THE LAPORTE, INDIANA, PRECIPITATION ANOMALY

ABSTRACT

An abrupt ecotone in the vicinity of Valparaiso, Indiana, which separates forest communities consisting principally of beech and sugar maple from those dominated by black oak and white oak, coincides with the western margin of the LaPorte, Indiana, precipitation anomaly. This ecotone is spatially related to a subsoil texture gradient, but its relationship to the precipitation pattern is doubtful. Tree-ring variation in living trees near LaPorte reveals patterns of cross-dating and climatic correlation which might be expected if the described precipitation pattern is real. Subsident mesoscale air flows (the lake breeze) from Lake Michigan in summer might contribute to occasional unexpected rainfall in northwestern Indiana.

KEY WORDS:

• Ecotone
• Lake breeze
• Soil texture
• Tree-ring variation