Abundance, growth and mortality of very large trees in neotropical lowland rain forest
Abundance, growth and mortality of very large trees in neotropical lowland rain forest
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DOI：
10.1016/0378-1127(95)03607-5
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发表时间：
1996-01-01
影响因子：
3.7
通讯作者：
Clark, DA
中科院分区：
文献类型：
--
作者：
Clark, DB;Clark, DA
非常大的树木，任意定义为那些直径超过70厘米以上的扶壁，占了新热带雨林地上生物量的主要部分。由于特定物种的个体数量稀少，难以准确测量，因此很少有关于经常达到紧急状态的物种的生长、死亡和丰度的物种水平数据。我们报告这样的数据非常大的个人从古老的热带潮湿森林在拉塞尔瓦生物站在大西洋低地的哥斯达黎加共和国。使用515个0.01公顷的样方位于网格点，在500公顷的古老森林面积的所有物种达到超过70厘米直径的规模丰富的评估。在2301茎直径10厘米或以上的总样本中，非常大的个人占2%的茎，23%的断面积，估计地上生物量的27%。在500公顷的地块内的150公顷的面积内，定期达到紧急状态的五个物种的生长和生存进行了测量。生存的282个非常大的个人的五个物种进行了测量超过6年。总样本的平均年死亡率仅为0.6%（-1）。平均年直径生长增量变化从1.9到5.2毫米年（-1）之间的物种，并在五个物种的直径呈负相关。对于一个样本的193个人超过7年的测量，增长几乎完全等于基面积和生物量的损失，由于死亡率。由于所有这些物种都定期招募新的树木超过70厘米直径的类，生物量在大的个人大小类的增加超过150公顷的古老的生长研究区。历史干扰和/或目前的气候变化被假设为占增加。我们确定缺乏标准的直径测量标准，和小的和潜在的不具代表性的地块位置作为两个问题，在评估非常大的树木在其他新热带森林的作用。今后的研究应在更大的地区进行取样;这将增加结论的普遍性，并将有可能在物种水平上对非常大的热带树木的生态进行比较。
Very large trees, arbitrarily defined as those over 70 cm diameter above buttresses, account for a major portion of the above-ground biomass in neotropical rain forests. Owing to the scarcity of individuals of a given species and the difficulty of accurate measurement, there are few species-level data on the growth, mortality, and abundance of species that regularly reach emergent status. We report such data for very large individuals from old-growth tropical wet forest at the La Selva Biological Station in the Atlantic lowlands of the Republic of Costa Rica. The landscape-scale abundance of all species reaching over 70 cm diameter was assessed using 515 0.01-ha quadrats located at grid points in a 500 ha area of old-growth forest. In the total sample of 2301 stems 10 cm or more in diameter, very large individuals accounted for 2% of the stems, 23% of the basal area, and 27% of the estimated above-ground biomass. Growth and survival for five species that regularly attain emergent status were measured in a 150 ha area within the 500 ha plot. Survival of 282 very large individuals of the five species was measured over 6 years. The mean annual mortality rate of the total sample was only 0.6% year(-1). Mean annual diameter growth increments varied from 1.9 to 5.2 mm year(-1) among species, and were negatively correlated with diameter in four of the five species. For a sample of 193 individuals measured over 7 years, growth almost exactly equalled losses in basal area and biomass due to mortality. Because all of these species are regularly recruiting new trees into the over 70 cm diameter class, the amount of biomass in the large-individual size class is increasing over the 150 ha old-growth study area. Historic disturbance and/or current climatic change are hypothesized to account for the increase. We identify lack of standard diameter measurement criteria, and small and potentially unrepresentative plot locations as two problems in assessing the role of very large trees in other neotropical forests. Future studies should sample larger areas; this will increase the generality of the conclusions and will make possible a species-level comparison of the ecology of very large tropical trees.