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Journal article
Canopy structure modulates the sensitivity of subalpine forest stands to interannual snowpack and precipitation variability
Hydrology and earth system sciences, Vol.29(3), pp.701-718
2025
Abstract
A declining spring snowpack is expected to have widespread effects on montane and subalpine forests in western North America and across the globe. The way that tree water demands respond to this change will have important impacts on forest health and downstream water subsidies. Here, we present data from a network of sap velocity sensors and xylem water isotope measurements from three common tree species (Picea engelmannii, Abies lasiocarpa and Populus tremuloides) across a hillslope transect in a subalpine watershed in the Upper Colorado River basin. We use these data to compare tree- and stand-level responses to the historically high spring snowpack but low summer rainfall of 2019 against the low spring snowpack but high summer rainfall amounts of 2021 and 2022. From the sap velocity data, we found that only 40 % of the trees showed an increase in cumulative transpiration in response to the large snowpack year (2019), illustrating the absence of a common response to interannual spring snowpack variability. The trees that increased water use during the year with the large spring snowpack were all found in dense canopy stands – irrespective of species – while trees in open-canopy stands were more reliant on summer rains and, thus, more active during the years with modest snow and higher summer rain amounts. Using the sap velocity data along with supporting measurements of soil moisture and snow depth, we propose three mechanisms that lead to stand density modulating the tree-level response to changing seasonality of precipitation:
1. Topographically mediated convergence zones have consistent access to recharge from snowmelt which supports denser stands with high water demands that are more reliant and sensitive to changing snow.
2. Interception of summer rain in dense stands reduces the throughfall of summer rain to surface soils, limiting the sensitivity of the dense stands to changes in summer rain.
3. Shading in dense stands allows the snowpack to persist deeper into the growing season, providing high local reliance on snow during the fore-summer (early-summer) drought period.
Combining data generated from natural gradients in stand density, like this experiment, with results from controlled forest-thinning experiments can be used to develop a better understanding of the responses of forested ecosystems to futures with reduced spring snowpack.
Details
- Title
- Canopy structure modulates the sensitivity of subalpine forest stands to interannual snowpack and precipitation variability
- Authors/Creators
- Max BerkelhammerGerald PageFrank ZurekChristopher StillMariah CarboneWilliam TalaveraLaura HildebrandJames ByronKyle InthabandithAngellica KucinskiMelissa CarlsonKelsey FossWendy BrownRosemary CarrollAustin SimonpietriMarshall WorshamIan BreckheimerAnna RykenMaxwell ReedDavid GochisMark RaleighEric SmallKenneth Williams
- Publication Details
- Hydrology and earth system sciences, Vol.29(3), pp.701-718
- Publisher
- Copernicus Publications on behalf of the European Geosciences Union
- Number of pages
- 18
- Grant note
- Biological and Environmental Research: DE-SC0019210 Department of Energy's Office of Science "Biological and Environmental Research" (BER) program: HQ-00342010037 US Department of Defense's National Defense Education Activity via the Educational and Research Training Collaborative at the University of Illinois Chicago: DE-SC0021139, DE-SC0024218 Department of Energy's Biological and Environmental Research programRMBL graduate fellowship: DE-AC02-05CH11231 US Department of Energy's Office of Science: 1761441 National Science Foundation: DE-AC02-05CH11231 US Department of Energy's Office of Science BER program
The authors would like to acknowledge the supporting staff at the Rocky Mountain Biological Lab (RMBL). Max Berkelhammer and Christopher Still acknowledge support from the Department of Energy's Office of Science "Biological and Environmental Research" (BER) program (grant no. DE-SC0019210). The work of William Talavera, Angellica Kucinski and Kyle Inthabandith was supported by the US Department of Defense's National Defense Education Activity via the Educational and Research Training Collaborative at the University of Illinois Chicago (grant no. HQ-00342010037). Mariah S. Carbone acknowledges funding from the Department of Energy's Biological and Environmental Research program (grant nos. DE-SC0021139 and DE-SC0024218) and an RMBL graduate fellowship to Austin Simonpietri. Rosemary W. H. Carroll acknowledges support from the US Department of Energy's Office of Science (grant no. DE-AC02-05CH11231). This material is based upon work supported by the National Science Foundation under grant no. 1761441 to Mark Raleigh and Eric Small. This material is also based upon work undertaken as part of the Watershed Function Scientific Focus Area funded by the US Department of Energy's Office of Science BER program under grant no. DE-AC02-05CH11231.
- Identifiers
- 991005739917907891
- Copyright
- © Author(s) 2025.
- Murdoch Affiliation
- College of Environmental and Life Sciences; School of Environmental and Conservation Sciences
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.40 Forestry
- 3.40.55 Forest Dynamics
- Web Of Science research areas
- Geosciences, Multidisciplinary
- Water Resources
- ESI research areas
- Geosciences