Canopy Processes at HJA: Ecophysiological and Microclimate Linkages to Atmospheric and Soil Dynamics

The Discovery Tree

The Discovery Tree Met Station was first installed with a thermal infrared camera in March 2014, which collects surface temperatures of the old-growth forest and the adjacent secondary-growth forest. Since then, the scope of information being acquired in real-time has increased to include temperature, leaf wetness, relative humidity, soil temperature, soil moisture, wind direction and speed. This suite of data serves as a glimpse into the canopy and soil processes we are unaware of when our feet are planted firmly on the ground.


The upper-canopy of forests is known to experience a very different microclimate than the rest of the forest: it is often simultaneously brighter, hotter, windier, and drier. The upper canopy also contains most of the leaf area, and because it absorbs most of the solar radiation, it accounts for the great majority of carbon and water exchanges in most forests. Critically, this is also the zone where most climate variations and stress likely manifest. Finally, the upper canopy is the region of the forest that is sampled by satellite imagery. With intensive canopy microclimate monitoring, we can provide connections to satellite-based imagery at varying temporal and spatial scales in order to scale across the Andrews landscape. A focus on canopy microclimate would thus yield large dividends in our understanding of forest function and its response to climate change. It would complement and leverage ongoing, long-term climate measurements collected in the sub-canopy and at the climate stations located across the Andrews forest, and potentially link with Lidar data on canopy structure and planned soil moisture measurements.


The primary goal of the proposed research is to understand whether and how the forest canopy is 'de-coupled' from the understory and connected to larger-scale climate processes, and thus might also be experiencing regional warming and drought and heat stresses. We also hope to demonstrate how canopy microclimate observations can advance fundamental biological understanding of canopy processes and properties and their linkages to atmospheric and sub-canopy dynamics. To achieve these goals, we have established new canopy thermal imaging and microclimate measurements for ecophysiological applications such as monitoring the response of forest tree canopies to climate variations, including heat and drought stress.

Discovery Tree Meteorological Station: 7d overview plots
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Air Temperature (Fan-aspirated)
Fan aspirated air temperature, © HJ Andrews, LTER (AND), OSU
Leaf Wetness
Leaf wetness, © HJ Andrews, LTER (AND), OSU
Relative Humidity
Relative humidity, © HJ Andrews, LTER (AND), OSU
Soil Temperature
Soil temperature, © HJ Andrews, LTER (AND), OSU
Wind Speed
Wind speed, © HJ Andrews, LTER (AND), OSU
Wind Direction
Wind direction, © HJ Andrews, LTER (AND), OSU
Soil Moisture
Soil moisture, © HJ Andrews, LTER (AND), OSU
Dendrometer Mature Stand
Circumference dendrometer, © HJ Andrews, LTER (AND), OSU
Dendrometer 2nd Growth
Circumference dendrometer, © HJ Andrews, LTER (AND), OSU
Air Temperature (Non-aspirated)
Non-aspirated/no shield air temperature, © HJ Andrews, LTER (AND), OSU

Caution: These are provisional real-time data
that have not been quality checked! These data will change.