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Ludong University (2019)

Effects of Warming and Changed Precipitation on Litter Decomposition in Horqin Sandy Land

魏建华;

Titre : Effects of Warming and Changed Precipitation on Litter Decomposition in Horqin Sandy Land

Auteur : 魏建华;

Grade : Master’s Theses 2019

Université : Ludong University

Résumé
Since the 1950 s,human activities have had a significant impact on global climate change.The average temperature of the earth’s surface has been rising year by year,and the frequency of extreme drought has been increasing.These changes have resulted in serious economic losses and ecological problems.The effects of climate change on the hydrothermal conditions of ecosystems and biological communities in soil will change the decomposition rate and process of litters.Shrub is one of the most important vegetation types in terrestrial ecosystem.In arid and semi-arid areas of northern China,it plays an irreplaceable role in community succession and regionally ecological environment protection.Dynamic changes of litter decomposition in desert and sandy shrubs in northern China may change nutrient release rate,organic matter formation in soil and ecosystem nutrient balance.The trend of temperature rising and extreme drought will be more apparent in the future.Because litter is very sensitive to temperature and water,the response of exploring desert and sandy shrub litter to climate heating and extreme drought in northern China is particularly urgent.In this study,the experimental site was located in Horqin sandy land in eastern Inner Mongolia.The litter of dominant shrub Artemisia halodendron and Caragana microphylla were selected as the research materials.Quantification of residual mass,C and N content and analysis of microbial OTUs(Operational Taxonomic Units)in litter were carried out.In order to explore the internal mechanism of litter decomposition in response to climate change,we studied the effects of warming and drought on litter decomposition,which will be help for providing scientific basis for vegetation and litter management in shrub ecosystem in China.The main results were as follows :(1)The litter decomposition of A.halodendron and C.microphylla was inhibited by warming,rainfall reduction and their interaction.Compared with the control,the decomposition rates of A.halodendron litter were reduced by 5.10%,9.47% and 16.10% with warming,rainfall reduction and their interaction treatments,respectively.The decomposition rates of C.microphylla litter were respectively reduced by 1.48%,6.40% and 9.00% with the treatments above.The interaction of warming and rainfall reduction had the strongest inhibition effect on litter decomposition.(2)There were significant interspecific differences in the effects of warming,rainfall reduction and their interaction on net C release rate.The net C release rate of A.halodendron litter decreased with warming,rainfall reduction and their interaction.Compared with the control,the net C release rate of A.halodendron litter decreased by 2.13%,8.21% and 11.68% with warming,rainfall reduction and their interaction treatments,respectively.The net C release rate of C.microphylla litter was increased by 4.56% with the warming treatment.The net C release rate of C.microphylla litter was decreased by 12.03% and 12.80% with rainfall reduction and their interaction treatment,respectively.(3)There were significant interspecific differences in the effects of warming,rainfall reduction and their interaction on the net N release rate.There was no significant difference in the net N release rate of A.halodendron litter among different treatments.The net N release rate of C.microphylla litter increased by 4.74% with warming treatment.The net N release rate of C.microphylla litter decreased by 7.40% and 10.75% with rainfall reduction and interaction treatments,respectively.(4)Warming,rainfall reduction and their interaction reduced the diversity and richness of bacterial species in the litter of A.halodendron and C.microphylla.At the level of bacterial phylum,the relative abundance of Proteobacteria in litter of A.halodendron and C.microphylla increased and the relative abundance of Actinobacteria decreased with the warming,rainfall reduction and their interaction.At the level of fungal phylum,the abundance of Ascomycota and Basidiomycota in litter of A.halodendron and C.microphylla increased with the warming,rainfall reduction and their interaction.The difference of litter microbial community was significantly affected by surface and subsurface temperature,surface and subsurface accumulated temperature,soil moisture content(10cm depth),C,N content and mass loss of litter.

Mots clés : Artemisia halodendron; Caragana microphylla; litter; soil organisms; warming; rainfall reduction;

Présentation (CNKI)

Page publiée le 19 novembre 2019