Studies On The Comprehensive Managing Technology Of Aerially Seeded Pinus Massoniana Stands In Hunan Province

Afforestation by aerial seeding started earlier in Hunan province. It had gone through 30 years from testing in 1964 to the end in 1993 and two stages that one is testing and spreading stage, the other is regaining and developing stage. It concerned to 14 districts, 94 counties and 540 seeding sections. Presently, these aerially seeded Pinus massoniana stands are distributed over different sites, live on the different growing stages and have different stands densities. Meantime, considering of different managing situations, stands structures, etc., we selected the 176 plots in Xiangxiang, Anhua, Liling, Ningyuan, Zixing, Xinshao, Pingjiang, and Yuanling. By the means of locational studying and random sampling, we studied the growth regulation, biomass, productivity, nutrient cycle and the reasonable management density of aerially seeded Pinus massoniana followingly.On the basis of 176 standard plots data, making the site index as the establishing model unit, selecting the best one from many models, we imitated and analyzed the growing process of DBH, height and volume in Pinus massoniana stands. It was very imporant for guiding intensive management and effective production.Through the classifying and combining of site condition, forest age and density, single-tree biomass, forest biomass and productivity of aerially seeded Pinus massoniana had been studied in this paper. The results were as follows:For every combination type, the biomass of single-tree or stands all showed the regularity of trunk > root > branch > bark > leaf; there existed a positive relationship between the different organ biomass of single-tree or stands biomass and age, site index and stand density; when the site index and forest age were given, the biomass of the single-tree was reduced and stands biomass was increased with the increasing of the stand density; in different site indexes and stand densities, the net productivity had extraordinary difference for different ages so that the bigest is 19.4 times as much as that of the lowest, excessing 5.52 t/hm2.a; the net productivity of stands and its every combination increased with the increasing the stand density and ages to some extent, then reduced when the stands becoming older.Nutrient cycle in three types of standing density of aerially seeded Pinus massoniana of were also studied in this paper.The results showed that nutrient contents were highest in leaves and lowest in stem.The contents of N, K, Ca were higher than P, Mg in macro-elements. Accordingly, the contents of Mn was highest and Cu was lowest in micro-elements .Nutrient accumulation of individual tree decreased with the increase of the standing density.and low density forests' accumulation was 2.75, 4.04 times as much as medium density and high density respectively.In different density plantations,the amount of nutrient accumulation was in sequence of N>K, Ca>Mg>P>Mn>Fe>Zn>Cu.With the density increasing, nutrient accumulation quantities of arbor layer would increase, so opposite is the ground layer. Annual net accumulation also increased with the increase of the standing density. In various elements.annual net accumulation of N was the highest and the lowest in Cu.Every element's absorption and preservation would increase when the stand density added, however, the cycling velocity of nutrient elements would step down. The cycling velocity of macro-element was faster than micro-element.In view of existing situations of aerially seeded Pinus massoniana in Hunan province, the reasonable management density had been studied in this paper. Two different study methods wereadopted respectively. One was according to the relationship of DBH and crown area, the other was dynamic programme based on the double effect density model. The results would provide a scientific basis for its rational tending thinning and scientific managing.Based on effectively integrating expert system, simulation technique and modern stand management technique, the comprehensive managing expert simulation system of aerially seeded Pinus massoniana in Hu...