固定沙丘生物结皮层藓类植物形态结构及其适应性研究

Morphological and Structural Properties as well as Adaptation of Mosses in Microbiotic Soil Crusts on Fixed Dunes

对腾格里沙漠沙坡头地区及其毗邻区域固定沙丘生物土壤结皮层6种有代表性藓类植物形态解剖结构及其适应性进行了观察和系统分析,结果表明:优势种真藓、土生对齿藓和刺叶赤藓植物体密集丛生,其中真藓和土生对齿藓易于通过茎叶碎片或芽胞进行无性繁殖,其茎的结构中皮部细胞壁明显增厚、中轴分化明显;刺叶赤藓和芦荟藓叶片结构最复杂,刺叶赤藓叶片具两层细胞,细胞密被透明马蹄形细疣,芦荟藓叶片内卷成兜形,中肋扁宽,背部有多层厚壁细胞,腹部着生许多绿色丝体;绿色流苏藓和盐土藓的叶片细胞也发生了明显的分化。藓类植物多样的形态结构特征使其适应沙漠环境中水分缺乏、基质不稳、强光辐射伤害等不利环境因子。植物体集群生长状态是其形态适应性的重要特征,与繁殖过程中植物体的连续分枝和原丝体反复再生及外延生长特性直接相关,个体和种群形态结构上的适应性对减缓细胞内生理条件的剧烈变化,减弱细胞器受损害的程度,加快其生理功能的恢复速度有重要作用。

The adaptive morphological and anatomical structures of 6 species mosses in the soil microbiotic crust on fixed dunes in Shapotou region (37°27′ N, 104°57′ E) of the Tengger Desert and the adjacent region are observed and systematically analysed. The result showed that the plants of the dominant species of Bryum argenteum,Didymodon vinealis and Syntrichia caninervis grow densely. In addition, B. argenteum and D. vinealis, the stems of which have distinct central strand and small obvious incrassation on the sclerenchyma of the external cortex, reproduce easily through the fragments of the plants and gemmae. The leaf structures of Syntrichia caninervis and Aloina rigida are more complex than other species. The leaves of the S. caninervis consist of two layer cells with tiny transparent lycotropal tubercles,while those of A. rigida incurve into packet-shape,the flat costa of which has ventral photosynthetic filaments and dorsal multi-layered thickened-wall cells. The leaf cells of Crossidium chloronotos and Pterygoneurum subsessile also have obvious differentiation. The varied morphological structures of the mosses make possible the endurance to the disadvantageous environmental factors in the desert, such as water shortage, matrix instability and strong ray radiation. The important adaptive properties of tufted distribution of the plants are directly related to the reproductive characteristics of the stems' continual branching and the protonema's repeated and extensive reproduction. All these adaptive properties might also play a very important role in slowing down the acute physiological change in the cells, alleviating the damage to the cellular organ and promoting the rapid recovery of the physiological function.