约1000米的几乎平坦的地形。560米，在岛上
Scalesia pedunculata is a fast growing, short-lived tree of the Asteraceae, which forms dense, monospecific stands in the humid forest zone at middle elevations on Isla Santa Cruz of the Galfipagos Islands (Bowman, 1961, Itow, 1965; Wiggins and Porter, 1971). The species apparently evolved from a herbaceous ancestor. Between 1935 and 1940 Scalesia pedunculata underwent mass mortality according to observations recorded by a long-term local resident (Kastdalen, 1982). The forest thinned down to only a few scattered remnants until the flowering, coincident with a dry period during the early 1940s, and the forest area became densely restocked with seedlings of the same species. The first named author of the present paper has been interested in the ecology and behavior of the species and carried out investigations of the size distribution of Scalesia pedunculata populations on his visit to the Galfipagos in 1970, 1978 and 1981. The data he gathered showed that each stand of the forest consists of one or a few even-aged cohorts without any young generations, but the data were not published (a part of which are appearing in the present paper). Based on his field studies he noted some ecological characteristics of S. pedunculata such as (1) its pioneering behavior, (2) the species-poor constitution of the forest, (3) the absence of young tree generations in the stands, (4) the synchronized collapse of canopy tree populations at a post-mature life-stage, and (5) a self-cyclic or build-up-and-collapse succession (Itow, 1978, 1983: Original in Japanese). Hamann (1979) also reported on the pioneering behavior of the species and the cyclic replacement of the forest. The 1982-1983 E1 Nifio brought extremely high rainfall to the Galfipagos Islands (Robalino, 1985), and mature populations of S. pedunculata died then and afterwards (Hamann, 1985; Lawesson, 1987). The present paper focuses on the population structure of S. pedunculata before the 1982-83 E1 Nifio and its change afterwards, and further on a comparison of stand-level dieback phenomena with other Pacific island forests. The study area is Los Gemeros, a nearly level terrain at an altitude of ca. 560 m, on Isla