Effects of stand age on soil enzyme activity and chemical properties of Pinus tabulaeformis plantation in Horqin sandy land

To study the change process of soil nutrients and enzyme activities in different forest ages of Pinus tabulaeformis in Horqin sandy land, so as to provide a reference for vegetation restoration in this area.

Taking the shifting sandy land as the control (0 a), the sand-fixing 18, 34, 48, 56 a Chinese pine plantation land was selected as the research objects, and the soil samples were collected in layers for the determination of soil chemical properties and enzyme activities. The redundancy analysis method was used to explore the change process of soil enzyme activity at different forest ages and its relationship with soil physical and chemical properties.

Compared with the control, the contents of organic matter, total nitrogen, total phosphorus and available potassium increased significantly with the increase of stand age, but total potassium and available nitrogen had no obvious changes. The activities of catalase, dehydrogenase, urease, neutral phosphatase and neutral protease in the 0-2 cm soil layer under different forest ages were significantly higher than that of the control with obvious superficial polymerization, sucrase activity was the highest at 18 a and then decreased. Stand age, soil layer and their interaction significantly affected soil enzyme activity. Redundancy analysis showed that soil total nitrogen, total potassium, available phosphorus, available potassium and soil urease, dehydrogenase, and catalase all had extremely significant positive correlations. The accumulation of 7 chemical properties in the first two axes explained 76.06% of soil enzyme activity, and the order of importance to soil enzyme activity was total nitrogen, available phosphorus, total potassium, organic matter, total phosphorus, available potassium, and available nitrogen. Total nitrogen is the key factor affecting the difference of soil enzyme activity.

The Chinese pine plantation can effectively improve the sandy soil fertility and soil enzyme activity, and the improvement effect will increase with the increase of the forest age.