中文摘要：

以东北东部山区蒙古栎（Quercus mongolica）、五角槭（Acer mono）、春榆（Ulmus japonica）、水曲柳（Fraxinus mandshurica）、胡桃楸（Juglans mandshurica）、黄波椤（Phellodendron amurense）、白桦（Betula platyphylla）和紫椴（Tilia amurensis）8个阔叶树种为研究对象,通过SPAD-502叶绿素仪分析以上树种SPAD日变化特征,计算不同测定时间SPAD值估测叶绿素面积质量误差。结果表明：SPAD值日变化最大值75%出现在12：00—18：00,最小值近90%出现在04：00—06：00,变化率在2%~17%;SPAD最小值低估叶绿素面积质量误差达10%~20%,其他时间段误差在±9%内（除了蒙古栎春季）。叶片SPAD与光量子通量密度、叶绿素面积质量、叶面积质量、含水率相关性因树种和测定时期而异。建议该地区SPAD值测定时间最好在08：00—18：00。

英文摘要：

We studied the diurnal characteristics of SPAD values,and calculated the estimation errors from different measurement time of SPAD using the portable nondestructive optical chlorophyll meters SPAD-502 for Quercus mongolica,Acer mono,Ulmus japonica,Fraxinus mandshurica,Juglans mandshurica,Phellodendron amurense,Betula platyphylla,and Tilia amurensis in northeast China.The diurnal maximum SPAD values mostly occurred between 12： 00 to 18： 00,and minimum values in 04： 00-06： 00,with the variation in 2%-17% in clear days during the growing season.Minimum estimation error were 10%-20% for eight tree species,occurring in 04： 00-06： 00,while error was within ±9% during the other measurement time period except for the Spring of Q.mongolica.The correlation between leaf SPAD and PPFD（photosynthetic photon flux density）,chlorophyll content,LMA（leaf mass area）,and LWC（leaf water content） was not consistent with tree species and measurement period.The SPAD measurement time was better in 08： 00-18： 00 in northeast China.