濒危植物秦岭冷杉结实特性的研究

 秦岭冷杉(Abies chensiensis) 是松科冷杉属常绿乔木，为我国特有珍稀濒危植物。该文在秦岭冷杉分布最为集中的秦岭地区分高、低2个海拔高度采集当年球果和种子, 通过野外观察、室内实验和对比分析，研究秦岭冷杉的结实特征以及球果和种子的基本性状，并探讨这些特征在不同海拔高度的差异。结果表明，与冷杉属其它树种相比，秦岭冷杉球果和种子较大、单果种子数较多，但空粒多、饱满度低。自然状况下饱满度为12.0%，人工目视分选后饱满度21.6%，风选后可达到38.1%，其余种子大部分为空粒、涩粒，有少量虫粒。随海拔高度增加，秦岭冷杉天然群体成龄个体中结实母树比例降低，结实量减少。秦岭冷杉总体结实母树比例为55%，低海拔处结实母树比例较高，为76%，高海拔结实母树比例为34%。秦岭冷杉单株母树的平均结实量为113个，结实量小于100个的母树占64.5%，其中50%的母树结实量在50～100个，结实量在100～200个的占16.1%, 200个以上的占19.4%。200个以上球果的个体均生长在低海拔区间，高海拔处结实量多在100个以下。方差分析表明，两个海拔高度间球果和种子特征差异是显著的，绝大部分球果和种子性状指标的平均值在低海拔处大于高海拔处。因此，从结实特性以及球果和种子的特征来看，低海拔处秦岭冷杉生殖生长好于高海拔处。

FRUITING CHARACTERISTICS OF THE ENDANGERED SPECIES ABIES CHENSIENSIS

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.