THE LIGHT ENVIRONMENT AND GROWTH OF C-3 AND C-4 TREE SPECIES IN THE UNDERSTORY OF A HAWAIIAN FOREST
THE LIGHT ENVIRONMENT AND GROWTH OF C-3 AND C-4 TREE SPECIES IN THE UNDERSTORY OF A HAWAIIAN FOREST
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DOI：
10.1007/bf00384537
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发表时间：
1983-01-01
期刊：
影响因子：
2.7
通讯作者：
PEARCY, RW
中科院分区：
文献类型：
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作者：
PEARCY, RW
利用连接便携式数据采集系统和条图记录仪的光合光子通量密度传感器，以及树冠的半球形鱼眼照片，对夏威夷一种C4树种大戟（Euphorbia forbesii）林下的光环境进行了表征。1980年7月，86亩。在林下吸收了Mol cm-2 day-1，其中。apprx。40%是晒斑造成的。林下吸收了到达冠层顶部的光的2.4%。几乎所有太阳斑的峰值光子通量密度都大于250 .mu。Mol m-2 s-1，但2/3 < 0.5 min。在任何地点每天接收到的日晒分钟数是高度可变的，取决于云量和上层树冠结构。在一个相对晴朗的日子里，在不同的样本地点观察到晒斑的分钟数相差10倍。从半球状照片中获得的估计值被用来计算大戟属和一种C3树种cloxylon sandwich的树苗每天接受太阳晒斑的年平均潜在分钟数。两种树苗的生长都与太阳晒斑的分钟数高度相关，而且两种树苗的生长都很相似。虽然C4光合作用通常存在于高光环境下的原生植物中，但在森林林下低光条件下，它显然不会给紫杉的生长带来任何不利影响。
The light environment in the understory of a Hawaiian forest containing a C4 tree species, Euphorbia forbesii, was characterized using photosynthetic photon flux density sensors connected to portable data acquisition systems and a strip chart recorder, and hemispherical fisheye photographs of the canopy. During July 1980, 86 .mu.mol cm-2 day-1 was received in the understory of which .apprx. 40% was contributed by sunflecks. The understory received 2.4% of the light reaching the top of the canopy. Nearly all sunflecks had peak photon flux densities greater than 250 .mu.mol m-2 s-1, but 2/3 < 0.5 min in length. The number of minutes of sunflecks received per day at any site was highly variable, depending on cloudiness and the overstory canopy structure. On a relatively clear day a 10-fold difference in the number of minutes of sunflecks was observed between sample sites. Estimates obtained from hemispherical photographs were used to calculate the annual mean potential number of minutes of sunflecks per day received by saplings of Euphorbia and a C3 tree species, Claoxylon sandwicense. The growth of saplings of both species was highly correlated with the estimates of the minutes of sunflecks and was similar for both species. Although C4 photosynthesis is usually found in plants native to high-light environments, it apparently does not confer any disadvantage in terms of growth to E. forbesii in the low-light conditions of the forest understory.