On Multi-scale Land Quality Assessment In Hilly Region

It had become a key issue for land science how to maintain the agricultural production capacity of land resource because of land degradation,eco-environment deterioration and so on.By monitoring response of land use change to agro-ecosystem and environment,land quality assessment has recently become an effective measure for maintaining sustainable land use.As far as land quality assessment is concerned, indicator systems and evaluation methods have become its focus.At the present,Indicator systems which had been widely used in China were originated from soil quality indicator system.Pressure-state-response (PSR) assessment indicators system was established based on the theory of ecology-economy-society complex ecosystem.There have still been many problems in construction of indicator system,for example indexes were not chosen completely and impressed in some regions.Moreover,the assessment indicators in Pressure-state-response(PSR) assessment indicators system have given more emphasis to characteristics of ecology and soil and little economy.Traditional land quality assessment methods were little combined with GIS,so that their evaluations were sometimes arbitrary.It has been paid little attention to study the effect of land use pattern and ecological procedure on land quality.Most studies emphasized single scale and ignore of the relationship among scales.So the role of land monitoring and policy establishing were not reflected in land quality assessment.Therefore,this paper dealt with multi-scale land quality assessment in hilly-land regions under consideration of major influencing factors with various scale land use pattern,taking representative blocks of Hechuan,Gaolong land consolidation project area and Hechuan city for example.This study would enrich and improve land quality assessment system by anatomizing similarities and differences of multi-scale land quality in hilly-land regions.1.Land quality at land patch scaleForty plots chosen in Hechuan were covered with cropping patterns in whole city,and field parcels' natural quality,households' disturbance and topography landforms should be mainly considered.The basic data were obtained from peasant household investigation to typical and adjacent blocks,getting 137 valid questionnaires,and analytic dates of soil.The change of agricultural production efficiency from 2000 to 2007 was analyzed by using stochastic frontier production function.The ecosystem services value was used to quantify sub eco-function in each patch.Farmers' efficiency,ecological value and geomorphic characteristics were integrated to evaluate,and further discuss the driving force for this scale.(1)Stochastic frontier production function was suit for describing household behavior,taking into account agricultural unavailability problems.Under a significance level of 0.01 andγ=0.9217＞0.5, results showed that farmers were influenced by many random factors,causing production efficiency loss in actual production process.The constant term ofβ1,β1 andβ2 in this study on 0.01 level were obvious,and all theβcoefficient were positive.The elastic coefficient of labor input was 0.3494,and productive investment was 0.5215.So it suggested that these inputs can improve agricultural output.The coefficient of explanatory variables such as farmers' age,number of working force,cultivated area,education level, policy factor and the distance between plot and Hechuan city center had no significant difference.And it meant that there explanatory variables caused technical inefficiency.The coefficient of farmers' age was negative,and it showed that the age unavailability had negative influence on household income.That is to say,it can enhance technical efficiency.But the coefficients of other explanatory variables were positive values which had a positive correlation with technology ineffectiveness,and they restricted technical efficiency.(2)The differences among production in each patch were derived from farmers' behavior,and ecological function had not contributed to it.By analyzing the relationship among agricultural production efficiency,food production,gas regulation,water supply,soil formation and nutrient cycling ecosystem services,it was found these sub ecosystem functions can't enter the regression equation (y=-E-05x+0.874,R~2=0.0822) under a significance level of 0.05.In other words,there was not relationship between ecological service value and agricultural production efficiency.The ecological service values in the unit area under various cropping patterns were garden＞wheat maize sweet potato rotation cropping system＞orchard＞paddy-upland rotation＞winter paddy field.Food production and nutrient cycling ecological functions had the most important service values.(3)Selecting such as elevation,slope and aspect ten indicators to evaluate land quality,these patches were dominated by medium and finest grade farmland,and the overall land quality was better.By analyzing the relation among indices,it suggested that land quality was the results of common action among terrain,soil,ecology and farmers,and those can't be replaced each other.2.Land quality at village scaleLand consolidation projects had significant effect on land quality at village scale.This paper detailedly analyzed the changes of land quality from three respects:landscape pattern,household behavior and ecological functions,which were driven by land consolidation taking Gaolong land consolidation project for example.The fundamental datum were land use map,land use planning map(map scale is 1:2000) and 163 valid questionnaires.(1)Land consolidation,as a type of human disturbance,can improves land production efficiency and changes landscape distribution through their land parcels reallocation.FRAGSTAT3.3 and buffer zone analysis were used to reflect those changes.The results indicated that the shape of land use patch become more regular and agglomeration of little-patches contributes to changes in the distribution of land cover after LCP in total area at the landscape level,but the changes of dry land and paddy land were much more intense than other land use patterns at class level.Land leveling project decreased the slope of dry land and made them flatten to convenient for agricultural production and reduce soil erosion.Ditch system and road network were representative ecological corridors,so it was important to study those corridor effects using buffer zone analysis.Those systems strengthen infrastructure construction,but increased fragmentation. LCP was not just the reallocation of fragmented parcels,but also improved agricultural conditions. Meanwhile,35m buffer zone of ditch system was critical point of human interference,and the patched from 25m to 50m buffer zone of road network were changed most markedly with obvious.(2)This paper analysis technology efficiency,scale efficiency and total factor productivity trend of farmers' behavior and willingness response to land consolidation using Malmquist-DEA and C~2R-DEA model,respectively.The results indicated that technical progress was the main factor to constrain the development.The implementation of LCP can promote the development of studying villages,but its performance demonstration was later at Jifu village.Technical progress was the main factor to constrain the development,and technologies innovation was still lower.Technical efficiency,pure technical efficiency and scale efficiency,of Jifu village,were better than others,which suggested it can expand production scale to make reasonable resources allocation.But other villages needed to reduce scale.The relationship between land consolidation and farmers' material capital investment can be further analyzed through the change rule between farmers' income and investment structure from 2004 to 2007.The agricultural incomes were mainly from breeding industry,and affected mainly by livestock input.In some year,the agricultural income was also affected by seed input,chemical fertilizer input and other farming input.This result further indicated that technical progress was the major factor to affect TFP.(3)Shadow price method,reflection engineering method and reforestation cost method were used to quantitatively reflect the significance of special ecological functions under land consolidation impacts.In addition,engineering design and shadow price method were integrated to quantify the value of disturbance regulation,and it is a new method for eco-benefit evaluation in other land consolidation projects.And meanwhile,Benefit and cost analysis was used to reveal its' economic significance to forecast the ecological variation of research area in the future.The disturbance function was the centralized reflection of irrigation and drainage engineering,roading engineering and land levelling project.The ecosystem service values before and after land consolidation were 5995.98 million yuan and 8330.11 million yuan respectively.All sub-functions had increased in a certain extent after this project.Nutrient cycling function increased most and soil conservation function increased least.Land leveling project increased 123.56 million yuan.The benefit-cost rate maintained the fast growth from the seventh year to thirty-fifth year,and it tended to be stable after the thirty-sixth year.It illustrated there were weak ecological pressure and less losses of ecosystem service value,and land consolidation project made eco-environment positively developed and improved.(4)System dynamics based on feedback control theory and computer simulating techniques was an effective methodology for modeling and analyzing complex social,economic,and ecological systems. Land use sub-system,ecology sub-system,economy sub-system and society sub-system were integrated into land quality system,and system dynamics were used to analyze these relationships among sub systems. The flow map of land quality system was established based on internal circular relation,and the monetization representation of land quality was introduced to predict the change of land quality from 2004 to 2007.The monetization representation of land quality was 79548300 yuan under current model. Supposing the residual field ridge changed into cropland,unutilized lands were exploited into cropland,and new-increased cultivated land rate was 3%all the time.Household income,the monetization representation of land quality,cultivated land's ecological service value and total value reached maximum in 2012, subsequently decreased.This monetization representation of land quality was also the maximum value in various scenarios.3.Land quality at county scaleLand quality in county scale was discussed from farmland quality and its spatial distribution pattern.Data from 234 valid questionnaires in whole county were analyzed based on agricultural land classification and gradation.(1)Influence coefficient was used to modify natural quality index based on the investigation to households.It turned out that the farmers' input-output made cultivated land natural quality reduced.Only considering natural quality,it can't reflect farmlands' actual production capacity.Therefore,this influence coefficient made adjusted quality indices economization.To simulate the relationships between natural quality index and household incomes,curve equations were established.It suggested that trinomial equation were fitted to reflect relationships under dry land among Yanjing town,Qiantang town and Shuanghuai town,and binomial equation were suitable for Longxing town and Nanjin subdistrict office. But the better equation of Qingping town,under dry land were logarithmic,inverse and exponential model, respectively.Under paddy land,trinomial equations were fitted to Longxing town and Yanjing town,and power model were suitable for Nanjin subdistrict office and Qingping town.Xiaojia town,and Yunmen town used exponential model,and Qiantang town and Shuanghuai town used S model.Household incomes are not only depended on natural attributes of cultivated land,but also affect by input and management.In addition,household incomes with investment behaviors are estimated Cobb-Douglas production function. Household incomes are restricted by one of investment factors,so incorrect investment structure can be adjusted from elasticity coefficient to improve cultivated land quality.(2)Spatial autocorrelation analysis was used to reflect the spatial agglomeration of farmland by GeoDA.The distribution of adjusted quality grade under paddy land and dry land had remarkable positive correlation in space,and concentration phenomenon was obvious.There were 538 HH type paddy land patches,and 409 were LL type.That meant there were positive correlation between HH and LL type patch. 93 LH type and 296 HL type of paddy land had negative correlation in space.273 HH type and 661 LL type of dry land had positive correlation in space,and 236 LH type and 149 HL type of dry land had negative correlation in space.(3)Land use maps from 1993 to 2006 were used to analyze the spatial pattern of land use.The results showed that over a long period of time,the forestland and rural residential area increased day by day.But, grasslands and croplands decreased quickly.PD was slightly increased,while PAFRAC and FRACAM were decreased.SHDI and SHEI were increased.The factor of policy and the drives of economic interests were the main reasons that drive the landscape pattern change.Croplands' leading position became weak, but the dominant position of forestlands was gradually presented due to the conversion of cropland to forest policy.Ecological service value coefficient assigning different categories of land use raised by Costanza was generally adopted.So we used this coefficient to quantify the change of ecological service value at county scale.The values of forestland and orchard were increased,while the values of other land use patterns were reduced owing to area decreasing from 1993 to 2006.Sensitivity analysis was used to reflect the dependence of our estimates of changes in ecosystem service values on the applied coefficients.The results showed that the changes of river's sensitivity were highest from 0.7180 to 0.6407.4.Construction of land quality assessment system for multi-scaleA comparative analysis was conducted on three scales of patch,village and county scale,in view of evaluation units,indicator system and evaluation methods.Meanwhile,this paper presented the concept and theoretical specification of a multi-agent based on model for land quality assessment.(1)Landscape analysis was based on grid which was in accordance with the total area investigated. Independent block was the unit of farmer research,but the selected foundation of investigated household was different.Cropland plague of land use map was natural quality study unit,while independence land use pattern was the unit of ecological service function.All indices can be divided into ecological quality and production quality.Ecological quality emphasize on land attribute and ecology attribute,but production quality reflected production capacity,carrying capacity and economic ability.Efficiency model was used to analyze household behavior at patch and county scale,but influence coefficient was adopted to reflect household's action.Ecology service value was an effective method to describe ecology structure. Landscape metrics was adopted at county and village scale,while spatial autocorrelation analysis was used to reflect the change of land use pattern at county scale.(2)A multi-agent based model for land quality assessment was represented by two components: indicator agent and method agent.Among them,indicator agent can be summarized as follow:land attribute agent,landscape ecology agent and household agent.The essential dimension of method agent was the implementation of cooperative relationship among indicators,and the evaluation interactive diagram of land quality was drawn.This model can be combined with GIS,mathematical method through agent database to achieve yardstick reasoning and intelligentized assessment.As what have mentioned above,this paper systematical study land quality at multi-scale in hilly reginons,south China,which wasn't limited to certain scale or traditional research method.Therefore,this study can enrich and perfect land quality research system.It can make up the research on land quality systemic for land consolidation project by analyzing the affection of agricultural infrastructure to land quality.In view of managers,household study was expression in production efficiency using stochastic frontier production function and data envelopment analysis.System dynamic was used to present the internal structure of land system to predict the change of future land.But only soil datum in a given time was got at certain scale,so it can't reflect the change process limited by datum.Based on that,the integration of multi-scale's yardstick reasoning will be the focus of future study and strengthen practical application.