【作者】 王鑫；

【导师】 叶晓馨；

【作者基本信息】 安徽大学 ， 生态学， 2023， 硕士

【摘要】 消落带作为湿地生态系统的一部分,是陆地生态系统和水生生态系统的过渡地带,在抵御洪水、调节气候和控制径流等方面起着重要作用。消落带丰富的植物资源为水鸟提供了高效的觅食场所,湿地植被作为初级生产者,在湿地中占据着重要生态位,是湿地生态状况最直接的指示器。湿地植物群落中优势种的相对生物量及其特定性状主导着生态系统过程的动态变化。因此研究消落带优势种植物在鸟类不同取食强度下的性状变化和响应机制对维持湿地生态系统的健康发展具有重要意义。本文以典型消落带优势种陌上菅(Carex thunbergii)为研究对象,通过不同围封时间的鸟类取食试验来分析群落组成、陌上菅的形态性状和化学计量特征如何响应鸟类取食。同时通过陌上菅与虉草(Phalaris arundinacea)的室内混合培养试验,明确两种植物在不同刈割高度模拟的鸟类取食下的叶绿素荧光、形态特征、抗氧化性、非结构性碳水化合物、化学计量特征的变化机制,分析不同刈割强度对陌上菅与虉草性状和竞争能力的影响。主要得出以下结论:(1)适度取食可以提高苔草群落的α多样性指数,丰富度、辛普森指数和香农多样性指数均在取食2个月下最高。取食2个月下的物种丰富度为5,取食1个月下的香农多样性指数比取食2个月下低55.80%,辛普森指数低57.40%。(2)不同取食时间显著影响陌上菅的形态性状,株高、根长(RL)、根表面积(RSA)、根体积(RV)、节点数(NL)和尖端数(NT)都随着取食时间的增加呈小型化。随着取食时间的增加,陌上菅根中的N和P浓度呈单峰变化,陌上菅的干重随着取食时间的增加而下降。与对照相比,叶干重在取食4个月下下降了27.70%,根干重下降了45.60%。结构方程模型表明:陌上菅根干重99%的变异由株高、比叶面积、根冠比、根长、节点数和叶干重引起,鸟类取食通过根长和根冠比间接影响根干重。(3)多年生陌上菅较虉草更具有竞争优势,但刈割使两者生物量都有所下降,在竞争生长下,陌上菅与虉草生物量的比值随刈割强度的增加而增加,在重度刈割下,陌上菅叶片和根系的N含量显著高于对照组;比叶面积结果表明,陌上菅和虉草的比叶面积都随着刈割强度的增强而增加,且两者在竞争生长下的比叶面积高于单独生长下。在刈割处理下,陌上菅的根冠比明显增加,陌上菅比虉草根部竞争力强。(4)适度刈割有利于提高陌上菅的PSII光活性,在单独生长下,随着刈割强度的增加,陌上菅的原初光能转化效率(Fv/Fm)、光化学淬灭系数(q_p)和电子传递速率(ETR)都呈先升高后降低的趋势,非光化学淬灭系数(NPQ)呈先降低后升高的趋势,非结构性碳水化合物的结果表明,在竞争生长中,陌上菅的根系碳水化合物增加,更容易捕获养分和水分,而虉草的叶片碳水化合物增加,更容易吸收光能;此外,叶片超氧化物歧化酶(SOD)和过氧化氢酶(CAT)随刈割强度的增加而增加,丙二醛(MDA)含量降低;对陌上菅来说,竞争生长下的SOD和CAT高于单独生长。刈割处理下陌上菅的表型可塑性更高,更能适应鸟类取食的环境。本研究探讨了鸟类取食对陌上菅的影响及刈割模拟的鸟类取食对陌上菅和虉草性状和竞争能力的影响,该研究结果对评估消落带优势种对鸟类取食的响应以及湿地植物种物多样性保护具有一定的参考价值。更多还原

【Abstract】 As a part of wetland ecosystem,the riparian zone is a transition zone between terrestrial ecosystem and aquatic ecosystem,which plays an important role in flood resistance,climate regulation and runoff control.The abundant plant resources in the riparian zone provide efficient foraging sites for waterbirds.As a primary producer,wetland vegetation occupies an important ecological niche in wetland and is the most direct indicator of wetland health.The relative biomass and specific traits of dominant in wetland plant communities dominate the dynamic changes of ecosystem processes.Therefore,it is of great significance for the healthy development of wetland ecosystem to study the changes of traits and response mechanism of dominant species in riparian zone under different foraging intensity of birds.Carex thunbergii,the dominant species in a typical riparian zone,was selected as the research object.Exclosure experiments were conducted to investigate the effects of bird foraging on the plant community composition,as well as on the traits and stoichiometric characteristics of C.thunbergii.Additionally,mixed culture experiments were conducted with C.thunbergii and Phalaris arundinacea to investigate the changing mechanisms of chlorophyll fluorescence,morphological characteristics,antioxidant enzyme activities,non-structural carbohydrates,and stoichiometric characteristics of the two plants under different mowing heights.The effect of different mowing heights on the traits and competitive ability of C.thunbergii and P.arundinacea were analyzed.The main conclusions are as follows:(1)Moderate foraging could increase theαdiversity index of Carex community,with the highest values of species richness,Simpson’s index,and Shannon-Wiener diversity index observed after 2 months of foraging.Specifically,the Shannon-Wiener diversity density index and Simpson’s index were 55.8%and 57.4%lower,respectively,under 1 month of foraging compared to the values obtained after 2 months of foraging.(2)The morphological traits of C.thunbergii were significantly affected by different foraging time.As the foraging time increased,the plant height,root length(RL),root surface area(RSA),root volume(RV),the number of tips(NT),and the number of links(NL)were reduced.The concentrations of nitrogen(N)and phosphorus(P)in the root of C.thunbergii followed a unimodal curve with increasing foraging time.Additionally,the dry weight of C.thunbergii decreased with increasing foraging time.For instance,after 4 months of foraging,leaf dry weight decreased by 27.70%,and root dry weight decreased by 45.60%compared to the control.Further analysis using a structural equation model(SEM)revealed that 99%of the variation in root dry weight was caused by multiple factors,including plant height,specific leaf area(SLA),root-shoot ratio(RSR),RL,NL,and leaf dry weight.Moreover,bird foraging indirectly affected root dry weight through RL and RSR.(3)C.thunbergii had a competitive advantage over P.arundinacea,but mowing decreased the biomass of both species.Under mixed culture,the ratio of the biomass of C.thunbergii to P.arundinacea increased with increasing mowing intensity.The N content of C.thunbergii in leaves and roots under heavy mowing was significantly higher than that of control.Additional,the SLA of both species increased with increasing mowing intensity,and the SLA of both species was higher under mixed culture than under monoculture.Under mowing treatments,the RSR increased significantly,with the roots of C.thunbergii being more competitive than those of P.arundinacea.(4)Moderate mowing was beneficial to improve the PSII photoactivity of C.thunbergii.Under monoculture,the primary light conversion efficiency(Fv/Fm),photochemical quenching coefficient(q_p)and electron transport rate(ETR)initially increase and then decrease with increasing mowing intensity,while the non-photochemical quenching(NPQ)firstly decreased and then increased.The root carbohydrate of C.thunbergii increased,enabling it to capture nutrients and water more effectively,while the leaf carbohydrate of P.arundinacea increases,allowing it to absorb more light energy.The superoxide dismutase(SOD)and catalase(CAT)levels in C.thunbergii increase with increasing mowing intensity,while malondialdehyde(MDA)content decreases.SOD and CAT levels are also higher in C.thunbergii under mixed culture than under monoculture.Overall,the results suggest that C.thunbergii exhibits higher competitive ability and phenotypic plasticity under mowing treatments,making it more adaptable to environments where birds are foraging.In this study,the effects of bird foraging on C.thunbergii and mowing simulated bird foraging on the characters and competitive ability of C.thunbergii and P.arundinacea.The results of this study have a certain reference value for evaluating the response of dominant species in riparian zone to bird foraging and for the conservation of wetland plant species diversity.更多还原