| The rapid advancement of urbanization has not only brought economic development and social progress,but also caused serious environmental problems such as resource depletion,environmental pollution,and ecological damage.Ecological land with a variety of ecosystem services plays an indispensable role in the protection of the regional ecological environment,but the irrational use of it also causes the problems of low connectivity and fragmentation of regional landscape pattern.The minimum ecological land refers to the spatial scope of the ecological land in a region,which does not hinder the expansion of urbanization and socioeconomic growth in a certain area without destroying the ecosystem services,Identifying and quantifying them is conducive to balancing urbanization development and ecological protection,and can provide a reference for regional land use planning.Based on this,this study takes the Dianchi watershed as the research object.Firstly,combined with the ecosystem service functions of the watershed,the evaluation index system for the importance of ecological land was constructed,and based on the evaluation results,the minimum ecological land in the study area was identified by Minimum Cumulative Resistance mode(MCR model)and Scenario Simulation method.Secondly,the study discussed the feasibility and rationality of the two methods in determining the minimum ecological land use in the Dianchi watershed through a comparative analysis of land use types and landscape pattern distribution.Finally,based on the theory of"concentration and decentralization",some suggestions were put forward to optimize the land use pattern of Dianchi watershed in the future.The main results are as follows:(1)The evaluation index system of ecological land importance is constructed from four ecosystem service functions,such as water resource supply,biodiversity conservation,soil conservation and water conservation,combining the characteristics of the ecosystem in the Dianchi watershed.The single factor evaluation results of the importance of four ecosystem services showed that the most important ecological land areas for water resource supply,biodiversity conservation,soil conservation and water conservation were 467.81km~2,227.36km~2,874.27km~2 and 1450.13km~2respectively,accounting for 20.65%,10.13%,39.00%and 64.65%of the total area of the study area,and the and use types were mainly forest land,water area and grassland,all of which are concentrated in large areas.The comprehensive evaluation results show that the ecological land areas from the most important to the unimportant are 1149.74km~2,328.28km~2,371.16km~2,230.60km~2 and 148.07km~2respectively.The most important ecological land area is the largest,mainly forest land and water area,which play the functions of storing water sources and inhibiting soil and water loss.(2)Based on the MCR model,the study quantizes the minimum ecological land use by constructing ecological"source"and"resistance surface".The results show that the minimum ecological land area is 1148.00 km2,accounting for 39.32%of the total area of the study area.It is mainly distributed in the northeast,mid-west and southeast of the Dianchi watershed.The land types include forest land,water areas,etc.,which play an important role in water conservation,soil and water conservation,and other ecosystem service functions.(3)Based on the Scenario Simulation method,through the division of the comprehensive evaluation value of the importance of ecological land,the study sets up scenarios accounting for 30%,40%,50%,and 60%of the ecological land area in the study area.The results show that the minimum ecological land area quantified by Scenario Simulation method is 1129.55km2,which accounts for 50%of the ecological land area in the Dianchi watershed and 38.96%of the total area of the study area.It is generally distributed in the central,western,southern and northeastern parts of the study area.The connectivity between the plates is good,and the distribution of each category is reasonable.(4)Comparative analysis of the minimum ecological land quantified by the MCR model method and the situational simulation method from the two aspects of land use type and landscape pattern distribution shows that:(1)In terms of land use types,in the study area level,the area of forest land in the minimum ecological land determined by the MCR model is 901.08 km~2,accounting for 78.17%of the minimum ecological land area and 82.49%of the same land area,other land types account for a small proportion of the area,the total area only accounts for 21.83%of the minimum ecological land area,which is unable to maintain the diversity of land use types.The forest land area of the minimum ecological land determined by the Scenario Simulation method is 534.48km~2,accounting for 47.32%,and the proportion of the land area of the same type in each category is between 30%-85%,which can better maintain the diversity of land use types;in the administrative boundary level,the minimum ecological land determined by the two methods fluctuates little in the area of each district and county.In contrast,the distribution of the land area of the minimum ecological land determined by the Scenario Simulation method is more stable.(2)In terms of landscape pattern distribution,the minimum ecological land determined by the MCR model and the Scenario Simulation method accounted for37.42%and 38.96%of the total area of the study area respectively,which satisfies the functional diversity and stability of the ecosystem to a certain extent.The maximum patch area,spread,aggregation,and patch density of the smallest ecological land determined by the two methods are 6.08%,38.67%,92.45%,6.50/100ha and 10.62%,39.57%,93.39%,5.08/100ha respectively,through the comparison of logarithmic values,it can be seen that the landscape pattern distribution of the minimum ecological land quantified by the Scenario Simulation method is more suitable,with better patch connectivity and lower fragmentation.(5)The minimum ecological land quantified by the Scenario Simulation method is determined as the minimum ecological land in the Dianchi watershed.The minimum ecological land area in the Dianchi watershed is 1129.55km~2,accounting for 38.96%of the total watershed area.The land use types mainly include forest land,water areas,etc.,such as Dianchi lake,Songhua reservoir,Xi mountain nature reserve,and Changchong Mountain are widely distributed throughout the study area.The minimum ecological land includes forest land,grassland,agricultural land,water area and other land,with an area of 534.48km~2,66.56km~2,286.67km~2,170.86km~2,and 70.97km~2 respectively.On the whole,there is a phenomenon of large area agglomeration,with high spatial connectivity among patches and less broken patches.It has obvious functions of water conservation,prevention of soil and water loss,protection of biodiversity and so on.At the same time,the proportion is relatively moderate,which does not hinder the social and economic development of the study area.It is the most important land to maintain the ecological balance and social development of Dianchi watershed. |
PDF Full Text Request