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Inner Mongolia University (2021)

Response of Litter Decomposition to Drought in Typical Steppe

吕梦渊

Titre : Response of Litter Decomposition to Drought in Typical Steppe

Auteur : 吕梦渊

Grade : Master These 2021

Université : Inner Mongolia University

Résumé partiel
As the basic carrier of nutrients,litter is also a collection of various organic matter.The decomposition processes and its function of litter are the key to maintain the carbon balance and material cycle of an ecosystem.Studying litter decomposition process and rate and its responses to environmental changes is of great significance for understanding and projecting the global carbon and nutrient cycles.There are many studies on plant litter decomposition in grassland ecosystem,however,most of them focused on the effects of nitrogen addition and increased rainfall.Our knowledge of responses of litter decomposition to drought in grassland ecosystem is still poor.As the most important natural ecosystem in northern China,the typical steppe in Inner Mongolia will face the challenge of climate change in the future,such as the decrease of precipitation,the extension of the drought period and increase of extreme drought events.Study on litter decomposition in response to different drought scenarios will help us to understand the nutrient cycling processes and mechanisms of the ecosystem under climate change,and provide a scientific basis for improving the nutrient management measures in this grassland in the future.This study explored the effects of different drought scenarios on litter decomposition of three dominant grasses(Leymus chinensis,Stipa grandis,and Cleistogenes squarrosa),a common forb species and the mixture of all species in a community in a typical steppe in Inner Mongolia by analyzing the mass loss and the release of hemicellulose,cellulose,lignin,non-structural carbohydrates(NSC)and macroelements and microelements after 115,352 and 717 days of decomposition.The results showed that :(1)Drought significantly inhibited the decomposition of litter,and the effects of different drought treatment were similar..Mass loss of litter showed a pattern of rapid decomposition in the early stage,and then gradually slow down.(2)There are significant difference among species in litter decomposition.The mass loss and nutrient release rate of forb species were significantly faster than that of grass and community litter during decomposition.During the decomposition process,nitrogen was released from L.chinensis,S.grandis and T.ptaloideum,and concentrated in C.squarrosa and community.K,Ca,Na,Mg,P,Fe,Mn,Cu and Al were accumulated with time in all kinds of litters,but the change of Zn was different among species and showed no consistent pattern.(3)Litter decomposition rate and nutrient release were significantly positively correlated with N concentration(P < 0.001),and negatively correlated with hemicellulose and C/N ratio(P < 0.001),while lignin/N was only negatively correlated with decomposition rate in grass litter.Litter decomposition was also affected by soil moisture,p H,inorganic nitrogen and phosphomonoesterase.This study quantified the litter decomposition rate under different drought scenarios,which is helpful to understand the nutrient cycling process of typical steppe and provide scientific reference for nutrient management of typical steppe

Mots clés : Temperate steppe ;litter decomposition ;drought;nutrient release ;grasses;forb ;

Présentation (CNKI)

Page publiée le 22 octobre 2021