Study On Effects On Tree Growth And Undergrowth Herb Diversity In Larix Principis-rupprechtii Plantation

Taking Larix principis-rupprechtii plantation with different density (225,525,645,750,855 plant per hm~2) from 35 years old to 39 years old as research object , effects about density to tree growth and under-tree herb species diversity are studied. The change laws are found out. The results showed as follows:(1) The average DBH generally decreased when density increased in Larix principis-rupprechtii plantation with different density in Saihanba Forest Farm.(2) The average Crown generally decreased when density increased in Larix principis-rupprechtii plantation with different density in Saihanba Forest Farm and there was a visible trend. When the age increased, growth competition of the average crown was aggravating gradually.(3) Density of the different age affected the average height invisibly in Larix principis-rupprechtii plantation with different density in Saihanba Forest Farm.(4) When density increased, the cw/d had a gradual decrement trend. This trend showed that the stand with low density could obtain the large nutrient area and had the better growth.(5) The h/d of the different age raised gradually when density increased. This showed that the stem form with the high density stand was better than the low density stand.(6) Taking undergrowth herb as object, S had a significant positive correlation with H and had no simple relation with the others. H had a very significant positive correlation with D and a significant positive correlation with Jsi, but H had no significant positive correlation with Jsw. Jsw had a significant positive correlation with D and a very significant positive correlation with Jsi, but Jsw had no significant positive correlation with the other indexes. D had a very significant positive correlation with Jsi.(7) Among all the impact factors, density had a significant positive correlation with richness and diversity indexes ,but density had no visible effects to evenness indexes.From the research the conclusion was made that different density had the important effects on the tree growth and the undergrowth herb diversity. It is good for forestry department to develop research and take positive actions to make forestry play economic, ecologic and social benefits.