| According to its unique geographic position and forest resources, Mao er Moutain in Guangxi Province became a National Nature Reserve. Nowadays, people pay more attention to its flora and fauna, soil types and the utilization of eco-tourisim resources. Less attention was paid to forest eco-system, especially its biomass, carbon storage, nutrient content, distribution of nutrient and so on. So there is an important practical significance of research on biomass and nutrient distribution of forest ecosystem in Mao er Moutain.The present research was intended to investigate the community structure, the distribution, quantity and allocation of biomass, macronutrient and soil properties of four typical forest ecosystems. This study not only provided basic data and scientific reference about forest management, but also the estimation of carbon storage in the regional level.(1) Moso bamboo plantation and Chinese fir plantation are painted forest, schima superba forest is secondary forest, and Cyclobalanopsis stewardiana forest is natural forest. Affected by special situation in mountaintop, Cyclobalanopsis stewardiana forest became elfin forest. The tree, shrub and grass in forest have distinct layer. Trees in arborous layer have uniform height, and crown density ranged from 0.8 to 0.98, which lead to the bad growth of understory vegetation. The tree layer of moso bamboo plantation was composed of Phyllostachys pubescens, its shrub layer mainly consisted of Camellia sinensis, Acer davidii Franch., and Viburnum dilatatum Thunb., belonging to 6 families 6 generas and 6species. The grass layer mainly consisted of Carex cruciate, Lophatherum gracile, Lycianthes lysimachioides, belonging to 8 families 8generas and 8 species. The Chinese fir plantation’s tree layer is composed of Chinese fir, moso bamboo, Cyclobalanopsis oxyodon and Osmanthus fragrans ’Yugui’. The shrub layer is mainly composed of Symplocos sumuntia,Ilex chinensis Sims and Litsea cubeba, belonging to 5 families 5 generas and 5 species. The herb layer is mainly composed of Hemiboea henryi Clarke, Lophatherum gracile and Rubus alceaefolius, belonging to 8 families 8 generas and 8 species. In schima superba forest, the aborous layer is mainly composed of Schima superba, Manglietia fordiana, belonging to 9 families 10 generas and 10 species; the shrub layer mainly by the composition of Symplocos grandis Hand.-Mazz., Machilus pingii and Dendrobenthamia hongkongensis, belonging to 7 families 10 generas and 12 species; the grass layer is mainly composed of Rubus morifolius, Lycianthes lysimachioides, Gynostemma pentaphyllum and Rubus corchorifolius, belonging to 5 families 5generas and 6 species. The aborous layer of Cyclobalanopsis stewardiana forest mainly consisted of Cyclobalanopsis stewardiana, Prunus spinulosa, belonging to 8 families 12generas and 12 species. The composition of shrub layer in Cyclobalanopsis stewardiana forest was simple, only having Indocalamus longiauritus. The herb layer was composed of Ophiopogon japonicas and Carex cruciate.The age structure of Moso bamboo plantation, Chinese fir plantation and schima superba forest are stationary, and that of Cyclobalanopsis stewardiana forest is senescent.(2) The total biomass of Moso bamboo plantation is 55.0764 t·hm-2, the biomass of arborous layer is 54.41 t·hm-2, understory layer is 151.11 kg-hm"2, litter layer is 519.49 kg·hm-2.The total biomass of Chinese fir plantation is 77.6172 t·hm-2, The biomass in tree and undergrowth layer are 75.52 t·hm-2 and 255.72kg·hm-2, respectively. The biomass of litter layer is 1841.43 kg·hm-2。The total biomass of schima superba forest is 264.2865 t-hm’2. The biomass in arborous layer and undergrowth layer are 257.31 t·hm-2and 341.75 kg·hm-2, respectively. The biomass of litter is 6633.74 kg·hm-2.The total biomass of Cyclobalanopsis stewardiana forest is 310.0403 t·hm-2. The biomass in arborous layer and undergrowth layer is 306.06 t·hm-2 and 941.82 kg·hm-2, respectively. And litter’s biomass is 3038.47 kg·hm-2.The biomass of forest ecosystem increased with the positive succession of plant community. More and more organic matter accumulated in aborous layer. And the biomass of understory decreased with development of community.(3) The mean concentration of macronutrients in soil of four forest was:N 0.83-3.22 g·kg-1, P 0.22-0.75 g·kg-1, K 4.07-4.63 g·kg-1, Ca 1.61-2.51 g·kg-1,Mg 1.01-1.67 g·kg-1.The mean concentration of macronutrients is aborous trees was:N 3.76-11.62 g·kg-1, P 0.43-0.84 g·kg-1, K 0.96-1.84 g·kg-1, Ca 2.53-39.8 g·kg-1, Mg 0.18-0.37 g-kg-1.The rangement of macronutrients in shrubs was:N 2.4-21.87 g·kg-1, P 0.46-1.4 g·kg-1, K 1.34-7.22 g·kg-1, Ca 0.51-72.60 g·kg-1, Mg 0.16-1.32 g·kg-1. And the rangement of macronutrients in herbs was:N0.31-29.98 g·kg-1, P 0.36-1.41 g·kg-1, K 1.84-8.89 g·kg-1, Ca 1.66-100.75 g·kg-1, Mg 0.26-1.58 g·kg-1.The mean concentration of macronutrients in litter layers was:N 0.12-18.99 g·kg-1, P 0.64-0.98 g·kg-1, K 0.28-0.58 g·kg-1, Ca 4.13-28.96 g·kg-1, Mg 0.14-0.3 g·kg-1(4) The total storage of macronutrient in each forest, including Moso bamboo plantation, Chinese fir plantation, schima superba forest and Cyclobalanopsis stewardiana forest is59032.62 kg·hm-2,72937.27kg·hm-2,55919.36 kg-hm-2,47932.56 kg-hm"2, respectively.The storage of each macronutient element in Moso bamboo plantation is K>Ca>N>Mg>P, that in Chinese fir plantation and schima superba forest is K>Ca>Mg>N>P; that in Cyclobalanopsis stewardiana forest is K>N>Ca>Mg>P. In conclusion, P is the limiting factor for plants in study site.The spatial distribution of nutrient storage in each forest is soil>aborous layer>litter layer>understory layer. Most nutrient still remain in soil, and soil is the biggest pool of nutrient in forest ecosystem. And the main pool of nutrient in abourous layer is trunk. |
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