Study On The Changes Of Three Dominant Herbaceous Plant Communities In Tian-E-Zhou Wetland,Shishou City

Tian-E-Zhou Mi Lu Deer Reserve is a national nature reserve with the main purpose of the protection of Milu deer,in which there are abundant animal and plant resources.Recently,due to the increase of Milu deer population,wetland environment and climate change,It led to obvious degradation of wetland plant community in Tian-E-Zhou Mi Lu Deer Reserve.Based on this,three dominant herbaceous plant communities(Hemarthria altissima community,Carex argyi community,Phragmites australis+Triarrhena lutarioriparia community)were selected as representatives to study the changes of three dominant herbaceous communities in Tian-E-Zhou Wetland.The succession and change mechanism of wetland plant communities,the seasonal and annual changes of three dominant herbaceous communities and the response of three dominant herbaceous communities to water level changes were studied in order to understand the succession and change mechanism of wetland plant communities.It will provides theoretical basis and reference for the management and maintenance of wetland community in Tian-E-Zhou Mi Lu Deer Reserve.The results show as follow:1.The soil substrate environent in Hemarthria altissima community was mainly sandy soil,its soil organic matter content and the soil nitrogen content was low.Seasonal variation of Hemarthria altissima community will change from the dominant species with drought tolerance(Astragalus sinicus,Carex argyi,Hemarthria altissima)in spring to the dominant species with waterlogging tolerance(Carex argyi,Phalaris arundinacea,Phragmites australis in high water level,Hemarthria altissima,Carex argyi,Phragmites australis in low water level)in summer.With the rising of water level,those annual species gradually disappear in summer.With the decline of water level in autumn,the annual biological species Xanthium sibiricum began to appear,and the perennial species resumed their growth through underground buds,forming a community consisting of the dominant species(Hemarthria altissima,Carex argyi,Phragmites australis+Xanthium sibiricum).There was no significant change in dominant species in Hemarthria altissima community in the past 3 years,and the species changes in the community mainly occurred in the associated species and rare species,and the transformation from underground bud plant and annual plant to annual plant which mainly propagates by seed is the associated species.2.The soil matrix of Carex argyi community is mainly sandy loam soil,its soil organic matter content is moderate,and its soil nitrogen content is high.As a result of the long-term moderate water level,the community of Carex argyi has formed a plant community consisting of the dominant perennial,waterlogging-tolerant secondary species,(Carex argyi,Triarrhena lutarioriparia,and Phragmites australis),And the dominant species basically have no change all the year,while the accompanying species have changed.In spring and summer,the annual species are the main associated species,and the biennial species are the associated species in autumn and winter.The dominant species in the Carex argyi community had no annual change.The dominant species of Carex argyi,Artemisia selengensis and Phragmites australis were dominant species and constructive species of Carex argyi community.Only the associated species had difference among the years,and most of the associated species were annual species.3.Soil substrate environment of Phragmites australis+Triarrhena lutarioriparia community was mainly loam,and the content of soil organic matter was the highest.The seasonal variation of Phragmites australis+Triarrhena lutarioriparia community mainly had happened in the upper layer plant species and the overground layer of the built-up species with the change of the water level,and the difference is obvious in spring and summer.In spring,the water level was low and there was no clear water on the surface.The Phragmites australis+Triarrhena lutarioriparia community formed Carex argyi,Phragmites australis,Triarrhena lutarioriparia group,and the ground surface formed the Oenanthe javanica and Sambucus chinensis as the dominant species.With the rising of water level in summer,the surface of Phragmites australis+Triarrhena lutarioriparia community was submerged by water,and the water tolerance of Oenanthe javanica and Sambucus chinensis was no longer the dominant species because of their water tolerance.In the third layer,there were a large number of Paederia scandens and Cayratia japonica as the dominant species,and those climbs occupy the upper layer space in the upper layer of the formation composed of the Phragmites australis+Triarrhena lutarioriparia community.There was no significant change between dominant species and establishment species in the Phragmites australis+Triarrhena lutarioriparia community.There was also no annual change in the number of associated species in the community,and the change of most life-form species was happened in the community,from water-resistant Oenanthe javanica to drought-resistant Humulus scandens,Sambucus chinensis,and drought-resistant wild roses.4.The plant community succession changes will occur in the dry season and in the dry season in the three plant communities.The Hemarthria altissima community can be transformed from the dominant species Astragalus sinicus,Carex argyi,Hemarthria altissima and Xanthium sibiricum in dry season to the dominant species Carex argyi,Phragmites australis,Triarrhena lutarioriparia and Phalaris arundinacea in the wet season.The dominant species of the Carex argyi community is not changed,only the variation of the accompanying species and the occasional species happened and the structure of the Carex argyi community was not affected.The Phragmites australis+Triarrhena lutarioriparia community can be transformed from the dominant species Carex argyi,Phragmites australis,Triarrhena lutarioriparia,Carex cinerascens,Oenanthe javanica and Humulus scandens in dry season to the dominant species Carex argyi,Phragmites australis,Triarrhena lutarioriparia,Paederia scandens and Cayratia japonica in wet season.