Effect Of Slash Burning On Soil And Two Provenance Seedlings Of The Deforested Land Of Chinese Fir Planatation In Rainy Area Of West China

Slash burning as traditional land-clearing methods, has been widely applied at planting. Slash burning not only burns the harvesting residues and the ground vegetation, but also changes the soil nutrients, which affects tree growth. And then, many researchers focus on the trade-off of slash burning. Therefore, the slash burning experiment was conducted on the deforested land of the28-old-year Chinese fir and Chinese fir plantation to study its short-term effects on soil nutrients, soil carbon pool and the growth of two Chinese fir seedlings from Huitong County and Hongya County. The results as followings:1. Slash burning increased soil pH value significantly; but after9months, pH value of the40-60cm soil layer increased slightly. There are significantly positive correlations between pH value and soil total N, available P, and K. Compared to control, sash burning decreased the bulk density of each soil layer slightly.2. After slash burning, total soil N, P and Ca concentrations were significantly increased. After9months, total soil N, P and Ca concentrations were slightly increased. After slash burning, soil K, Mg increased at first and then decreased; after9months, total K concentration of20-40cm layer increased than that of the control, and the other layers decreased than the control. Mg concentration of0-20cm layer increased significantly, the other layers decreased than those of the control. There’re significant positive correlations between total N, total P and available P, total K, Mg, available K, available N, and available P. But there’re significant negative correlation between total P and Ca. There’re significantly negative correlation between Mg and Ca, and there’re highly significant positive correlation between Mg and available N.3. Beginning of slash burning, soil available N concentration increased slightly. After7months, it increased significantly, and soil available N concentration increased highly significant than the control after9months. There’re significant positive correlations between available N and total N, total P, K, Mg, and available K, and there’re significant negative correlation with Ca.After slash burning, available P concentration was significantly higher than those of control, and there’re significant correlations with pH, total N and available K. Soil available K concentration in the soil of20-40,40-60cm in early slash burning decreased, and then increased. After9months, available K of soil 20-40cm was less than control, but the other two layers were higher than those of control. There are significant correlations between available K and pH, total N, total P, Mg, available N, available p, and total K, and no significant correlation with Ca.4. After slash burning, soil organic carbon (SOC) content significantly decreased.9months after slash burning, the SOC of40-60cm decreased slightly. The soil carbon storage continued to decrease after slash burning. During the study time, there’re significantly positive correlations between the SOC of soil surface and total N, available P, available K, but negative correlations with total P and Mg. There’re significantly negative correlations between the SOC of soil middle and total K, available N.And there’re highly significant negative correlations between the SOC of soil middle and Ca.5. As to seedlings, the biomass of branches, coarse root and fine root have no differences between provenances; the leaves biomass, main stem biomass and total biomass form Huitong were significantly higher that form Hongya; and the biomass allocation of all seedlings showed out leaves> branch> main stem> coarse root> fine root. The seedling height of Huitong were significantly shorter than those of local seedlings; the branch, base diameter, new main stem, leaf area, leaf length, and C/N of leaf decreased slightly than those of the local seedlings; the ratio of root and above-ground biomass, and leaf width increased slightly than those of the local seedlings. For Huitong seedlings, there’re significantly negative correlation between the total biomass and total K, leaf area and available P, leaf N and available N, respectively. There’re significantly positive correlation between the total biomass and SOC, leaf C and available N, respectively. As for Hongya seedlings, only highly significant negative correlation existed between leaf area and total K. Therefore, Hutong seedling was more sensitive to slash burning in short-term.