Abstract:
With Larix principis-rupprechtii as research subject, we studied the influence of stand ages, site conditions, initial densities, stand reserved densities and land preparation methods on the stock volume of L. principis-rupprechtii by survey of individual tree. Then we analyzed the productivity of L. principis-rupprechtii in Saihanba of Hebei Province and comprehensively compared the productivities of L. principis-rupprechtii in Hebei, Inner Mongolia, Shanxi, Shaanxi, and Ningxia provinces in northern and northwestern China. The results were as follows: 1) stock volume of L. principis-rupprechtii increased first and then decreased with the increase of stand age, and the stock volume of 39-year-old forest was the maximum with 193.5 m3/hm2. 2) L. principis-rupprechtii stock volumes in 3 site conditions ranked in Mann (98.55-288.90 m3/hm2) rich ubac (59.10-263.10 m3/hm2) thin adret (45.60-176.10 m3/hm2). 3) Stock volume with the initial density of 4 995 plants per hectare (53.94 m3/hm2) was significantly higher than that with 3 330 plants per hectare (24.89 m3/hm2). 4) Stock volume increased with increasing stand reserved density, that was as 975 plants per hectare (98.68 m3/hm2) 1 500 plants per hectare (122.37 m3/hm2) 1 950 plants per hectare (128.51 m3/hm2) 2 475 plants per hectare (137.57 m3/hm2) 3 150 plants per hectare (138.02 m3/hm2).5) Stock volumes with both mechanical (150.70 m3/hm2) and artificial land preparation (150.68 m3/hm2) were not significantly different(P 0.01), i.e., mechanical was slightly higher than the artificial land preparation. 6) With the age increasing, the productivity of L. principis-rupprechtii in Saihanba was described as a single peak curve, the maximum for 26-30 years stands with 5.72 m3/(hm2·a), the minimum for 11-15 years stands with 3.22 m3/(hm2·a), and over 45 years stands with 3.92 m3/(hm2·a). 7) Regarding different regions, the productivities of L. principis-rupprechtii in Shanxi (6.78-16.57 m3/(hm2·a)), Hebei (6.13-9.74 m3/(hm2·a))and Inner Mongolia (5.20-9.90 m3/(hm2·a)) were remarkably more than that in Shaanxi (2.41-4.59 m3/(hm2·a)) and Ningxia(1.83-3.92 m3/(hm2·a)). This study identifies the response of stock volume to main factors and presents the productivity overview of L. principis-rupprechtii in Saihanba and differences of L. principis-rupprechtii productivity in different regions of northern and northwestern China, and provides effective references for the management of L. principis-rupprechtii forests.