Planting spacing affects canopy structure, biomass production and stem roundness in poplar plantations
2018
Tun, Tet Nay | Guo, Jiao | Fang, Shengzuo | Tian, Ye
To improve the productivity and wood quality of poplar plantations, effects of four planting spacing on canopy characteristics, biomass production and stem roundness in poplar plantations were evaluated over 8 years. Planting spacing influenced canopy characteristics of the plantations, and further affected the understory vegetation and plantation productivity. Understory vegetation biomass and Shannon-Wiener index were negatively correlated with leaf area index, but both diversity indexes and aboveground biomass of understory vegetation were higher in stands with a wider spacing. Tree diameter growth increased with increasing planting spacing, while the increment in plantations of square configurations (5 × 5 m and 6 × 6 m) was higher than those with rectangular configurations (3 × 8 m, 4.5 × 8 m). The highest poplar biomass production was achieved in the plantation with 5 × 5 m spacing at age 8. Moreover, poplar trees showed a tendency with better stem roundness in a square configuration. The results suggest that planting spacing not only affect canopy characteristics, understory vegetation and tree growth but also wood quality, and square configurations (5 × 5 m and 6 × 6 m) could be a better option for poplar plywood timber production at similar sites.
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