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Research Spending & Results

Award Detail

Awardee:PRESIDENT AND FELLOWS OF MIDDLEBURY COLLEGE
Doing Business As Name:Middlebury College
PD/PI:
  • Andrea H Lloyd
  • (802) 443-3165
  • lloyd@middlebury.edu
Award Date:08/21/2006
Estimated Total Award Amount: $ NaN
Funds Obligated to Date: $ 167,386
  • FY 2006=$167,386
Start Date:09/01/2006
End Date:08/31/2011
Transaction Type:Grant
Agency:NSF
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.078
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research/RUI: Past, Present and Future Productivity of Arctic Woody Vegetation in a Warming Climate
Federal Award ID Number:0612346
DUNS ID:020651675
Parent DUNS ID:020651675
Program:ARCSS-Arctic System Science

Awardee Location

Street:14 OLD CHAPEL ROAD
City:MIDDLEBURY
State:VT
ZIP:05753-6000
County:Middlebury
Country:US
Awardee Cong. District:00

Primary Place of Performance

Organization Name:Middlebury College
Street:14 OLD CHAPEL ROAD
City:MIDDLEBURY
State:VT
ZIP:05753-6000
County:Middlebury
Country:US
Cong. District:00

Abstract at Time of Award

The expansion of forest vegetation within and into the Arctic is one of the profound transformations that the Arctic land surface is likely to undergo in the coming decades. The spread of forest vegetation has significant ramifications for the arctic system, as it is likely to cause both positive and negative feedbacks on climate, and to alter the availability of crucial natural resources. Although forest expansion within and into the Arctic has been widespread in recent decades, there is growing evidence that non-linear responses to warming may prevail within areas of expanding forest. In particular, large areas of 'browning' (declining trends in NDVI) have recently been identified in the southern Arctic. The goal of this research is to assess the relationships among tree growth, climate, and NDVI in order to identify the causes of non-linear responses to temperature (i.e., the 'browning' response) and better understand the likely effects of future warming on the productivity and dynamics of forest vegetation expanding into the Arctic. The proposed research tests three hypotheses. First, it is hypothesized that the 'browning' response in the southern Arctic represents a non-linear response to temperature induced by drought stress. The researchers propose to test this hypothesis by compiling a circum-arctic database of tree-ring chronologies, representing all major Arctic tree species and regions. Most of these chronologies are readily available in an existing data archive; they propose fieldwork in years 2 and 3 of the project to update chronologies from two key areas. They will use regression tree analysis to model the climate-tree growth relationships. Second, they hypothesize that trends in NDVI are consistent with trends in tree growth: they expect that a drought-induced threshold response to temperature explains both tree growth and the NDVI data. They will test this hypothesis by comparing the AVHRR-NDVI record with the tree-ring data. Finally, they hypothesize that temperature and precipitation will continue to influence trends in NDVI and arctic forest productivity in the future. They will test this hypothesis at a limited number of sites using a customized version of the Biome-BGC model, an ecophysiological forest growth model. This modeling exercise will allow them to explore, in a qualitative fashion, the implications of spatially variable tree growth (and NDVI) for C dynamics in the southern Arctic during the next several decades. The research should yield the first circum-arctic analysis of tree growth response to climate, addressing the critical question of the prevalence (and causes) of non-linear responses to climate in Arctic forests. This will provide important insight into the likely future trajectory of land cover change in the southern Arctic: if non-linear responses to temperature prevail, then future expansion of forests into the Arctic seems far less certain than if responses are primarily linear. Second, the proposed research will link the site-level climate responses to C dynamics, allowing us to determine, at least for a subset of sites, how non-linear climate responses alter forest C flux.

Publications Produced as a Result of this Research

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Berner, LT; Beck, PSA; Bunn, AG; Lloyd, AH; Goetz, SJ "High-latitude tree growth and satellite vegetation indices: Correlations and trends in Russia and Canada (1982-2008)" JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES, v.116, 2011, p.. doi:10.1029/2010JG00147  View record at Web of Science

Lloyd, AH; Bunn, AG; Berner, L "A latitudinal gradient in tree growth response to climate warming in the Siberian taiga" GLOBAL CHANGE BIOLOGY, v.17, 2011, p.1935. doi:10.1111/j.1365-2486.2010.02360.  View record at Web of Science

Lloyd, Andrea H. "Responses of the circumboreal forest to 20th century climate variability" Environmental Research Letters, v.2, 2007, p.045013. doi:10.1088/1748-93262/4/045013 

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