Abstract:

Abies chensiensis is an endangered tree that occurs primarily in the Qinling Mountain of China and is distributed across a wide range of elevations extending from 1 350 m to 2 500 m. The objectives of our study were: i) to investigate the fruiting and basic characteristics of the cones and the seeds; and ii) to determine how the characteristics of the cones and seeds of Abies chensiensis vary with elevation. Cones of Abies chensiensis were collected from trees in a high elevation and low elevation population. Through field investigations, laboratorial experiments and comparisons with other Abies, it was found that the cones and seeds of Abies chensiensis were bigger than other Abies species and had more seeds per cone but fewer full developed seeds per cone. Also, it was found that only 12.03 percent of the seeds were fully developed under natural conditions; this percentage increased to 21.6% after hand selecting seeds and to 38.1% after machine selection. Other seeds were empty, rigid or worm infested. At higher elevation, the percentage of adult trees that fruited and the number of cones produced per tree was reduced. The mean percentage of fruiting trees was 55% across sites; however, at low elevation, 76% of the trees fruited whereas only 34% fruited at high elevation. The mean number of cones per tree was 113. About 64.5 percent of fruiting trees produced no more than 100 cones with half of them producing 50 to 100 cones. Also, 16.1 percent of the fruiting trees produced from 100 to 200 cones and 19.4 percent produced over 200 cones. Trees with more than 200 cones all grew at low elevations; at high elevation, most trees produced less than 50 cones. Further analyses indicated significant differences in the characteristics of cones and seeds between the two elevations. Most traits were higher at low elevation sites than at higher elevations. From these analyses, we conclude that the reproductive potential of Abies chensiensis was greater at low elevation than at high elevation, most likely due to more suitable climatic conditions, more fertile soils and less steep topography at low elevation.

Key words: Abies chensiensis, Cones, Seeds characteristics, Elevation