Effects of eucalypt plantation replacing masson pine nature forest on the carbon accumulation of forest ecosystems.

Eucalyptus grandis ×E. urophylla plantation (10 a) and Pinus massoniana nature forest (15～20 a) in the south area of Qinzhou in Guangxi were taken as the research object,using the average wood and quadrant harvesting biomass method,and collecting samples of plants and soil samples respectively,using potassium dichromate hydro-heat in determination of the content of carbon,to explore effects of Eucalyptus grandis ×E. urophylla plantation replacing Pinus massoniana nature forest on the forest ecosystem carbon content,carbon accumulation and its distribution. The results showed that the average carbon content of Eucalyptus grandis ×E. urophylla (The organs biomass-weighted) is 47.32%,5.7% lower than that of Pinus massoniana(50.17%).The total carbon accumulation of Eucalyptus grandis ×E. urophylla plantation is 123.086 t/hm2,which is 1.40 times that of Pinus massoniana nature forest (88.238t/hm2);its vegetation (including litter)biomass is 115.082 t/hm2,which is 2.83 times that of Pinus massoniana nature forest (40.686 t/hm2) and the carbon accumulation is 53.712 t/hm2,which is 2.77 times that of Pinus massoniana nature forest (19.421 t/hm2),there are extremely significant differences (p0.01).The diversity in carbon accumulations between the two kinds of forest vegetations and that between the biomasses are consistent,which indicates that if Eucalyptus plantation replaces Pinus massoniana nature forest the productivity and the carbon sequestration capacity of the forests will be improved.