Comparing Ecological Restoration and Northern Goshawk Managment Guidelines Treatments in a Southwestern Ponderosa Pine Forest

• Main Author: Tuten, Matthew C.
• Format: Thesis
• Language: English
• Published: NAU School of Forestry, http://www.for.nau.edu 2008
• Subjects: SD Forestry; Accipiter gentilis; Northern Goshawk
• Online Access: http://openknowledge.nau.edu/2873/; http://openknowledge.nau.edu/2873/1/Tuten_2008_thesis.pdf

We compared forest structure patterns resulting from application of revised Northern Goshawk Management Guidelines (GMG) and Ecological Restoration Guidelines (ERG)-based silvicultural thinning approaches in ponderosa pine (Pinus ponderosa C. Lawson var. scopulorum Engelm.) forests on replicated sites on the Kaibab Plateau in Northern Arizona. These management approaches have been proposed for wide application across tens of thousands of hectares of southwestern National Forests within Northern Goshawk (Accipiter gentilis) foraging areas. Both sets of guidelines use patterns and densities of presettlement forest evidences in the form of old forest remnants (pre Euro-American settlement era trees, stumps and snags) to guide their tree marking methodologies. Tree densities resulting from application of these treatment approaches and estimated presettlement densities were not significantly different. GMG-based treatments retained a larger proportion of trees in middle to large size classes, resulting in statistically significantly higher canopy cover and basal area. Tree spatial point patterns and tree patches (e.g., groups of trees with interlocking crowns) were analyzed. GMG-based treatments resulted in more consistent tree aggregation at fine-scales (<15 meters), than ERG-based treatments, a pattern similar to presettlement evidence patterns. GMG-based treatments resulted in significantly fewer isolated individual trees, a higher mean density of trees within patches and more high density tree patches than ERG-based treatment results. No difference was observed in average diameter range of trees within groups. We conclude that with minimal modification, initial thinning approaches similar to those described in this study are highly compatible, both with each other and presettlement conditions, especially within forest landscapes where reintroduction of naturally ignited fires is a management goal. Despite this similarity, ERG and GMG-based stand management approaches will differ over the long term. The goal of ERGbased management is forests that can be regulated by natural processes, most notably surface fires similar to those common in the Southwest. The GMG approach, while allowing the use of fire, will require continual forest structure regulation and will inevitably result in future removal of large, old trees.