Abstract:

Clearcutting with varied width was carried out in a secondary growth mixed broadleaved forest and a low-quality birch coppice forest in the Daxing’an Mountains in 2009. Each cutting strip was divided into three sections. Pinus sibirica, Larix gmelinii and Pinus sylvestris var.mongolica were planted in each section, respectively. Soil physical and chemical properties were then analyzed in August, 2011. Results showed that soil density reduced while soil capillary water holding capacity and capillary porosity increased after clearcutting. Compared to the control site, soil total nitrogen increased in the whole experimental site in the mixed broadleaved forest(98.26%, 72.70%, and 44.91% increase in the larch forest, Siberian Korean pine forest and Mongolica pine forest, respectively). Soil total phosphorus decreased for both Siberian Korean pine and the Mongolica pine forests while it remains contant of 3.35 g·kg^-1 in Larch forest. In comparison with the control site, both soil total nitrogen and total phosphorus decreased to a various degree. The soil total phosphorus decreased 38.90%, 33.15%, and 11.78% for Siberian Korean pine forest, Larch forest, and Mongolica pine forest, respectively. The soil total nitrogen decreased 36.02%, 36.75%, and 37.68% for Siberian Korean pine forest, Larch forest, and Mongolica pine forest, respectively. Generally, there was a significant positve correlation( P ﹤0.05) between the soil organic matter content and soil total nitrogen and total potassium. The soil pH value, organic matter content, total nitrogen and total potassium content had the largest variation coefficient in Siberian Korean pine forest over different cutting widths, which suggested that cutting width had significant effects on soil physical and chemical properties of the induced Siberian Korean pine forest.

Key words: low-quality forest, induced transformation, soil physical and chemical properties, Daxing'an Mountains