Browsing by Subject "Itasca State Park"
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Item Dynamics of old-growth forests of Minnesota.(2009-08) Rauchfuss, JuliaDisturbances are an essential part of almost every ecosystem. I studied disturbances in three different old growth forests in Minnesota. These old-growth remnants include the white and red pine forest of the Lost 40 in northern Minnesota, the balsam fir and white spruce forest at Itasca State Park in northern Minnesota, and the hardwood forest of the Big Woods in south-central Minnesota. In the Lost 40, white and red pine are not regenerating and shade-tolerant trees are abundant in the understory and canopy. This lack of regeneration is probably due to the lack of a disturbance like fire. If a management plan were to be implemented, the advancement of the shade-tolerant species into the canopy and the shifting climate space of white and red pine need to be taken into consideration. The white and red pines in Itasca State Park are actively managed, but not the fir-spruce forest. Now, mature fir-spruce forest is dying because of a recent spruce budworm outbreak. Spruce budworm, a defoliating insect that prefers balsam fir and spruce, has been in the park before the most recent outbreak. Before the two outbreaks that were reconstructed, the climate was wet, whereas other studies found dry conditions before an outbreak of the spruce budworm. In reconstructing canopy disturbances of eight remnants, I tested several methods for evaluating canopy disturbance in closed canopy forests. The sequential t-test (regime shift) method had best results when reconstructing canopy disturbances of these forests. I then used the sequential t-test method to reconstruct the canopy-disturbance history. Although a drought-disturbance relationship was detected by other authors, I did not find a consistent relationship in my data. I studied three different old-growth forests in Minnesota. In these stands, disturbances are an integral part. Methods of disturbance-history reconstructions were tested and one (sequential t-test) subsequently used. I made contributions to reconstructing canopy disturbances using release and suppression periods in tree rings of forest types that previously had not been studied this way. The information that I gathered could now be used to inform a management plan, to apply a possibly more precise method to reconstruct a canopy-disturbance history, and to inform the public.Item Effects of Zooplankton Density and Diversity on Water Clarity in Five Lakes within Itasca State Park, Minnesota(2012-03-05) Stephenson, Robert; Forsberg, Chet; Mavencamp, BrianThe effects of zooplankton density and diversity on water clarity were studied on five different lakes within Itasca State Park (northwest Minnesota). Water turbidity is affected by suspended organic material and dissolved organic material, and zooplankton graze on this suspended organic material and thus clarity of the water increases. It has been shown that with increased density of zooplankton, especially herbivorous zooplankton, that there is a correlated increase in water clarity. In our study, zooplankton diversity also increased with greater zooplankton densities. It is not clear, however, that diversity has any effect on the clarity of the water itself since some zooplankton feed on other zooplankton and not phytoplankton. The lake with the lowest secchi reading showed the lowest diversity of zooplankton, although it did have the third highest density of zooplankton. The lake with the highest secchi reading, however, showed the highest density and highest diversity of zooplankton. All of the lakes tested followed a trend of increasing water clarity with increasing density and diversity of zooplankton, with the exception of Deming. Average absorbance of chlorophyll-a showed no statistical correlation between zooplankton density or zooplankton diversity. This suggests that there is a correlation between zooplankton density and diversity towards water clarity.Item Expanding the Tree Ring-Based Fire History Reconstruction of Itasca State Park(2022-06) Brumm, DanielItasca State Park is among the most iconic and visited state parks in Minnesota, and was established to protect the headwaters of the Mississippi River as well as to preserve an example of the old growth pine forests that once characterized the region. The red pine-dominant, fire dependent forest communities of Itasca support a close association between frequent fire events and forest composition, with many fire-scarred trees and remnant stumps preserving the park’s fire history within their annual growth rings. This research uses remnant, fire-scarred red pine stumps to expand upon previous fire history research by enhancing spatial coverage of tree-ring sample collection, strengthening the temporal assignment of fire events, and providing the first assessment of historic fire seasonality across the entire park area. Increasing evidence has been better documenting the role of people as critical ignition sources in fire regimes of the Upper Great Lakes. To better understand the role people may have had in influencing the fire regime of Itasca State Park, I investigated the cultural history of the area to provide important contextual information.I reconstructed a conservative fire history in Itasca State Park, dating 98 of 129 total tree-ring cross-sections that were collected in 2019, 2020 and 2021. I recorded 27 fire events from 348 individual fire scars between 1649 and 2015 (366 years), with the earliest and latest tree-ring documented fires recorded in 1697 and 1920 respectively. During this time, shorter and longer fire intervals were noted, with intervals being similar to other red pine fire history reconstructions. Fires tended to be synchronous across the park, with four fire years being recorded by at least 70% of the recording samples. Other fires with lower replication still exhibit a synchronous nature, as many events were recorded by samples collected at spatially distant sites. Fire seasonality could be determined on 180 (51.7%) fire scars, 78% of which affected the earlywood of the associated tree ring, indicating the early-growing season as the primary season of fire occurrence in Itasca State Park. Superposed Epoch Analysis found a significant relationship between fire occurrence and dry conditions the year before, and the year of fire events. Written records for the broader park area, however, indicate that most forest fires were ignited by human activities, and occurred in the spring, prior to the usual period of lightning strikes and fire occurrence (June-August). It is possible for Native American agency to have played an important role alongside dry conditions and lightning as an ignition source of historic fire events. Findings from this research affirm previous findings that fires were influential to the park’s forest conditions before Euro-American intervention. Results also identify the possibility of influence on the fire regime by Native American peoples who lived in or visited the park in the past. This fire history research may be a place to begin discussions, relationships, and partnerships with Native American communities in the area, as well as with management personnel to explore how fire may be returned to the park landscape with consideration of the park’s cultural history, and the association between fire and climate.Item Itasca State Park related research conducted under the aegis of the College of Forestry, University of Minnesota : a bibliography.(University of Minnesota, 1987-03) Kurmis, Vilis