Canopy Chemistry Study at Harvard Forest 1992

As part of NASA's Accelerated Canopy Chemistry Program (ACCP) analyses were performed for the determination of carbon constituents and nitrogen content in fresh forest foliage. Samples were analyzed using a series of extraction's that yielded different carbon constituents: non-polar, polar, cellulose and lignin. Nitrogen analyses were conducted using a standard combustion procedure. Approximately 1000 leaf samples were collected from 5 geographically distinct sites and were analyzed at the University of New Hampshire to ensure consistency in analysis. Results were used as a calibration set for Visible/NIR reflectance and the estimation of carbon and nitrogen concentrations at both the leaf and canopy level. The canopy level study uses high spectral resolution data from NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) to estimate canopy level nitrogen and lignin concentration for the Harvard Forest and other study areas. The current link to this data from the Harvard Forest LTER site is to an archive at the University of New Hampshire. Additional information on this study, including, leaf level spectra and remote sensing data are available from a NASA DAAC site (http://www-eosdis.ornl.gov/daacpages/accp.html). Additional foliar chemistry data is also available on a searchable on-line database at http://www.folchem.sr.unh.edu.作为美国国家航空航天局（National Aeronautics and Space Administration, NASA）加速冠层化学项目（Accelerated Canopy Chemistry Program, ACCP）的组成部分，研究团队针对新鲜森林叶片完成了碳组分与氮含量的测定分析。样品通过一系列萃取流程得到四种碳组分：非极性组分、极性组分、纤维素与木质素。氮含量分析则采用标准燃烧法开展。研究团队从5个地理分布独立的采样点采集了约1000份叶片样品，并在新罕布什尔大学完成全部分析，以保障分析结果的一致性。分析结果被用作可见光/近红外反射光谱的校准集，用于估算叶片及冠层尺度的碳与氮浓度。冠层尺度研究借助美国国家航空航天局机载可见光/红外成像光谱仪（Airborne Visible/Infrared Imaging Spectrometer, AVIRIS）获取的高光谱分辨率数据，对哈佛森林及其他研究区域的冠层氮与木质素浓度进行估算。目前，哈佛森林长期生态研究（Long Term Ecological Research, LTER）站点指向该数据集的链接，跳转至新罕布什尔大学的存档库。本研究的更多相关信息（包括叶片尺度光谱数据与遥感数据）可从美国国家航空航天局分布式主动存档中心（Distributed Active Archive Center, DAAC）站点获取，网址为http://www-eosdis.ornl.gov/daacpages/accp.html。此外，更多叶片化学数据可通过新罕布什尔大学的可检索在线数据库获取，其网址为http://www.folchem.sr.unh.edu。