Abstract

The morphological and anatomical traits of needles are important to evaluate geographic variation and population dynamics of conifer species. Variations of morphological and anatomical needle traits in coniferous species are considered to be the consequence of genetic evolution, and be used in geographic variation and ecological studies, etc. Pinus tabuliformis is a particular native coniferous species in northern and central China. For understanding its adaptive evolution in needle traits, the needle samplings of 10 geographic populations were collected from a 30yr provenience common garden trail that might eliminate site environment effect and show genetic variation among populations and 20 needle morphological and anatomical traits were involved. The results showed that variations among and within populations were significantly different over all the measured traits and the variance components within population were generally higher than that among populations in the most measured needle traits. Population heritabilities in all measured traits were higher than 0.7 in common garden sampling among populations. Needle traits were more significantly correlated with longitude than other factors. First five principal components accounted for 81.6% of the variation with eigenvalues greater than 1; the differences among populations were mainly dependent on needle width, stomatal density, section areas of vascular bundle, total resin canals, and mesophyll, as well as area ratio traits. Ten populations were divided into two categories by Euclidean distance. Variations in needle traits among the populations have shown systematic microevolution in terms of geographic impact on P. tabuliformis. This study would provide empirical data to characterize adaptation and genetic variation of P. tabuliformis, which should be more available for ecological studies.

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