Study On The Effect Of Needle Damage On Growth Of Spruce In The West Of Sichuan

As one of the important forest tree species in Sichuan, spruce has significant economic, ecological and social values for Sichuan Province. Spruce needle cast phenomenon was first discovered in the 1990s in Aba, various areas during this period to take different levels of prevention and control measures and harvest a certain effect. But in recent years, Sichuan province spruce coniferous forest appears yellow, broken needle drop phenomenon again. Its occurrence was expanded to include the whole of Western Sichuan spruce distribution area, showing a large-scale, centralized outbreak trend, make trees blocked the growth, economic and ecological benefits of severely damaged.. In 2014-2015, on the 4 trip to Mianyang, Ganzi, Aba and Ya'an 10 Sichuan spruce main distribution area. Through field investigation and stem analysis and so on spruce fall needle damage investigation, aims to analyze the fall needle diseases on spruce growth effect and the growth loss situation of quantitative analysis, estimation of the province's loss. The main contents include Sichuan spruce needle harm the overall situation occurs, spruce growth and harm the relationship between the needle, the needle on the damage estimate, hazard loss estimation model and so on. The results are as follows:1. The overall situation of the needle drop is very serious in the west of SichuanAccording to the survey results of 10 surveys,20 standards and 1171 strains of spruce in Sichuan, Spruce falls the harm mainly occurs in the West Sichuan high mountain, the sub alpine area 20-40 year old spruce artificial pure fores. The average age of the spruce is 19.4-29.4a. The average tree high is 6.7m, average DBH is 10.87cm, stand average height above sea level is 2943.8m and canopy density is 0.55, density is 1480 plants/ha. The average number of the damage of spruce needles is 10.8A, and the average disease index is 45.76%. The main diseases causing the phenomenon of falling needles were spruce needle disease and spruce leaf rust. The first place where appear spruce needle cast is Aba in Sichuan.2. The growth of spruce decreased with the increase of the disease level.The correlation coefficient of disease grade and tree height, DBH and disease grades are less than 0.9 in the survey, showing significant negative correlation. This shows that under the same conditions, the more serious the harm is, the worse the spruce growth is. According to parse tree annual growth analysis, disease stage and spruce diameter at breast height, tree height annual growth exist significant differences. The growth rate decreased with the increase of the disease level, especially ?, ? level more serious harm. Different disease grade spruce peeled wood Jinian were growth showed significant differences, between adjacent disease growth difference is not very obvious, but volume growth decreased with the aggravation of the disease.3. The drop needle harm causes severe volume lossSpruce needle harm were carried out according to Comparative three aspects of volume loss estimate:From the disease level of high and low contrast, spruce per plant of the province's average DBH, tree height and volume growth loss rate respectively is 24.6%,21.1%,46.6% and 0.968 cubic metres per hectare timber Jinian average loss, economic value of more than RMB 967.5. From the diseased were compared, according to the analytic tree data to calculate the individual tree diameter at breast height, tree height, volume and the average annual growth of loss rate were 15.8%,14.9%,50.1%, per hectare, the average volume loss of 185.9 square meters, the economic loss of 1859 yuan. According to the calculation formula of tree volume per hectare volume average annual economic loss of 4611 yuan. From before and after the onset of the contrast, fall after the needle damage diameter at breast height, tree high annual growth curve showed a trend of decline, the annual volume growth curve rises slowly, after the onset of individual spruce diameter at breast height, tree height growth average were reduced 0.838cm,1.625m, individual volume growth in the value of the loss is 0.02419 stere, per hectare volume economic losses 35982.6 yuan.4. loss modelAccording losses and research data, to establish a needle drop hazards associated with spruce tree timber volume loss mathematical model:Disease stage and plant spruce diameter, height, volume growth loss ratio model are Y= 13.493X-26.996, Y= 12.314X-25.367, Y= 20.09X-33.587.Disease index and volume loss rate model Y= 53.7411n (X)-180.28.