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  Submersible Space Training Suit Preliminary Test Results and Review

  Smith, Cameron; Tresch, Trent; University of Arizona Center for Human Space Exploration (Center for Human Space Exploration - The University of Arizona (Tucson, AZ), 2026-04)
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  A Dendroecological Fire History for Central Corsica/France

  Szymczak, Sonja; Braeuning, Achim; Haeusser, Martin; Garel, Emilie; Huneau, Frederic; Santoni, Sebastien (2020-01)

  Forest fires are an important factor shaping Mediterranean ecosystems and determine the distribution of different species. Information about past forest fires can be obtained with pyrodendroecology. Here, we present a fire history for three sites in the mountain forest belt on the island of Corsica in the Mediterranean Basin. The dating of scars from cores, stem discs, and wedges from 101 pine trees (Pinus nigra and Pinus pinaster) allowed the reconstruction of six definite fire events between 1800 and 2017. Additionally, we reconstructed the spatial extent of a large fire event at AD 2000 with remote sensing data. The study sites are affected by different types of fires. The even-aged forest structure at two sites is clear evidence of past lethal fires, whereas the old-growth Pinus nigra forest at the third site represents the final stage of succession under current climate conditions. The current distribution of both pine species can at least partly be regarded as a result of varying fire frequency at different sites. Although Pinus pinaster stands dominate in areas with frequent fires and can even replace Pinus nigra in cases of high fire frequency, Pinus nigra dominates in areas with low fire frequencies.
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  Edge Effects Modify the Growth Dynamics and Climate Sensitivity of Araucaria Angustifolia Trees

  Albiero-Junior, Alci; Venegas-Gonzalez, Alejandro; Rodriguez-Caton, Milagros; Oliveira, Juliano Morales; Longhi-Santos, Tomaz; Galvao, Franklin; Temponi, Livia Godinho; Botosso, Paulo Cesar (2020-01)

  Edge effects are a major cause of natural dynamics of fragmented forests; however, studies that evaluate edge effects during the lifetime of trees are relatively rare. Through a long-term perspective of tree growth, dendroecology can contribute to a better understanding of the influence of edge effects. In order to frame our interpretation, we raised the following hypotheses: (1) trees located close to a forest edge have lower growth rates compared to trees growing far from edges, and (2) climate sensitivity of trees naturally growing on the forest edge is different from the trees in the interior. This study was conducted in Southern Brazil, where 21 Araucaria angustifolia located 50 m from the edge and 19 individuals located 4000 m from the forest edge were sampled. Dendrochronological study followed the usual procedures and growth patterns were evaluated using basal area increment, specific threshold value of fast and slow growth, and principal components analysis. During the 54 years analyzed, results indicated that the edge effect reduced growth by 30% in diameter increment and wood production of A. angustifolia trees. Regarding the influence of climatic variability on tree growth, we observed that edge effects may exert strong pressure on growth responses to climate in A. angustifolia located on forest edges, making individuals in those environments potentially more sensitive to variations in temperature and rainfall, mainly at warmer times of year. We therefore emphasize the importance of considering edge trees as potential bioindicators of historical environmental changes and forest fragmentation. Future studies should be carried out in other forest types and with different tree species (e.g. pioneer vs. shade-tolerant, trees vs. shrubs) to test the reliability of our results and provide more robust conclusions about this phenomenon.
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  Increment Coring Induced Traumatic Resin Ducts in White Spruce But Not in Lodgepole Pine

  Klutsch, Jennifer G.; Kee, Chen X.; Cappa, Eduardo P.; Ratcliffe, Blaise; Thomas, Barb R.; Erbilgin, Nadir (2020-01)

  Injury from sampling increment cores may induce defense responses in trees, which may vary between species and reflect differing defense allocation strategies against attack by insects and pathogens. We recorded presence of systemic induction of traumatic resin ducts from early-season increment coring in mature white spruce (Picea glauca) and lodgepole pine (Pinus contorta var. latifolia) trees. In the year of coring, traumatic resin ducts formed three months later, 20 cm below the initial coring site in the xylem of white spruce and showed little variation in response among the spruce families. In contrast, lodgepole pine did not form traumatic resin ducts in trees cored earlier in the growing season. Although traumatic resin ducts are induced by biotic and abiotic disturbances, we found a species-specific defense response to increment coring in two common boreal forest tree species.
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  Wallace (Wally) S. Broecker 1931-2019 In Memoriam

  Leavitt, Steven W. (2020-01)

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