Simulating Chinese Fir Plantation Carbon Storage And Evapotranspirtion Using The 3-pg Model

Based on meteorological data observed in Huitong National Forest Ecosystem Research station during 1990-2005, The objectives of this study are to first parameterize and validate the process-based 3-PG model using long-term field measurements from a Chinese fir plantation collected at the Huitong National Forest Ecosystem Research Station. Second, to determine the C storage and allocation capacity of different age sequences of stands using the 3-PG model in order to provide core data of forest C to use for sustainable forest management. Third, to estimate the monthly and annual evapotranspiration in a Chinese fir plantation. Results suggest that the model competently simulated leaf area index (LAI), stem biomass, net primary productivity (NPP), carbon storage, carbon allocation, monthly and yearly evapotranspiration. The results shows that:(1) An increasing trend in total biomass of C storage in stands up to the age of 41 years was observed (184.02 tC·hm-2 for stand,124.09 tC·hm-2 for stem) at which point the trend reversed. C storage capacity of roots and foliage increased to its highest value at 44 years (45.09 tC·hm-2 for root,13.04 tC·hm-2 for foliage) and then declined after this point, but C storage capacity of litterfall continued to increase as the stand aged. Stems had the highest proportion (approximately 64.8%) of C storage, followed by roots (approximately 23.5%) and foliage (approximately 8.7%). Litterfall had the lowest proportion (approximately 3%). (2) The monthly evapotranspiration was the lowest in January and then increased up to the highest in July, at which point the reverse trend occurred. The average monthly evapotranspiration was.90.1mm, accounting for 72.12% of the average monthly rainfall (122.14mm). Except in August and September, the other months had a higher rainfall than evapotranspiration. The annual evapotranspiration varied insignificantly among each year (933 mm for the lowest,1299 mm for the highest). The average annual evapotranspiration was 1049 mm, accounting for 77.7% of the average annual rainfall (1350 mm). The evapotranspiration had a smaller proportion in abundant rainfall years than that in the lower rainfall years.