The first thinning age of Pinus massoniana plantation

The relationship between the ratio of the average crown width to the average distance and the age were analyzed by using the data obtained year by year during 11-year-old Pinus massoniana from the different planting density experiment stands.And it was fitted by Richards equation.The results show that the first thinning ages of Pinus massoniana plantation were generally determined by the mean of the age when trees crown totally overlapped and the age when the ratio of the average crown width to the average distance was nearly equal to its limit parameter;the first thinning ages of Pinus massoniana plantation in 4 different kinds of planting density(1 667(A)、3 333(B)、5 000(C)and 6 667 trees·hm-2(D)) were about at the age of 9,7,5 and 5 years respectively.The models between the first thinning age and planting density of Pinus massoniana were established,and the coefficient of determination were above 0.98.Compared with traditional methods,the first thinning ages were basically consistent,which indicated that the method for determining the first thinning age was effective and feasible.Because this method is a qualitative method and its calculation is simple,it has important theoretical and practical significance and can provide the references for the thinning technology system of plantation.