Study On The Characteristics Of Stand Structure And Productivity In Larix Gmelinii Natural Forest

On the basis of investigated sample plots of forest ecosystem research station at Daxingan mountains, This study analyzed influences of Larix gmelinii forest structure on stand regeneration, tree competition, stand growing and productivity of biomass, expounded the characteristic of spatial productivity in Larix gmelinii natural forest. The characteristics of Larix gmelinii classifies stems growth and stand gap structure were disclosed.1.①herbage—Larix forest, the age is within 40~50a, and the density is 983~3263 trees/hm~2,when the stand density is 2359 trees/hm~2,the density of stand regeneration and volume are highest. The proportion of classified stem—ⅣandⅤis highest, and each of them is 53.3%,23.3%;②the age is within 51~60a and the density is within 315~2792 trees/hm~2,when the stand density is 2045 trees/hm~2,the proportion of classified stem—Ⅴis highest and the value is 37.3%. The total, average and current annual increment of breast diameter of stand average stem are best. The stand volume, total biomass and the tree productivity are highest;③Ledum—Larix forest, the age is within 51~60a and the density is 865~2241 trees/hm~2, the density of stand regeneration, volume, total biomass and the tree productivity are highest when the stand density is 1691 trees/hm~2;④the density of regeneration gradually became higher along with the increment of dead and the decay level of trees.2.①herbage—Larix forest and Ledum—Larix forest, the age is within 40~60a, the stand volume and total biomass have increased tendency along with the increment of Larix proportion in stand composition when their site conditions and density are close;②competition of 51~60a herbage—Larix forest is stronger than the 40~50a age forest under the same density ;③there is a stronger competition in herbage—Larix forest than in Ledum—Larix forest when the age is within 51~60a.3.①In the community distribution pattern of 40~60a herbage—Larix forest and 51~60a Ledum—Larix forest, proportions of even distribution, random distribution and clustered distribution are 6.3%, 50%, 43.8% respectively;②A ccording to the forest type to classify, both of clustered and regular distribution are 11% in the commurity distribution pattern of herbage—Larix forest, the random distribution is 78%.ledum—Larix forest is regular distribution;③The cluster distribution is mainly concentred within the composition of 7 Larix and betula—9 larix and 1betula.4.①The classified stems of Larix gmelinii has transformed phenomenon in different age stages, and the transformation rate is 31.5%, the transformation rate of average stem is highest, and accounts for 47.1%;the transformation rate of dominating stems accounts for 35.3%;the transformation rate of overtopped stems is lowest, and accounts for 17.6%. For the over—topped stem, the non—transformation rate accounts for 83.3%;②For the classified stems, the transformation rate of dominating stem—average stem, average...