草业学报
草業學報
초업학보
Acta Prataculturae Sinica
2015年
11期
10-19
,共10页
王婧%刘廷玺%雷慧闽%张圣微%段利民
王婧%劉廷璽%雷慧閩%張聖微%段利民
왕청%류정새%뢰혜민%장골미%단이민
净生态系统交换量%驱动因子%涡度相关系统%科尔沁沙地
淨生態繫統交換量%驅動因子%渦度相關繫統%科爾沁沙地
정생태계통교환량%구동인자%와도상관계통%과이심사지
net ecosystem exchange (NEE)%meteorological factors%eddy covariance%Horqin sand
以2013年10月-2014年9月连续观测的 CO2通量数据为基础,分析了科尔沁草甸生态系统净碳交换量(NEE)的时间变化特征及其驱动因素。结果表明,NEE 日变化季节差异明显,生长季变化幅度大,净 CO2日吸收速率7月>8月>9月>6月>5月;生长季内,NEE 主要受控于叶面积指数和光合有效辐射。NEE 与光合有效辐射(PAR)之间的关系可用直角双曲线方程来描述,拟合得到的表观初始光能利用率α为0.0015μmol CO2/μmol PAR,最大光合速率 P max 为0.65μmol CO2/(m2·s)。叶面积指数(LAI)对 NEE 的影响可由分段函数表示,当LAI>3.08时,表现为渐进饱和型,且 LAI 越大 NEE 对 PAR 的响应越明显;当高饱和水汽压差(VPD)在1.5~2.0 kPa 时,光合作用开始降低,NEE 明显受到 VPD 值的抑制;短暂强降雨(累计降雨量>40 mm/d)对昼间 NEE 有一定的抑制,而持续低强度降雨(降雨时长>15 h)对夜间 NEE 存在激发作用;夜间 NEE 随土壤温度呈指数增长,温度敏感系数(Q10)为2.63。
以2013年10月-2014年9月連續觀測的 CO2通量數據為基礎,分析瞭科爾沁草甸生態繫統淨碳交換量(NEE)的時間變化特徵及其驅動因素。結果錶明,NEE 日變化季節差異明顯,生長季變化幅度大,淨 CO2日吸收速率7月>8月>9月>6月>5月;生長季內,NEE 主要受控于葉麵積指數和光閤有效輻射。NEE 與光閤有效輻射(PAR)之間的關繫可用直角雙麯線方程來描述,擬閤得到的錶觀初始光能利用率α為0.0015μmol CO2/μmol PAR,最大光閤速率 P max 為0.65μmol CO2/(m2·s)。葉麵積指數(LAI)對 NEE 的影響可由分段函數錶示,噹LAI>3.08時,錶現為漸進飽和型,且 LAI 越大 NEE 對 PAR 的響應越明顯;噹高飽和水汽壓差(VPD)在1.5~2.0 kPa 時,光閤作用開始降低,NEE 明顯受到 VPD 值的抑製;短暫彊降雨(纍計降雨量>40 mm/d)對晝間 NEE 有一定的抑製,而持續低彊度降雨(降雨時長>15 h)對夜間 NEE 存在激髮作用;夜間 NEE 隨土壤溫度呈指數增長,溫度敏感繫數(Q10)為2.63。
이2013년10월-2014년9월련속관측적 CO2통량수거위기출,분석료과이심초전생태계통정탄교환량(NEE)적시간변화특정급기구동인소。결과표명,NEE 일변화계절차이명현,생장계변화폭도대,정 CO2일흡수속솔7월>8월>9월>6월>5월;생장계내,NEE 주요수공우협면적지수화광합유효복사。NEE 여광합유효복사(PAR)지간적관계가용직각쌍곡선방정래묘술,의합득도적표관초시광능이용솔α위0.0015μmol CO2/μmol PAR,최대광합속솔 P max 위0.65μmol CO2/(m2·s)。협면적지수(LAI)대 NEE 적영향가유분단함수표시,당LAI>3.08시,표현위점진포화형,차 LAI 월대 NEE 대 PAR 적향응월명현;당고포화수기압차(VPD)재1.5~2.0 kPa 시,광합작용개시강저,NEE 명현수도 VPD 치적억제;단잠강강우(루계강우량>40 mm/d)대주간 NEE 유일정적억제,이지속저강도강우(강우시장>15 h)대야간 NEE 존재격발작용;야간 NEE 수토양온도정지수증장,온도민감계수(Q10)위2.63。
The objectives of this study were to investigate the main drivers of ecosystem carbon dynamics in meadow grasslands in the Horqin Sand Lands,and to understand the relationship between net ecosystem CO2 exchange (NEE)and key meteorological factors in this region.We continuously measured (NEE)and environ-mental factors in meadow grasslands in the Horqin Sand Lands from October 2013 to September 2014 using the eddy covariance method.The results showed that the diurnal variation in NEE differed significantly among sea-sons,especially among vegetation growing seasons.The highest seasonal diurnal absorption rate of CO2 was in July,followed by August,September,June,and then May.The NEE was controlled by photosynthetically ac-tive radiation (PAR)and the leaf area index (LAI)during vegetation growing seasons.The relationship be-tween NEE and PAR was expressed by a rectangular hyperbolic function.The simulated apparent initial aver-age light-use efficiency was 0.0015 μmol CO2/μmol PAR,and the maximum photosynthetic rate (P max )was 0.65 μmol CO2/(m2 ·s).The NEE was influenced by LAI,which was expressed by piecewise functions.When the LAI was greater than 3.08,NEE-PAR showed a gradual saturation-type relationship.The higher the LAI,the stronger the response of net carbon exchange to the amount of PAR.A light saturation response occurred when 1.5<VPD<2 kPa,and NEE was significantly inhibited under high VPD.The day-time net CO2 exchange was inhibited by heavy rainfall (cumulative rainfall>40 mm/day),while sustained low-intensity rain-fall (rainfall length>15 h)stimulated soil respiration at night.The night-time respiration rate of the ecosystem (R eco )increased exponentially as the soil temperature (T s )increased,and the temperature-sensitive coefficient Q10 was 2.63.