Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Effects of Fire Frequency Treatments on the Karst Rocky Desert Shrub Forest in Central Guizhou,China

Auteur : 代丽

Grade : Master 2022

Université : Guizhou University

Résumé
Fire,one of the most common disturbance factors,has two sides effects to natural ecosystems.Although prescribed fire is known to bring benefits in some ecosystems,fire does not apply equally to all ecosystems.Therefore,this study takes the karst rocky desert shrubs in central Guizhou as the research object,and uses prescribed fire as a means to explore the impact of fire frequency treatment on vegetation and soil,in order to deeply understand the value of fire,provide theoretical basis and technical reference for soil improvement and vegetation restoration of shrubs,and scientifically use fire tools to promote karst rocky desertification comprehensive treatment in the future.The prescribed fire frequency at ending of winter–beginning of spring in 2016-2020 a was set as 3 times（T1）,2 times（T2）and 1 time（T3）of burning in 3 years,and no burning（CK）,4 treatments and 3 repeated experiment design.By observing the plant diversity index,biomass,stand structure index,seedling renewal,soil physicochemical properties and enzyme activity within the end of the year after the fire-treated every year,the effects of different fire frequency treatments on the vegetation and soil,and annual changes of vegetation growth and regeneration status,soil properties and enzyme activities were analyzed.Key findings were as follows:The Pielou index of shrub plants in T1,T2 and T3 treatments showed a slow upward trend year by year.After 3 years of fire-treated,the Margalef index,species number and density of herbaceous plants in T1 and T2 treatments all increased.Different treatments reduced the aboveground biomass of shrub and annual biomass of herbs and litter increased first and then decreased.After 4 years of fire-treated,compared with CK,different fire-treated frequencies treatments resulted in a decrease for ground diameter and plant height in shrub,along with a decrease for crown width in shrub at T2 and T3 treatments,and an increase and decrease for height in herb at T2 and T3 treatments,respectively.During the years,T1 treatment reduced ground diameter,plant height,under-branch height and crown width of shrub,while new stem thickness and length increased ;T2 treatment reduced ground diameter,under-branch height,crown width of shrub and herb height ;T3 treatment reduced the under-branch height of the shrub.Under different treatments,the renewed seedlings density of shrub showed an upward trend during the whole years,and the spatial distribution pattern showed a clustered distribution.Annual changes in different treatments resulted in an overall increase in soil density and an overall decrease in water holding capacity and porosity,accompanied by first decreased and then increased for organic matter,total nitrogen and hydrolyzed nitrogen total potassium and available potassium content,cation exchange capacity and exchangeable bases,along with total phosphorus decreased and available phosphorus increased overall,together with an overall decrease for urease activity and catalase activity,and with first increased and then decreased for the sucrase activity and with decreased first and then increased for the alkaline phosphatase activity.Overall,different fire frequency treatments weakened the correlation between topsoil fertility and shrub growth

Mots clés : Fire frequency treatment ;Karst rocky desert shrub forest ;Plant diversity ;Biomass;Stand structure ;Soil physical and chemical properties ;Soil enzyme activity ;

Présentation (CNKI)