Coupling Relationship Between Landscape Structure And Water Environment Quality Of Wetland Park

As a new form of wetland protection in China,wetland parks are essentially to build a new wetland protection system that integrates the protection and utilization of wetland ecological resources,the adjustment and restoration of wetland functional structure,and the development and construction of wetland science,education and cultural tourism.At present,the construction of Wetland Park in China is still in the development stage,In order to formulate and carry out the planning and management of wetland park more scientifically and reasonably,this paper is based on suzhou national wetland park landscape structure features and water environment quality,through exploring the coupling relationship between the two,it provides scientific basis for the optimization of landscape structure,improvement of water environment quality,and long-term maintenance of wetland ecosystem health and ecological service function,and also provides reference for wetland protection in Taihu Lake Basin and even in China.Taking six national wetland parks in Suzhou as the research objects,the research contents of this paper mainly includes five parts: Theoretical basis and technical method research;Research area overview and data processing;Landscape structure and water environment quality characteristics analysis;Landscape structure and water environment quality coupling relationship research;Wetland park landscape structure optimization strategy based on water quality improvement.The main technology path can be divided into the following four steps:First,based on the remote sensing image data of the Gaofen-2 satellite(2019),use Arc GIS 10.6 to extract the landscape type map of the study area;Fragstats4.0 is used to obtain the landscape feature index representing the degree of aggregation,fragmentation,dominance and diversity,respectively calculated at the type level and landscape level.Secondly,according to the extracted six landscape types including forest land,grassland,and water area,while referring to the 3 functional zoning conditions of wetland conservation,restoration and reconstruction,and rational utilization,53 water quality monitoring sample points were selected where the characteristics were obvious;The 12 months from February 2019 to January 2020 are divided into three typical seasons:low-flow period,mean-flow period,and high-flow period.the water quality is sampled once a month,taking data integrity into consideration,five indexes of TN,TP,DO,COD and BOD,which play an important role in water pollution,were selected.Thirdly,analyze the four types of landscape structure characteristics from the two aspects of landscape type and landscape architecture: block-like uniform type,multi-layer cofferdam type,multi-pond structure type,and block-shaped agglomeration type;And use the water quality identification index method to explore the temporal and spatial characteristics of water quality in Suzhou National Wetland Park.Finally,the paper uses Pearson’s correlation analysis,multiple stepwise regression analysis,and redundant analysis(RDA)methods to analyze the coupling relationship between the landscape structure and water environment quality in Suzhou National Wetland Park,draw the coupling relationship between landscape type,landscape structure and water environment;And based on the theory of "source and sink",combined with research results,proposed wetland park landscape structure optimization strategies and water environment management strategies.The main conclusions of this paper are as follows:(1)Quality characteristics of water environment:Sort the degree of water pollution from large to small,BOD>TN>COD>TP>DO.Among them,DO is Class I water,TP is Class III water,COD and TN are Class IV water,and BOD is inferior to Class V water.Seasonally,the water quality of SSD,TH,SJB,HB,TL is better in high-flow period than in low-flow period and mean-flow period,while TF results are opposite.From a functional point of view,the water quality of TH,SJB,HB,and TL is in the order of rational utilization area> restoration and reconstruction area> wetland conservation area,and the comprehensive water quality identification index is in the range of Grade III to IV.SSD is restoration and reconstruction area > wetland conservation area > reasonable utilization area,and the water quality is in the range of class II to class III.The water quality of TF is wetland conservation area> restoration and reconstruction area> rational utilization area,and the water quality is in the range of Grade III to IV.(2)Landscape structure characteristics:Sort the purification effects of landscape structure on water quality from large to small,which is multi-layer cofferdam type >block-shaped agglomeration type > multi pond structure type > block-like uniform type;Among them,block-like uniform type has high crushing degree,low aggregation degree,low dominance and high diversity;The multi-layer cofferdam type has low crushing degree,high aggregation,high dominance,and low diversity;Multi-pond structure type has high crushing degree,low aggregation,low dominance,and high diversity;The Block-shaped agglomeration type has low crushing degree,high aggregation,high dominance,and low diversity.(3)Coupling relationship between landscape structure and water quality:The correlations are sorted from large to small,high-flow period> low-flow period> mean-flow period.Among them,forest land and water area have a positive ecological effect on water quality,while construction land,grassland and garden land have the opposite result.At the type level,the larger the NP and PD,the worse the water quality;The larger the water area LSI,the better the water quality.The LSI results for garden,grassland,and construction land are the opposite,the correlation between forest land LSI and water quality is unclear;The larger the water area and forest land LPI,the better the water quality,the LPI results of cultivated land and construction land are opposite,the larger the LPI of garden land,the worse the DO and BOD,and the better the COD;The larger the AI of water,forest land,and grassland,the better the water quality,while the result of garden AI is opposite.At the landscape level,the positive ecological effects of COHESION and CONTAG are significant,and the negative ecological effects of SHDI are significant.(4)Landscape structure optimization strategy: The rationality of the landscape structure of the block-like uniform type Wetland Park is the worst,should continue to maintain the "sink" landscape area,control the "source" landscape area,reduce the number of patches,and enhance the aggregation degree and maximum patch area of the dominant "sink" landscape;The landscape structure of multi-layer cofferdam type Wetland Park is the most reasonable,which can further adjust the "sink" landscape type,control the "source" landscape area,increase the ecological bank slope and ecological floating island,and slow down the excessive water flow speed;The landscape structure of multi-pond structure type wetland park is poor,but slightly better than that of Block-like uniform type Wetland Park,should increase the "sink" landscape area,reduce the "source" landscape area,and enhance the aggregation degree and maximum patch area of the dominant "sink" landscape;The landscape structure of block-shaped agglomeration type Wetland Park is reasonable,but the construction time is short,the management is not perfect,and the relativity of water quality is poor,We should continue to maintain the "sink" landscape area,control the "source" landscape area,and reduce the invasion of external pollution sources,thus causing water pollution.It can be further summarized as follows: increase the area of "sink" landscape,reduce the number of "source" landscape,improve the water permeability rate of "source" landscape;or use forest land as a buffer zone to separate "source" landscape,improve the dominance and connectivity of "sink" landscape such as forest land and water area,reduce the fragmentation of "sink" landscape,and improve the heterogeneity of landscape.