Presentation Title

Tree spatial patterns modulate peak snow accumulation and snow disappearance

Authors' Names

Eryn SchneiderFollow

Presentation Type

Oral Presentation

Abstract/Artist Statement

Forests and snow covered regions frequently co-occur across the northern hemisphere. In these environments, forests are structurally and spatially complex mosaics of tree neighborhoods that are intrinsically linked to ecosystem functions. Tree and canopy structures influence snow accumulation and disappearance processes through interception and radiation attenuation. However, it is unclear to what extent if spatial heterogeneity within the forest canopy induces heterogeneity in snow accumulation and persistence. Using a forest-based approach, we identified and tested the differential effects of within-forest neighborhoods on snow processes. Neighborhood types included individual ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii) and western larch (Larix occidentals) trees, tree clumps, openings, and regeneration patches. Neighborhoods were identified within a mixed-conifer forest and paired with intensive measurements of snow accumulation (density and depth) and persistence. Overall, neighborhood type and year had a significant effect on accumulation and snow disappearance. Openings were significantly different from clumps and individuals, always accumulating more snow. Openings retained snow significantly later than clumps but were not significantly different from individuals. Within the individual tree neighborhood, a nested species effect indicated no differences in accumulation but significant differences in disappearance between deciduous and evergreen conifers, with snow persisting longer beneath deciduous western larch. Our results suggest that canopy interception is the primary mechanism driving the accumulation phase, while snow disappearance patterns are a consequence of increased longwave radiation. Reducing canopy interception and longwave radiation by creating widely spaced single trees and small openings will increase snow depth and duration and thus water yield, while maintaining a heterogeneous canopy structure that includes tree clumps can be used to meet multiple objectives including diverse wildlife habitat, timing of green-up, and plant biodiversity.

Mentor Name

Andrew Larson

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Feb 22nd, 2:50 PM Feb 22nd, 3:05 PM

Tree spatial patterns modulate peak snow accumulation and snow disappearance

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Forests and snow covered regions frequently co-occur across the northern hemisphere. In these environments, forests are structurally and spatially complex mosaics of tree neighborhoods that are intrinsically linked to ecosystem functions. Tree and canopy structures influence snow accumulation and disappearance processes through interception and radiation attenuation. However, it is unclear to what extent if spatial heterogeneity within the forest canopy induces heterogeneity in snow accumulation and persistence. Using a forest-based approach, we identified and tested the differential effects of within-forest neighborhoods on snow processes. Neighborhood types included individual ponderosa pine (Pinus ponderosa), Douglas-fir (Pseudotsuga menziesii) and western larch (Larix occidentals) trees, tree clumps, openings, and regeneration patches. Neighborhoods were identified within a mixed-conifer forest and paired with intensive measurements of snow accumulation (density and depth) and persistence. Overall, neighborhood type and year had a significant effect on accumulation and snow disappearance. Openings were significantly different from clumps and individuals, always accumulating more snow. Openings retained snow significantly later than clumps but were not significantly different from individuals. Within the individual tree neighborhood, a nested species effect indicated no differences in accumulation but significant differences in disappearance between deciduous and evergreen conifers, with snow persisting longer beneath deciduous western larch. Our results suggest that canopy interception is the primary mechanism driving the accumulation phase, while snow disappearance patterns are a consequence of increased longwave radiation. Reducing canopy interception and longwave radiation by creating widely spaced single trees and small openings will increase snow depth and duration and thus water yield, while maintaining a heterogeneous canopy structure that includes tree clumps can be used to meet multiple objectives including diverse wildlife habitat, timing of green-up, and plant biodiversity.