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Pak. J. Bot., 47(3): 911-918, 2015.

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DYNAMICS OF THE POPULATION QUANTITY OF JUGLANS MANDSHURICA MAXIM. IN DIFFERENT HABITATS IN XINJIANG, CHINA

WEI ZHANG^1,2, YUNFEI YANG^1* AND JIANDONG LI¹

Abstract: Transects were arranged on the shady and sunny slopes, as well as at different elevations of the main, eastern, central, and western gullies in the Wild Walnut Nature Reserve in Xinjiang, China to survey a large sample of Juglans mandshurica. The structures of height class and diameter at breast height (DBH) class were used to represent age structure to compare and analyze the dynamics of the population quantity of J. mandshurica in different habitats. Results showed that J. mandshurica population comprises numerous young seedlings, which develop into young plants with a high death rate. The number of adult plants is stable. J. mandshurica population is r-strategists in the young stage, and k-strategists supplemented by r-strategists in the juvenile and subsequent stages. The structures of height class and DBH class fluctuate at different slope aspects and elevations. The growth of young seedlings into adult plants is discontinuous. Tree height and DBH are relatively uniform in the same age class, and the coefficient of variation is independent of slope aspect and elevation. The maximum numbers of age classes in J. mandshurica population with different height and DBH classes differ at three elevations. Low- and medium-age classes are dominant in all situations. That is, population is mainly composed of juvenile and adult trees, and age structure is classified as a growth type. Without strong external interference, J. mandshurica population will maintain its superior position in the community.

Keywords: Juglans mandshurica; Population; Age structure; Slope aspect; Elevational gradient.

１Ministry of Education, Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Changchun 130024, China

２School of Chemistry and Bioscience, Yili Normal College, Yining 835000, China

^*Corresponding author’s e-mail: yunfeiyangcn@126.com; Tel.: +86 431 85099590; Fax: +86 431 85693965