Variation in radial growth and wood density of Cyclocarya paliurus across its natural distribution

Abstract

As a multiple function tree species, Cyclocarya paliurus is planted and managed for timber production and medicinal use. However, it remains unclear to what extent geographical gradients in growth and wood quality are shaped by the environment. We used data of 197 trees from 22 natural populations to assess geographic variation patterns in radial growth and wood density, and their correlations with environmental factors. Significant differences in mean annual DBH and wood basic density were observed among the 22 populations (p < 0.05). Based on mean annual DBH and wood basic density, the 22 populations were classified into three groups by hierarchical cluster analysis. Within its natural distribution, soil nutrients are more closely associated with DBH growth than are temperature and precipitation. However, correlations between wood density versus altitude and annual precipitation were found (p < 0.01). Trend surface analysis revealed that mean annual DBH growth and wood density displayed an increasing trend from north-west to south-east across its natural distribution. Our study provides valuable insights into the geographical patterns in growth and wood quality of C. paliurus, and an opportunity to improve tree growth and wood quality through phenotypic selection and selecting suitable sites for planting.