| This paper takes Hebei province Luan of the first month of forest and natural secondary forest of Betula platyphylla Heilongshan forest as the research object, through the analysis of stem analysis method under different site conditions of birch natural secondary forest growth differences, including the growth of diameter, tree height growth and stem volume growth regularity. And using the diameter number distribution, Weibull distribution function and fitting inspection method, analysis of different regions of birch natural secondary forest diameter structure differences. Through the use of mixed degree and angle scale spatial structure parameter, analysis of different regions of Betula platyphylla secondary forest tree species isolation degree, horizontal distribution characteristics. And the black dragon hill forest birch in young and middle aged forest harvesting and forest stand growth and structure were analyzed, mainly including: the average diameter of stand diameter structure, accumulation, spatial structure, etc.. As the area of natural birch forest operation to provide a theoretical basis and technical support. This study mainly draws the following conclusions:(1) under different site conditions of birch growth differences exist in the natural secondary forest, Betula platyphylla forest in Luan of the first month average diameter growth rate is rapidder,15A reaches a peak, the current annual increment to about 10A reached a peak, then decreases, and the black dragon hill forest birch diameter average growth rate is slower, the current annual increment about 20A reached its peak; tree height growth in Luan of the first month of forest growth is rapidder, tree height growth and average annual growth volume of around 10A appeared a peak in the black dragon mountain forest, tree height growth and current annual increment in 10A also appeared a peak; volume growth in the two regions have not reached the maximum value, description of birch arrived without a quantitative maturity stage.(2) birch sapling forest diameter structures in Luan of the first month forest and black dragon mountain showed" J" type distribution, and fit the lognormal distribution, the result is good. The two differ, Luan of the first month forest farm forest more class, while the black dragon hill forest birch sapling forest maximum diameter is 9, and the tree numbers less. Forest diameter structures in two areas are Shuangfeng mountain shape curve, but Luan of the first month forest birch diameter structure fitting effect is poor, were not consistent with the existing model of distribution. As the dragon mountain forest birch diameter structure fitting with logarithm normal distribution.(3) birch sapling forest level distribution structure in two regions showed aggregated distribution, the average angle of large scale. Black dragon hill forest birch sapling forest aggregation degree than Luan of the first month forest birch sapling forest aggregation degree is bigger. Birch forest, in two regions were mixed with other tree species, but the main tree species are still birch, similarly, forest were aggregated distribution, must carry out effective measures for horizontal adjustment of spatial structure. Luan of the first month in the birch forest mixed forest is less, only two species. In the black dragon hill forest, Betula platyphylla forest mixed with five kinds of other species, the average mixed degree is 0.47, is conducive to the stability and growth of forest stand.(4) the black dragon mountain forest birch natural secondary forest harvesting three years later, in diameter, young forest structure by a " J" type distribution gradient as a single peak mountain shape distribution. And the young middle aged forest in different retaining structures are also different density diameter. Young forest control standard diameter no prescribed distribution structure, except for the control of extraterrestrial, four reserve density, greater density of stand diameter structure, presents one peak mountain shape distribution, close to the normal distribution, and less dense stand diameter structure exhibits a peak mountain form the peak of right distribution; forest land diameter control distribution exhibits a" J" open distribution, the other four reserve density, greater density of stand diameter structure showed a single peak mountain shape distribution, density smaller exhibits a peak mountain form the left distribution. Effects of cutting on forest spatial structure, whether young forest or forest, with the increase of density angle scale value is greater, the greater the stand together.(5) the birch in young forest reserve density spatial distribution of different level with the increase of density angle scale increasing, young forest density maximum standard for control standard HY-3, followed by HY-1, HY-2, HY-4, HY-5, the average angular scales are respectively 0.565,0.554,0.532,0.521 and0.512; forest maximum density standard for control standard HZ-3, followed by HZ-5, HZ-4, HZ-2and HZ-1, the average angular scales are respectively 0.573,0.549,0.543,0.521 and0.516.(6) harvesting on young forest growth effect is more obvious, harvested after 3 years, the average diameter of stand growth has increased markedly, but increase with the increase of density decreased gradually. In 3years, stand volume change volume density increases, but the cutting than no logging variation; middle aged forest harvesting after 3 years, the average diameter than the standard stand unused forest in. Stand the total volume is contrary, logging3 years after the stand volume less than did the logging of forest stands, the main reason is the cutting intensity is larger, not cutting in forest trees more, total volume corresponding to a larger. |
