人工高效经营雷竹林CO2通量估算及季节变化特征

利用涡度相关技术观测高效经营雷竹林生态系统的1a碳通量变化过程,初步计算分析了碳收支以及影响的环境因子.数据结果表明,雷竹林系统全年碳收支情况为碳汇,固碳能力小于毛竹林和杉木林,同时也小于水稻田和北方农田.全年净生态系统碳交换量(NEE)为-126.303Cg·m-2·a-1,生态系统呼吸(RE)为1108.845 Cg·m-2·a-1,生态系统总交换量(GEE)为-1235.15Cg·m-2·a-1.其中冬季(12月-2月)覆盖时为碳源,其余月份为碳汇.各月碳吸收量以11月最高,6月次之,呈双峰变化,碳排放量以1月为最高.计算全年平均固碳效率为11％,12-2月为负值,11月最高33％.生态系统呼吸呈单峰变化,以夏季最高,冬季覆盖提高地温后生态系统呼吸随之增加,全年RE受温度影响显著成指数关系.人工经营下温度是影响雷竹林CO2通量过程的主要因素,同时大量有机物覆盖增加了碳排放.

Estimation of CO2 fluxes and its seasonal variations from the effective management lei bamboo (Phyllostachys Violascens)

Greenhouse gas emissions broken the balance of the carbon budget in global biogeochemical cycles. Forest ecosystems plays a great important role in maintaining the carbon-oxygen biosphere balances by absorbing CO₂. Quantifiable forest carbon sinks has become hot spot in worldwide research. As species of high economic value, Phyllostachys violascens was widely planted in south of Yangtze River with an expanding planting area. Due to shorter growing season and efficient operations, bamboo forestcould not olny brings significant economic benefit but also has a meaningful impact on climate change and forest carbon sinks.Under a special style management as well as its own eco-physiological processes, Phyllostachys violascens has both characteristic of forest and farmland system. Comparing other types of forest, Phyllostachys violascens had a greater annual photosynthesis intensity, a shorter cuttingcycle, masses of planting area and consideralbe potential capacity of the carbon sink.But about bamboo flux process and solid carbon ability reported in the literature at home and abroad is very few,enhancing the research is highly requirement. In subtropical regions to establish long-term continuous observation of the flux tower, to reveal bamboo carbon source and sink process and the mechanism which influence carbon balance has profound significance for regional scale characteristics of ecosystem carbon balance research and it have inspired guiding role. In the Zhejiang, linan city establishedbamboo forest flux observation tower, pick up three dimensional ultrasonic anemometer,H₂O/CO₂ infrared analyzer, and multi-layer gradient of the temperature and humidity, wind speed, the radiation of the conventional meteorological instruments, from September 2010 observation so far. In a year of observation data basis, through coordinate rotation correction data, through the threshold to eliminate quality control, the application of average daily variation method (MDV)plug fill a gap of data, and related calculation and analysis.Annual carbon fluxes from high-efficiency management of bamboo forest were measured using eddy covariance technology. The observation were to investigate the variation of CO₂ fluxes on seasonal scale, analyze the relationship between carbon budget and related environmental factors. Results showed that annual carbon budget of bamboo forest ecosystem was a carbon sink. Carbon sequestration capacity of bamboo forest was less than that of Phyllostachys heterocycla, Cunninghamialanceolata, paddy fields and farmland in northern China. The research indicated: annual NEE (Net Ecosystem Exchange,NEE) (126.303 gC·m^-2·a^-1),RE(Ecosystem Respiration,RE)(1108.845 gC·m^-2·a^-1)and GEP(Gross Ecosystem Exchange,GEE) (1235.15 gC·m^-2·a^-1). Except covered in winter (December-February), carbon budget for other months was carbon source. Carbon sequestration peaked in November,then in June. It showed a double-peak curve. Carbon emissions peaked in January. The diurnal variation of bamboo forest carbon flux was significantly changing with seasonal pattern.With mean annual value of 11%, the annual carbon sequestration efficiency was highest in November(33%) and was negative from December to February. Ecosystem respiration peaked in summer, which would be increasing along with the higher soil temperature by straw mulching in winter. Annual RE has an exponential relationship with temperature. In winter, temperature in plantations was a major factor in CO₂ fluxes variation. Meanwhile a large number of organic mulch leaded to an increasing carbon emission.