Growth Characteristics And CNP Stoichiometry Of Two Kinds Of Pearl Forest Protection Forests In Youjiang District

The Project of the Pearl River Basin Shelter Forest is important to the construction of the ecological safety in the Pearl River Basin. At present, the Pearl River Basin Shelter Forest construction scale is expanding constantly, but the scientific research and evaluation are rarely reported.In this study, the Eucalyptus usurphylla forest and Pinus massoniana forest in Youjiang Distric were used to study the growth pattern, biomass productivity, and CNP ecological stoichiometry, which is helpful to the scientific construction and sustainable management of The Project of the Pearl River Basin Shelter Forest. The results show that:(1) The 6-year-old Eucalyp forest growth effect is obviously superior to 6.5 years old Pinus massoniana forest, Eucalyptus forest plant growth of DBH is slightly higher than that of P. massoniana forest, but the former tree height, total volume increment was significantly higher than that of the latter.(2) Eucalyptus forest biomass and productivity were 85.74 t/hm2 and 12.90 t/hm2.a, P. massoniana forest as 33.61 t/hm2 and 3.94 t/hm2.a, respectively.(3) The carbon storages of the 6 year old Eucalyptus forest ecosystem and 6.5 year old pine forest ecosystem were 108.15 t/hm2 and 82.51t/hm2, both of which are soil layer> vegetation layer.(4) The nitrogen reserves of the 6 year old Eucalyptus and 6.5 year old pine forest ecosystem were 9.83 t/hm2 and 9.43 t/hm2, respectively, and the soil layer N reserves were 28.71 times and 35.52 times of the vegetation layer.(5) The phosphorus reserves of the 6 year old Eucalyptus and 6.5 year old pine forest ecosystem were 7.38 t/hm2 and 5.62 t/hm2, respectively. The soil layer phosphorus reserves were 295.9 and 257.5 times of the vegetation layer respectively.(6) C:N ratios in the arbor layer of 6 years old Eucalyptus forest and 6.5 years old of P. massoniana plantation were 12.259 and 157.84. C:P ratio as 1886.16,994.66 respectively. The Eucalyptus trees forest can use relative less nitrogen, phosphorus to fix more carbon than P. massoniana could do.(7) The higher N:P ratio in vegetation layers and the lower N:P ratio of the soil layer were found, which showed that the potential supply capacity of soil nitrogen in the two stands was lower than that of the potential supply of soil phosphorus.