| In this paper, C. equisetifolia that was Fujian Province coastal shelterbelt main tree species had so series of questions in growth recession, single species, updates difficulties and protective function decline, that the growth characteristics, biomass, nutrient characteristics and vegetation carbon storage capacity were studied in an A. crassicarpa plantation, to found gist and practical basis for A crassicarpa as the coastal shelterbelt species. The main results of the study were as follows:1. The A. crassicarpa plantation of nine years old had the average tree height of9.04m, slightly lower than8years old of C. equisetifolia (9.26m), average DBH (10.51cm) was higher than8.69cm of C.equisetifolia, and average individual volume was0.04083m3greater than0.02839m of C. equisetifolia. The A. crassicarpa plantation monoclonal average biomass was51.42kg, the C. equisetifolia plantations monoclonal average biomass was25.87kg, as2times weighs as the C.equisetifolia. Visible the A. crassicarpa growth rate is very fast, and can adapt to the harsh environment of the coastal sand and have a good performance.The biomass of tree layer in A. crassicarpa plantation was128.57t·hm-2, higher than the C. equisetifolia’s114.97t·hm-2, its biomass of the organs in the tree layer ranked order of trunk> branch> root> leaf, the biomass of trunk was54.69t·hm-2, which accounted for the entire plantation biomass42.54%, the leaf biomass was at least, only8.1%. The biomass of tree layer in the C. equisetifolia plantation randed order was trunk> root> branch> leaf, with difference of A.crassicarpa, the C. equisetifolia plantation root biomass accounted for28.14%of the whole tree layer biomass, only lower than the trunk, the leaf biomass was at least, only8.87%. The biomass of A Crassicarpa plantation and C.equisetifolia plantations were143.3t·hm-2and125.46t·hm-2, there biomass of tree layer and litter layer accounted89.72%,10.28%and91.64%,8.36%of the total biomass, respectively.A. crassicarpa roots underground grew up to1.2m deeper than Casuarina0.8m,nearly half of the casuarina root biomass accumulation in the0-20cm,and<0.05cm fine root biomass accounted for was less than<0.2cm fine roots biomass nearly1/2. Both having rhizobia, the Casuarina (97.2g) was more than the A. crassicarpa (20.9g).2. The A.crassicarpa and C. equisetifolia standard trees of major nutrient elements assigned characteristics in various organs. The order in the A. crassicarpa N content was leaf> root> branch> bark> trunk, and different with the A. crassicarpa which order was leaf> bark> root> branch> trunk; its P and K content were leaf> bark> root> trunk> branch. The A. crassicarpa leaves P content reaches0.6387mg·kg-1was twice than the branches. The P content of the A. crassicarpa are greater than the same organs of Casuarina; the A. crassicarpa various organs of the aerial parts of K content was less than Casuarina, but the underground parts (roots) K content was higher than the Casuarina. The A. crassicarpa organ Ca content was significantly less than Casuarina, the order in which the content of the various organs were leaf> trunk> branch> root> bark. The Mg content in the trunks, branches and roots of the A. crassicarpa were less than Casuarina, highest Ca content of the leaves in all organs.Na content in the Acacia tree trunks and branches was less than Casuarina, but the leaves and roots content was higher than that in Casuarina, both the content of the leaves were higher than other organs; Fe content, the two species were roots> leaves> bark> trunk> branch, but A. crassicarpa organ contained lower than Casuarina. A.crassicarpa was far below the Casuarina in Mn content, Mn content was only the1/4-1/26of Casuarina, Mn content in of A. crassicarpa organ order is leaf> bark> trunk> branch> root; the Acacia Zn content of the order of performance were trunk> branches> leaves> roots> bark, branches and tree trunks, the Acacia Zn were greater than the same organ Casuarina. A. crassicarpa organ Cu content is less than Casuarina, part of the content of the earth, an average only Casuarina1/2, A. crassicarpa was much higher than the aerial part of the underground part of the content of Cu, manifested as root> leaf> stem> branches> bark.3. The amount of plantations annual litter of A. crassicarpa and C. equisetifolia was7616.60kg·hm-2and8218.07kg-hm’2respectively, Acacia litter’s highest values occur in March reached to1552.60kg·hm-2, the lowest in November were114.00kg·hm-2; Casuarina litter’s highest value in July amounted to2048.76kg·hm-2, account for a major part of the content is leaf litter, litter components accounted the annual litter which amounted for93.1%and75.6%. The monthly dynamic changes in the total amount of A.crassicarpa plantation was litter bimodal mode, its highest peak of the total amount of litter were in March and June in the year; the C. equisetifolia plantation litter total month dynamically change showed a single peak pattern, the peak was in July.4. The N years return of A. crassicarpa litter nutrient restitution amount was more than the amount of C.equisetifolia artificial, which annual returned a total of120.514kg·hm-2·a-1, C.equisetifolia was95.585kg·hm-2·a-1; P annual returned in A. crassicarpa was to3.813g·hm-2, greater than C equisetifolia of2.246kg·hm-2·a-1; A. Crassicarpa’s K annual return was less than Casuarina, were20.182kg·hm-2·a-1and28.387kg·hm-2·a-1respectively; both quite in the annual return of the amount of Na and Zn,0.041kg·hm-2·a-1(0.043kg·hm-2·a-1)and0.313kg·hm-2·-a-1 (0.324kg·hm-2·a-1); A.crassicarpa litter Fe, Mn and Ca were far less than that of Ca Casuarina, both annual return of1.965kg·hm-2·a-1(4.067kg·hm-2·a-1),1.523kg·hm-2·a-1(4.773kg·hm-2·a-1) and36.57kg·hm-2·a-1(76.838kg·hm-2·a-1); the difference of Cu’s annual return in the amount between the two little Acacia were slightly less than C. equisetifolia, both annual return of0.037kg·hm-2·a-1and0.046kg·hm-2·a-1respectively; Mg the annual returns of A.crassicarpa was less than C.equisetifolia,23.667kg·hm-2·a-1and17.964kg·hm-2·a-1respectively. A.crassicarpa plantations of various nutrients in the annual return order was N>Ca>Mg>K> P> Fe>Mn>Zn>Na>Cu; the C.equisetifolia in various nutrients annual return in a sequential was N>Ca>K>Mg>Mn>Fe>P>Zn> Cu>Na.5. The physical properties of the soil analysis resulted:Acacia crassicapa soil bulked more density than the forest of Casuarina equisetifolia plantation soil bulk density of great heavy porosity of soil layer in the0-40cm of Acacia crassicarpa forest increases,20-40cm porosity of40.05%, about twice of0～10cm porosity (20.6%). C. equisetifolia total porosity in the forest soil layer difference was less obvious, and was significantly larger than the heavy porosity of Acasia crassicarpa forest, its0-10cm range of porosity and capillary water-holding capacity was more than twice of Acacia crassicapa respectively, in0-10cm soil moisture was more than10times of A. crassicapa. C. equisetifolia mean soil water content was higher than that A. crassicapa plantation. The pH values of both were basically the same, from ground to underground on a rising trend.6. The Acacia crassicarpa plantation soil nutrient content at different levels (full volume) analysis:thick soil N content of A. crassicarpa and C. equisetifolia plantations from ground level to the underground on a gradually declining trend; thick soil layers of A. crassicarpa and C. equisetifolia plantation content owed more even distribution of Na and K in and around. Acacia crassicapa forest soil P content showed a decreasing trend in the level of four, a rising trend in forest of C. equisetifolia; Mg contents in soils of two tree species with soil depth increased and decreased; A. crassicarpa and Ca equisetifolia varioued levels of Fe and Mn contents in soil, each level of Fe content was slightly greater than the thickness of C. equisetifolia and A. crassicarpa; all levels of Zn contents in soils of A. crassicapa varied, C. equisetifolia zinc content difference was not evident at all levels; all levels of Cu contents in soils of A. crassicapa diminished as the soil better.Active determination of nutrient elements in soil:A. crassicapa20-40cm hydrolysis of soil N concentrations was lower than0～10cm and10-20cm, C equisetifolia hydrolysis of nitrogen in surface soil concentrations was higher than that of A. crassicapa. Both basically the same on the available P content, content of soil surface was higher than other levels, at various levels, there was little difference in content of the two.20-40cm quick-impact of Acacia crassicapa K was greater than the same level of C. equisetifolia K content.7. The A.crassicarpa tree layer carbon storage was63.99t·hm-2,the various organs of the size of the carbon storage order:trunk> branches> roots> leaves, carbon storage were27.84t·hm-217.38t·hm-2、13.57t·hm-2and5.20t·hm-2respectively, accounted of the entire mangium tree layer carbon storage were43.50%,o27.16%,21.21%and8.13%. The Casuarina carbon storage was53.16t·hm-2, the Casuarina in carbon stocks order was different with A. crassicarpa,the root was greater than the tree’s branches, the specific size of the order was trunk> roots> branches> leaves, carbon storage were23.75t·hm-2,14.86t·hm-2,9.79t·hm-2and4.76t·hm-2, respectively, accounted for the total carbon storage,44.67%,27.95%,18.42%and8.96%. Litter of A. crassicarpa and C. equisetifolia total carbon storage of6.28t·hm-2and4.56t·hm-2, which accounted for the major part of the leaf litter. The carbon storage of9a A. crassicarpa plantations and8a Casuarina plantation were70.27t·hm-2and57.72t·hm-2, the tree layer are accounted of the total carbon storage91.1%and92.1%respectively.The litter carbon of A. crassicarpa annual returned was3.863t·hm-2, slightly higher than the Casuarina (3.825t·hm-2). The litter carbon of leaves and branches in the A. crassicarpa plantation annual restitution were3.61t·hm-2and0.253t·hm-2, respectively. Casuarina litter the annual return of the amount of performance leaves> fruit> branch. The seasonal variation of litter carbon restitution in9years old Acacia crassicarpa plantation were summer> spring> winter> autumn; that8years old Casuarina Plantation were summer> spring> autumn> winter. Two species in the summer litter carbon restitution volume was significantly higher than the other seasonal, its litter carbons restitution amount were not significantly different in spring. |
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