PARENT SESSION
Oral Session # 72: GIS and Remote Sensing I.
Presiding: J Drake
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 203.

Spectral sensing of foliar water conditions in two conifer species.

Stimson, Hugh^*,1, Breshears, David ², Kefauver, Shawn ¹, Ustin, Susan¹, ¹ University of California, Davis, Davis, CA² Los Alamos National Laboratory, Los Alamos, NM

ABSTRACT- Despite the fundamental importance of plant water stress in determining properties and dynamics at ecosystem and landscape-scales, approaches for assessing plant water stress at these scales are largely lacking. We evaluated the relationships between foliar water content and spectral changes in two coniferous species—Pinus edulis and Juniperus monosperma—which are codominants of extensive pinon-juniper woodlands in North America. Two indices of foliar water condition, plant water content (% mass) and plant water potential, were compared to four spectral analyses: continuum removal of the 1200 and 970 nm water absorption features, the Normalized Difference Water Index (NDWI), and the "red edge" position. For P. edulis, plant water content was significantly correlated with all four indices, red edge position (R²= 0.45) and 1200 nm continuum removal (R²=0.64) were exceeded by the NDWI (R²=0.91) and the 970 nm continuum removal (R²=0.92). Although the correlations were weaker than for plant water content, plant water potential for P. edulis was significantly correlated with red edge position (R²=0.31), 970nm (R²=0.41) and NDWI (R²=0.48). The relationships were weaker for J. monosperma: water content was significantly related to the 970 nm and 1200 nm continuum removal (R²=0.35 and R²=0.37 respectively) and the 1200 nm continuum removal was related to water potential (R²=0.40).

Key words: foliar water content, conifer species, spectral remote sensing, water potential