| Based on the case study of Hainan Forest Ecosystem Research Station of Wenchang forest, secondary forest, coconut forest, artificial regeneration of Casuarina equisetifolia pure Acacia forest and pure forest as the object of study. In the soil parent material, soil type and climate conditions are basically the same, on the carbon storage and0-100cm all types of forest litter amount, the soil organic carbon characteristics (organic carbon, light fraction organic carbon, dissolved organic carbon and labile organic carbon content) for the comparative study, so as to accurate assessment of our Province coastal terrace in forest soil carbon sequestration potential, prediction and maintenance of forest ecosystem long-term productivity of main forest types in coastal areas, to guide the sustainable management and provides a reference for upgrading. The main conclusions are as follows:(1)There is a significance in litter input in different forest types. Forest litter biomass and carbon storage is proportional to the pure forest of Casuarina, acacia plantation and coconut Lin Linxia floor litter content greater than the secondary forest and artificial regeneration forest, which to a large extent determined the biological characteristics of species, but in different forest types in each sub layer of the existing proportion of different litter decomposition, and their own strength. Under the same climate condition in each sub layer, litter C reserves as semi decomposed layer was greater than the decomposition layers, and coconut forest, secondary forest and artificial promoting regeneration of secondary forest litterfall pattern consistent month.(2)There is a significance between the different forest types in0?100cm soil organic carbon content, carbon and nitrogen content, performance for the secondary forest, coconut forest and artificial regeneration of secondary forest were significantly higher than those of Casuarina and Acacia forest, layer by layer decreases and the surface aggregation phenomenon significantly with soil profile depth, show the effects of litter intake and human disturbance on soil organic carbon content and carbon storage of the maximum. The ratio of soil carbon and nitrogen in the soil profile variation is inconsistent, but progressively in Casuarina equisetifolia pure forest and Acacia plantations. The results show that, the contributions of different forest types on soil fertility rate have obvious difference, in contrast, coconut trees and two kinds of secondary forest is more conducive to soil carbon sequestration.(3)Soil easily oxidized organic carbon content, soil carbon distribution and activity were decreased with the depth of0-100cm soil layers in different forest types. Among them, the pure forest of Casuarina and Acacia plantations soil easily oxidized organic carbon content is too small, only in the range0.20g/kg to2.16g/kg, the content of each soil layer were significantly lower than that of secondary forest, artificial promoting regeneration secondary forest and coconut plantations. Soil easily oxidized organic carbon distribution ratio, soil carbon activity in the range of49.3%?70.1%,0.61?2.35, the maximum value appeared in the pure forest of Casuarina and Acacia plantations. Research shows that, the intensity of rainfall and surface runoff may be the coastal terrace forest soil easily oxidized organic carbon changes the important influence factors, by contrast, coconut trees and two kinds of forest soil carbon with high stability.(4)Each forest type in0-100cm soil light fraction carbon, nitrogen content and C/N are quite different in all soil layers. The pure forest of Casuarina and Acacia plantations of light fraction organic carbon content was low, the content of each soil layer value under1g-kg-1, were significantly lower than that of secondary forest, secondary forest and coconut plantation artificial promoting regeneration. Soil light fraction organic carbon distribution ratio ranged from13.72%to38.6%, showed a trend of first increased and then decreased in the soil profile, the secondary forest, artificial promoting regeneration forest and coconut forest was significantly higher than that of Casuarina equisetifolia and Acacia forest. The results of the study show that, the difference between vegetation types and soil structure is the important factor for the change of carbon content in soil of coastal platform forest soil, compared with Casuarina and acacia trees, coconut trees and two kinds of forest soil carbon with high stability.(5) The secondary forest and artificial promoting regeneration of secondary forest and coconut plantation soil soluble organic carbon and nitrogen content in the0?100cm profile with the soil depth decreased, and the seasonal dynamic changes, manifested as the dry season was higher than that of the rainy season. Soluble organic carbon distribution ratio of dry season in the range of1.2%-3.6%, with the increase of soil depth ratio increases, and the depth of40-100cm to2.6%-3.6%, is higher than the surface soil layer soil. Soil dissolved organic carbon and nitrogen ratio was significantly different in different forest types, and the deep layer, the greater the difference. That coastal terrace soil soluble organic carbon, nitrogen leaching by rain intensity, between different forest types of dissolved organic carbon and nitrogen content, there is a big difference in the sensitivity of the rainfall intensity.(6) The organic carbon, soil labile organic carbon, light fraction organic carbon, dissolved organic carbon and nitrogen and soil bulk density had significant or extremely significant negative correlation, there is significant and extremely significant positive correlation with total nitrogen, but with the soil water content, soil pH, soil carbon and nitrogen than the correlation is not obvious, there are significance and different forest types. Soil light fraction organic carbon, readily oxidizable organic carbon, dissolved organic carbon and nitrogen, soil organic carbon, total nitrogen and the two two are closely related, the correlation was significant. |
PDF Full Text Request