Access Type

Dissertation/Thesis

Date of Award

January 2019

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biological Sciences

First Advisor

Daniel M. Kashian

Abstract

Jack pine-dominated forests in northern Lower Michigan were historically characterized by a frequent, severe fire regime that produced a patchwork of dense stands interspersed with open barrens. This structure also provided breeding habitat for Kirtland’s warblers, a migratory songbird. Fire suppression management caused forests to become older and reduced Kirtland’s warbler habitat, resulting in severe population losses. Kirtland’s warblers were designated as endangered, and subsequent habitat management has produced homogeneous forests that lack historical structural and compositional diversity. Moreover, future climate may increasingly complicate forest and fire management moving forward. In a landscape defined by disturbance, novel disturbances or changes to the established regime may cause profound change.

To investigate effects of disturbance attributable to forest management we interpolated historical survey data to determine the age structure of forests prior to significant Euro-American settlement. We compared current and historical age distributions and found that Kirtland’s warbler habitat management has significantly altered the age structure of the forests, resulting in younger, more homogeneous stands.

Naturally-produced structural variability has also been affected by Kirtland’s warbler management. Living forest remnants (stringers) are common following wildfires but are often harvested for timber, and their effects on post-fire plant community composition and structure have not been examined. Our field-based project found that stingers affect post-fire landscape structure, plant community composition, and sapling age distributions, and as such should be preserved or emulated in landscape management.

Populated fire-prone areas must adapt wildfire management to future fire regimes considering global climate change. Jack pine barrens were historically common on the landscape but have been drastically reduced due in large part to Kirtland’s warbler habitat management. We used LANDIS-II to model fire severity and barrens distributions under various predictions of future climate. We found that climate change caused increased fire severity and number, but reduced cover of barrens. Further, our model predicted large-scale losses of currently dominant species, perhaps signaling the development of novel ecosystems under extreme climate scenarios. As a whole, these projects provide context for applying historical variability and structure to future management decisions to maintain the unique character of this highly managed landscape.

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