Effects of Different Thinning Intensities on the Growth of Pinus taiwanensis Plantations

Taking the 14-year-old Pinus taiwanensis plantation in the multi-purpose forest management model base of the state-owned Huangbaishan Forest Farm in Henan Province as the research object. Using randomized block method, 4 kinds of thinning intensity were set, and the continuous measurement data of 5 years after cutting was used to study the effects of different thinning intensity on the growth of P.taiwanensis plantation. Results show that T₄₅, T₃₄ and T₂₃ have significant effects on the growth of DBH and volume of P.taiwanensis, and the more obvious the effect is with the increase of thinning intensity. With the increase of thinning intensity, the height and stand volume growth rate of P.taiwanensis shows an increasing trend, but there is no significant among them. Thinning has no significant effect on the growth of both height and stand volume. The descending orde of biomass growth rate of P.taiwanensis plantation are T₄₅, T₃₄, CK and T₂₃, and the mutual difference insignificant, thinning has no significant effect on biomass growth.