A Study On The Framework Of Dynamic Monitoring Sites Of Arable Land Based On The National Gathering Of Reference Land Unit

The dynamic monitoring for arable land quality based on reference land units is established on the basis of the contribution of indicator system and evaluation method for cultivated land classification. Through standardized monitoring, the system monitors the reference land units with a certain time interval.The paper makes use of the result of provincial gathering and sets the central nine provinces as study area, including Heilongjiang, Jilin, Liaoning, Shanxi, Henan, Anhui, Hunan and Hubei. Through combining the result of national gathering of reference land units with the dynamic monitoring for arable land quality for the first time, we make preliminary discussion about the selection of monitoring sites. The research of the paper involves that:1. The establishment of the databank for national gathering of reference land units in the central nine provincesThe databank of national gathering of reference land units is established in the operation interface of GIS, combining graphic visibility with attributive accuracy and photo introductory, including 131 national reference land units and 3388 provincial reference land units.2. The analysis of the distribution of national reference land units in different ratings and secondary regionsThe study area includes 30 natural quality ratings, utilization ratings, economic ratings and 24 secondary regions. Because all the provinces set the national reference land units in the higher ratings of the classification units, and some national reference land units are dispersed so intentively in certain provinces that the national reference land units in different ratings and secondary regions distribute unequally.3. The selection of dynamic monitoring sites for arable land quality based on reference land unitsThe paper selects 35 natural quality monitoring sites, 32 utilization monitoring sites and economic ratings , 24 secondary regions monitoring sites, the proportion of national reference land units in total monitoring sites are 80%,75%,88% and 63%. If the national reference land units can't cover the area, choose provincial ones as supplement.Through the construction of the databank and the selection of monitoring site, some problem and deficiency exist in the reference land unit system turn up. The following is some reference advice: The attribution of reference land units should be collected, disposed and gathered according to the unitary national standard, and the capture of the landscape and profile should be regulated; The conception of"rating"and"secondary region"should be further deepen in order to insure the even distribution of reference land units in them; The scientificalness of the system, the rationality of the distribution and the practicability of the achievements should reflect in the setting of reference land units.