Köster Nils, Friedrich Karoline, Nieder Jürgen, Barthlott Wilhelm
Nees Institute for Biodiversity of Plants, University of Bonn, Bonn, Germany.
Conserv Biol. 2009 Aug;23(4):911-9. doi: 10.1111/j.1523-1739.2008.01164.x. Epub 2009 Feb 6.
Epiphytes are diverse and important elements of tropical forests, but as canopy-dwelling organisms, they are highly vulnerable to deforestation. To assess the effect of deforestation on epiphyte diversity and the potential for epiphyte conservation in anthropogenically transformed habitats, we surveyed the epiphytic vegetation of an Ecuadorian cloud forest reserve and its surroundings. Our study was located on the western slopes of the Andes, a global center of biodiversity. We sampled vascular epiphytes of 110 study plots in a continuous primary forest; 14 primary forest fragments; isolated remnant trees in young, middle-aged, and old pastures; and young and old secondary forests. It is the first study to include all relevant types of habitat transformation at a single study site and to compare epiphyte diversity at different temporal stages of fragmentation. Epiphyte diversity was highest in continuous primary forest, followed by forest fragments and isolated remnant trees, and lowest in young secondary forests. Spatial parameters of habitat transformation, such as fragment area, distance to the continuous primary forest, or distance to the forest edge from inside the forest, had no significant effect on epiphyte diversity. Hence, the influence of dispersal limitations appeared to be negligible or appeared to operate only over very short distances, whereas microclimatic edge effects acted only in the case of completely isolated trees, but not in larger forest fragments. Epiphyte diversity increased considerably with age of secondary forests, but species assemblages on isolated remnant trees were impoverished distinctly with time since isolation. Thus, isolated trees may serve for recolonization of secondary forests, but only for a relatively short time. We therefore suggest that the conservation of even small patches of primary forest within agricultural landscape matrices is essential for the long-term maintenance of the high epiphyte diversity in tropical cloud forests.
附生植物是热带森林中种类多样且重要的组成部分，但作为栖息在树冠层的生物，它们极易受到森林砍伐的影响。为了评估森林砍伐对附生植物多样性的影响以及在人为改造的栖息地中附生植物的保护潜力，我们对厄瓜多尔一片云雾森林保护区及其周边地区的附生植物植被进行了调查。我们的研究位于安第斯山脉的西坡，这是一个全球生物多样性中心。我们在一片连续的原始森林中的110个研究样地、14个原始森林片段、年轻、中年和老年牧场中孤立的残留树木以及年轻和老年次生林中对维管束附生植物进行了采样。这是第一项在单一研究地点涵盖所有相关类型栖息地改造并比较碎片化不同时间阶段附生植物多样性的研究。附生植物多样性在连续原始森林中最高，其次是森林片段和孤立的残留树木，在年轻次生林中最低。栖息地改造的空间参数，如片段面积、到连续原始森林的距离或从森林内部到森林边缘的距离，对附生植物多样性没有显著影响。因此，扩散限制的影响似乎可以忽略不计，或者似乎仅在非常短的距离内起作用，而微气候边缘效应仅在完全孤立的树木情况下起作用，而在较大的森林片段中不起作用。附生植物多样性随着次生林年龄的增长而显著增加，但孤立残留树木上的物种组合随着隔离时间的推移明显变得贫乏。因此，孤立的树木可能有助于次生林的重新定殖，但仅在相对较短的时间内。因此，我们建议在农业景观矩阵中保护哪怕是小片的原始森林对于热带云雾森林中高附生植物多样性的长期维持至关重要。
