陕北撂荒地上优势蒿类叶片解剖结构及其生态适应性

Foliar anatomical structures and ecological adaptabilities of dominant artemisia species of early sere of succession on arable old land after being abandoned in Loess Hilly Region

对陕北丘陵区撂荒地上处于自然恢复演替不同时期的3种优势种蒿类铁杆蒿(Artemisia gmelinii Web.)、茭蒿(Artemisia giraldii Pamp.)、猪毛蒿(Artemisia scoparia)的叶片解剖结构进行了观察研究的结果表明,随着演替序列的发展,3种蒿类的栅栏组织随演替时间的推移呈现出全栅型-环栅型-过渡型的趋势,叶片解剖结构说明越靠近演替前期的蒿类对干旱的适应性越强。此外,3种蒿类的栅栏组织排列都很紧密,表皮细胞排列不规则,且具有表皮毛和腺毛等旱生适应结构;在猪毛蒿和茭蒿中还发现了特化的气腔结构。这些特征均能说明这些蒿类植物具有很好的抗旱适应性,作为环境改造的先锋物种,它们在当地的自然植被恢复演替中起着积极的正向推动作用。

Artemisia species are dominant in early succession of abandonned farm lands in hilly regions of Loess. The faliar anatomy of three Artemisia species belonging to different seral stages was examined. Results showed mesophyll tissue structure differentiation from total-palisade to ring-palisade transitional forms in species of advancing seral stages, illustrating how the adaptability of Artemisia species to dry environments decreases as succession proceeds. In addition, the Artemisia species presented tight alignment of mesophyll ceils and anomalous shapes of epidermal-cells. The leaf surface of all three species had the tentacle and epidermal fur structures often found in drought-tolerant plants. In A. scoparia and A. giraldii, a special air cavity was found in the leaves. The Artemisia species examined are well adapted to dry areas through both anatomical and ecological strategies explaining their important role as the pioneer indigenous plants in the seral succession of Loess hills.