Comparison of Spatial Structure and Competitiveness of Tsoongiodendron odorum in Bamboo-wood Mixed Forest

From March to May 2020, three selection cutting methods (HW, HE, JW) were adopted in the bamboo-wood mixed forest in Xiayang Township, Mingxi County, Fujian Province.The survey, taking forest stand without tending cutting as the control check, Tsoongiodendron odorumas the observation group, and four trees adjacent to Tsoongiodendron odorumas competing trees, got the main indexes of spatial structure, including mixing degree (M_i), angular scale (W_i) and density (C_i), which were analized by Hegyi competition model to calculate the competition index of Tsoongiodendron odorum.The results showed that the M_i, W_iand C_iof Tsoongiodendron odorum in the control group were 1.0, 0.6667 and 0.7083 respectively, which was regarded as extremely heavy mixed forest with clumpy and dense distribution.The competition index of trees at the same height level is basically higher than that of woods with selection cutting treatment.The competitiveness of Tsoongiodendron odorum is low due to unreasonable spatial structure, because the Tsoongiodendron odorum are covered and occupied space by the competing trees, mainly Phyllostachys heterocycla.Tsoongiodendron odorum with HE treatment(with the target trees as the center and all competing trees within a radius of 2 m) had the best effect, the M_i, W_iand C_iof which were 1.0, 0.3125 and 0.2500.The mixing degree was still extremely severe, but the distribution pattern was uniform and open, and the competition index of the same height class was significantly reduced.Tsoongiodendron odorum competitiveness increased; the average competition index of Tsoongiodendron odorum with different height classes is different.When the height is less than 10~12 m, the average competition index of Tsoongiodendron odorum is basically higher than 0.5.When the height is higher than 10~12 m, the competition index of Tsoongiodendron odorum is between 0.1280 and 0.4870.The competition index decreases significantly and tends to be stable, and the competitiveness of Tsoongiodendron odorum is enhanced.Based on the survey, it is necessary and key technical measures to take manual intervention before the height of Tsoongiodendron odorum reaches 10 m.