黄土高原不同植被带内草地植物叶片解剖性状的变异规律

叶片作为植物与外界进行物质交换的桥梁，其解剖性状能够相互协调以应对外界环境对植物生长造成的不利影响，从而反映出植物对环境变化所采取的适应策略。通过对黄土高原不同植被带(森林草原带、典型草原带、荒漠草原带)草地群落中常见115种植物(包括单子叶植物，双子叶植物，木本植物和草本植物四种功能型植物)叶片进行取样，并运用石蜡制片技术和光学显微技术获得叶片解剖性状(包括表皮厚度、栅栏组织厚度、海绵组织厚度、叶肉厚度和叶片厚度),旨在研究不同植被带内草地植物叶片解剖性状的变异规律及其与群落内物种相对优势度之间的关系，为黄土高原植被恢复和生态环境改善提供理论依据。结果表明：(1)沿着干旱梯度，从森林草原带、典型草原带到荒漠草原带，除叶肉厚度外，植物各叶片解剖性状值均呈现增大趋势，表明干旱地区叶片的旱生结构特征明显。(2)不同功能型植物叶片解剖性状与环境因子的关系各异。木本植物和草本植物的栅栏组织厚度和栅海比均与降水和土壤养分呈显著负相关关系(P<0.05)。同时，木本植物的叶片厚度与水分呈显著负相关关系(P<0.05),而草本植物表皮厚度仅与土壤养分呈显著负相关关系(P<0.05)...

Variation in leaf anatomical traits of grassland plants in different vegetation zones on the Loess Plateau

As a bridge connecting plants and the external environment, leaves can coordinate each anatomical traits to deal with the adverse effects of extrinsic factors on plant growth. Therefore, variation in leaf anatomical traits reflecting the adaptation strategies of plants to the environmental changes. In this study, the leaves of 115 common plants (including monocotyledonous plants, dicotyledonous plants, woody plants and herbaceous plants four functional types of plants) from different vegetation zones (including forest-steppe, steppe and desert-steppe) on the Loess Plateau were sampled, and the leaf anatomical traits (including epidermal tissue thickness, palisade tissue thickness, sponge tissue thickness, mesophyll tissue thickness and leaf thickness) were measured by using paraffin sectioning technique and optical microscopy technique. We aimed to examine the variation in leaf anatomical traits and their relationships with the each species'' relative dominance within communities of different vegetation zones, in order to provide theoretical basis for vegetation restoration and ecological environment improvement on the Loess Plateau. Our results showed that, except mesophyll tissue thickness, other six parameters of anatomical traits increased from forest-steppe to steppe and desert-steppe, indicating that the xerophytic characters of leaves became more obvious in these habitats which had less precipitation. Moreover, the environmental influences on leaf anatomical traits differed among different plant growth and cotyledon types. The palisade tissue thickness and palisade-spongy tissue thickness ratio were significantly negatively correlated with precipitation and soil nutrients for both herbaceous and woody species (P<0.05). However, the epidermis tissue thickness of herbs was only significantly negatively correlated with soil nutrients (P<0.05), and the mesophyll tissue thickness of woody species was significantly negatively correlated with precipitation (P<0.05). For dicotyledons, the thickness parameters of anatomical traits (expect for sponge tissue thickness and mesophyll tissue thickness) were significantly negatively correlated with precipitation and soil nutrients (P<0.05). However, environmental factors didn''t exert significant influences on the leaf anatomical traits of monocotyledons (P>0.05). In addition, the relationships between leaf anatomical traits and species'' dominance differed among different vegetation zones. Specifically, the species dominance was significantly negatively correlated with mesophyll tissue thickness and leaf thickness in forest-steppe (P<0.05), indicating that these plants with thin-leaves were more competitive than those plants with thick leaves in this zone. In desert-steppe, there was a significantly positive correlation between species dominance and palisade tissue thickness, which suggests that stronger photosynthetic capacity the species had, higher competitiveness they could own (P<0.05). However, no significant correlation between species dominance and leaf anatomical traits was observed in steppe (P>0.05).