Temporal And Spatial Variation And Simulation Of Rice Terraces In Subtropical Monsoon Region Of China

As a unique cultivated land resource in mountainous areas of China,Terrace is a stepped field formed by adapting to the natural environment and meeting the needs of survival.It takes into account various functions such as grain production,Soil and water conservation,Maintaining agricultural biodiversity and aesthetic services.Under the background of the decrease of cultivated land area,Terrace resources are seriously threatened,Which not only destroys the stability of terrace ecosystem,but also affects the sustainable development of terrace landscape.Therefore,How to deeply understand the temporal and spatial variation characteristics of terraces,Clarify the future development status of terraces,And optimize the allocation of terrace resources for the sustainable development of terraces is an urgent problem to be solved.The core areas of Jiabang,Longji,Ziquejie,Lianhe and Hani terraces are typical representatives of rice terraces in subtropical monsoon regions of China,Which play an important role in rice grain production in China.Based on the terrace distribution data interpreted by remote sensing images,This paper uses spatial analysis technology and geographic detector model to analyze the spatial and temporal variation characteristics and influencing factors of the above terraces.On this basis,The Markov-PLUS coupling model is used to simulate the distribution and change of terraces in 2030 from two scenarios of natural development and cultivated land protection.The main conclusions are as follows:(1)From the change of terrace area and dynamic degree,During 2010～2020,the terrace area in the core area of Jiabang,Longji,Ziquejie,Lianhe and Hani terraces was mainly reduced,Among which Ziquejie terrace area decreased the most(7.68km~2),and Lianhe terrace area decreased the least(0.91km~2).In the whole research stage,The dynamic degree of each terrace was negative,Among which the area of Ziquejie terrace decreased the most(-4.08%),And the area of Jiabang terrace decreased the least(-0.91%).From the perspective of the spatial transfer of terrace patches,From 2010 to 2020,terraces were mainly transferred out,Among which the core area of Hani terraces was the largest(23.18km~2),Followed by Ziquejie(9.06km~2),Longji(3.33km~2)and United terraces(1.88km~2),And the area of Jiabang terraces was the least(1.44km~2).Moreover,The edge part of the terrace patch distribution in each terrace area is the main area where the terrace is easy to transfer out;From the perspective of the change of the core density of terrace patches,From2010 to 2020,The total distribution area of terraces in the core area of Jiabang,Longji,Ziquejie,Lianhe and Hani terraces in the medium density,Medium high density and high density areas was more than 80%,Of which the core area of Hani terraces reached more than 90%.From the perspective of change,During the whole study period,With the decrease of terrace area,The high-density area gradually changed into medium-high density,Medium density and medium-low density,While the area of low-density area scattered in terrace patches was gradually shrinking.From the perspective of pattern change characteristics,The fragmentation degree of terrace patches in Jiabang,Longji and United terraces decreased from 2010 to 2020,While the fragmentation degree of terrace patches in the core area of Ziquejie and Hani terraces increased.(2)The results of factor detection showed that the maximum intensity of terraces in the core areas of Jiabang,Longji,Ziquejie,Lianhe and Hani terraces was the distance from highway,The distance from administrative villages,Slope,Topographic relief and Altitude.The interaction results showed that the interaction between years showed nonlinear enhancement and two-factor enhancement.Among them,in different periods,the interaction factors with the greatest explanatory power for Jiabang terraces were altitude/distance from rivers(2010,0.059)(2015,0.059),Distance from roads/slope(2020,0.057).The interaction factors with greater explanatory power for Longji terraces were distance from administrative villages/distance from rivers(2010,0.079)(2015,0.081),Distance from rivers/precipitation(2020,0.087).The interaction factors with greater explanatory power for Ziquejie terrace were distance to river/altitude(2010,0.081),Population density/slope(2015,0.069),Distance to river/slope(2020,0.068).The interaction factor with greater explanatory power for joint terraces was topographic relief/distance from the river(2010,0.163)、(2015,0.164)、(2020,0.164).The interaction factor with greater explanatory power for the core area of Hani terraces is the distance from the river/altitude(2010,0.232)、(2015,0.209)、(2020,0.219).(3)Through the simulation of terraces,it is found that the area of terraces in the core area of Jiabang,Longji,Ziquejie,Lianhe and Hani terraces still shows a decreasing trend in 2030.Under the natural development scenario,The area of Ziquejie terrace(5.98km~2)decreased the most,Followed by the core area of Hani terrace(5.3km~2),Jiabang(1.05km~2)and Longji(2.15km~2),And the combined terrace(0.74km~2)decreased the least.Under the scenario of cultivated land protection,The Ziquejie terraced field decreased the most(4.58km~2),Followed by Longji(1.39km~2),Hani terraced core area(0.93km~2)and Jiabang terraced field(0.78km~2),And the United terraced field(0.26km~2)decreased the least.In contrast,the reduction of terraces under the scenario of cultivated land protection is smaller,And it is conducive to the sustainable development of terrace resources in the future.