基于实际蒸散量辽西地区春玉米生物量及产量评价

为了确定辽西地区春玉米各发育阶段生长状况及最终产量的评价方法,基于2011—2015锦州农业气象试验站开展的玉米分期播种试验,利用锦州地区气象观测数据、玉米发育期数据和玉米各发育阶段地上生物量及产量数据,采用Penman-Monteith方法和数理统计方法分析锦州地区玉米不同发育阶段实际蒸散量与地上气象生物量和气象产量的相关关系,并建立玉米各发育期生长状况及最终产量评估模型。结果表明:2011—2015年锦州地区玉米各发育阶段实际蒸散量与地上气象生物量和气象产量之间的线性关系显著,播种—七叶阶段二者呈显著的相关关系(P<0.05),播种—拔节、播种—抽雄、播种—乳熟和播种—成熟阶段二者呈极显著的相关关系(P<0.01)。建立的玉米各发育期生长状况及产量评估模型的预报准确率为77.8%—94.5%。辽西地区玉米正常生长全生育期水分供应的下限为333.2 mm,其中播种—七叶、七叶—拔节、拔节—抽雄、抽雄—乳熟和乳熟—成熟阶段水分供应的下限分别为49.9 mm、23.3 mm、83.4 mm、118.9 mm、57.7 mm。玉米各发育阶段干旱对产量影响的程度由重至轻依次为:拔节—抽雄>抽雄—乳熟>七叶—拔节>播种—七叶>乳熟—成熟。本文基于玉米实际蒸散建立的辽西地区春玉米生物量及产量评估方法,可以满足农业气象产量预报服务的需求,在实际业务中具有应用价值。

Biotic effects dominate the inter-annual variability in ecosystem carbon exchange in a Tibetan alpine meadow

The alpine meadow ecosystem in Tibet is fragile and sensitive,and its carbon sink function with respect to climate change has become a matter of widespread concern.Therefore,this study aims to clarify the inter-annual variations(IAVs)in the carbon fluxes in an alpine meadow and to further quantify the contributions of the driving factors to the IAVs.Based on 7 years of flux data(2012-2018)and the corresponding climatic and biotic data,a set of look-up tables was used to separate and quantify the IAV sources.Furthermore,linear perturbation analyses were employed to quantify the contributions of each key factor.During 2012-2018,the net ecosystem productivity(NEP),gross primary productivity(GPP)and ecosystem respiration(Re)of this alpine meadow were 3.31±26.90,210.18±48.35 and 206.88±28.45 g C m^(-2) y^(-1),respectively,which indicated relatively large IAVs.When the contributions of climatic and biotic effects were distinguished and quantified,the dominant effects of biotic factors emerged.Additionally,negative interactions between climatic and biotic effects were detected.Among the climatic factors,only soil water content contributed relatively more to the IAVs and played a role in regulating the interactions between climatic and biotic effects.These results suggest that biotic effects must be carefully considered to reduce the uncertainties associated with future carbon flux estimates.