Investigating Tree Phenology as an Indicator of Autumn Seasonal Carbon Flux Variation within a Northern Mixed Forest
Abstract
The timing of leaf senescence (coloring and subsequent fall; i.e., phenology) during autumn has large impacts on energy and carbon exchange between mid-latitude land surfaces and the lower atmosphere. However, spatial variations in autumn phenological timing at the plant community level have not been widely measured or analyzed, and underlying environmental drivers are not well understood. Thus, detailed autumn phenological data offer considerable opportunities for assessing landscape-level spatial variations crucial for accurate scaling-up measurements to larger areas or downscaling information from atmospheric general circulation models. This paper reports on-going results from a project measuring and analyzing spatial variability of autumn native tree phenological data at the community level in a northern mixed forest, and comparing them to microclimatic, carbon flux, and both near-surface and satellite-derived remote sensing measurements. Spatial variability of autumn phenological data is assessed from five-week field campaigns during 2010 and 2012 in the vicinity of the WLEF Ameriflux tall tower, near Park Falls, WI, USA (45.9459°N, 90.2723°W). The three largest dominant species trees were identified and tagged at each of 288 plots within two 600 x 600 m areas, for a total of 634 deciduous trees. The autumn results-to-date suggest that: 1) phenology progresses quite differently for different tree species in the study area with only some accelerated by cold temperature events; 2) autumn phenology modulates in step with changes in the autumn "turn-down" of carbon accumulation, with as much as 30 days of interannual variation; and 3) the rate of changes in autumn phenology appear to be considerably variable among years.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.B13G..05S
- Keywords:
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- 0426 BIOGEOSCIENCES / Biosphere/atmosphere interactions;
- 0428 BIOGEOSCIENCES / Carbon cycling