Hillslope Position Influences Variations in Tree Growth Over Time

Education Level

Undergraduate

Faculty Advisor(s)

Professor Joel Singley

Academic Department(s)

Biology, Marine Biology, and Environmental Science

Comments

This research was presented at the 2024 Rhode Island Summer Undergraduate Research Symposium, held on Friday, July 26, at the University of Rhode Island and supported by NSF EPSCoR.

Symposium Date

2024

Abstract

Tree growth depends on interactions between adjacent vegetation, local climate, and landscape properties. In arid, semi-arid, and Mediterranean climatic regions, hillslope position has been recognized as an important mediator of annual tree growth and its resilience to hydroclimatic variation, such as periods of drought. This relationship has garnered less research in humid, temperate regions such as Rhode Island, despite the fact that post-glacial landscapes can exhibit large variability in subsurface properties over small spatial scales. To begin addressing this gap, we cored 42 oak trees along a hillslope in Tiverton, Rhode Island, during the summer of 2024. We used image analysis software to measure annual growth for each tree. Our preliminary analyses identified greater maximum and median annual ring widths for trees lower on the hillslope compared to their similarly aged, but smaller diameter, counterparts higher on the hillslope. We also found that the minimum annual ring width was approximately the same regardless of hillslope position, and despite systematic differences in tree size. Broadly, all trees exhibited reductions in annual ring width at older ages, but the magnitude of these signals varied among hillslope positions, with trees at lower positions displaying the largest age-related changes in growth. The greater median and maximum ring widths of lower trees may indicate that conditions were more favorable for rapid growth at the bottom of the hillslope, especially in the early stages of their lives. In trees located on the upper part of the hillslope, the smaller absolute range of ring widths could suggest that these trees grew more consistently, regardless of climatic conditions. Overall, these results reveal that hillslope position is an important control on interannual growth patterns of oaks in this area. This provides a basis from which we will extract and analyze other growth signals that are indicative of sensitivity to hydroclimatic variability over the past century. Ultimately this work will provide further insight into the relative importance of stand age, topography, and climate as controls on the resilience of local forests.

This document is currently not available here.

Share

COinS