| As a typical freshwater swamp wetland,Honghe National Nature Reserve has complex ecosystem functions and rich biodiversity.It is a living fossil of the original swamp wetland and a concrete and representative portrayal of the freshwater swamp wetland in the SanJiang Plain.In recent years,with the frequent increase of human activities in the reserve and the influence of natural factors,the wetland of Honghe National Nature Reserve has seriously degraded:wetland area,surface water,and groundwater reduced,biodiversity decreased,and so on.It has aroused the attention of wetland scientists and managers at home and abroad,and the demand for wetland protection and restoration is becoming more and more urgent.In order to provide a scientific basis for the protection and restoration of the Honghe protected area,the preliminary work of this study collected a large number of vegetation,soil and remote sensing image data in the protected area,and prepared for the next content analysis.First of all,taking Honghe National Nature Reserve and its surrounding two kilometers and five kilometers as the object,exploring the evolution of protected areas and surrounding areas over the past 30 years,and expounds the evolution process of the landscape pattern.Clarify the driving force of landscape pattern evolution in honghe nature reserve.Secondly,based on the field survey sampling method,sorting the succession order of vegetation in Honghe Nature Reserve,and analyzed the dominant factors affecting community succession.Finally,using the Markov model,combined with land use changes in 1987,1993,1999,2005,2011 and 2017,the landscape change in 2023 is predicted in a six-year cycle,which provides scientific basis for ecological protection and restoration of Honghe Nature Reserve.The study found that although the wetland area has decreased by 10.63 km~2 in the past 30 years,but the wetland area is still the largest dominant landscape in the protected area.From 1987 to 2017,the woodland area changed in a"U"pattern.Over the past 30 years,the woodland area of the reserve has increased by 3.02 km~2,from1987 to 2011.Farmland has tended to increase,while the farmland area has increased by 7.69 km~2,from 2011 to 2017,the farmland area decreased by a small margin,with reduction of 0.11 km~2.The area of the water changed little,and only increased 0.02km~2 from 1987 to 2017.The landscape change(two kilometers and five kilometers)on the periphery of the reserve is divided into three stages:1987-1993 as the first stage,wetland as the main peripheral landscape,1999-2005 as the second stage and dryland as the peripheral dominant landscape;2011-2017 was the third stage,paddy fields became the dominant landscape of the region.Overall,the landscape pattern within the reserve has not changed much,and the peripheral landscape pattern has changed dramatically.Human activities have not only changed the landscape pattern of the periphery,but also affected the energy flow,species migration,and material circulation between the peripheral region and the interior of the protected area.Finally,the landscape pattern in the reserve was changed,and agricultural reclamation is the main driving factor of the change.The DCA ranking analysis of the vegetation communities in Honghe Nature Reserve showed that the community succession experienced four groups:swampy meadow group,wet meadow group,shrub meadow group and island-like forest wetland group.Water condition is the dominant factor affecting community succession.With the decrease of water content,wetland plant species develop from swampy meadow group to island-like forest group,the wetland area is gradually less,and the woodland area increased correspondingly.With the further decrease of water content,the connectivity of freshwater wetland decreased greatly,the wet environment gradually changed to the xeric environment,the dry vegetation such as irrigation jungle,Arbor and so on began to appear,and the connectivity of woodland was highly raised.As the ecological environment gradually drought,a new type-dry land began to appear.Markov model plays a good role in predicting the evolution of Honghe Nature Reserve.The prediction results show that the wetland area in 2023 is 203.67 km~2,with an increase of 2.94 km~2,compared with that in 2017.The woodland area is 38.49 km~2,with an increase of 0.67 km~2.The water area is 0.87 km~2,with an increase of 0.79 km~2.According to the predicting changes of three land types and the changes of land classes in previous years.The prediction results show that the wetland in the study area will develop in a positive direction. |
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