|
Assessing the influence of local phenology on the response of forest productivity to changes in growing season length
Andrew
Elmore, UMCES Appalachian Laboratory, aelmore@umces.edu
(Presenter)
David
Nelson, UMCES Appalachian Laboratory, dnelson@umces.edu
(Presenter)
The timing of spring leaf development, trajectories of summer leaf area, and the timing of autumn senescence have profound impacts to the water, carbon, and energy balance of ecosystems, and are likely influenced by global climate change. A trend towards a longer growing season, here defined by the number of days between the spring onset and autumn offset of greenness, has been observed in regional- to global-scale remote sensing time-series spanning the past 30 years. Increased tree productivity in regions experiencing a longer growing season might create a negative feedback to increasing atmospheric carbon dioxide concentration and climate change, although uncertainty surrounds this hypothesis due to complexity between phenological timing and ecosystem responses. If annual variation and long-term trends in growing season length are influencing forest productivity, we hypothesize that this influence will be a function of phenological variability occurring at local scales. We are using a combination of high-resolution remote sensing data and dendroecological analysis to investigate the influence of changes in phenology on the productivity of forest trees in the eastern US. Our phenology observations come from dense stacks of Landsat TM and ETM+ data, organized by day of year and summarized using a 7-parameter curve fitting algorithm to extract the growing season length and the stability of summer greenness (greendown) at 30m resolution. We observe that fine-scale variation in phenology is widespread throughout our study region with elevation, urban centers, and tidal water all contributing to spatial variation. To date we have cored 20 sites and analyzed tree rings for basal area increment and carbon and nitrogen isotopes. Preliminary results suggest important phenological controls on tree productivity implicating greendown as an important indicator of forest productivity.
Presentation:
2013_Poster_Elmore_31_17.pdf (15035k)
Presentation Type: Poster
Session: Poster Session 1-B
(Tue 4:30 PM)
Associated Project(s):
Poster Location ID: 31
|