Based on domestic studies about insurance scale,this paper analyses the significant affecting factors which influence insurance density in China by using the method of co-integration regression,and sets Compertz model to simulate insurance density in China,which means insurance industry in China is promising.

The paper explores the spatial correlation of China\'s provincial insurance density through spatial econometrics,and finds that the insurance density is characterized by regional clustering and its convergence in the national level has been strengthened at the same time.

Although China’s insurance industry has gained a rapid and continuous development in recent years,it is far from that of developed countries in insurance density and depth,which suggests that the effective demand of the Chinese market for insurance fails to be uncovered.

Four thinning intensities with the reserved densities of 5 600,4 100,3 700 and 1 830 tree/hm2,and a concontrol,with reserve density of 8 000 tree/hm2 were established in the 9-year-old air-seeded Pinus tabulaeformis stands in of Yanqing Country,Bejing.

A reserve density of 1 500 trees/hm~2 was considered to be optimum, giving the maximum annual growth in tree height (0.

The effect of reserve density and exposure on the aerial seeding forests of Pinus tabalaeformis were studied according to the investigating data of standard site of Liuling forestry centre in Danfeng-county.