Structural comparison of tropical montane rain forests along latitudinal and altitudinal gradients in south and east Asia
Structural comparison of tropical montane rain forests along latitudinal and altitudinal gradients in south and east Asia
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DOI：
10.1007/bf00033897
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发表时间：
1991-12
期刊：
影响因子：
--
通讯作者：
Masahiko Ohsawa
中科院分区：
文献类型：
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作者：
Masahiko Ohsawa
研究了南亚和东亚热带山地雨林沿纬度梯度的地理格局、区系组成和结构特征。在赤道山区，热带山地雨林生长在海拔1000米以上。在中纬度，它们进一步下降，在北纬35°到达海平面，因此，森林相当于纬向、水平带系列的亚热带雨林。它们的区系组成和结构在海拔和纬度梯度上均呈逐渐变化。在赤道山区，它们分为三种类型，即热带低山地、高山地和亚高山森林。在低山林中，涌现型、散在型和倒j型三种树木更新类型共存，而在高山林和亚高山林中，只有倒j型树种和少量散在型树种。靠近北纬极限，赤道山区的三个热带山地森林带的区别变得不那么明显。这可以用温度条件来解释：在赤道山区，温度之和为85°C，控制了低山地森林的上限，最冷的月平均温度为-1°C，控制了常绿阔叶树，分别出现在摄氏2500米和摄氏4000米。海拔2500 ~ 3800 m是森林的上限，被高山和亚高山森林覆盖。另一方面，在纬向北缘，由于上述两种温度条件几乎出现在同一点，热带高山和亚高山森林无法存在。因此，在热带山地森林的北纬极限，赤道山脉的三个带合并成一个单一的亚热带低地森林群落。这是由于日本中部和中国中部等中纬度地区的季节性温度气候造成的。
Geographical patterns of altitudinal zonation, floristic composition, and structural features of tropical montane rain forests were examined along latitudinal gradients in south and east Asia. On equatorial mountains, the tropical montane rain forests occur above 1000 m. Toward middle latitudes, they come farther down and reach sea level at c. 35° N. Thus, the forests are equivalent to the subtropical rain forests of the latitudinal, horizontal zonation series. They exhibit gradual changes in floristic composition and structure along both altitudinal and latitudinal gradients. On equatorial mountains, they are divided into three types, i.e. tropical lower montane, upper montane, and subalpine forests. The three tree regeneration types, having emergent, sporadic and inverse-J type stem-diameter class frequency distributions, coexist in the lower montane forests, but the upper and subalpine forests display only the inverse-J type species with a few species of the sporadic type. Toward the northern latitudinal limit, the distinction between the three tropical montane forest zones in equatorial mountains becomes less clear. This can be explained by temperature conditions: on equatorial mountains, a temperature sum of 85° C months which controls the upper limit of the lower montane forests, and a coldest month mean temperature of-1° C which controls the evergreen broad-leaved trees, appear at c. 2500 and c. 4000 m respectively. The altitudinal range between 2500 m and 3800 m, which is the upper forest limit, is covered by upper montane and subalpine forests. On the other hand, at the latitudinal northern limit, the tropical upper montane and subalpine forests cannot exist because the above mentioned two temperature conditions occur at nearly the same point. Thus, at the northern latitudinal limit of the tropical montane forests, the three zones of equatorial mountains amalgamate into a single subtropical lowland forest community. This is due to the seasonal temperature climate in middle latitudes in, e.g., central Japan and central China.