Research On Growth Characteristics Of Mongolian Pine On Different Sites In Yulin Sandland Area

Mongolian pine is the main afforestation species in arid and semiarid area in North China. Growth characteristics of the tree directly affect its effect on wind breaking and sand stabilization and also on the improvement of local environment. To systematically study the growth characteristics of Mongolian pine on different sites in sandy area and also to provide evidence for the management of Mongolian pine in Yulin Sandland Area, the author investigated the growth characteristics of Mongolian pine on different sites in Yulin Sandland Area. There are five sites include: lower land between dunes, flat sandy land, lower part of the dune, middle part of the dune and upper part of the dune. Main results as follows:1. The height, diameter, crown width and volume of the pines which grow on different sites were different. The greatest value appeared in lower part of the dune in which the mean annual increament and the peak value in the fast growing period were also the greatest. On the contrast, the values on upper part of the dune were the smallest. The values of flat sandy land, lower part of the dune and middle part of the dune were in between.2. The growth progress of height, diameter, crown width and volume of Mongolian pine on different sites could all be described by Logistic Model y = k/(1 +eα?γt) (y is height, diameter, crown width or volume, t is age, k ,α,λare parameters). The fitting precisions were all over 0.90.3. The start and ending time of the fast growing period of height, diameter, crown width and volume for pines on different sites could all be described by the third derivative of Logistic Model: d 3 y/ dt3= kγ3eα?γt (e2lnα?2γt?4eα?γt+1)(1+eα?γ)?4. The results showed that the pine on lower part of the dune begined its fast growing period first and the duration was the longest; the pine on upper part of the tune was on the contrast. The pines on flat sandy land, lower part of the dune and middle part of the dune were in between.4. The relationship between height and diameter of Mongolian pine on the five sites were described by the model of h = adb (a, b are parameters). The parameters were different according to the change of the sites. The fitting precisions were all over 0.99. The relationship of the diameter and the crown width was described by the model of c = 0.6103 + 0.17979d(c is crown width) and the fitting precision was over 0.95. The relationship of the height and the crown width could be described by the model of c = 0.3405 + 0.2955h and the fitting precision was over 0.95.