The CO_(2)effl ux of branches and leaves plays an important role in ecosystem carbon balance.Using a carbon fl ux system,the effl ux of Larix gmelinii var.principisrupprechtii(Dahurian larch)was investigated in 27 yea...The CO_(2)effl ux of branches and leaves plays an important role in ecosystem carbon balance.Using a carbon fl ux system,the effl ux of Larix gmelinii var.principisrupprechtii(Dahurian larch)was investigated in 27 years(immature),31 years(near-mature),and 47 years(mature)stands at diurnal,seasonal,and spatial scales(direction and height)as well as its connection with environmental factors from May to October 2020.Diurnal variation in effl ux was a single peak,and the maximum occurring between 14:00 and 16:00.Seasonal variation also exhibited a single peak,with the maximum in late July and the minimum in early October.From May to September,effl ux on the south side was the largest among the three stands,and mean values on the south side of 27 year-old,31 year-old,and 47 year-old trees were 0.50,0.97 and 1.05μmol·m^(–2)·s^(–1),respectively.The minimum occurred on the north side.Except for the maximum in July and September in the 27 year-old stand in the middle of the canopy,the maximum effl ux in the upper canopy,and the means in the 27 year-old,31 year-old,and 47 year-old stands were 0.49,0.96 and 1.04μmol·m^(-2)·s^(-1),respectively;the minimum occurred in the lower canopy.Temperatures and relative humidity infl uenced seasonal variations in effl ux.Seasonal variation in temperature sensitivity coeffi cient(Q 10)was opposite that of temperature,increasing with decreasing temperature.At the spatial scale,maximum Q 10 occurred in the mid canopy.With the effl ux and temperature data in diff erent locations,it is possible to better estimate effl ux variations in each stand.展开更多
为了解中西太平洋金枪鱼围网渔业的渔获组成及其时空变化规律,根据1984—2020年中国、美国、西班牙围网作业渔船在中西太平洋海域的生产统计资料,对金枪鱼渔获量、单位捕捞努力量渔获量(catch per unit effort,CPUE)以及鲣(Katsuwonus p...为了解中西太平洋金枪鱼围网渔业的渔获组成及其时空变化规律,根据1984—2020年中国、美国、西班牙围网作业渔船在中西太平洋海域的生产统计资料,对金枪鱼渔获量、单位捕捞努力量渔获量(catch per unit effort,CPUE)以及鲣(Katsuwonus pelamis)、黄鳍金枪鱼(Thunnus albacares)和大眼金枪鱼(Thunnus obesus)3种金枪鱼渔获量比例等进行分析,重点研究了渔获率的年代间变化。结果表明:1)同一作业方式的不同船队鱼种渔获量比重相似;自由集群与人工集鱼装置(fish aggregation devices,FADs)的鱼种渔获量组成存在显著差异(P<0.05,R=0.528),近年间,自由集群作业方式渔获比重增大。2)各船队捕捞区域主要集中于太平洋西部海域,不同年代捕捞热点区域与物种组成存在差异,而同一年代内各物种渔获量比例较为相似,统计年间渔场中心呈从西部海域向东南方向移动的趋势。3)3种金枪鱼CPUE季间差异较小,鲣年间CPUE差异较大,呈连年增加的趋势。研究结果可为中西太平洋金枪鱼围网渔业的可持续发展提供科学参考。展开更多
基金supported by the National Natural Science Foundation of China(No.31870387),China Scholarship Council.
文摘The CO_(2)effl ux of branches and leaves plays an important role in ecosystem carbon balance.Using a carbon fl ux system,the effl ux of Larix gmelinii var.principisrupprechtii(Dahurian larch)was investigated in 27 years(immature),31 years(near-mature),and 47 years(mature)stands at diurnal,seasonal,and spatial scales(direction and height)as well as its connection with environmental factors from May to October 2020.Diurnal variation in effl ux was a single peak,and the maximum occurring between 14:00 and 16:00.Seasonal variation also exhibited a single peak,with the maximum in late July and the minimum in early October.From May to September,effl ux on the south side was the largest among the three stands,and mean values on the south side of 27 year-old,31 year-old,and 47 year-old trees were 0.50,0.97 and 1.05μmol·m^(–2)·s^(–1),respectively.The minimum occurred on the north side.Except for the maximum in July and September in the 27 year-old stand in the middle of the canopy,the maximum effl ux in the upper canopy,and the means in the 27 year-old,31 year-old,and 47 year-old stands were 0.49,0.96 and 1.04μmol·m^(-2)·s^(-1),respectively;the minimum occurred in the lower canopy.Temperatures and relative humidity infl uenced seasonal variations in effl ux.Seasonal variation in temperature sensitivity coeffi cient(Q 10)was opposite that of temperature,increasing with decreasing temperature.At the spatial scale,maximum Q 10 occurred in the mid canopy.With the effl ux and temperature data in diff erent locations,it is possible to better estimate effl ux variations in each stand.
文摘为了解中西太平洋金枪鱼围网渔业的渔获组成及其时空变化规律,根据1984—2020年中国、美国、西班牙围网作业渔船在中西太平洋海域的生产统计资料,对金枪鱼渔获量、单位捕捞努力量渔获量(catch per unit effort,CPUE)以及鲣(Katsuwonus pelamis)、黄鳍金枪鱼(Thunnus albacares)和大眼金枪鱼(Thunnus obesus)3种金枪鱼渔获量比例等进行分析,重点研究了渔获率的年代间变化。结果表明:1)同一作业方式的不同船队鱼种渔获量比重相似;自由集群与人工集鱼装置(fish aggregation devices,FADs)的鱼种渔获量组成存在显著差异(P<0.05,R=0.528),近年间,自由集群作业方式渔获比重增大。2)各船队捕捞区域主要集中于太平洋西部海域,不同年代捕捞热点区域与物种组成存在差异,而同一年代内各物种渔获量比例较为相似,统计年间渔场中心呈从西部海域向东南方向移动的趋势。3)3种金枪鱼CPUE季间差异较小,鲣年间CPUE差异较大,呈连年增加的趋势。研究结果可为中西太平洋金枪鱼围网渔业的可持续发展提供科学参考。
