淮北相山不同群落中3种禾草叶片的生态解剖

对淮北相山早期恢复演替系列中3种禾草叶片的解剖观察表明,荩草和黄背草为C4植物,其叶片表皮厚,叶肉细胞形态相同,气孔主要分布在下表皮,“花环型”维管束。远东芨芨草为C3植物,其叶片表皮薄,近上下表皮的叶肉细胞呈栅栏状,气孔主要分布在上表皮,维管束鞘由一层厚壁细胞和一层薄壁细胞组成。3种禾草的叶片结构都随群落的恢复演替而表现出较大的可塑性,可塑性大小依次为:远东芨芨草(0.24)>黄背草(0.19)>荩草(0.17)。与混交林相比,灌丛和灌草丛群落中植物叶片更趋于旱生特征:角质层厚度、表皮厚度、叶片厚度以及维管束厚度等显著增加,气孔变小。逐步多重回归分析表明,土壤含水量和风速是影响叶片结构的主导因子。随着土壤含水量的增加,荩草的上下表皮厚度、叶片厚度、叶肉组织厚度,远东芨芨草的叶片厚度和叶肉组织厚度,黄背草的上表皮厚度和维管束厚度均呈减小趋势。随着风速的增加,荩草下表皮气孔长度、黄背草的上表皮气孔长度逐渐变小,远东芨芨草维管束呈增大趋势。因此,叶片的解剖特征反映了不同群落中植物的生态适应特性,可作为研究群落演替机理的重要手段。

Leaf ecoanatomy of three Gramineae species in different communities in Xiangshan Mountain,Huaibei,China

The results of eco-anatomic observation on leaf blades of 3 Gramineae species in early successional communities in Xiangshan Mountain,Huaibei,China,indicated that Arthraxon hispidus and Themeda japonica(C4 plants),share characteristics of thicker epidermis and homomorphism mesophyll cells with stomata mostly distributed in the upper epidermis and with "Kranz-type" vascular bundle sheaths.Achnatherum extremiorientale(C3 plant) on the other hand,is characterized by a thinner epidermis,mesophyll cells near the epidermis that are palisade-like,stomata are mostly distributed in the lower epidermis,and the vascular bundle sheath consists of one layer of parenchyma cells and one layer of sclerenchyma cells.In different successional communities,the lamina of 3 Gramineae species showed great anatomical plasticity in the order: A.extremiorientale(0.24)>T.japonica(0.19)>A.hispidus(0.17).Compared with mixed forest,the leaves collected in the shrub and shrub-herb tend to have more xeromorphic features such as thicker leaf and epidermis,mesophyll,and vascular bundles,and smaller stomata.The result of stepwise multiple regressions indicated that lamina structure is commonly influenced by many environment factors,of which soil water content(SWC) and wind velocity(WV) are the principle factors.With an increase of SWC,thickness of upper and lower epidermis,leaf and mesophyll thickness of A.hispidus,leaf and mesophyll thickness of A.extremiorientale,thickness of upper epidermis and vascular bundle of T.japonica are all reduced.With the increase of WV,the stomatal length in the lower epidermis of A.hispidus,and in the upper epidermis of T.japonica were reduced,but the thickness of the vascular bundle of A.extremiorientale increased.The stomatal length in the lower epidermis of A.extremiorientale decreased with the degree of coverage.