Remote sensing of intra-annual tree growth dynamics in a boreal forest
Abstract
Relationships between gross primary productivity (GPP) and the remotely sensed photochemical reflectance index (PRI) suggest that time-series of foliar PRI may provide insight into climate change effects on carbon cycling. However, because a large fraction of carbon assimilated via GPP is quickly returned to the atmosphere via respiration, we ask a critical question - can PRI time-series provide information about longer term gains in aboveground carbon stocks? Here, we explore the suitability of PRI time-series to understand intra-annual stem-growth dynamics at one of the world's largest terrestrial carbon pools - the boreal forest. We collected tree-level measurements to link PRI observations unambiguously with information on radial tree growth dynamics collected via high resolution point dendrometers. The results from a mixed-effects model showed that PRI was a statistically significant (p<0.0001) predictor of intra-annual radial tree growth dynamics, and tracked these dynamics in remarkable detail with conditional and marginal coefficients of determination of 0.48 and 0.96, respectively. Furthermore, we show that the seasonal onset of photosynthetic activity as determined by PRI time-series was significantly earlier (p<0.05) than the onset of radial tree growth determined from the point dendrometer time-series. In contrast, seasonal decline of photosynthetic activity and cessation of radial tree growth was statistically similar (p>0.05) when derived from PRI and dendrometer time-series, respectively. Our findings at the tree level suggest that PRI could provide novel insights into the nuances of carbon cycling dynamics by alleviating important uncertainties associated with vegetation response to continued warming.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B11D..07E
- Keywords:
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- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCES