| Abstract:This paper first studies on the ecosystem characteristic of twelve bamboos in coastal sandy area, including:Dendroclamps is. Oldhamli, Dendrocalamus. Minor, Dendrocalamus affinis, Dendroclamps is beecheyana var. pubescens, Dendrocalamus brandisii, Phyllostachys makinoiii, Acidosasa edulis Wen, OIigostachyum lubricum, Phyllostachys praecox, P. prominens W. Y. Xiong, P.vivaxcv. Vivax, CV. Ventricousintcrnode, and including biomass, nutrient, energy and the decomposition characteristic, and we have got these results as follows:1．The annual mean biomass of fine roots of bamboos forestry in coastal sandy area was between 1．302 t·hm (Dendrocalamus affinis, lowest) and 2．562 t·hm(P. prominens W. Y. Xiong, highest) . Overally looking, the biomass of fine roots of bamboos undulated fiercely in one year and had remarkable seasonal dynamic and showed double apices .The peak occurred generally in May and September.2．In one year, among the different bamboos, the biomass of fine roots changes most stable in January and was about 1．0 t·hm for both cluster bamboos and loose bamboos . Overally looking in whole year, the loose bamboos changed more stable than the cluster bamboos.3．The biomass of fine roots of various soil layers was basically below 1．0 t·hm, did not surpass 2．0 t·hm and reduced gradually along with increasing of the soil layer's depth. But the surface layer changed most fiercely, and it was basic constant in 20-30cm and below 30cm in one year; the seasonal dynamic of the biomass of fine roots of various soil layers was similar with total biomass, but the surface layer seasonal variation was more remarkable than the bottom floor.4．The total biomass of fine roots of various bamboos distributed mainly in the 0-20cm(>80%) and it had basically no fine roots below 30cm(<5%)and 5-10cm(28%), 10-20cm(20%), 20-30cm(10%). Regarding the identical soil layer, the biomasses of fine roots of various bamboos had no remarkable changes. Especially for the 20-30cm and the >30cm, it was nearly close; the vertical distribution of fine roots between cluster bamboo and loose bamboo had no obvious difference.5．Generally speaking, in the whole year, the decomposition of fine roots of bamboos in coastal sandy area was fierce. Especially in the first four months, it had decomposed 30 50% nearly through 120 days, namely.nearly about half. Two mopths following its decomposition flattened out and speeded up after 180 days: Overally looking, the Phyllostachys makinoiii decomposed most quickly and its remnant ratio was only 11% after one year. The Oligostachyvm lubricum decomposed most slowly and its remnant ratio was 22．4% after one year. The decomposition rate between cluster bamboo and loose bamboo had no obvious difference.6．The N content of fine roots of bamboos in coastal sandy area was low and annual mean could not surpass 10 g/kg generally and undulated fiercely in one year. Overally looking, the N content of Phyllostachys praecox was highest (10．964 g/kg) and CV. Ventricousinternode was lowest (4．535 g/kg) . It undulated most fiercely from January to March for various bamboos and smallest from September to November .Except for Phyllostachys praecox , the N content of cluster bamboos was generally higher than loose bamboos .7．The P content of fine roots of bamboos in coastal sandy area was low and annual mean could not surpass 1．0 g/kg generally and undulated fiercely in one year . The P density was very low from September to November and was steady basically for every bamboo. Overally looking, P content of Phyllostachys makinoiii was highest (0．9714 g/kg) and P. vivax cv. Vivax was lowest(0．1362 g/kg). The P content undulated fiercely among different bamboos in identical month, especially from January to March and later was closer and closer along with the end of living period. Overally looking, the P content of cluster bamboos was generally higher than loose bamboos.8．The K content of fine roots of bamboos in coastal sandy area was low and annual mean could not surpass 2．8 g/kg generally and undulated fiercely in one year. Overally looking, K content of 01 igostachyum lubricum was highest (2．761 g/kg) and Dendrocalamus. Minorvias lowest (1．127 g/kg). The K content undulated fiercely among different bamboos in identical month, especially from January to March and later was closer and closer along with the end of living period. It had no obvious difference between cluster bamboos and loose bamboos.9．The dry weight calorific annual mean value of fine roots of bamboos in coastal sandy area had no remarkable differences among bamboos and concentrated between 10 kJ /g and 17 kJ /g. Phyllostachys makinoiii was highest(15．6428 kJ /g) and Dendroclampsis beecheyana var. puhescens was lowest (11．4320 kJ /g). Generally speaking, it was high in the winter and low in summer. It was similar between cluster bamboos and loose bamboos.10．The standing crop of N for fine roots of bamboos in coastal sandy area undulated fiercely in one year and the annual mean value was between 6 kg/hm and 19 kg/hm. Acidosasa edulis Wen was highest (18．8004 kg/hm) and Dendroc lamps is oldhamli was lowest(6．2495 kg/hm).Except for Dondrocalamus brandisii. Phyl lostachys makinoiii and Dendroc lamps is oldhamli, others bamboos showed basically double apices ( "M" ).The peak occurred in March and September. Overally looking, it had no obvious difference between cluster bamboos and loose bamboos.11．The standing crop of V for fine roots of bamboos in coastal sandy area did not undulate fiercely in one year. Except for Acidosasa edulis Wen , the annual mean was below 1．0 kg/hm. Acidosasa cdulis Wen was highest (1．5108kg/hm) and P. vivax cv. Vivax was lowest(0．1745 kg/hm). For the P. prominens W. Y. Xiong, Dendrocalamus brandisi i, Dendroclampsis oldhamli, Phyllostachys praecox, Oligostachyum lubricum, P. vivax cv. Vivax, it showed singer apex . The standing crop of P started to increase from January and achieved the maximum in July, afterwards started to drop, and the peak was July. For Phyllostachys makinoiii, Dendroclampsis beecheyana var. pubescens, Dendrocalamus. Minor, it did not undulate fiercely in one year and started to drop gently continuously from January. Overally looking,, the cluster bamboos were generally higher than the loose bamboos.12．The standing crop of K for fine roots of bamboos in coastal sandy area undulated fiercely in one year and the annual mean value was between 1．0 kg/hm and 5．0 kg/hm. Phyllostachys praecox was highest (4．1749 kg/hm) and Dendroclampsis oldhamli was lowest (1．7254 kg/hm).It changed gently from January to July for every bamboo and September was an universal peak. Overally looking, the loose bamboos were generally higher than the cluster bamboos.13．Except for Dendroclampsis oldhamli , the standing crop of energy for fine roots of bamboos in coastal sandy area undulated fiercely in one year. Overally looking, Dendrocalamus affinis was highest (3．2975×10 J/m) and Phyllostachys makinoiii was lowest( 1．6532×10 J/m). The change of Dendroclampsis oldhamli is stablest,about 1．5×10 J/m. Overally looking, the cluster bamboos were close to the loose bamboos .14．Tn the decomposition process of fine roots of bamboos in coastal sandy area, the density of N, P. K were respectively orderly. After 300 day's decomposition, N and K displayed nutrient release, but release of K was more than N. The loss of K was most, all above 90%, highest 99．13 %( Oligostachyim lubricum). The loss of N might achieve 93．41% {Dendrocalamus affinis); But P displayed nutrient concentration after decomposition and the density had surpassed the initial level greatly.15．The energy loss after one year's decomposition of fine roots of bamboos in coastal sandy area was more, all above 60%, and most might reach 77．74% {P. prominens W. Y. Xiong). |
