Study On Growth Of Pinus Massoniana And Cupressus Funebris And Its Health Management In Three Gorges Reservoir Area

In this paper, the forest health conditions were classified using the forest inventory data and historical documentation about forest insects of the main counties/cities in the Three Gorges Reservoir Area. The geographic information system of forest insect frequency was established based on the different classification and gradation of forest insect and frequency. The growth trends of main tree species were analyzed and the correlation model of main tree species in different regions and elevation gradients was simulated. Forest health management measures have been adopted to control the harm of Chinolyda flagellicorn through changing forest environment. The results are shown as follows:1. The relationship of Pinus massoniana radial growth with climatic factors of different elevations was assessed by dendrochronological techniques including correlation functions and single-years analysis. Finally the correlation model of tree ring width index and climatic factors in different elevations was simulated by multi-factor regression. The results showed that the character of ring width index of Pinus massoniana is different because of the altitude gradients due to complex topography. And growths in different elevations had significantly different responses to temperature and precipitation. In normal climatic conditions, the growth at the elevation of 300m was significantly affected by mean monthly precipitation and humid index of last June and October, and there is no significant correlation to climatic factors of the current year. The growth at the elevation of 600m was significantly correlated to the temperature of last June and mean monthly precipitation and humid index of current July. At 900m the growth was not only affected by the temperature of current February, but also affected by the mean precipitation and humid index of December. The relationship was verified by single year analysis.2. Tree-ring cores were collected from the low and upper altitude limits of Pinus massoniana in Yunyang County, Chongqing City. Two tree-ring width chronologies were established using standard dendrochronological methods, respectively. The two sampling sites are located close to each other but at different elevations. Results indicated that the chronology fluctuation of the upper altitude limit is higher than that of the low limit. The statistical character of the chronology shows that signal to noise ratio (SNR.) and express population signal (EPS) of upper limit are higher than those of low limit. Therefore, the sensitivity of trees'response to the climatic changes increased with increasing altitude. In order to understand the varying response of tress at different elevations to environmental changes, the correlations between the chronology indices and precipitation and between air temperature in different seasons and different months were calculated. The results show that the growth of Pinus massoniana of upper limit was affected by temperature and precipitation of previous year, and that of low limit was only affected by precipitation of current year. It showed that there is lag-effect of the growth of upper limit in response to climate factors.3. The relationship of Pinus mussoniana radial growth in upper reaches of the Three Gorges Reservoir Area in China with climate change was assessed by dendrochronological techniques including correlation functions and single-years analysis. The results showed that Pinus mussoniana growths at high and low elevations had significantly different responses to temperature and precipitation. At low elevation, Pinus mussoniana growth was significantly correlated to the mean precipitation and the humid indices of May and June, but at high elevation, it had a more complicated relationship with the environment. Besides the mean temperature of May and June, the humid index of last November was significantly correlated with the Pinus mussoniana tree-ring width. Therefore, it was not the same relationship of the same tree species with different environmental gradients. Finally the correlation model at different elevations of tree ring width index and climatic factors was simulated by multi-factor regression.4. The frequent area, accidental area and safety area were classified in Hubei province of the Three Gorges Reservoir Area (TGRA) according to frequency of forest insects and diseases based on documented records. Zigui County is the most serious county in TGRA. In Zigui County the frequent area is Maoping Town; accidental areas include Guojiaba Town and Guizhou Town, and the other areas are safety area. In Yiling Couty, the frequent areas are Taipingxi Town, Letian Town and Xiaoxita Town; accidental areas are Sandouping Town and Yaqueling Town, while others are safety areas.5. Various climate factors have an integrated effect on the occurring of Dendrolimuspunctatus Walker. Air temperature and sunlight time are the premier driving factors and wind speed is secondary in Zigui county; The occurring area of Dendrolimuspunctatus Walker is significantly related to air temperature, temperature maximum and minimum and sunlight time of current April.6. The relationships between Dendrolimuspunctatus Walker occurring area and climate factors are same in Yiling County with Zigui County. Precipitation, sunlight time and air temperature significantly affect the insect occurring area in Yiling County. The occurring area was found to be mainly positively correlated with the average temperature and sunlight time of April, and total monthly precipitation of May.7. We try to control Chinolyda flagellicornis by changing forest environment with the measure of strip reform. The result showed that: the influence on forest composition structure mostly focuses on smaller diameter class. Whatever width the strip reform was taken to, the number of smaller diameter class increases significantly, and there is no great effect on larger diameter class. As the sunlight becomes stronger after strip reform, the temperatures of soil and air in forest are higher, and air humidity is lower. All these changes affect the regeneration of Cupressus funebris.8. Effects of strip reform to cypress plantation were analyzed in the view of biodiversity and forest stand environment including index of biodiversity of undergrowth vegetation species, air temperature in stands, and soil temperature of different strip width treats. The result showed that: there were different effects on undergrowth biodiversity by strip reform to different width. For 6 m width strip reform, only index of D, H from shrub layer has increased and there was no significant effect on S and D, H, S of herb layer. , The species composition was not significantly changed after 20 m width strip reform except different importance values. Mbawmagyabceij of Rhamnaceae replaced Rosaceae plants and became the dominant species in 6 m width strip reform in shrub layer identically, and biological diversity of shrub layer was different at different strip width. Monocotyledon was replaced by dicotyledon gradually as the dominant species as the sun plants increasing as the result of the forest stand environment change. The influences on air temperature and soil temperature of different strip reforms are different. The soil temperature variance is lower than in 20m width strip and air temperature variance of 6m width strip is higher than 20m width strip.9. The average air temperature of September and October in 6m strip reform was 0.85℃, 0.62℃higher than in 20m strip reform respectively. The maximum temperature difference between the two strip widths was about 0.39℃and 0.77℃respectively which means the temperature difference in 6m strip width is lower than in 20m strip reform. All these were resulted from the difference of shade density caused by the different width strip. The soil temperature difference is lower than air temperature after strip reform operation in either width.10. There is significant difference of the number of larva of Chinolyda flagellicorn in the strip and the edge of the strip, and no significant difference with the width of strip. The number of larva in soil inside the strip is larger than that in forest edge, and there is no significant difference with the width of strip. The time of larva going into earth is consistent with the different width strip, mainly during 9-18 of May. There are about 85% and 78% larva going into the earth respectively in 6m and 20m width strip during the ten days. 84 percent of total larva goes into earth during 9-18 of May averagely.11. The soil physical and chemical properties have been comparatively studied with different width strip reforms. The result showed that: decrease extent of soil capability in the depth of 20-40cm soil layer in 20m width strip reform is much higher than in 6m, but the result is converse in 0-20cm soil layer. The total soil porosity increased by 4.7%, 1.6% in 0-20cm and 20-40cm respectively in 6m width strip, and by 23.4% in 0-20cm in 20m width strip, while the total soil porosity decreased by 29.4% in 20-40cm soil layer to the contrary. The soil organic matter increased by 15.0%,28.4% in 0-20cm and 20-40cm soil layer respectively after 20m width strip reform because of the difference of decomposition speed. Available N increased 32.779mg·kg-1 in 20～40cm soil layer after 6m width strip reform. Available N Available N, available K, total P and total K increased to certain extent in 20m width strip reform. The soil structure and its physical and chemical properties have been improved after strip reform. It will provide a scientific basis for the ecological improvement planning and the choice of project model for the Three Gorges Reservoir Area through the research on growth of Pinus massoniana and Cupressus funebris plantation and health management.