Improvement and Compilation of Density Management Diagram of Larix principis-rupprechtii Mayr Forest in Northern Hebei

Stand density management diagram is an average stand model that indicates forest growth at different stages, providing a scientific basis for the mastery of stand density, the prediction of forest growth, the control of water conservation and the measurement of carbon storage. Larch forests in northern China, that is faced with such environmental problems as sand storm and smog, serve the functions of wind break and sand fixation as well as water conservation. This paper makes some improvement to the density management diagram by adding a crown width line to obtain appropriate stand density. In this research: 1. A stand density management diagram is constructed to show growth information in Saihanba Forestry, Hebei province, into which contour lines of constant tree height, degree of closeness, natural thinning, diameter at breast height and crown width are included. 2. The planting density should be set at 3,000 plants.hm^-2 and 300 m³ timbers are expected to be obtained from harvest cuttings. Two harvest cuttings should be arranged between 16 and 29 years, with cutting intensities of 28.4% and 36.4%, respectively. The density management diagram is to be constructed to predict the growth of Larch forests in northern China, so as to provide reference for the making of forest management plans and the reasonable arrangement of stand density.