Correlation between non-spatial structure distribution characteristics and productivity of natural coniferous and broad-leaved mixed forests in Zhejiang

Abstract

Objective The objective of this study is to explore the distribution characteristics of non-spatial structure and the correlation between non-spatial structure and productivity of coniferous and broad-leaved mixed forests in Zhejiang Province, so as to provide theoretical basis and technical support for improving forest quality. Method Based on the data of natural coniferous and broad-leaved mixed forest sample plots and sample wood from the consecutive forest resource inventory in 1999, 2004, and 2009, the diameter at breast height(DBH), tree height, volume, and non-spatial structure factors and accumulation per unit area of conifer species were extracted. Patterns of non-spatial structure distribution in each period was modeled to explore characteristics of change. The continuous function method of biomass conversion factor was used to estimate biomass and productivity, and then the partial correlation analysis between non-spatial structure and productivity was performed. Result There existed regular distribution characteristics of forest non-spatial structure factors in different periods. The non-spatial structure factors and productivity showed a positive correlation. From 1999 to 2009, the proportion of coniferous species in the coniferous and broad-leaved mixed forest in Zhejiang Province increased gradually, and the productivity in the first period (1.39 t·hm−2·a−1) was higher than that in the second period (1.15 t·hm−2·a−1). The mean value of DBH, tree height and volume per plant were approximately normal. Conclusion In the management of coniferous and broad-leaved mixed forests, priority should be given to the proportion of coniferous and broad-leaved mixed forest in order to maintain the high productivity of the forest stand. The proportion of species should be kept above 50% and the mixed forests with a low proportion of coniferous species should be artificially intervened. If DBH is lower than 10.00 cm, tending should be strengthened, and if DBH is higher than 12.00 cm, cutting should be carried out in time. The average volume and tree height of per plant should be maintained at 0.040−0.070 m3·plant−1 and 7.00−10.00 m respectively. [Ch, 6 fig. 5 tab. 34 ref.]