Remote Sensing of Forest Growth and Response to Climatic Variations
in Northeastern Kansas, U.S.A.
- James S. Aber, Kham N. Nang and Naomi Wilkins, Earth Science Department, Emporia
State University, Emporia, KS 66801-5087.
- Hengchun Ye, Dept. of Geography, University of Idaho, Moscow, ID 83843.
- John Harrington, Dept. of Geography, Kansas State University, Manhattan, KS 66506.
- Matthew C. Nowak, Natural Resources Director, 600 Thomas Ave., Ft. Leavenworth, KS 66027-1399.
This research is part of a project to model sustainable rural-resource systems within
the state of Kansas, U.S.A. The overall methology is based on remotely sensed
datasets in combination with climatic data and ground observations, with a special
emphasis on identifying vegetation changes related to climatic events. Our research
focuses on forest cover in the uplands of northeastern Kansas, where small stands of
hardwood (oak-hickory), deciduous forest are present. We utilized a nature preserve
at Fort Leavenworth for detailed ground observations. Our working hypothesis is that
interannual changes in forest conditions are primarily reflections of climatic
conditions in this situation. Land cover was classified from Landsat TM datasets
using tassled-cap and isocluster techniques, which effectively separated upland
forest patches from all other types of vegetation, and July NDVI was analyzed for
interannual variations of selected years. Kite aerial photography was utilized for
low-altitude, large-scale views of forest canopy. Tree-ring cores, collected from
various oak species, provide direct evidence for yearly growth conditions, and nearby
weather stations record climatic variables during the period of study (1970 to
Preliminary results suggest complicated relationships between climatic events, tree
growth, and NDVI. Growth of tree rings is closely correlated to climatic events of
the same year--tree rings are especially narrow during years of drought (1988-89).
However, July NDVI values decline only slightly during these years. Substantial
decline in NDVI values seems to lag a year (or more) after drought, by which time
tree-ring growth has recovered to normal. This suggests that annual growth of tree
leaves and NDVI values are not in phase with climatic events that affect growth of
tree rings. Our tentative finding is that NDVI values should be used cautiously for
reaching conclusions about climatic effects and long-term sustainability of deciduous
forest in the central United States. Funding for this project is provided by a NASA
Kansas EPSCoR grant.
Summary abstract for poster presentation at 27th International Symposium on Remote
Sensing of Environment, Tromsø, Norway, June 8-12, 1998.
Return to NASA EPSCoR at Emporia State University.
Posted on 2 June 1998.