Effects Of Alternanthera Philoxeroides And Cladophora Glomerata Litter Input On The Decomposition Of An Aquatic Macrophyte (Zizania Latifolia)

Plant decomposition refers to the process of gradual decay and degradation of litter organisms.For shallow lakes,the decomposition of aquatic macrophyte is an important process of carbon storage and nutrient cycling,which affects the material cycle and energy flow of the entire aquatic ecosystem.In aquatic ecosystems,one of the most important energy sources is the input of litter.Studies have found that the input of plant litter will affect the quality of litter entering the aquatic ecosystem,and this change can affect the composition and structure of the decomposer community(microorganism and invertebrate),and then affect the decomposition of aquatic plant litter,and finally have a direct or indirect effect on the structure and function of the ecosystem.However,it is still unclear whether and how the input of plant litter affects the decomposition of aquatic plants.In addition,compared with terrestrial ecosystems,aquatic ecosystems are rarely studied.In this study,aquatic macrophyte(Zizania latifolia)was used as the research object,and the effects of different types of litter inputs(Alternanthera philoxeroides,Cladophora glomerate)and decomposers(microorganism and invertebrate)and plants(single and mixed)were studied as research content.Using the decomposition bag technique,the effects of litter input types on the decomposition of aquatic macrophyte(Zizania latifolia)and its possible mechanism were investigated by measuring the decomposition rate,microbial respiration rate,invertebrate abundance and richness.The main findings are as follows:(1)The decomposition rate of Zizania latifolia in native habitat is significantly higher than that in invaded habitat,while the decomposition rate of the mixture of Zizania latifolia and Alternanthera philoxeroides is opposite,but whether it is native or invaded habitat,the decomposition rate of the mixture of Zizania latifolia and Alternanthera philoxeroides is significant higher than that of Zizania latifolia.After the litter input of Alternanthera philoxeroides,the time to the maximum respiration rate of the microorganisms involved in decomposition showed a lagging trend,and the correlation between the microbial respiration rate of the experimental materials in the decomposition bag and the dry weight remaining changed from negative to no;Propsilocercus akamusi and Galba pervia are the main dominant species in the process of decomposition.The decomposition of Zizania latifolia in the native habitat lacks the participation of shredders.The decomposition of the mixture of Zizania latifolia and Alternanthera philoxeroides in the native habitat lacks the participation of predators,while in the invaded habitat,it mainly depends on collectors and scrapers.For all the experimental treatments,the abundance and richness of the macroinvertebrate involved in decomposition were negatively correlated with the dry weight remaining,while macro invertebrate abundance were negatively correlated with macroinvertebrate richness in the native habitat,while positively in the invaded habitat.(2)There are significant differences in the initial quality characteristics of Zizania latifolia and Cladophora glomerate,the contents of carbon,lignin,cellulose,hemicellulose,carbon to nitrogen ratio,and carbon to phosphorus ratio of Zizania latifolia are significantly higher than that of Cladophora glomerate;In the decomposition bag with the same mesh size,the decomposition rate of the mixture of Zizania latifolia and Cladophora glomerate was significantly higher than that of Zizania latifolia alone,and the dry weight loss rate of the former was significantly faster than that of the latter;Compared with the individual decomposition of Zizania latifolia,the maximum respiration rate of the microorganism appeared earlier when Zizania latifolia and Cladophora glomerate were mixed;The richness of the macro-and meso-invertebrate involved in the decomposition of Zizania latifolia was less than that of the mixed decomposition of Zizania latifolia and Cladophora glomerate.when the Zizania latifolia were decomposed separately,the relative contributions of macro-,meso-and microinvertebrate to litter dry weight loss were 6.7%,8.37%and 5.61%,respectively,and for the decomposition of the mixture of Zizania latifolia and Cladophora glomerate,which were 12.33%,14.11%,and 9.35%.Sampling time had a significant effect on the relative contribution of macro-,meso-and micro-invertebrate to litter dry weight loss.This study shows that the allochthonous input of Alternanthera philoxeroides significantly reduced the decomposition rate of Zizania latifolia alone,and significantly increased the decomposition rate of the mixture of Zizania latifolia and Alternanthera philoxeroides,and macroinvertebrate play an important role in the effect of Alternanthera philoxeroides allochthonous input on the decomposition of Zizania latifolia.The autochthonous input of Cladophora glomerate significantly increases the decomposition rate of the mixture of Zizania latifolia and Cladophora glomerate,among which,macro-,meso-and micro-invertebrate are involved in the decomposition of aquatic macrophyte litter,their relative contribution to litter dry weight loss is mainly affected by sampling time.This study deeply understands the role of macroinvertebrate in the decomposition of aquatic plants,and provides reference materials for the study of different types of invertebrate-aquatic plant decomposition interactions.