Study On Optimal Model Selection And Application Of Coastal Protective Forest In Northern Jiangsu Province

The study has compared the four main coastal protective forest models in northern Jiangsu province through measuring forest biomass, growth rules, porosities and soil physical and chemical properties .Based on these,this paper discusses the optimal model of coastal protective forest in northern Jiangsu province. The results are described as follows:1. Annual average increase of biomass of poplar forest above ground in unit area is greater than water fir's, Chinese cryptomeria's and black locust's. Poplar's biomass accumulating rate under ground is the biggest, while black locust's is the smallest. Annual average increase of total biomass of four protective forest is: poplar> water fir> Chinese cryptomeria> black locust.2. Poplar's height growth speed in prophase is greater than the other three tree species. Black locust's maximum of height mean annual increment and current annual increment are 0.94 m/a, 0.85 m/a, water fir's are 0.99 m/a, 1.24 m/a .Chinese cryptomeria's are 0.81 m/a, 0.94 m/a and Poplar's are 2.20 m/a, 2.87 m/a.While six years old, Poplar's mean annual increment is 0.0262 m3/a. It is 20.96 times as black locust's, 21.83 times as water fir's and 25.69 times as Chinese cryptomeria's. The growth speed is: poplar> water fir> Chinese cryptomeria>black locust.3. Soil bulk density, salt content, organic matter content, total nitrogen contend and PH value of different layers of four coastal protective forest models'plot are smaller than bottomland's. These indicate that each protective forest can improve coastal soil.Because of the difference of tree species and time of afforestation , the benefit of improvement are different.4. Water fir, Chinese cryptomeria and black locust's average porosity are 30%~33%, but poplar's is 48.46% . So the shelterbelt's protective effect of Water fir, Chinese cryptomeria and black locust are better than the poplar's.5. As a result, we should plant black locust and false indigo or cogon etc salt resistent herbage in the first seawall. In the second or third seawall we should plant poplar and other accessory species or shrub such as black locust, cypress, Ch. hackberry, glossy privet and false indigo.