E.stimation Of CO₂Fluxes And Energy Flux And Its Seasonal Variations From The Plantation Lei Bamboo

This research concentrates on the observation of carbon flux by eddy covariancein the Lei bamboo pure forest which is located in Taihuyuan Town Linan CityZhejiang province. From January2011to December2011, the observation lasted ayear and the data concluded carbon flux and the meteorological data such astemperature and humidity of air and soil, wind speed and direction, radiation and soon. And then obtain the important parameter characterization of ecological systemenergy balance through analysis and calculation. The important parameter includingsensible heat flux (H), latent heat flux (LE), energy closure, net ecosystem exchange(NEE) and so on. The investigation released:(1) The anaual net radiation of Lei bamboo froest is2928.924MJ m-2, sensibleheat flux is1384.903MJ m-2, latent heat flux is927.543MJ m-2, soil heat flux is-28.274MJ m-2. The daily and monthly variation of every energy component ispresent as unimodal curve. Sensible heat flux is the main component of energy loss,which is47.28%of net radiation. Latent heat flux is31.67%of net radiation. Theaverage intercept of energy closure of Lei bamboo froest is4.71W·m-2·s-1, averageslope is0.59, average correlation coefficient is0.84in the time scale of half hour.When the time scale is month, the difference is obvious. The lowest closure is0.46inSeptember and the higest is0.95in Dectember, the monthly average is0.808. Theannaul Bowen ratio of Lei bamboo change as “U”, valley value in June and peakvalue in February. The latent heat flux is less than sensible heat flux from April toNovember, variate between0.285and0.792. The latent heat flux is greater thansensible heat flux from Dectember to March, variate between1.212and2.062.(2) The annual NEE of Lei bamboo froest is-126.303Cg·m-2·a-1, RE is1108.845Cg·m-2·a-1,GEE is-1235.15Cg·m-2·a-1. Net carbon absorbing capacity is126.303Cg·m-2·a-1. The Lei bamboo froest is carbon sink totality. NEE is positive inwinter from December to February, the Lei bamboo froest is carbon souce. Leibamboo froest is carbon sink in spring, summer and autumn. The annual carbon fluxis variate as bimodal. The first peak is June (-21.39gCm-2month-1) and the secondpeak is November (-35.89gC m-2month-1). The highest emission is in January(16.061gC m-2month-1).(3) The temperature and NEE of canopy of Lei bamboo froest is variate asquadratic polynomial in the time scale of half hour and monthly. When thetemperature is15℃, quadratic polynomial reach the peak, means NEE is the negative maximum. NEE of Lei bamboo froest at night and soil temperature of5cm have theindex relationship, but the correlation coefficient is only0.3. This means NEE changewith temperature nonlinear. The correlation is change with temperature. Thecorrelation coefficient between RE and NEE is0.4, The correlation coefficientbetween GEE and GEE is0.09, The correlation coefficient between RE and GEE is0.87, which is higher than comparision with NEE. This showed that breathing drivedby total exchange capacity of ecosystem, but the net exchange capacity is almostuncorrelated with breathing.(4) The soil temperture rise cause by cover in winter. The average temperture isabove10℃. This is promotes for the breathing of ecosystem. According to theindicial equation of soil temperture and night NEE, simulate the breathing ofecosystem without cover. From December to Febuary NEE increase respectively21.56g，26.52g，20.53g when have cover. The covering in winter in Lei bamboo froestincreases the breathing ecosystem. It increased the production bamboo shoots,improved economic benefit, but increased carbon emissions. NEE of Lei bamboofroest generally less than subtropical forest system, and the Yangtze river deltaecological positioning station close; With farmland system NEE is less than average.(5) Bamboo has a strong forest carbon potential, reasonable cultivation measures,science cutting old bamboo, maintain ecosystem vitality, can maintain terrestrialecosystem carbon oxygen balance to respond to climate change to make positivecontribution. In the bamboo forest development depend on eddy covariancetechnology throughput observation, and at the same time auxiliary relatedexperiments, can further explain bamboo forest carbon cycle process.