Social security or profitability? Understanding multifunction of rural housing land from farmers' needs: Spatial differentiation and formation mechanism-Based on a survey of 613 typical farmers in Pinggu District

The function of rural housing land is an important manifestation of the living needs of farmers. Multifunctional research on rural housing land can provide a scientific basis for the formulation of practical and effective systems of rural housing land. Based on the survey data of 613 typical farmers, this paper identifies each function, analyzes functional spatial distribution features of rural housing land by using the kernel density estimation method, and constructs a multinomial logistic regression model to quantitatively measure the influencing factors and to reveal the mechanism of functional spatial distribution under the combined effect of the "farmers-rural housing land-village" system. This research shows the following: 1) Rural housing land has mainly a social security function(SSF), while a profit function(PF) and a retaining function(RF) have also appeared, with the proportions being 71.78%, 10.60% and 17.62%, respectively in the Pinggu District of Beijing. 2) SSF is strongest in the economically depressed mountainous areas, whereas PF and RF are strongest in the economically developed plain areas and the economically secondary semimountainous area, with the proportions being 77.31%, 15.91% and 22.10%, respectively. Various functions present a spatial gradient change. 3) Agglomeration analysis shows that SSF presents two strong cores: the hilly and mountainous areas in the far north and the plain areas in the suburbs with a better economy, with the "point-surface" distribution. PF concentrated in the tourist spots in the hilly and mountainous areas, the urban belt vicinity with a good economy and the MF industrial park, with the "point-and-belt" pattern. RF focused in the economically secondary semimountainous area and the industrial zone in the southwestern part of the city, showing a "multiband" shape. 4) The function of rural housing land arises from the farmers' needs according to conditions of their own family and rural housing land under the positioning of certain villages. The village characteristics, such as economy, are external factors that present a continuous adjustment effect on the function of rural housing land with the form of long-term action; the characteristics of rural housing land, such as location, are restrictive factors that show two-way feedback effects on the function of rural housing land with the form of foundational action. Both the family characteristics, such as non-agricultural income ratio, and the householder characteristics, such as age, are internal factors that present stage stimulating effects on the function of rural housing land with the form of direct action. 5) Trying to divide the right of use and qualification of RF housing, the right of use of PF housing, through innovating acquisition system of rural housing land and constructing mechanism of rural housing land replaces town security room, which aim to improve the functional efficiency of rural housing land.