Effects of Tending on Stand Growth and Spatial Structure in Picea asperata Plantation
2018, 33 (12):
Forest tending is the basic requirement of scientific, efficient and sustainable management of forests. Taking two experimental areas of young and middle-aged Picea asperata plantation in Shatan National Forest Park, Gansu as the research objectives, the spatial structure, non-spatial structure of forest after five different adjustment measures and a no-optimizing (control) treatment were investigated and analyzed continuously in six years. The five kinds of tending methods were forsook, sanitary cutting, mechanical thinning (cut one row every one other row, cut one row every two other rows), and ecological thinning measures, hereinafter referred as FJ, WF, JF1, JF2 and SF. In the young forest, we found that forest tending significantly influenced the average DBH of the stand, height, diameter, individual volume and volume growth. After six years, the average stand DBHs tended by FJ , WF, JF1 , JF2 and SF were -0.3, 0.2, 2.1, 4.5 and 2.3 cm higher than that of control trees, respectively. The volume of individual tree tended by FJ , WF, JF1, JF2 , and SF tending measures were 1.2, 1.1, 4.0, 7.8 and 10.2 times higher than that of control trees, and volume growth were 1.5, 1.4, 1.8, 8.1 and 10.4 times higher than that of control trees. In the middle-aged forest, we found that forest tending significantly increased not only the average stand DBH but also the stand volume growth. After six years, the average stand DBHs of trees tended by FJ, WF, JF1, JF2 , and SF were 0.2, 0.3, 2.8, 2.6 and 1.6 cm higher than that of control trees, respectively. The stand volume of trees tended by FJ, WF, JF2 and SF were 2.1, 2.6, 11.7 and 18.2 times higher than that of control trees, respectively, except the stand volume of trees tended by JF1 which increased -16.8 m3/hm2. In addition, the tending measures of SF was the most favorable one in improving the stand volume. The forest tending did not significantly increased the degree of spatial separation, which had less influence on the size differentiation of trees, but it significantly decreased the forest uniform angle index. It was near normal distribution that the left side of the frequency is greater than the right side, and the spatial distribution of stand was adjusted to random distribution or uniform distribution. The results of our comprehensive analysis show that the most effective forest tending measures for Picea asperata plantation is SF and JF2 in young forests whose stand density was 4 500-4 800 trees per hectare, but only SF can used in middle-aged forests whose stand density was 1 630-2 151 trees per hectare. However, to achieve an increase in stand DBH and total volume growth, the stand density should be 3 200-3 500 trees per hectare in young forests and around 1 500 trees per hectare in middle-aged forests.
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