Abstract: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.