Shelter Field Theory And Its Application On Coastal Protection Forest

The status and existed problems were discussed in this paper.Based on the ecological field discipline,demonstrated the shelter field theory,and established the definitions and sympols model about shelter field and it's eigenfunction.Furthermore,discussed the content,significanace and charactiristic of shelter field.Discussed the application of shelter field on coastal protectiv forest,surveyed the wind speed and temperature,and analysized the wind cut effect field and temperature effect field about shelterbelt of Casuarina equisetifolia.The thesis defined the shelter field as the distribution and effect in the time and spatial domain generated by shelter forest.The eigenfunction of shelter field contain shelter potential, intensity of shelter field,gradient of shelter field,and domain of shelter field.Defined potential shelter field as potential function of shelter-belt;Intensity of shelter field was the current function of shelter-belt;Gradient of shelter field was the change ratio of intensity of shelter field;Domain of shelter field was the biggest influence area of shelter-belt;The Intensity of shelter field and Gradient of shelter field were not exits while the domain of shelter field to was maximum.The experiment was done by selecting trunk shelter-belt,forest bands and farmland shelter-belt of Casuarina equisetifolia at different development stages as targets in Damao mountain area of Dongshan in Fujian Province.Measured the wind speed from Nov.2006 to Mar. 2007and temperature in Nov.2007 on different sites inside and outside of the selected targets. Datas was interpolated calculation with Kriging software,and draft contour maps,3D surface map and change ratio map of wind speed and temperature.The main experiment results were as follows:(1)Wind speed in trunk shelter-belt of Casuarina equisetifolia is in declining trend.The wind speed cut ratio respectlly reach the max at 1h and 5h in young and middle young stages of development,while the value respectly were 58%and 71%.The wind speed cut ratio respectlly were 70%,74%and 69%reach the max at 10h,20h and 20h while at middle,mature and super-mature stages of development.3D surfer map was cancave as two sides high and low in the middel.(2)Wind speed behind the trunk shelter-belt of Casuarina equisetifolia is in a rising trend. wind speed at 25h is nearly the speed at spacious place,but it declined at some sites.Declining sites are between 5h and 8h while at young,middle young,and middle forest,while mature and over-mature forest are at 12h to 18h.the wind speed cut ratio are respectlly 32%,10%,11%,0%and 3.8%.wind speed tendency in trunk shelter-belt of Casuarina equisetifolia is parabola of opening upward and described as:y=0.1125x~2-1.9799x +9.6244.decling in forest and rising out of forest.(3)Trunk shelter-belt and forest bands of Casuarina equisetifolia have the same discipline rules,and the fitting function is y=0.3638x~2-3.6141x+910.548.the wind speed reach the minimum at 10h in forest bands and the wind speed cut ratio is respectlly 100%,75%,67%50%,and 48%at different developed stands.The wind speed behind the forest bands is in a rising trend,and wind speed at 10h is maximum which is nearly the speed in specious place.(4)Analyzing the wind speed at all sites in farmland shelter-belt shown that wind speed at 10h reach the minimum at middle,mature and over-mature developed stages,and the wind speed cut ratio were respectilly 33%,325,and 255.It is fitting functin is y=0.2327x~2-2.3387x+9.6018.(5)Statistical analysis shown that:density,Under branch height and width canopy have a main relationship with the wind speed cut ratio within 5h in trunk shelter-belt and forest bands of Casuarina equisetifolia,but within 5h to 10h,tree height,density and under branch height are major effect factors of wind speed cut ratio.In farmland shelter-belt,tree height and density have mainly relationship with the wind speed cut ratio.(6)Analyzing the temperature at all survey sites in trunk shelter-belt and forest bands of Casuarina equisetifolia shown that:inside which the temperature was a temperature low-pressure zone,and outside was temperature high-pressure ridge.the edge was a transition area and the temperature difference was 1℃-2.5℃.Temperature in farmland shelter-belt forming a belt-shaped low temperature area while the outside forming a big high temperature area.the edge area have a more acute temperature change than other areas.The difference inside and outside was from 0.96℃to 1.54℃.Shelter field theory play an important role in the establishment and management of coastal protective forest,it put forward some new requests to the seedling cultivates,growth and frame of trees,and have a great deal of enlightening significance for the building and management of coastal proeetive forest of Casuarina equisetifolia.We shoule pay attention to cultivate trees seed which have more ability of growth ability,resistance sandstorm and insect pest.Experiment and analysized indicate that:Shielding effect have Remarkable advanced by the ways of mixed forest of Multi-tree species,intermediate cuttings,belt cuttings,interplanting and density adjustment.