Abstract:

The dead branches and leaves can hang on living trees for as long as ten years or so in Chinese fir plantation.The biomass of dead branches and leaves on living trees is 4108.0 kg·hm^-2 in a first rotation stand of Chinese fir plantation with 14 site index and 13 years old, located in Dagang mountain area, Fenyi of Jiangxi. It is equal to 35.4% of the litter biomass of the stand.Determinations show the decay rates of dead branches and leaves taken from the canopy to the floor in the litter environment are far fast to the decay rates in the canopy.Therefore it is important for improving nutrient supply during the quick-growing phase and pole phase of Chinese fir plantation to take dead branches and leaves from the canopy to the floor to let them decay in the litter environment. There are four layers of dead branches and leaves distributing from 3.5 m to 8.0 m above the floor in the canopy. Because the dead time, the decay duration and suffered leaching intensity of one layer are different from another,so the decay rate of every layer in the canopy environment was determined separately.There are relatively distinct differences between decay rates of upper layers and decay rates of lower layers in the canopy environment. The decay rate of every layer in litter environment was determined also separately. There are a little differences between decay rates of upper layers and decay rates of lower layers in the litter environment.The decay mass of dead branches and leaves taken from the canopy to the floor in the litter environment is 2.3 times as much as that in the canopy.The total mass of nutrient return from the decaied branches and leaves in the litter environment is 3.5 times as much as that in the canopy.So taking dead branches and leaves on living trees from the canopy to the floor in good time during the quick growing phase and pole phase is one of effective measures to keep the productivity of Chinese fir plantation for long time.

Key words: Chinese fir plantation, Dead branch and leaves on living trees, Decay, Litter environment, Canopy environment