Browsing by Author "Butler, Ethan E."

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    Climate-biome envelope model for the Western Great Lakes Region
    (2021-02-16) Toot, Ryan; Frelich, Lee E.; Butler, Ethan E.; Reich, Peter B.; tootx001@umn.edu; Toot, Ryan; Forest Ecology Lab
    Research Highlights: We modeled climate-biome envelopes at high resolution in the Western Great Lakes Region for recent and future time-periods. The projected biome shifts, in conjunction with heterogeneous distribution of protected land, may create both great challenges for conservation of particular ecosystems and novel conservation opportunities. Background and Objectives: Climate change this century will affect the distribution and relative abundance of ecological communities against a mostly static background of protected land. We developed a climate-biome envelope model using a priori climate-vegetation relationships for the Western Great Lakes Region (Minnesota, Wisconsin and Michigan USA and adjacent Ontario, Canada) to predict potential biomes and ecotones—boreal forest, mixed forest, temperate forest, prairie–forest border, and prairie—for a recent climate normal period (1979–2013) and future conditions (2061–2080). Materials and Methods: We analyzed six scenarios, two representative concentration pathways (RCP)—4.5 and 8.5, and three global climate models to represent cool, average, and warm scenarios to predict climate-biome envelopes for 2061–2080. To assess implications of the changes for conservation, we analyzed the amount of land with climate suited for each of the biomes and ecotones both region-wide and within protected areas, under current and future conditions. Results: Recent biome boundaries were accurately represented by the climate-biome envelope model. The modeled future conditions show at least a 96% loss in areas suitable for the boreal and mixed forest from the region, but likely gains in areas suitable for temperate forest, prairie–forest border, and prairie. The analysis also showed that protected areas in the region will most likely lose most or all of the area, 18,692 km2, currently climatically suitable for boreal forest. This would represent an enormous conservation loss. However, conversely, the area climatically suitable for prairie and prairie–forest border within protected areas would increase up to 12.5 times the currently suitable 1775 km2. Conclusions: These results suggest that retaining boreal forest in potential refugia where it currently exists and facilitating transition of some forests to prairie, oak savanna, and temperate forest should both be conservation priorities in the northern part of the region.
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    Data and code for spectral canopy transmittance in diverse tree communities
    (2024-12-02) Williams, Laura J.; Kovach, Kyle R.; Guzman Q., J. Antonio; Stefanski, Artur; Bermudez, Raimundo; Butler, Ethan E.; Glenn-Stone, Catherine; Hajek, Peter; Klama, Johanna; Moradi, Aboubakr; Park, Maria H.; Scherer-Lorenzen, Michael; Townsend, Philip A.; Reich, Peter B.; Cavender-Bares, Jeannine; Schuman, Meredith C.; laura.williams@westernsydney.edu.au; Williams, Laura
    Light may shape forest function not only as a source of energy or a cause of stress but also as a context cue: plant photoreceptors can detect specific wavelengths of light, and plants use this information to assess their neighborhoods and adjust their patterns of growth and allocation. Here, we examined how the spectral profile of light (350-2200 nm) transmitted through tree canopies differs among communities within three tree diversity experiments on two continents (200 plots each planted with one to 12 tree species). This dataset includes data and metadata on canopy transmittance and leaf area index (LAI) measured on these plots as well as leaf-level transmittance measured for each species in monoculture plots. Data processing code and example analysis code are also provided.
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    Phenology matters: Extended spring and autumn canopy cover increases biotic resistance of forests to invasion by common buckthorn (Rhamnus cathartica)
    (Forest Ecology and Management, 2020) Schuster, Michael J.; Wragg, Peter D.; Williams, Laura J.; Butler, Ethan E.; Stefanski, Artur; Reich, Peter B.
    Forest light availability strongly regulates understory community composition, and low availability may confer resistance to invasion by exotic species, yet common buckthorn (Rhamnus cathartica L.) invades North American temperate forests with a broad range of light habitats. It is unclear to what extent buckthorn’s success is due to high mid-season shade tolerance versus shade avoidance permitted by early leaf out and late senescence. We used buckthorn seedlings planted into a forest diversity experiment in Cloquet, Minnesota, USA and a combined buckthorn physiology-canopy light model to test (1) how buckthorn germination, growth, and survival depend on canopy shading and (2) how canopy species richness and phenology affect light availability and buckthorn performance. Based on the mean of May, August, and October light measurements, we found that canopies that permitted ≤3% transmission of incoming light had almost complete mortality of buckthorn and that growth of surviving buckthorn was strongly tied to light availability, but not canopy richness. Compared to deciduous canopies or deciduous-evergreen mixtures, evergreen canopies restricted light availability the most and led to the smallest and least likely to survive buckthorn. Our canopy models further indicated a tight linkage between buckthorn performance and spring and autumn light availability, but not summer light availability. We conclude that spring and autumn light availability are key regulators of buckthorn performance and that buckthorn relies on shade avoidance via an extended phenology to succeed in temperate forests. Consequently, we suggest species with extended spring or autumn canopy cover offer the greatest resistance to invasion, and communities which are often leafless during such periods are most vulnerable to invasion by buckthorn and similar invasive shrubs.