Short-term economic benefit analysis under different management modes of Pinus massoniana plantation

  Objective  This paper aims to clarify the differences in the yield and economic benefits of three different management modes in varied specifications of diameter timber, as well as to provide reference for the economic feasibility of forest management projects and forest sustainable development.

  Method  Taking the Pinus massoniana plantation in the Experimental Center of Tropical Forestry, Chinese Academy of Forestry Sciences as the research object, the observation data of the stand for 10 years (2008−2018) under the three management modes of near-natural transformation, conventional management (rotation operation) and control sample plot were selected. The wood values of large, medium and small diameter timber and the seedling value of replanted broadleaved trees were calculated by cash flow and replacement cost method, respectively. Dynamic economic indicators and sensitivity analysis method were used to evaluate the economic feasibility and risk tolerance of the three management modes, and the economic benefits of three management modes were comprehensively compared.

  Result  There were obvious differences in the dynamic changes of wood structure of P. massoniana under the three management modes. From the 2nd to 10th year, the yield of large diameter timber increased from 1.22 to 56.85 m³, the yield of medium diameter timber increased from 23.34 to 79.57 m³, and the yield of small diameter timber decreased from 69.79 to 68.76 m³. In the mode of rotation management, yield of large diameter timber increased from 0.29 to 38.97 m³, the yield of medium diameter timber increased from 22.51 to 90.89 m³, the yield of small diameter timber decreased from 80.69 to 78.83 m³. In the mode of control management, the yield of large diameter timber increased from 0.25 to 27.97 m³, the yield of medium diameter timber increased from 20.95 to 93.69 m³, and the yield of small diameter timber decreased from 189.39 to 181.98 m³. During the past 10 years, the net profit (NP) under the three management modes of the near-naturalized transformed stand, the rotation management stand and the control all showed monotonous increasing trend, and the return on investment (ROI) of the three management modes showed a monotonous increasing trend, first increasing and then decreasing trend according to the above sequence. In the 10th year, the net present value of the near-naturalized transformed stand, the conventional management stand and the control were 594, 265, 193, respectively, the NP was 87 384.96, 85 745.21 and 71 935.09 CNY/ha, and the ROI was 8.02%, 7.92% and 5.95%, respectively. In the past 10 years, the seedling value of broadleaved tree species replanted under the crown continued to increase under the near-natural transformation mode, and the proportion of seedling value to stand economic income (W value) presented the trend of increasing-decreasing-increasing-decreasing. In the 4th−6th year, the fast-growing native tree species such as Quercus griffithii and Manglietia conifera reached the standard of medium and small diameter timber, and the W value decreased to 11.26%. In the 8th−10th year, as the Castanopsis hystrix, Erythrophleum fordii, Michelia hedyosperma and other precious tree species reached the standard of small diameter timber, the W value decreased again to 11.93%.

  Conclusion  The P. massoniana plantation under three management modes are economically feasible investments. The initial cost of near-natural transformation is higher, but it is more conducive to cultivating large diameter timber, promoting the subsequent development and utilization of native precious and fast-growing species resources, and meeting the needs of different markets; the conventional management (rotation operation) tends to single tree species nurturing management, pursuing fast-growing and abundant production and relatively intensive management; the proportion of large diameter timber in the stand without management measures is lower, and natural regeneration is scarce, which is not conducive to the sustainable use of forest resources.