Pioneer trees in Amazonian floodplains: Three key species form monospecific stands in different habitats
Pioneer trees in Amazonian floodplains: Three key species form monospecific stands in different habitats
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亚马逊洪泛区的先锋树：三个关键物种在不同的栖息地形成单一物种
DOI：
10.1007/bf02804233
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发表时间：
2002
影响因子：
1.2
通讯作者：
W. Junk
中科院分区：
文献类型：
--
作者：
P. Parolin;Â. C. Oliveira;M. Piedade;F. Wittmann;W. Junk
三个先锋树种-柳humboldtiana，Cecropia latiloba，番泻叶-形式在中央亚马逊白水泛滥平原的单种。与此相反，toterra firma森林的物种组成是不可预测的，即使是先锋物种，在中央Amazonianvárzea的主要殖民物种的发生似乎是可以预测的。这种可预测性与特有的生境条件和先驱物种数量少有关。这种对不同生境的偏好反映在三个主要物种的不同萌发和早期生长、结构和生理特征以及生殖和形态适应上。所有种的种子萌发率均在90%以上，种子萌发所需的时间从柳属的1天到Cecropia的14天不等。柳属和天葵属的茎伸长量在10 cm以上，番泻叶属的茎伸长量在50 cm左右。木材的比重从0.33 g cm−3（Cecropia）到0.45 g cm−3（Senna）不等。年生长量分别增加1.20 cm（天仙子属）、1.23 cm（柳属）和2.14 cm（番泻叶属）。所有物种都产生了不定根、芽和/或茎肥大。叶片光合作用介于17和20 µmol m−2s−1之间，在番泻叶中达到最大值30 µmol m−2s−1。柳属植物全年都有开花结实，而天葵属和番泻叶属植物则集中在淹水期，柳枝柳主要生长在淹水时间长、沉积速率高的低洼地。一旦柳已经形成了茂密的森林，沉积和水流减少在这些网站和Cecropia latiloba可能接管。该物种生长在洪水梯度的低至中海拔地区，水流和沉积速率较低。番泻叶不耐受淹没，并在洪水梯度较高的地方定居，这些地方可能有强水流和高沉积。
Three pioneer tree species —Salix humboldtiana, Cecropia latiloba, Senna reticulata — form monospecific stands in the Central Amazonian white-water flood plain. In contrast toterra firma forests where species composition is unpredictable even for pioneer species, in Central Amazonianvárzea the occurrence of the main colonizing species seems to be predictable. This predictability is linked to characteristic habitat conditions and the low number of pioneer species. This preference for different habitats is reflected by different germination and early growth, by the structural and physiological characteristics, as well as by the reproductive and morphological adaptations of the three main species. The germination rate was above 90% in all species, and the duration until germination ranged between one day inSalix and 14 days inCecropia. Stem elongation was more than 10 cm per month inSalix andCecropia, and about 50 cm per month inSenna. Wood specific gravity ranged from 0.33 g cm−3 inCecropia to 0.45 g cm−3 inSenna. The annual wood increment increased by 1.20 (Cecropia), 1.23 (Salix) to 2.14 cm per year (Senna). All species produced adventitious roots, lenticels and/or stem hypertrophy. Leaf photosynthesis was between 17 and 20 µmol m−2s−1, and reached a maximum of 30 µmol m−2s−1 inSenna. Flowering and fruiting inSalix occurred throughout the year, whereas inCecropia andSenna they were concentrated in the flooded period.Salix humboldtiana occurs mainly at low sites subjected to long periods of inundation and high sedimentation rates. OnceSalix has formed dense forest stands, sedimentation and water currents are reduced at these sites andCecropia latiloba may take over. This species grows on low to middle elevations in the flooding gradient at sites with lower current and sedimentation rates.Senna reticulata does not tolerate submergence and colonizes habitats that may have strong currents and high sedimentation on higher levels in the flooding gradient.