Soil nutrients and enzyme activities in Larix principis-rupprechtii plantations in the Qinling Mountains,China

Larix principis-rupprechtii was introduced in Shaanxi Province more than 50 years ago, and most of these trees were planted in the Qinling Mountains. In order to study the fertility of soil in different-aged Larix principis-rupprechtii plantations in this area, we chose young, middle, and near-mature-aged Larix principis-rupprechtii plantations in the Nantan Nursery Garden of Taibai and Huoditang of Ning-shan in Shannxi Province as the experimental sites, and established three 20 x 20-m plots in each age stand plantation in 2012. In each plot, soil samples were collected from three depths at five randomly located points. This study indicated that because of the lack of soil available N and available P in this area and the rapid growth of plants, the fertility of plantations in the Qinling Mountains until Larix principis-rupprechtii reaches an age of 20 years. Accordingly, on the basis of the findings, we suggest that fertilizer should be applied to soil until Larix principis-rupprechtii plantations reach 20 years of age in order to avoid nutrient limitation for plant growth.