Research On Biological Productivity And Characteristics Of Soil Nutrients Of Main Tree Species For Shelterbelt In Haitan Island

The biomass and productivity is the representation of matter and energy accumulation of the forest ecosystem. In the article,investigation was carried out to determine the biomass of main tree species for shelterbelt in Haitan County, namely Casuarina equisetifolia L, Acacia confusa Merr, Pinus thunbergii Parl and Pinus elliottii. Meanwhile, the disks, the litter and soil samples collected in the field were used to estimate the net primary productivity and carbon density of the four tree species.The results indicated that:(1) From the distribution of the four tree species, the order of the total biomass from large to small was Pinus elliotii> Casuarina equisetifolia> Pinus thunbergii Parl> Acacia confusa Merr> Casuarina equisetifolia with bad slash regeneration. From the analysis of the litter, but for Casuarina, two peak of litter return were in May and September.September is the peak of the another three tree species litter,.(2)From the estimation of the the four tree species productivity, the net primary productivity of Pinus elliotii and Pinus thunbergii Parl fluctuated significantly. The productivity of normal Casuarina reached the maximum at the age of 15. The productivity curve of Casuarina equisetifolia with bad slash regeneration did not manifest an obvious peak. The productivity of Acacia confusa Merr increased continuously.(3) The four tree species had a positive relationship with three climatic factors.(4) According to the analysis of soil nutrient, the undergrowth soil nutrient of Acacia confusa was relatively abundant, and.the fertility of the soil in Haitan Island was comparatively poor on the whole.(5) The carbon density of Pinus elliotii and Casuarina equisetifolia was higher.The carbon density of Acacia confusa Merr and Pinus elliotii was higher.