长期不同放牧强度下荒漠草原建群种短花针茅(Stipa breviflora)叶片解剖结构变化

Leaf anatomical changes of Stipa Breviflora under long⁃term different grazing intensities in desert steppe

植物叶片解剖结构随放牧强度的变化而发生变化。以短花针茅荒漠草原长期(19年)固定监测放牧样地为研究区,以建群种短花针茅叶片作为实验材料,测量不同放牧强度(对照(CK)、轻度放牧(LG)、中度放牧(MG)、重度放牧(HG))下短花针茅叶片保护组织、输导组织、机械组织、同化组织有关的14个解剖结构指标,分析短花针茅叶片解剖结构随长期不同放牧强度的变化,从生理角度探讨荒漠草原植物对长期放牧的适应及响应。研究结果表明:(1)叶片层次上,短花针茅通过增加其叶片横切面面积和叶厚度去适应放牧干扰;(2)保护组织方面,与对照区相比,重度放牧区角质层厚度增加,但未达到差异显著性(P>0.05),角质层厚度占叶厚度比例随放牧强度的增加整体呈增加趋势;(3)输导组织方面,木质部面积随放牧强度的增加呈下降趋势,而韧皮部面积、主导管面积、维管束面积等指标均随放牧强度的增加呈增加趋势,但没有达到显著性(P>0.05);(4)机械组织方面,厚壁组织面积和厚壁组织占叶面积比例均随放牧强度的增加呈增加趋势;(5)同化组织方面,随着放牧强度的增加,短花针茅叶片叶肉组织面积显著增加(P<0.05)。可见,在长期不同放牧条件下对荒漠草原植物解剖结构进行研究,在丰富荒漠草原放牧生态学研究内容的同时,对脆弱生态系统的合理利用和保护提供科学依据。

The anatomical structure of plant leaves changed with different grazing intensities.Desert steppe which located at the grassland⁃desert ecotoneis an ecosystem that is very sensitive to global changes.Grazing is one of the most important uses of desert grassland.Changes in livestock rates seriously affect the growth and development of plants in desert grasslands.S.breviflora is a desert steppe plant species found widely in central Asia,and is a major forage plant in the desert steppe region of Inner Mongolia.The response of leaf anatomical structure of S.breviflora to grazing intensity can provide a reference for studying the anti⁃interference of dominant species in desert steppe.In this study,a long⁃term(19 years)grazing field in S.breviflora desert steppe was used as the research area,and the leaves of the dominant species S.breviflora were used as the experimental materials.Fourteen anatomical structure indexes related to protective tissue,transport tissue,mechanical tissue and assimilation tissue of S.breviflora leaves under different grazing intensities(CK,LG,MG,HG)were measured to analyze the changes of leaf anatomical structure of S.breviflora with long⁃term different grazing intensities,and to explore the physiological adaptation and response of desert steppe plants to long⁃term grazing.The results showed that:(1)at the leaf level,S.breviflora adapted to long⁃term grazing disturbance by increasing leaf cross⁃sectional area and leaf thickness.(2)In terms of the protective tissue,compared with the control,the thickness of cuticle increased under heavy grazing,but the difference was not significant(P>0.05).The proportion of cuticle thickness to leaf thickness increased with the increase of grazing intensity.(3)In terms of the conducting tissue,xylem area showed a decreasing trend with the increase of grazing intensity,while phloem area,dominant vessel area,and vascular bundle area showed an increasing trend with the increase of grazing intensity.There was no significant difference among different treatments(P>0.05),indicating that the response of productive tissues to grazing disturbance was relatively stable.(4)In terms of mechanical tissue,the area of sclerenchyma and the ratio of sclerenchyma to leaf area increased with the increase of grazing intensity.(5)In terms of assimilation tissue,the area of mesophyll tissue of S.breviflora leaves increased significantly with the increase of grazing intensity(P<0.05).Therefore,the study of plant anatomical structure in the desert steppe under long⁃term different grazing conditions can not only enrich the research content of grazing ecology,but also provide scientific basis for rational utilization and protection of fragile ecosystem.