Landscape variation in canopy nitrogen and carbon assimilation in a temperate mixed forest
Abstract
Canopy nitrogen (N) is a key factor regulating carbon cycling in forest ecosystems through linkages among foliar N and photosynthesis, decomposition, and N cycling. This analysis examined landscape variation in canopy nitrogen and carbon assimilation in a temperate mixed forest surrounding Harvard Forest in central Massachusetts, USA by integration of canopy nitrogen mapping with ecosystem modeling, and spatial data from soils, stand characteristics and disturbance history. Canopy %N was mapped using high spectral resolution remote sensing from NASA’s AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) instrument and linked to an ecosystem model, PnET-II, to estimate gross primary productivity (GPP). Predicted GPP was validated with estimates derived from eddy covariance towers. Estimated canopy %N ranged from 0.5 to 2.9% with a mean of 1.75% across the study region. Predicted GPP ranged from 797 to 1622 g C m−2 year−1 with a mean of 1324 g C m−2 year−1. The prediction that spatial patterns in forest growth are associated with spatial patterns in estimated canopy %N was supported by a strong, positive relationship between field-measured canopy %N and aboveground net primary production. Estimated canopy %N and GPP were related to forest composition, land-use history, and soil drainage. At the landscape scale, PnET-II GPP was compared with predicted GPP from the BigFoot project and from NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) data products. Estimated canopy %N explained much of the difference between MODIS GPP and PnET-II GPP, suggesting that global MODIS GPP estimates may be improved if broad-scale estimates of foliar N were available.
Department
Earth Systems Research Center
Publication Date
7-12-2018
Journal Title
Oecologia
Publisher
Springer
Digital Object Identifier (DOI)
Document Type
Article
Recommended Citation
Zhou, Z., S.V. Ollinger and LC. Lepine. 2018. Landscape variation in canopy nitrogen and carbon assimilation in a temperate mixed forest. Oecologia. https://doi.org/10.1007/s00442-018-4223-2.
Rights
© Springer-Verlag GmbH Germany, part of Springer Nature 2018