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Abstract
Snowpack regimes are projected to change in western North America in the coming decades. There is uncertainty about how forests will respond to this change across species and topography. In the absence of experimental data, growth-climate correlations from tree-ring data offer an indirect window onto tree physiology. We analyzed tree-ring data from ponderosa pine (Pinus ponderosa) from four sites in Idaho, USA to examine relationships between snow-water-equivalence (SWE) and growth from 1981-2023 and precipitation, temperature, and growth from 1920-2023. This analysis suggests a current-water-year spring snowpack growth limitation combined with an unexpected positive lag effect of previous water year SWE (max r = 0.63; p < 0.05). We posit that this effect may result from carbon sink limitation followed by release. Future field experiments are needed to confirm or refute these physiological explanations considering the projected decline in snowpack. Such work can inform future management of this important conifer species.