Study On The Carbon Storage And NPP In Plantations Phoebe Bournei Based On FORECAST Model

Taking Phoebe bournei plantation in mid subtropical zone as research object, the temporal and spatial variation of carbon storage and NPP of Phoebe bournei plantation were studied under different site conditions, various mixed ratio and various initial planting densities forest in 300 years using ecosystem management model FORECAST. It may provide scientific basis for the evaluation of forest carbon storage and carbon sequestration functions, may also provide reference for intensive management pattern of Phoebe bournei plantation. The result shows that:(1) Under rich and medium site conditions, Phoebe bournei pure plantation and mixed forest with the initial planting densities 2500 N/hm2 have the highest accumulation of carbon storage. With the rotations of continuous planting increasing, the soil organic carbon pool is increasing. Under poor site condition, the stand has the highest accumulation of carbon storage with the initial planting densities 4000 N/hm2.(2)In 300 years simulation, soil organic carbon storage of Phoebe bournei with Chinese fir mixed forest present increasing trend with the mixed ratio 3:1,4:1 and 5:1. The soil carbon storage of Phoebe bournei with Chinese fir mixed forest with the mixed ratio 1:3 and 1:1 is decreasing in 300 years simulation, while the lower the Phoebe bournei mixed ratio is, the more serious the soil degradation degree will be. Within a management, the plantation has the biggest whole tree and stem carbon storage with the mixed ratio 3:1, this management is beneficial to the accumulation of soil organic carbon pool. The management of Phoebe bournei with Chinese fir mixed forest with the mixed ratio 3:1 may obtain more carbon storage whether from economic value perspective or from improving soil organic carbon pool perspective.(3)The accumulation of the whole tree carbon storage with the mixed ratio 5:1,4:1, 3:1.1:1 and 1:3 is respectively 611.14t/hm2,626.30t/hm2,630.41 t/hm2,617.19 t/hm2 and 465.64 t/hm2 in 300 years. The whole tree carbon storage of Phoebe bournei and Chinese fir pure forest is respectively 492.45 t/hm2 and 554.82 t/hm2 in 300 years. It shows that: in the mixed forest, when the strain of Phoebe bournei is no more less than that of Chinese fir, the carbon storage of Phoebe bournei is more than that of pure forest. (4)Taking the NPP of Phoebe bournei plantation under meddium site as example, the annual NPP of initial planting density 1000N/hm2.1600N/hm2.2500N/hm2 and 4000N/hm2 is separately 8.32t/(hm2·a),10.44t/(hm2·a),11.90t/(hm2·a) and 12.41t/(hm2·a),4000N/hm2>2500N/hm2>1600N/hm2>1000N/hm2. the annual NPP of Phoebe bournei is less than average NPP 13.5t/(hm2·a) in mid subtropical zone. The average annual fixed carbon content of Phoebe bournei plantation is 538.38 gC/(m2·a). it's lower than average annual fixed carbon content in mid subtropical zone, but higher than annual fixed carbon content of Chinese fir plantation in subtropical zone, it obviously shows that the mixed carbon ability of Phoebe bournei is stronger.(5)the soil carbon storage, aboveground carbon storage, underground carbon storage, ecosystem carbon storage, net primary productivity, annual average fixed carbon content of rich site is better than that of medium site, that of medium site is also better than that of poor site.