GROWTH-RESPONSES OF TROPICAL SHRUBS TO TREEFALL GAP ENVIRONMENTS
GROWTH-RESPONSES OF TROPICAL SHRUBS TO TREEFALL GAP ENVIRONMENTS
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DOI：
10.2307/1940257
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发表时间：
1990-02-01
期刊：
影响因子：
4.8
通讯作者：
STRAIN, BR
中科院分区：
文献类型：
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作者：
DENSLOW, JS;SCHULTZ, JC;STRAIN, BR
为了研究光照和养分供应差异对生长的影响，我们种植了两个属的7种灌木，Miconia（Mecuataceae）和Piper（Pancreaceae），到中心，边缘，和相邻的森林林下4个天然树落间隙（275-335平方米）在热带，前山地雨林的哥斯达黎加。我们一方面使用典型的森林林下环境物种的生根插条，另一方面使用大的空地或干扰区域。我们还比较了三种Miconia种生长在阴凉处的房子下，2，20和40%的全日照的增长率。这些大小的新形成的差距，光和养分的有效性强烈缓冲的冠层和根系周围的森林。林隙中心的总入射辐射（9-23%全日照）高于林隙边缘（3-11%）或完整林冠下（0.4-2%），但在不同地点的相似微生境中存在差异。所有野外生长植物的相对茎生长率（RGR）在林隙中心显着大于边缘或森林下层植物下方。施肥没有显着影响生长速度在任何光环境。光似乎是最关键的资源限制增长在这些差距的大小。在一般情况下，耐荫的物种比光需求的物种塑料少，但在这些差距的大小增长一样快或更快的差距中心。在遮荫室中，耐荫种在20%全光照下生长最快，需光种在40%全光照下生长最快。我们发现没有证据表明这些物种的生长和叶酚浓度之间的权衡。
To investigate the effects of differences in light and nutrient availability on growth, we planted seven species of shrubs in two genera, Miconia (Melastomataceae) and Piper (Piperaceae), into the centers, edges, and adjacent forest understory of four natural treefall gaps (275-335 m2) in the tropical, premontane rain forest of Costa Rica. We used rooted cuttings of species typical of forest understory environments on the one hand and large clearings or disturbed areas on the other. We also compared growth rates of three Miconia species grown in shade houses under 2, 20, and 40% full sunlight. Both light and nutrient availiability in newly formed gaps of these sizes were strongly buffered by the canopy and root systems of the surrounding forest. Total incident radiation was higher in gap centers (9-23% full sunlight) than in gap-forest edges (3-11%) or under intact forest canopy (0.4-2%), but varied among similar microhabitats from different sites. Relative stem growth rates (RGRs) of all field-grown plants were significantly greater in gap centers than at edges or beneath forest understories. Fertilization did not significantly affect growth rate in any light environment. Light appears to be the most critical resource limiting growth at these gap sizes. In general, shade-tolerant species were less plastic than light-demanding species, but at these gap sizes grew as fast or faster in the gap centers. In shade-houses, the shade-tolerant species grew fastest at 20% full sunlight and light-demanding species grew fastest at 40% full sunlight. We found no evidence of a trade-off between growth and foliar phenolic concentration in these species.