Dynamic changes of carbon storage in trunk volume of Pinus tabulaeformis,Robinia pseudoacacia and Populus euramericana

In order to select suitable tree species for carbon sink and determine forest management cycle,we used a new analytical method to study carbon storage and its dynamics in major afforestation species in the north of China.Results show that 1) the mature age of Pinus tabulaeformis,Robinia pseudoacacia and Populus euramericana were 67,40 and 30 years,respectively.2) Wood density of P.tabulaeformis and R.pseudoacacia presented a slowly-increasing trend in the initial phase and reached the maximum value at age 30.After age 30,wood density of P.tabulaeformis decreased gradually until reaching a stable value,while those of R.pseudoacacia declined continuously.For P.euramericana,wood density increased quickly before age 4,increased slowly from age 4 to 18 and declined from age 18 to 28.3) The carbon storage of P.tabulaeformis showed a relatively large variation,with the maximum value of 60.52% at age 20 and the minimum value of 46.14% at age 40.In contrast,the carbon storage of R.pseudoacacia varied greatly before age 25 and then became stable,with the maximum value of 56.96% at age 5 and the minimum of 42.58% at age 25.The carbon storage of P.euramericana changed little;it declined slowly from the maximum value of 48.64% to the minimum of 46.64%.4) The average carbon storage of P.tabulaeformis,R.pseudoacacia and P.euramericana peaked at age 70(2.5267 kg),40(3.7939 kg) and 30(2.7810 kg),respectively.