| The research object of this study is pinus massoniana forest of Qingyang Lake state-owned forest farm of Hunan Province Ningxiang Country, under the guide of "Forest Ecosystem services Assessment Norms" and some other materials, with the help of combining sample investigation with locating observation, and combining field survey with laboratory experiments, we studied the influence of thinning to pinus massoniana forest from the aspects of forest structure, species composition, diversity of understory vegetation, physical and chemical properties of soil, ecosystem services and other aspects of pinus massoniana forest, and finally revealed the change law of pinus massoniana forest community structure and functional value of ecosystem services under different thinning intensities. The study provides scientific basis for ecological public-welfare forests and proposes management measures that is the most suitable for the growth of pinus massoniana forest, and make it is advantageous to the sustainable development of forest resources and ecological benefits. The study shows that:(1)After the measures of tending and thinning, the increase of thinning intensity can significantly promote the stand average breast diameter of pinus massoniana forest, the pinus massoniana forest which under the severe thinning has the largest average DBH with the diameter of15.96cm, compared with the contrast sample plot, it increased by17.96%. Under the condition of weak thinning and severe thinning, the average heights of pinus massoniana forest are12.7m and12.9m respectively. Compared with the contrast sample plot, they increased by12.12%and13.8%respectively. Thinning could increase the stand of individual volume of pinus, however, the effect of different thinning intensity to individual volume of pinus massoniana forest doesn’t have significant difference. Compared with the contrast sample plot, under the weak thinning, the stand individual volume increased by31.2%. Taking both number and individual volume into consideration, after the thinning with different intensity, the stand volume is weak thinning> contrast sample plot> severe thinning> medium thinning, the pinus massoniana forest has the maximum total stand volume of70.65m3/hm2while in the condition of weak thinning.(2) Changes in understory vegetation types thinning intensity differences under the obvious, have shown a thinning intensity increases with increasing regularity. Thinning increased the number of plants and shrubs pinus massoniana forest cover, the weak degree of thinning pinus massoniana forest under the most favorable growing shrub plant density in55-75cm height level reached its highest point2175/hm2, coverage reached71.5%. After the emergence of pinus massoniana forest plantation Thinning processing plants to increase substantially the number of herbs, especially the weak degree of thinning is increased by93%, the total density of9025/hm2. Under different thinning intensities, pinus massoniana forest shrub species diversity index increased, especially in moderate thinning higher diversity index, so moderate thinning treatment can significantly increase the species diversity vegetation. Important changes in the value of the thinning of the vegetation seen based on the total irrigation, increased number of species after thinning shrubs, herbaceous, but the important values of each species declined.Under Thinning shrub biomass maximum for4688.2kg/hm2. Weak degree of thinning down the largest herbaceous biomass for378.9kg/hm2. So can effectively improve the productivity thinning pinus massoniana forest under vegetation help maintain stability Pinus massoniana forest ecosystem.(3) The soil bulk density increases, porosity and soil aeration reduces in the pinus massoniana forest after intermediate cutting. The water holding capacity of the forest soil falls, which cuts the storage capacity of soil to rainfall. After different intensity of intermediate cutting, the soil structure is damaged, which reducing the soil permeability, water storage and supply capacity. Also, the water holding capacity of pinus massoniana forest’s0-30cm soil declines overall, respectively, for the control plots67.38t/hm2, weak intermediate cuttings58.62t/hm2, moderate intermediate cuttings47.29t/hm2, strong intermediate cuttings44.87t/hm2.Strong intermediate cuttings can increase water conservation capacity of litter layers. After weak intermediate cuttings, pinus massoniana forest litter’s maximum of water holding capacity is maximal, which is52.68t/hm2; contrast sample area pinus massoniana forest litter’s maximum of water holding capacity is36.83t/hm2. The services function total value of water conservation of pinus massoniana forest after different intensity of intermediate cuttings is intermediate cuttings sample plot(680.16yuan/hm2)>contrastsample area(636.83yuan/hm2)>moderate intermediate cuttings sample plot (499.15yuan/hm2)> strong intermediate cuttings sample plot (420.13yuan/hm2).(4)The pinus massoniana forest’s total value of soil and water conservation service function in different intermediate cuttings is:weak intermediate cuttings sample plot(110,530yuan/hm2)>Control plots(96,120yuan/hm2)>moderate intermediate cuttings sample plot (70,210yuan/hm2)>strong intermediate cuttings sample plot (58,080yuan/hm2).(5)The Pinus massoniana forest’s total value of soil conservation service function in different intermediate cuttings is:moderate intermediate cuttings sample plot (618,042yuan/hm2)>strong intermediate cuttings sample plot (610,403yuan/hm2)>weak intermediate cuttings sample plot (552,218yuan/hm2)>Control plots(406,693yuan/hm2).(6)The order of value of air purification services function of pinus massoniana forest is:weak intermediate cuttings sample plot(283.769thousand yuan/hm2)>strong intermediate cuttings sample plot(275.148thousand yuan/hm2>control plot(216.180thousand yuan/hm2)>moderate intermediate cuttings sample plot(212.774thousand yuan/hm2)(7) Comprehensive consideration the ecological service function such as function of water conservation, preserving water and soil, conservation of soil,and air purification services, the ecological service function value of pinus massoniana forest after different intensity of intermediate cutting is:weak intermediate cuttings sample plot(941.197thousand yuan/hm2)>strong intermediate cuttings sample plot(944.051thousand yuan/hm2)>moderate intermediate cuttings sample plot(901.525thousand yuan/hm2)>control plot(719.63thousand yuan/hm2).In conclusion, we can comprehensive consider that weak intermediate cuttings(20%-30%) is best for the construction of pinus massoniana forest and its ecological effect. |
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