青藏高原东缘野生暗紫贝母形态特征对高山环境的适应

Morphological adaptation of wild Fritillaria unibracteata to alpine conditions in the eastern Qinghai-Tibet Plateau

通过分析海拔梯度、群落类型、群落盖度和生活史阶段4个变量对暗紫贝母形态特征的影响,探讨不同环境因子与生活史阶段对暗紫贝母形态特征的综合效应,并主要探究不同海拔梯度和生活史阶段其形态特征的差异.结果显示:1)海拔梯度和生活史阶段对暗紫贝母株高、单叶面积和比叶面积的影响差异极显著(P<0.01),且存在明显的交互作用.2)各生活史阶段暗紫贝母形态特征对海拔梯度变化响应趋势相似,株高、鳞茎的横轴与纵轴长、单叶面积和比叶面积均随海拔的升高而极显著(P<0.01)降低.3)暗紫贝母形态特征随其生长发育差异明显:株高随生活史阶段的增加极显著(P<0.01)增加,鳞茎横轴和纵轴长则表现出先增加后减小的趋势,而单叶面积和比叶面积随之极显著(P<0.01)减小.研究表明,暗紫贝母长期生长于严酷的高山环境中,在形态方面形成了一系列的适应策略.对这些策略的揭示无疑有助于了解青藏高原东缘多年生高山草本植物变异的普遍规律,同时为名贵中药材"松贝"的最佳生长条件选择提供理论参考.

Fritillaria unibracteata is a liliaceous perennial forb, mainly distributed in the alpine belt of the eastern Qinghai- Tibet Plateau. Because of the over-harvest due to its prominent medicinal value, F unibracteata is becoming endangered in its native habitats. It is important thus to understand the ecological adaptation of F. unibracteata to alpine conditions, which may hopefully promote conservation of its wild populations. This study aimed at answering three scientific questions regarding F. unibracteata： 1） Whether environmental factors in alpine belt and the current life stages of the plant affect the morphological characteristics？ 2） How do the morphological characteristics change along with altitudinal gradients？ and 3） How do the morphological characteristics vary during the growth and development of the plant？ Field sampling survey was carried out to collect wild F. unibracteata at different elevations in the alpine belt of Songpan County. Plant height （PH） was measured in the field. Collected samples were cleaned and different organs separated in the laboratory; the horizontal axis length （HAL） and vertical axis length （VAL） of bulbs, single leaf area （LA） of F. unibracteata were measured. Then, the measured leaves were weighed after oven dry at 65 ~C to calculate the specific leaf area （SLA）. The results showed that both elevation and life stage significantly affected PH, LA and SLA, and the interaction between elevation and life stage was significant. Besides, the morphological characteristics of F. unibracteata presented obvious spatial and temporal variations. Firstly, the PH, HAL and VAL of bulbs, LA and SLA of F. unibracteata decreased strikingly in response to altitudinal changes at all life stages. In fact, altitude with the increase of elevation, showing a similar tendency gradient representing a temperature factor was important in limiting the growth and development of alpine plants such as F. unibracteata. Secondly, with the shift of life stages, the PH increased obviously. Both the HAL and VAL of bulbs increased at first and then decreased with the advance of life history. The LA and SLA, however, showed a decreasing trend along with the growth and development of plants. The results indicated that the morphological characteristics of F. unibracteata can adjust to the alpine environmental variations, which is important for their long-term survival in such a harsh environment.