Seasonal structure-function interactions: fusing solar induced fluorescence and terrestrial LiDAR for holistic ecosystem measurement
Abstract
Dynamic changes in forest structure drive trends in ecosystem-level photosynthesis globally, but gross primary production (GPP) and forest structure remain challenging to accurately quantify in detail across space and time. Most estimates of GPP are based on modeling and flux observations, but both approaches are indirect and coarse in spatial scale. Solar induced fluorescence (SIF) is directly linked to biophysical processes at the leaf level, providing essential information for estimating GPP at ecosystem scales. SIF measurements are directly impacted by horizontal canopy structure - increasing leaf area increases GPP. However, the impact of vertical structure or complexity on SIF measurements is not well understood and may enhance GPP at the canopy-scale. A monitoring framework that disentangles the structural signal in both horizontal and vertical dimensions would ultimately provide essential information for maximizing the utility of ground-based SIF observations. We monitored spring and fall phenology and quantified changes in canopy structure to investigate seasonal structure-function relationships at a mixed temperate forest site in Virginia. We deployed high frequency terrestrial LiDAR to quantify fine-scale seasonal changes in canopy structure and increasing LAI. Tower-based SIF measurements provided estimates of GPP over the study period for comparison to structural changes. Both acquisitions were augmented with ongoing flux tower observations, weekly drone flights, and hemispherical photography to capture major shifts in ecosystem function due to structural change. We present preliminary findings from the first year of seasonal observations and discuss potential future applications for fusing 3D structural measurements with ongoing monitoring of photosynthesis at ecosystem scales.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B31N2696S
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0480 Remote sensing;
- BIOGEOSCIENCESDE: 1631 Land/atmosphere interactions;
- GLOBAL CHANGE