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Moose winter diet and heightened vulnerability of Quaking aspen to fungal cankers

Moose winter diet and heightened vulnerability of Quaking aspen to fungal cankers . Lesley Seale CU Boulder EBIO 4100 Spring 2012 . Quaking Aspen ( Populus Tremuloides ). Keystone species (Kaye et al. 2005) Provides habitat Stabilizes erosion Tolerant

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Moose winter diet and heightened vulnerability of Quaking aspen to fungal cankers

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  1. Moose winter diet and heightened vulnerability of Quaking aspen to fungal cankers Lesley Seale CU Boulder EBIO 4100 Spring 2012

  2. Quaking Aspen (Populus Tremuloides) • Keystone species (Kaye et al. 2005) • Provides habitat • Stabilizes erosion • Tolerant • Disturbance site species • Thin, soft bark  vulnerability • SW Colorado is experiencing aspen dieback/decline (St.Clair et al. 2010)

  3. Cankers specific to Aspen in the Rockies Cryptosphaeria/ Snake Canker Sooty Bark Canker Hypoxylon Canker Black Canker Cytospora Canker (Hinds, 1981)

  4. Cervid Winter Diet • Elk (Cervuselaphus)and Moose (Alcesalces) in the montane/subalpine • Moose near MRS • Aspen bark provides protein • During winter, range concentrated near feeding grounds (Hart and Hart, 2001) • Elk browsing decreases the vigor of mature stems; harming cambium, increasing mortality and pathogen infection. (Kaye et al. 2005, 1284) • Reduced aspen stand size and habitats (Hart and Hart, 2001)

  5. The question…. Do aspens with moose gnawing have fungal canker infections?

  6. Methods • Study design – Sample aspen in moose habitats to determine if there is a relation between infected trees and wounds from browsing. • Implementation of design • Two 30m x 30m plots: Rainbow Lakes trailhead and near C-1. • Sample all aspens within the plot and record • Limitations—time, sample size, breadth of data

  7. 2 1

  8. Data Collection • Measurements • DBH • Canker symptoms • Browsing evidence • 1: this season • 2: callus not formed by dry and teeth marks still seen • 3: callusing, some teeth grooves still seen • 4: fully healed, all teeth marks gone OLD HEALED GNAW 4 FRESH GNAW 1

  9. Results • 211 tree sampled • Classified as: • Only gnawed (10) • Only cankered (20) • Gnaw and cankered (31) • No gnaws or cankers (150) • Test for Independence • Freshness Distribution • Gnaw DBH proportions

  10. Data

  11. Χ2Test of Independence • H0: Canker and moose gnawing are independent of each other. • HA: Cankers are related to moose gnawing. • Χ2 : 73.5 • P(Χ2 > 73.5)= 0.0039 • P-value (0.0039) is less than the significance level (0.05), H0 is rejected. • Supports that there is an association

  12. Freshness (1-4) OLD HEALED GNAW 4 FRESH GNAW 1

  13. Gnawed DBH

  14. Discussion • Elk browsing does create a wound in the bark for fungi to infect. • Injured stems usually succumbed to invasions by pathogenic fungi rather than from mechanical injury alone. (Hart et al. 2001, 197) • Studies by Thomas Hinds prove that discoloration is actual precenence of the fungi in tree tissue, proved by floresent properties of the fungi. • It is likely that fluorescence is the oxidizing of acids and phenols to be more toxic quinines, which are then polymerized to insoluble nontoxic melanin causing the discoloration around the perimeter of infection. (Hinds 1981) • More fires and/or fewer cervids would favor the growth of aspen. (Hart et al. 2001, 197) • Other damages harm • Falling trees • Carvings • Burrowing insects • Other fungus

  15. Further Questions • Presence of predators?(Weisberg et al. 2003, 152) • Do elk/moose avoid canker trees? Could some of the trees already have fungus inhabitants prior to elk feasting? • Photosynthesis in the trunk decreased? • How is the fungus transporting? • Does cambium damage in the winter create cavitation that is more damaging to the tree than in other seasons, increasing vulnerabilty? • Angiosperms in general, and aspen specifically, show greater sensitivity to freeze–thaw induced cavitation than conifers (St. Clair et al. 2010, 371) • In riparian zones that aspens are highly browsed will willows threaten to take over, instead of conifers?

  16. Aspens are a keystone species, important to the biodiversity in the forest. Winter ranges of cervids heavily depend on the presence of aspens as a source of protien. Decline in aspen stands can be in part attributed to the joint devastation of trees by cervids and fungi. Loss of aspen stands means loss of habitat for more than just moose.

  17. Literature Cited • Hart, John H. and D.L. Hart. " Interaction Among Cervids, Fungi, and Aspen in Northwest Wyoming." USDA Forest Proceddings RMRS-18 (2001): 197-205. • Hendreyx, Jessica. "Pests and Environmental Problems at High Altitude Landscapes." Montana State University. http://plantsciences.montana.edu/horticulture/HighAltitudeLandscapes/Aspencanker.htm (accessed February 10, 2012). • Hinds, Thomas. "Cryptosphaeria Canker and Libertella Decay of Aspen." Phytopathology 71 (1981), • Kaye, Margot, Dan Binkley and Thomas Stohlgren. "Effects of Conifer and Elk Browsing on the Quaking Aspen Forests in the Central Rocky Mountains, USA. ." Ecological Applications 15 (2005): 1284- 1295. • St. Clair, Samuel B., John Guyon and Jack Donaldson. "Quaking Aspen’s Current and Future Status in Western North America: The Role of Succession, Climate, Biotic Agents, and Its Clonal Nature." Progress in Botany 71 (2010): 371-400. • Weisberg, Peter J. and Michael B. Coughenour. "Model-Based Assessment of Aspen Responses to Elk Herbivory in Rocky Mountain National Park, USA." Environmental Management 32 (2003): 152-169.

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