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Abstract• This study analyses the sex ratios, and the effect of gender, neighboring competition and habitat factors on the stem growth of dioecious F. mandshurica trees in the Changbai Mountains of NorthEastern China.• The general sex ratio of the flowering trees did not significantly deviate from 1:1. The sex ratio varied among age classes. A female-biased sex ratio was found in the age classes of 65-75 years and 85-95 years, but departure from 1:1 was not significant in other age classes.• An analysis of variance revealed that the growth rate was extremely sensitive to gender and tree size, as shown by a highly significant gender-related and size-dependent effect. Male trees had a faster stem growth rate than female trees, and the assumption is that trade-offs between reproductive and vegetative processes can induce the difference in stem growth rate between genders.• Stem growth rates are positively affected by soil moisture and tree size for both genders at all considered neighborhood distances. The growth rates of female trees were negatively affected by neighboring competition from other female trees at all neighborhood distances between 1 and 10 m, but were not significantly affected by male trees. The growth rates of male trees were negatively affected by neighboring competition from male trees for neighborhood distances between 3 and 10 m, but were not significantly affected by female trees.• These results suggest that intrasexual competition (male-male competition and female-female competition) may cause difference in stem growth for both genders. Intersexual differences in sensitivity to neighboring plants are considered to be an important factor driving gender-specific growth patterns. Mots-clés :modèle causal / croissance de la tige / concurrence intra-sexuelle / sex-ratio / espèces dioïques Résumé -Genres, compétition des voisins et effets de l'habitat sur la croissance des tiges des arbres dioïques chez Fraxinus mandshurica dans une forêt tempérée du Nord-Est de la Chine.• Cette étude analyse le sex-ratio, et les effets du genre, de la compétition des voisins et des facteurs de l'habitat sur la croissance de la tige des arbres dioïques chez Fraxinus mandshurica dans les montagnes de Changbai dans le Nord-Est de la Chine.• Le sex-ratio général de la floraison des arbres ne s'écartait pas de façon significative de 1:1. Le sex-ratio a varié entre les classes d'âge. Une tendance femelle du sex-ratio a été trouvée dans les classes d'âge 65-75 ans et 85-35 ans, mais l'exception 1:1 n'était pas significative dans les autres classes d'âge.• Une analyse de variance a révélé que le taux de croissance était extrêmement sensible au genre et à la taille des arbres, démontré par une liaison significative avec le genre et des effets dépendants de la taille. Les arbres mâles avaient un taux de croissance de la tige plus rapide que celle des arbres femelles, et l'hypothèse est que des compromis entre processus reproductifs et processus végétatifs peuvent induire la différence dans les taux de croissance entre les ...

Abstract:The sensitivity of Betula ermanii tree-ring growth to climate variation over an altitudinal gradient was assessed. Betula ermanii forest grows in the northern slope of Changbai Mountain from approximately 1,700 m above sea level (a.s.l.), and forms the upper tree line at nearly 2,100 m a.s.l.. Six study sites were constructed along the altitudinal gradient (1,670 to 2,010 m a.s.l.) and ring-width chronologies of Betula ermanii were built. The mean tree-ring series intercorrelation (RBAR) increased with elevation. In principal component analysis, the first unrotated principle component explained 77.1% of the total variance, indicating the tree-ring growth of Beutla ermanii over the altitudinal gradient was governed by regional climate. Correlation function analysis revealed that the radial growth of Betula ermanii was significantly similar in response to climatic conditions.

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