黄土丘陵区藓结皮优势种形态结构差异

Variation of morphological structure of dominant species in moss crusts in hilly Loess Plateau region

藓结皮对黄土丘陵区生态修复与重建有重要意义。以黄土丘陵区藓结皮优势种土生对齿藓(Didymodon vinealis(Brid.)Zand.)、短叶对齿藓(Didymodon tectorum(C.Mull.)Saito)、扭口藓(Barbula unguiculata Hedw.)和银叶真藓(Bryum argenteum Hedw.)为研究对象,通过形态解剖结构观察分析,研究了4个藓种形态结构差异。结果表明:土生对齿藓株高(6.1 mm)、茎直径(298.6μm)、中肋宽(65.5μm)以及叶宽(590.9μm)、叶片厚度(14.8μm)显著高于其他3个藓种,茎表皮细胞壁增厚且皮部细胞镶嵌排列;短叶对齿藓株高、茎、叶片及毛尖结构无显著优势;土生对齿藓茎和叶片结构粗壮,适应水分变异性大的环境,耐旱能力强;扭口藓叶片长度(3.2 mm)和叶片下部细胞面积(191.2μm2)显著大于其他3种藓类并含有大量叶绿体,中肋深陷呈"v"型,适宜水分充足环境,集水能力强但耐干性弱;银叶真藓茎皮部细胞面积987.8μm2,单个皮部细胞面积占茎横切面积的3.1%,毛尖长度(274μm)显著大于其他3个藓种且叶片上部细胞与毛尖呈透明状,耐旱并抵御强光辐射。以上结果表明,黄土丘陵区4个藓种的茎叶形态结构存在差异,适应水分、光照条件不同,体现了藓种的生态适应性差异,可为藓结皮耐旱藓种和人工培养藓种选择提供参考。

Moss-dominated crusts play important roles in ecological restoration in hilly Loess Plateau region, China. Four dominant moss species Didymodon vinealis （Brid.） Zand., Didymodon teetorum （C. Mull. ） Saito, Barbula unguiculata Hedw. and Bryura argenteum Hedw. in the community of biological soil crusts in the hilly Loess Plateau region were chosen as objects. The morphological and anatomical structure of the four moss species were observed and measured in this study. The results showed that D. vinealis had greater shoot height （6.1 ram）, stem diameter （298.6 txm）, midribs width （65.5 μm）, leaf width （590.9 μm） and blade thickness （14.8 μm） than the other three species; the stem epidermis cell wall of D. vinealis was obviously incrassate and the cortex cells were distributed in a mosaic patteru. D. tectorum did not show significant advantages in its stem and leaf structure. With coarse stems and leaves, D. vinealis had stronger desiccation tolerance than the other three species, and thus it was easy to adapt to the variability of environmental moisture. The leaf length （3.2 mm） and basal leaf cell size （ 191.2 μm2） of B. unguieulata were significantly higher than that of the other three species and contained much more chloroplasts. Their midribs were in sharp ＂v＂ form, and this morphological structure was closely related to their water harvesting. In B. argenteum, the cortex cell area was 987.8 μm2, and single cortex cell accounted ibr approximately 3.1% of stem transverse-sectional area. The leaf hair （274 μm） was significantly longer than that of the other three species and the upper leaf cells and leaf hair of this species were transparent, which endows it to grow in the conditions with periodical drought stress and to resist light radiation. Our study suggested that the differences in stem and leaf morphological structure existed among the four moss species, with different adaptation to various water and light conditions, which may reflect their ecological adaptability. Also, this study may provide reference for species selection in restoration of moss crusts.