Comparative study of additive basal area of conifers in forest ecosystems along elevational gradients
Comparative study of additive basal area of conifers in forest ecosystems along elevational gradients
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DOI：
10.1007/s11284-007-0338-3
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发表时间：
2007-05-01
影响因子：
2
通讯作者：
Kitayama, Kanehiro
中科院分区：
文献类型：
--
作者：
Aiba, Shin-ichiro;Hanya, Goro;Kitayama, Kanehiro
我们在日本屋久岛沿海拔梯度和婆罗洲基纳巴卢山的两个系列地质基底上研究了两种生命形式（针叶树和阔叶树）的基底面积。屋久岛总林分基面积从700 m急剧增加到1050 m，与针叶林的高优势度一致，表明在高海拔（1050 ~ 1300 m）针叶林阔叶混交林中存在针叶林加性基面积。在京那巴鲁的两个底物序列上，高海拔（1860 ~ 3080 m）的部分森林表现出较高的针叶林优势，但针叶林基面积不表现出加性。屋久岛混交林的阔叶树冠层上出现针叶树，而京那巴鲁混交林的单层冠层上通常有两种生命形式共存。作为生产力替代物的凋落物率在两个样地都随温度沿海拔的降低而降低，但屋久岛的下降速度较慢，高海拔混交林的凋落物率相对较高。因此，我们认为针叶树的附加基底面积与它们的涌现状态有关，并且它通过占据不同故事的两种生命形式对光的互补利用来提高生产力。在屋久岛，台风是一个主要的干扰，但并没有严重限制针叶树的高度生长，允许两层混交林的发展。在Kinabalu，厄尔尼诺导致的干旱是主要的干扰因素，对树高的水力限制可能解释了针叶树的非加性和非涌现性。
We examined the basal area of two life forms (conifers vs. broadleaf trees) along elevational gradients on Yakushima Island, Japan and on two series of geological substrate on Mount Kinabalu, Borneo. On Yakushima, total stand basal area abruptly increased from 700 to 1,050 m in accordance with the high dominance of conifers, indicating the presence of additive basal area of conifers in conifer-broadleaf mixed forests at higher elevations (1,050-1,300 m). Along two substrate series on Kinabalu, some forests at higher elevations (1,860-3,080 m) showed relatively high dominance of conifers, but conifer basal area did not appear to be additive. Conifers were emergents above the canopy of broadleaf trees in mixed forests on Yakushima, but two life forms usually coexisted in the single-story canopy in mixed forests on Kinabalu. Litterfall rate as a surrogate of productivity decreased with decreasing temperature along elevation on both the sites, but the rate of decrease was slower on Yakushima, where mixed forests at higher elevations showed relatively high rates. Thus, we suggest that additive basal area of conifers was linked to their emergent status, and that it enhanced productivity by complementary use of light by two life forms that occupy different stories. On Yakushima, typhoons are a major disturbance, but do not severely limit the height growth of conifers, allowing the development of two-story mixed forests. On Kinabalu, a major disturbance is El Nino-driven drought, and hydraulic limitation to tree height may explain the non-additive and non-emergent nature of conifers.