Browsing by Author "Johnson, Lane B."

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    Tree-ring reconstruction of island and mainland fire events along a historic canoe travel corridor in Minnesota's Boundary Waters Wilderness
    (2013-04) Johnson, Lane B.
    Tree-rings of ancient, well-preserved red pine (Pinus resinosa) stumps provide an exceptional opportunity to examine the proto-historic fire frequencies of red pine stands in the Quetico-Superior region of northern Minnesota and northwest Ontario. The primary purpose of this research undertaking has been to determine the level of human influence on fire occurrence along a historic canoe travel corridor in Minnesota's Boundary Waters Canoe Area Wilderness (BWCAW). I approached this research challenge by testing three research questions in a small portion of the naturally fragmented BWCAW landscape. First, can island fire frequencies be explained by rates of lighting-ignited fire occurrence alone? Second, are surface fires within the focus area synchronous in time and space? And third, are local surface fires significantly associated with patterns of regional drought? I developed spatially explicit and annually resolved records of surface fires using dendrochronological methods, with 71 stump cross-sections from an approximate 2,170 hectare study area on the islands of eastern Lac La Croix (centered at 48°18'08"N, 92°03'15"W). Between 1590 and 2010 there were 79 separate fires within the study area recorded by tree-rings. All but two of the reconstructed fires occurred before 1922. Sixty-one fires were recorded at single sites with the other 18 burning at 2-5 sample sites. Ten of the 79 fires were recorded at both mainland and island sites. In the same area, from 1929 to 2010, thirteen lightning-ignited fires have been detected and suppressed by the Superior National Forest (only two in island settings). When comparing the conservative, tree-ring reconstructed estimate of pre-modern fire occurrence and the nearly 100% complete modern lighting-caused fire record (1929 -present), there is a noticeable change in the distribution and frequency of fires within the study area. The tree-ring reconstructed fires are spatially and temporally asynchronous and, as a whole, are not strongly associated with regional drought (p > 0.05). My results suggest that proto-historic Ojibwe land use activities in this part of the Boundary Waters landscape likely contributed to the frequency of proto-historic fire occurrence. These findings have important and direct implications for fire and wilderness management practices in the BWCAW and the greater Quetico-Superior region.
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    Utilization of Fire-Impacted Timber: A Summary of a Survey of Mill Procurement Personnel and a Review of the Literature
    (University of Minnesota, 2022-05) Harberts, Isaac C.; Blinn, Charles R.; Gill, Kyle G.; Johnson, Lane B.
    Wildfire is an important ecological process and prescribed fire is a critical tool for the stewardship of fire-dependent forest lands. Continued interest in the use of prescribed fire as part of various silvicultural systems raises the question: How does fire-impacted timber influence timber utilization by mills? To help answer that question, a survey of mill procurement staff in the Lake States (Michigan, Minnesota and Wisconsin) and the southeastern US and a literature review were conducted. When it comes to utilizing fire-impacted timber, the "answer" is situation dependent on what the mill produces and their outlets for residual products. Charred wood and bark negatively impact the quality of products manufactured from pulpwood (e.g., paper, fluff pulp, cardboard) as small discolored flecks can appear in the final product. Utilization by mills which produce dimensional lumber generally isn’t a concern as the charred material can be removed by the debarking and slabbing processes. However, char-damaged wood fibers can result in weaker strength solid wood products. When considering the use of prescribed fire in a timber stand, it is important to consider local markets and their procurement specifications for fire-impacted timber. Waiting several years after a prescribed fire before harvesting timber may increase its utilization.