地面覆盖对皮叶两用杜仲(Eucommia ulmoides Oliv.)林冠层辐射能分布的影响

通过在杜仲林地种植白三叶草、覆膜和覆秸秆,研究了地面覆盖对8a生皮叶两用杜仲林冠层光能分布的影响.结果表明:地面种植白三叶草、覆膜、覆秸秆和不覆盖条件下,林冠中部的总辐射分别比林冠表面降低了18.8%、20.0%、17.1%、17 1%;在林冠层,不同地面覆盖的林冠下表面接受的地面反射辐射差异较大,种植白三叶草、覆膜和覆秸秆的林冠下表面接收的反射辐射分别较地面无覆盖的高42.8%、56.4%和8.1%,且林冠中部接受的地面反射辐射明显低于林冠下表面;种植白三叶草、覆膜和覆秸秆的林冠中部的净辐射能分别较地面无覆盖的高14.4%、18.5%和5.6%.不同覆盖处理的冠层净辐射垂直分布趋势基本一致,在冠层范围内,净辐射能随高度升高呈指数规律增大.

Effects of ground coverings on radiant energy distribution in the canopy of Eucommia ulmoides Oliv. coppice forest

Ground white clover (Trifolium repens Linn.) planting (CM), plastic film mulching (FM), and straw mulching (SM) were applied to an 8-year-old eucommia (Eucommia ulmoides Oliv.) forest to study the effects of these ground coverings on light energy distribution within the forest canopy. The forest none ground mulching (NM) was used as a control. Total radiation in the middle part of the forest canopy decreased by 18.8%, 20.0%, 17.1%, and 17.1% for the treatments of CF, FM, SM, and NM respectively compared with those in the upper part of the forest canopy with the same mulching treatments. There were relatively large differences among the amounts of ground-reflected radiation received by the lower part of the forest canopy with different coverings; the ground-reflected radiation received by the lower part of the forest canopy with CM, FM, and SM increased by 42.8%, 56.4%, and 8.1% respectively, compared with the control. The amounts of ground-reflected radiation received by the middle canopy were markedly lower than those received by the lower part of the forest canopy with these coverings. The net radiant energy in the middle forest canopy with CM, FM, and SM increased by 14.4%, 18.5%, and 5.6% respectively, compared with that in the lower part of the forest canopy without any covering. The net radiation distribution in the forest canopy with different coverings appeared to vary identically, and the net radiant energy values appeared to increase exponentially from the lower part to the upper part of the forest canopy. Our results showed that CM as an agricultural practice in orchards was the best ground cover than other two and had high potentials developed for non-timber forests in the Qinling Mountains.