A Broad Transition from Cloud Forest to Páramo Characterizes an Undisturbed Treeline in Parque Nacional Llanganates, Ecuador
A Broad Transition from Cloud Forest to Páramo Characterizes an Undisturbed Treeline in Parque Nacional Llanganates, Ecuador
复制标题
从云雾林到帕拉莫的大范围过渡是厄瓜多尔国家公园未受干扰的林线的特征
DOI：
10.1657/1938-4246-46.4.975
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
E. Narváez
中科院分区：
文献类型：
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作者：
R. Hofstede;K. Dickinson;A. Mark;E. Narváez
摘要：本研究旨在调查厄瓜多尔东科迪勒拉山脉相对未改造地区从安第斯山北部云雾林向帕拉莫草原过渡过程中的植被格局。沿海拔梯度，从 3400-3700 m 持续潮湿的安第斯山地云林到 3900-4000 m 的帕拉莫草原，将单个 20 × 10 m 样地随机放置在代表性地点。还取样了茎莲座丛 Espeletia pycnophylla var. 的分离株。 llanganatensis，位于该属连续分布范围以南约 200 公里处。确定了一些物理和化学土壤因素，包括-30厘米的温度。对每个地点的四种生命形式类别（乔木、灌木、草本植物、地被植物）的覆盖度进行视觉估计，揭示了它们沿海拔梯度的相对接近程度的相似性。有树木覆盖的林分比没有树木覆盖的林分物种更丰富，这主要是由于木本植物区系的差异分布。沿着这个梯度的物种混合没有发生突然的中断。土壤温度和海拔是解释植物群落结构和组成变异性的最重要的测量因素。沿海拔梯度没有明显的分带，植被结构和植物区系呈现连续变化。没有区分明确的森林上限。人们讨论了埃斯佩莱蒂亚在该地区的孤立存在，但关于其起源的理论仍然是推测性的。
Abstract This study aimed at investigating the vegetation pattern associated with the transition from upper northern Andean cloud forest to páramo grassland in a relatively unmodified area in Ecuador's Eastern Cordillera. Single 20 × 10 m plots were randomly placed in representative sites along an altitudinal gradient from continuously wet Andean montane cloud forest at 3400–3700 m to páramo grassland at 3900–4000 m. Also sampled was a disjunct stand of the stem-rosette Espeletia pycnophylla var. llanganatensis, some 200 km south of the limit of the otherwise continuous distribution of this genus. Several physical and chemical soil factors, including temperature at -30 cm, were determined. Visual estimates of cover in four life-form classes (trees, shrubs, herbs, ground cover) at each site revealed similarities related to their relative proximity along an elevation gradient. Stands with a tree cover were more species-rich than those without, due largely to the differential distribution of the woody flora. No abrupt discontinuity occurred in the mix of species along this gradient. Soil temperature and altitude were the most important factors of those measured to explain the variability in plant community structure and composition. There was no clear zonation evident along the altitudinal gradient, with vegetation structure and floristics displaying continuous variation. No clear upper forest limit was differentiated. The isolated presence of Espeletia in the area is discussed, but the theory about its origin remains speculative.