917 research outputs found
Data Supporting Reich et al 2022: Even modest climate change may lead to major transitions in boreal forests
No full textTo test the uncertainty of the sensitivity of forests to near–term warming and associated precipitation we used a five–year open–air experiment in southern boreal forest located at two research sites in northern Minnesota. The experiment used juveniles of nine temperate and boreal tree species that grew under ambient and seasonally warmed (+1.6C and +3.1C above- and belowground) and rainfall reduced (~30% less rainfall) conditions. Each year we surveyed all trees for their survival and growth and measured in situ light-saturated net photosynthesis (Anet) and leaf diffusive conductance (gs).Reich, Peter, B.; Bermudez, Raimundo; Montgomery, Rebecca, A.; Rich, Roy, L.; Rice, Karen, E.; Hobbie, Sarah, E.; Stefanski, Artur. (2022). Data Supporting Reich et al 2022: Even modest climate change may lead to major transitions in boreal forests. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/rv3y-4x19
Crafts in the Southern Mountains
No full textThis article appeared in the 1931, November/December issue of "Handicrafter" magazine. It traces author "P.B."'s travels to various craft centers in the southern Appalachian mountains. Mentioned in the article are Allanstand Cottage Industries, The Spinning Wheel, Clementine Douglas, Winogene Redding, Evelyn Bishop, Mrs. Stone, Blue Ridge Weavers, Penland's Weaving Institute, Penland Weavers and Potters, Crossnore School, Mrs. H. N. Johnson, Pi Beta Phi Fraternity School, and Berea College's Fireside Industries. The author only gives a brief impression of his or her visit to each place. It is likely that author P.B. is Paul Bernat, editor of "Handicrafter" magazine
A trait-based ecosystem model suggests that long-term responsiveness to rising atmospheric CO2 concentration is greater in slow-growing than fast-growing plants
No full textAtmospheric carbon dioxide concentration (Ca) has a direct and measurable effect on plant growth. However, it does not affect all plant species equally, which could lead to shifts in competitive dominance of species in ecosystems. We used a dynamic plant carbon-nitrogen model to systematically examine how species traits affect the long-term Ca responsiveness of C3 plants when growing as established monocultures in the field. The model was tested against responses of 7 C3 herbaceous species growing in a free-air Ca enrichment (FACE) experiment (BioCON) in Minnesota, USA. Model simulations showed that several species traits affected the Ca response strongly, giving rise to a number of testable hypotheses about interspecific differences in responsiveness to Ca. The largest responses to rising Ca were obtained for species with low carbon-use efficiency (net primary production: gross primary production ratio), low foliar carbon allocation, low stomatal conductance, low instantaneous photosynthetic nitrogen use efficiency and low specific leaf area. In general, our model predicted that, for established plants growing in resource-limited field conditions, species with slow growth rates would be most responsive to elevated Ca. This prediction was supported by data from the BioCON experiment. Our model also predicts that, for young plants growing in non-resource-limited conditions, species with high growth rates will be most responsive to elevated Ca. This difference in species ranking under different resource availabilities is largely explained by the indirect effects of Ca on leaf area. Leaf-area feedbacks favour fast-growing species the most during leaf-area expansion, but following stand maturation they favour slow-growing species the most. These results imply that species that respond strongly to elevated Ca in short-term (non-resource-limited) glasshouse experiments are unlikely to also be the most responsive in resource-limited field conditions, and therefore that we cannot directly extrapolate from glasshouse experiments to predict which species will be most responsive to elevated Ca in the long term
Catford et al. 2019 Ecol Lett_E93 modelled data.xlsx
No full textData from: Catford, J.A, Smith, A.L., Wragg, P.D., Clark, A.T., Kosmala, M., Cavender-Bares, J., Reich, P.B. & Tilman, D. (2019) Traits linked with species invasiveness and community invasibility vary with time, stage and indicator of invasion in a long-term grassland experiment. Ecology Letters
Catford et al. 2019 Ecol Lett_E93 modelled data.xlsx
No full textData from: Catford, J.A, Smith, A.L., Wragg, P.D., Clark, A.T., Kosmala, M., Cavender-Bares, J., Reich, P.B. & Tilman, D. (2019) Traits linked with species invasiveness and community invasibility vary with time, stage and indicator of invasion in a long-term grassland experiment. Ecology Letters
Experimental and computational study of the influence of pre-damage patterns in unreinforced masonry crack propagation due to induced, repeated earthquakes
No full textInduced seismicity in the north of the Netherlands has recently exposed unprepared, unreinforced masonry structures to considerable earthquake risk. While the ultimate-limit state capacity of the structures is vital to assess the individual’s risk, their behavior during more frequent, lighter earthquakes, leading to ‘lighter damage’, has shown to be strongly linked to economic losses and societal unrest. When observing the light damage caused by minor earthquakes, the existing state of the structure appears to be highly relevant for the final damage intensity and configuration: earthquakes that may have otherwise caused no apparent damage, may intensify existing damage. In particular, incipient damage due to settlements is common in the baked-clay and calcium-silicate brick masonry structures of the region.This paper details the study of full-scale laboratory walls, pre-damaged following typical (crack) patterns caused by settlements and tested with quasi-static lateral loads. The aggravation of the damage during a relevant number of load cycles is monitored using full-field digital image correlation. The damage is quantified objectively using a purposely-developed damage parameter.The tests are used (together with previous studies) to further calibrate computational finite element models, which coupled with detailed soil-structure interaction boundary conditions, are then employed to assess a larger number of structural geometries and pre-damaged configurations exposed to (repeated) induced earthquake acceleration histories.Both experimental and computational approaches show that settlement pre-damage in masonry structures increases the likelihood and the amount of further damage. This is more easily observed when some initial, yet limited damage exists and the masonry wall is exposed to moderate earthquake vibrations in the order of 30 millimeters per second.Accepted Author ManuscriptApplied Mechanic
Light access and leaf trait variation within and among tree species across diverse mixtures within a common garden
No full textLeaf trait measurements alongside estimates of light access for 2615 leaves from 12 common temperate-boreal tree species grown in diverse mixtures within a common garden.This dataset includes trait measurements for 2615 leaves of common temperate-boreal tree species alongside estimates of their light access. Trait values affect how plants function, with consequences that propagate through scales of ecological organization to affect ecosystem function. However, the pathway connecting trait expression to ecosystem function is complicated by feedbacks: trait expression may vary within species in response to community diversity, and trait expression also determines a community’s functional diversity. In this study, we quantify the extent to which light access – which past studies suggest affects trait expression and differs as a result of interactions among plants – differs consistently with community diversity and explains intraspecific trait variation in trees. In a common garden, trees of five angiosperm and seven gymnosperm species were planted to form 37 communities ranging widely in species and functional diversity whereby confounding environmental variation was minimized. We sampled leaves of each species to characterize intraspecific variation within crowns, among trees within communities, and among communities in three traits – leaf size, specific leaf area and nitrogen concentration – and estimated each leaf’s access to light.The University of Minnesota (College of Biological Sciences, College of Food and Natural Resources, Institute on the Environment, and Graduate School), the Canada Research Chair program, and an International Fulbright Science and Technology Award financially supported the collection of the data.Williams, Laura J; Cavender-Bares, Jeannine; Reich, Peter B; Paquette, Alain; Messier, Christian. (2019). Light access and leaf trait variation within and among tree species across diverse mixtures within a common garden. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/jt9r-tf03
A Critical Look At Mias
No full textIn this report the author brings a figure of the costs that go with the implementation of a landing aid, being a successor to the currently used system ILS. These cost figures should give the reader an insight in the possible costs necessary for the implementation of MIAS. Also a little discussion concerning the market value and the inherent political issues going with it are interwoven in part one of this thesis. Part two deals with the question of how other systems proved their required integrity norms. Especially a closer look at the way ILS System 4000 proved its maturity is given. Two possible methods to decide the service level of the equipment will be described and a list of works where several test specifications are described. Also, a new conception will be introduced, the “AI product”. Part three gives an answer to the following question: there is in the Kalman filter of MIAS the postulation of Gaussian shaped white noise, with a certain variance and on the other hand we want to fetch the stringent ICAO requirements (especially those for the system integrity). Do these two matters go hand in hand or do they conflict each other? Is there a way to fulfil the norms and in the meanwhile make use of the mathematical simplicity of Gaussian shaped white noise? As a reaction on these issues some approaches to adaptive Kalman filtering are described and a new manner of tuning a Kalman filter is set up, based on a system identification algorithm called MOESP.Applied SciencesElectrical EngineeringTelecommunications and Traffic Control Systems Grou
Further re-analyses looking for effects of phylogenetic diversity on community biomass and stability
No full textCardinale, Bradley J; Venail, Patrick; Gross, Kevin; Oakley, Todd H; Narwani, Anita; Allan, Eric; Flombaum, Pedro; Joshi, Jasmin; Reich, Peter B; Tilman, David; van Ruijven, Jasper. (2015). Further re-analyses looking for effects of phylogenetic diversity on community biomass and stability. Retrieved from the University Digital Conservancy, 10.1111/1365-2435.12540
Het voorkomen van enkele niet-oorspronkelijk wilde grassoorten in Zeeland
No full textThe distribution of Digitaria ischaemum (Schreb.) Miihlenb., D. sanguinalis (L.)P.B., Echinochloa crus-galli (L.)P.B., Setaria glauca I (L.)P.B.and S. viridisi (L.)P.B. in the province of Zeeland is described and discussed. These species were mostly rare or absent in this region until 1950, but are now more or less common especially along some main roads where conditions seem to be optimal for these thermophylic plants.
Also the distribution of Eragrostis multicaulis Steud., E. poaeoides P.B., Panicum miliaceum I -, Setaria verticillata (L.) P.B. and Sorghum halepense (L.) Pers. is given and discussed. Some aspects of the ecology of E. poaeoides are added. The author proposes to insert S. halepense in the Standardlist of the Netherlands Flora 1985 as a naturalized species
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