Dendroclimatic Responses of Sugar Maple Tapped for Maple Syrup: A Case Study from Pennsylvania

Abstract

Maple syrup is a regional, non-timber forest product in the United States that depends upon healthy, mature sugar maple (Acer saccharum Marshall). We examined whether tapping for maple syrup altered the dendroclimatic response of sugar maple. Ring width indices from two sites (tapped and reference) in central Pennsylvania were correlated with regional temperature, precipitation, and Palmer Drought Severity Index (PDSI). Both sites had significant correlations between summer and fall PDSI and radial growth. Spring PDSI was significantly correlated with growth at the reference site, but not at the tapped site. Both tapped and reference trees experienced below-average growth during years with dry spring conditions (PSDI < 0), but tapped trees had a higher percentage of years (27%) with below-average growth during years with moist spring conditions (PDSI > 0) compared to reference trees (15%). These results indicate that tapping for maple syrup may have altered the dendroclimatic response of sugar maple to moisture availability during the spring months. © 2017 by The Tree-Ring Society.