The Dynamics of the Litter and Soil Organic Matter in Four Densities of Hybrid Larch Plantations

Abstract

The dynamics of the litter and soil organic matter content of four densities (A: 2500/hm2，B:3300/hm2，C:4400/hm2，D:6600/hm2) of hybrid Larch plantations were studied in Jiangshanjiao forest farm of Heilongjiang province of China. (1) The annual litter stock under the hybrid Larch plantation was 4634.6 ~ 5453.4 kg/hm2, and the decreased order of the annual litter stock was under density of 4400, 3300 2500and 6600 trees per hectare. The decrease order of the litter stock no matter undecomposition and decomposition litter was under density of 3300, 4400, 2500 and 6600 trees per hectare, and the rate of the undecomposition litter stock to total litter stock was bigger than 50 %. (2) The seasonal dynamic of the soil organic matter under different densities of plantations basically had the same principle. In 0~10 cm soil layer, the soil organic matter was higher in June and August, was lower in May and July, and was flat or increased slightly in September, but was decreased in September under the plantations with density 4400 and 3300 trees per hectare. The soil organic matter in 10~20 cm and 20~40 cm layer had the same change principle, but the change range was flat and smooth. For the same density of plantation, the difference of the organic matter in the same soil layer between the different months was significantly (P < 0.05). (3) The difference of the soil organic matter content in the same soil layer under different densities of hybrid Larch plantation was significantly, and the decreased order of the soil organic matter in average was under density 4400, 3300, 6600 and 2500 trees per hectare. The results would provide the theories basis for manage the hybrid Larch plantations.