Study On The Ecosystem Characteristic And The Resistance Of Five Bamboos In Coastal Sandy Area

This text studied on the Ecosystem Characteristic of five Bamboos such as Bambusa.textilis,Dendrocalamus giganteus,Bambusa vulgarix cv.Vittata,Bambusa multiplex cv.Fernleaf and Bambusa multiplex var.riviereorum.These included structure of biomass,hydrology dynamic,nutrient characteristics and circulation.The paper studied on the resistance to salt and drought of Bambusa.textilis, Bambusa multiplex cv.Fernleaf and Bambusa multiplex var.riviereorum.The results have supplied the theory bases for cultivating the bamboo forestry in coastal sandy.The main findings were as follows:(1)The water rate of ten bamboos in coast was higher,and the water rate decreased with the ages.It was because that the new bamboos was on the instability and the woodiness was a maximum factor on the water rate of different organs.The water rate of branch was the highest and the leaf was the lowest over ground,and the sequence of organs under ground was stem underground＞root.(2)With the increasing of height,the biomass in one-year-old individual bamboo decreased,although increased and then decreased in two-year-old individual bamboo except for Bambusa multiplex cv.Fernleaf The differernt organs biomass of each bamboo had significant increase with the increase of age.In the distribution of organ biomass,the sequence was crop＞branch＞leaf over ground and stem underground＞root under ground.The total biomass of Bambusa.textilis forest was the most,which reached to 44.94 t·hm^-2,and that of Bambusa vulgarix cv.Vittata forest was the least,which reached to 11.65 t·hm^-2.In the distribution of biomass in bamboo forest,the arbor's biomass was the main part,which accounted for over 70%.The litter ranked second,and the herbage was last.(3)The bamboo forests can adjust rainfall's distribution.Rainfall was the dominant factor which affected interception,through fall and stem fall.In a certain rainfall class,with the increasing of rainfall,the interception,throughfall and stem fall increased.The annual amount of interception was the most,which occupied 31%in Bambusa multiplex cv.Fernleaf forest,while the annual amount of interception was the least,which occupied 26.1%in Bambusa vulgarix cv.Vittata forest.The annual amount of stem fall and throughfall were most.which reached to 35.4 mm and 688.8 mm respectively in Bambusa vulgarix cv.Vittata.(4)The water holding capacity of the forest was obviously different.The water holding capacity of arbor and litter were the most in Bambusa.textilis forest,which amounted to 36.17 t·hm^-2and 14.84 t·hm^-2 respectively.The water holding capacity of herbage was the most in Dendrocalamus giganteus forest,which reached to 8.35 t·hm^-2.That was the least in Bambusa vulgarix cv.Vittata forest,which only reached to 1.67 t·hm^-2.(5)The inherit characteristic and circumstance were the main factor on concentration of nutrition element in plant.N concentration of all organs was topmost in concentration of five elelments.Mg concentration was less higher than Ca concentration.P concentration was the least The sequence of all nutrient concentration was leaf＞branch＞stem over ground.However,the all nutrient concentration of root＞stem underground.(6)The individual distribution law of nutrient amount was not the same as that of biomass.The individual distribution law of nutrient element took on addition of distribution law of biomass and vertical distribution law of nutrient amount.The nutrient consent of stem was increasing with height,and the leaf and branch was decreased,although increased and then decreased.N concentration in each organ was the most,while P conecentration was the least.The sequence of N,Ca was root＞stem underground,and the sequence of P,K and Mg was stem underground＞root.(7)In the distribution of community nutrient amount in bamboo forest,arbor's was the main part.The arbor's nutrient amount was most,which reached to 459.29 kg·hm^-2in Bambusa multiplex cv.Fernleaf.N amount was the most in the arbor's nutrient amount.The herbage's nutrient amount in Bambusa multiplex var.riviereorum was the most,although that in Bambusa vulgarix cv.Vittata was the least.The little's nutrient amount in Bambusa multiplex cv.Fernleaf was the most,although that in Bambusa vulgarix cv.Vittata was still the least.(8)The litter's produce and its nutrient concentration and return amount varied in season obviously and had two peak periods in a year account of the growing law and environment.The litter's amount in Dendrocalamus giganteus and Bambusa multiplex var.riviereorum was the most.Average monthly N nutrient concentration of litter was the most.The nutrient return amount of litter in Dendrocalamus giganteus was the most,while that in Bambusa vulgarix ev.Vittata was the least.(9)The decomposing rate of leaf was the most,while that of branch and shoot hull was the least.The weight of leaf losted was fast at first and then slowed down,but the weight of branch and shoot hull losted was fast at first,then slowed down and was fast at last.(10)In different decomposing phase,because the nutrient elements existed in different forms in litter,the release and remove of element were complicated and various.During process of litter decomposing,the tendency of N,P concentration were increase-decrease-increase.However,the loss of Ca was intensive in the earlier stage,gentle in medium stage,and slight in.later stage.During the process of litter decompsing,K,Mg concentration inceased,and then decreased slimly at last.(11)Under the salt and water stress,the membrane permeability of each bamboo gradually declined,followed by the time of stress and the intension of stress.The cell velum was seriously destroyed under salt and water stress.The stronger the intension stress,the bigger membrane permeability.On the contrary,the membrane permeability became smaller.By analysis of variance,the membrane permeability of bamboo had extremely remarkable difference,following the time and intension of salt stress.(12)With the time and intension of salt stress,the content of chlorophyll varied slightly at first,and then declined obviously.The declining extent of chlorophyll.a was smaller than that of chlorophyll.b.The content of chlorophyll under the intensive water stress declined larger than tha under the middle water stress.The chloroplast of bamboo was lightly destroyed under the middle water stress.(13)The higher consistency and longer time of salt stress,the worse the ability of leaves' keeping water. The ability of leaves' keeping water in Bambusa.textilis was the biggest,and that in Bambusa multiplex cv.Fernleaf was the second,and that in Bambusa multiplex var.riviereorum was last.Under the water stress,the variety regulation of the ability of leaves' keeping water was the same as that of salt stress.The content of losing water of the bamboos' leaves under the stronger water stress was larger than that under the middle water stress.(14)Under the water and salt stress,the relatively water capacity of bamboos declined with the augment of the consistency and time of the stress,although the water saturation deficient was opposite.(15)The varieties of the N,P and K concentration of bamboos were related with the time and intension of the water and salt stress.Under the salt stress,the N,P concentration declined by the consistency and time of stress.On the contrary,the K concentration increased gradually.The N,P and K concentration of bamboos under the stronger water stress varied largelier than that that under the middle water stress.