Effects of undisturbed canopy structure on population structure and species coexistence in an old-growth subalpine forest in central Japan
Effects of undisturbed canopy structure on population structure and species coexistence in an old-growth subalpine forest in central Japan
复制标题
DOI：
10.1016/j.foreco.2004.06.036
复制
发表时间：
2004-10
影响因子：
3.7
通讯作者：
A. Mori;H. Takeda
中科院分区：
文献类型：
--
作者：
A. Mori;H. Takeda
我们调查了日本中部的古老亚高山森林的结构和组成特征，以确定森林动态和物种共存。森林似乎已经相当不受干扰，至少在最近几十年来，从最大占用空间的生活冠层树木和不变的冠层结构之间的死亡前和死亡后的阶段。这种稳定的森林表现出最小规模的动态，主要发生在一个单一的树规模。在该森林中，优势种为冷杉、冷杉和冷杉。veitchii和云杉Picea jezoensis var. hondoensis。这两种冷杉属植物的数量丰富，更新速度快，这与其耐荫性有关。另一方面，云杉表现出最大的断面积，尽管其密度较低。云杉表现出较陡的初始高径异速生长斜率，这表明其林下幼树可以增加高度更快地在阳光条件下。云杉再生，给予较大的干扰的机会，大约同龄的同伙，然后逃脱竞争，从其他耐阴的物种达到树冠的最高部分，导致树苗的高度快速增长，寿命更长，紧急可达到的高度。然而，在这片森林的未受干扰的树冠下，尽管有许多幼苗，但云杉完全缺乏更新个体，这表明它的更新处于相当有限的阶段。这表明，在未受干扰的森林，云杉的人口特征，其中其冠层树木的死亡率较低，可以弥补其较低的招聘，是不足以解释其与耐荫冷杉种稳定共存。因此，不仅人口特征，而且空间/时间的干扰幅度是很重要的云杉与冷杉共存的解释。因此，它似乎不仅平衡过程，如物种的生活史特征的差异，但也非平衡过程，如干扰，是至关重要的，他们在这亚高山森林在日本中部的共存。
We investigated structural and compositional characteristics of an old-growth subalpine forest in central Japan, to ascertain forest dynamics and species coexistence. The forest appeared to have been fairly-undisturbed, at least during several recent decades, judging from the maximum occupancy of space by living canopy trees and an unchanged canopy structure between pre- and post-mortality phase. This stable forest showed minimum-scale dynamics that occurred primarily at a single-tree scale. Within this forest, the dominant species were Abies mariesii, A. veitchii and Picea jezoensis var. hondoensis. The two Abies species were abundant and showed advance regeneration, resulting from their high shade-tolerance. On the other hand, Picea showed the greatest basal area, in spite of its lower density. Picea showed steeper initial height-diameter allometric slopes, suggesting that its understorey saplings could increase height more rapidly under sunny conditions. Picea regenerates, given the opportunity of larger disturbances, as approximately even-aged cohorts, and then escapes competition from other shade-tolerant species by attaining the uppermost part of the canopy, resulting from rapid height growth of sapling, longer longevity and emergent attainable height. However, beneath the undisturbed canopy of this forest, in spite of its many seedlings, Picea entirely lacked regenerating individuals, suggesting that its regeneration is in a fairly-limited stage. This suggests that within the undisturbed forest, a demographic trait of Picea, in which the lower mortality of its canopy trees can compensate for its lower recruitment, is not enough to explain its stable coexistence with shade-tolerant Abies spp. Thus, not only the demographic trait, but also the spatial/temporal disturbance magnitude is important for an explanation of the coexistence of Picea with Abies. Consequently, it seems that not only equilibrium process, such as species differences in life-history traits, but also non-equilibrium process, such as disturbances, is crucial for their coexistence in this subalpine forest in central Japan.