Browsing by Subject "forest"
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Item Data supporting: Century-scale wood nitrogen isotope trajectories from an oak savanna with variable fire frequencies(2020-09-09) Trumper, Matthew L; Griffin, Daniel; Hobbie, Sarah E; Howard, Ian M; Nelson, David M; Reich, Peter B; McLauchlan, Kendra K; trump022@umn.edu; Trumper, Matthew L; University of Minnesota Griffin Research LabFire frequency exerts a fundamental control on productivity and nutrient cycling in savanna ecosystems. A single fire event often increases short-term nitrogen (N) availability to individual plants, but repeated burning causes ecosystem carbon and N losses and can ultimately decrease soil organic matter and N availability. However, these effects remain poorly understood due to limited long-term biogeochemical data. Here, we leveraged one of the longest running prescribed burn experiments (established in 1964) to evaluate how fire frequency and changing vegetation composition influenced wood stable N isotopes (δ15N) across space and time. We developed multiple δ15N records across a burn frequency gradient from precisely dated Quercus macrocarpa tree-rings in an oak savanna at Cedar Creek Ecosystem Science Reserve, Minnesota, USA. Sixteen trees were sampled across four treatment stands that varied in temporal onset of burning and burn frequency, but were consistent in overstory species representation, soil characteristics, and topography. Burn frequency ranged from an unburned control stand to a high fire-frequency stand that burned in four of every five years during the past 55 years. Because N stocks and net N mineralization rates are currently lowest in frequently burned stands, we hypothesized that wood δ15N trajectories would have declined over time in all burned stands, but at a rate proportional to fire frequency. We found that wood δ15N records within each stand were remarkably coherent in their mean state and trend through time. A gradual, temporally synchronous decline in wood δ15N occurred in the mid 20th century in the no-, low-, and medium-fire stands, whereas there was no trend in the high-fire stand. The decline in the three stands did not systematically coincide with the onset of prescribed burning. Thus, we found limited evidence for variation in wood δ15N that could be attributed directly to long-term fire frequency in this prescribed burn experiment in temperate oak savanna. Our wood δ15N results may instead reflect decadal-scale changes in vegetation composition and abundance due to early to mid 20th century fire suppression.Item Effects of winter temperatures, spring degree-day accumulation, and insect population source on phenological synchrony between forest tent caterpillar and(Elsevier, 2016) Uelmen, Johnny A.; Lindroth, Richard L; Tobin, Patrick C.; Reich, Peter B; Schwartzberg, Ezra G; Raffa, Kenneth FGlobal climate change has the potential to dramatically alter multiple ecosystem processes, including herbivory. The development rates of both plants and insects are highly sensitive to temperature. Although considerable work has examined the effects of temperature on spring phenologies of plants and insects individually, few studies have examined how anticipated warming will influence their phenological synchrony. We applied elevated temperatures of 1.7 and 3.4 °C in a controlled chamberless outdoor experiment in northeastern Minnesota, USA to examine the relative responses in onset of egg eclosion by forest tent caterpillar (Malacosoma disstria Hübner) and budbreak of two of its major host trees (trembling aspen, Populus tremuloides Michaux, and paper birch, Betula papyrifera Marshall). We superimposed four insect population sources and two overwintering regimes onto these treatments, and computed degree-day models. Timing of egg hatch varied among population source, overwintering location, and spring temperature regime. As expected, the development rates of plants and insects advanced under warmer conditions relative to ambient controls. However, budbreak advanced more than egg hatch. The degree of phenological synchrony between M. disstria and each host plant was differentially altered in response to warming. The interval by which birch budbreak preceded egg hatch nearly doubled from ambient to +1.7 °C. In the case of aspen, the sequence changed from egg hatch preceding, to following, budbreak at +3.4 °C. Additionally, under temperature regimes simulating future conditions, some insect populations currently south of our study sites became more synchronous with the manipulated hosts than did currently coexisting insect populations. These findings reveal how climate warming can alter insect-host plant interactions, through changes in phenological synchrony, possibly driving host shifts among tree species and genotypes. They also suggest how herbivore variability, both among populations and within individual egg masses, may provide opportunities for adaptation, especially in species that are highly mobile and polyphagous.Item Fine-root biomass from Cloquet and Auclair IDENT sites(2022-03-14) Schuster, Michael J.; Williams, Laura J; Stefanski, Artur; Bermudez, Raimundo; Messier, Christian; Belluau, Michaël; Paquette, Alain; Gravel, Dominique; Reich, Peter B; schuster@umn.edu; Schuster, Michael JMean fine-root biomass data gathered from the IDENT experiments in Cloquet, MN and Auclair, Quebec.Item Notes of an eagle watcher : A land-owner's guide to protecting nesting bald eagles(U.S. Dept. of the Interior, U.S. Fish and Wildlife Service ; University of Minnesota, Agricultural Extension Service, 1984) U.S. Fish Wildlife Service; University of Minnesota. Agricultural Extension Service.Item Old Forest Extent and Changes in Minnesota 2003-2018(University of Minnesota Department of Forest Resources, 2021-03) Peters, Emily B.; Wilson, David C.; Edgar, Christopher B.; Ek, Alan R.Old forests are an important part of Minnesota’s landscape. Here we describe the extent and recent changes in the acreage of old forest in Minnesota by forest type. Statewide, the area of old forest increased from 3.8% of the total forest area in 2003 to 6.4% in 2018. The area of old forest increased for most forest types and across all major ownership categories, but there are exceptions, notably for forest types that occupy relatively small acreages, are actively managed for timber products, or have forest health issues.Item Signature Wood Modifications that Reveal Decomposer Community History(2015-02-13) Schilling, Jonathan; schillin@umn.edu; Schilling, JonathanCorrelating plant litter decay rates with initial tissue traits (e.g. C, N contents) is common practice, but in woody litter, predictive relationships are often weak. Variability in predicting wood decomposition is partially due to territorial competition among fungal decomposers that, in turn, have a range of nutritional strategies (rot types) and consequences on residues. Given this biotic influence, researchers are increasingly using culture-independent tools in an attempt to link variability more directly to decomposer groups. Our goal was to complement these tools by using certain wood modifications as 'signatures' that provide more functional information about decomposer dominance than density loss. Specifically, we used dilute alkali solubility (DAS; higher for brown rot) and lignin:density loss (L:D; higher for white rot) to infer rot type (binary) and fungal nutritional mode (gradient), respectively. We first determined strength of pattern among 29 fungi of known rot type by correlating DAS and L:D with mass loss in birch and pine. Having shown robust relationships for both techniques above a density loss threshold, we then demonstrated and resolved two issues relevant to species consortia and field trials, 1) spatial patchiness creating gravimetric bias (density bias), and 2) brown rot imprints prior or subsequent to white rot replacement (legacy effects). Finally, we field-tested our methods in a New Zealand Pinus radiata plantation in a paired-plot comparison. Overall, results validate these lowcost techniques that measure the collective histories of decomposer dominance in wood. The L:D measure also showed clear potential in classifying 'rot type' along a spectrum rather than as a traditional binary type (brown versus white rot), as it places the nutritional strategies of wood-degrading fungi on a scale (L:D=0-5, in this case). These information-rich measures of consequence can provide insight into their biological causes, strengthening the links between traits, structure, and function during wood decomposition.Item Soil Factors Affecting the Growth of Quaking Aspen Forests in the Lake States(Minnesota Agricultural Experiment Station, 1960-01) Stoeckeler, Joseph H.Item South Fork Caspar Creek Understory Evapotranspiration Data - 2019(2020-12-04) Hammerschmidt, Shelby R; Dymond, Salli F; sdymond@d.umn.edu; Dymond, Salli FThis dataset consists of evapotranspiration rates measured from different understory trees, shrubs, and ferns at the Caspar Creek Experimental Watersheds in northern California. Evapotranspiration rates were collected from 5 species at two times (June and July 2019) across five topgraphic positions ranging from streamside up to the ridgetop. Measurement species were located across a range of disturbance severities to test the hypothesis that changing light and water dynamics from different levels of disturbance will affect understory plant water use. Evapotranspiration rates were collected using a hand-made portable rapid ET chamber.