Data from: Trails-as-transects: phenology monitoring across heterogeneous microclimates in Acadia National Park, Maine

Climate‐driven shifts in phenology, which are being observed worldwide,
affect ecosystem services, trophic interactions, and community
composition, presenting challenges to managers in protected areas.
Resource management benefits from local, species‐specific phenology
information. However, phenology monitoring programs in heterogeneous
landscapes typically require serendipitous historical records or many
years of contemporary data before trends in phenological responses to
changes in climate can be analyzed. Here, we used a trails‐as‐transects
approach to rapidly accumulate monitoring data across environmental
gradients on three mountains in Acadia National Park, Maine, USA, and
compared our results to phenological changes observed in Concord,
Massachusetts, USA. In four years of intensive monitoring of transects on
three mountains, we found large variability in spring temperatures across
the mountains, but consistent patterns of advancing flower and leaf
phenology in warmer microclimates. Reduced sampling intensity would have
yielded similar results, but a shorter duration would not have revealed
these patterns. The plants in Acadia responded to warming spring
temperatures by shifting leaf and flower phenology in the same direction
(earlier), but at a reduced rate (as measured in d/°C), in comparison with
plants in southern New England (e.g., Concord, Massachusetts, USA). Our
approach takes advantage of topographical complexity and associated
microclimate gradients to substitute for long time series, allowing for
rapid assessment of phenological response to climate. Other climate
gradients (e.g., urban‐to‐rural, latitudinal, or coastal‐to‐inland) could
work similarly. This intensive monitoring over a short time period quickly
builds a robust dataset and can inform management decisions regarding
future monitoring strategies, including sampling designs for citizen
science‐based phenology monitoring programs.