The Variation And Trend Of Needle Trait Indexes Of Pinus Tabulaeformis Carr. Geographic Populations

The objectives of this study were to investigate the patterns of phenotypic variation in needle traits in Pinus tabulaeformis natural populations throughout its range, and to better understand the relationships between the phenotypic variation and geo-climatical factors. We studied 16 needle traits in 15 natural populations, including apparent, anatomical traits and comprehensive traits. The 16 characters are needle length (NL), needle width (NW), needle thickness (NT), stomatal rows number (SRN), number of stomata on 2 mm long stomata row (SR2N), resin canals number (RCN), needle section perimeter (NSP), needle section area (NSA), vascular tissue width (VBW), vascular tissue thickness (VBT), vascular tissue perimeter (VBP), vascular tissue area (VBA), needle volume (NV), needle surface (NS), the ratio of needle volume to needle surface (VSN), needle stomata density (NSD), the ratio of NSA to VBA (YQJB), the ratio RCN to YQJB (ZYB), the ratio of NSD to YQJB (QYB) and the ratio of RCN to NSD (ZQB). The obtained data was statistical analyses. The results showed that there were significant differences among populations and within populations for needle traits. The mean phenotypic differentiation coefficient (VST) was 33.74%, which was less than that of within populations. The coefficients of variation of the 20 phenotypic traits ranged from 7.71% to 26.86%, the NSP, NW, NT, VSN and YQJB were the comparatively stable traits, while the RCN, VBA, NV. NS. QYB. ZQB. NSD and ZYB were the comparatively variable traits. Most of the needle traits showed geographical variation, some traits were correlated with longitude(such as NT, SRN, RCN, VBT, VBA, QYB,ZQB,NSD and YQJB), or with latitude (such as NT and VBT), or with altitude (such as NL, SR2N, RCN,QYB. ZQB and YQJB) in spatial distribution. Most needle traits showed a significantly positive correlation with Gorcynski's continentality index(k). The relationship between geographic distance matrix and the values of 16 needle phenotypic traits matrix between paired populations analysed by Mantel test indicated no significant relationship (rM≤0.14). The 15 natural populations of P. tabulaeformis were divided into two large groups according to discriminant analysis, PCA and cluster anslysis, and there were significant differentiation between central populations and peripheral populations.