Public and private benefits from Shelterbelt Centre activities

Non-Peer ReviewedThe Agriculture and Agri-Food Canada – Prairie Farm Rehabilitation Administration (AAFC–PFRA) Shelterbelt Centre was established at Indian Head in 1901 and since then has been a major source of tree seedlings to prairie farmers and to other eligible interested agencies. The Centre has distributed over 576 million tree seedlings. On farms, these shelterbelts have become an important resource, both to the producers as well as to the society as a whole. A survey of producers attending the Shelterbelt Centre Field Day in 2003, indicated that shelterbelts lived up to their expectations and that both society and producers derive benefits from them. They affect the producers and society in a variety of ways – some directly and others indirectly through ecosystem functions. Based on the study, this value to the society (other than land owners) of the shelterbelts established since 1981 could exceed $150 million, and can even be as high as$940 million. Major benefits accrue from carbon sequestration, wildlife habitats and related activities, and from energy conservation. These benefits, although apparent to most of us, are difficult to estimate precisely, and require better data and an interdisciplinary approach

Differential Parental Care by Adult Mountain Plovers, Charadrius montanus

We studied chick survival of the Mountain Plover (Charadrius montanus) in Montana and found that chicks tended by females had higher survival rates than chicks tended by males, and that chick survival generally increased during the nesting season. Differences in chick survival were most pronounced early in the nesting season, and may be related to a larger sample of nests during this period. When compared to information about the nest survival of male- and female-tended plover nests, our chick data suggest a trade-off for adult plovers between the egg and chick phases of reproduction. Because Mountain Plover pairs have clutches at two nests at two different locations and show differential success between the sexes during the egg and chick phases, we offer that the Mountain Plover breeding system favours optimizing annual recruitment in a dynamic ecologic setting driven by annually unpredictable drought, grazing, and predation pressures

Forced versus coupled dynamics in Earth system modelling and prediction

International audienceWe compare coupled nonlinear climate models and their simplified forced counterparts with respect to predictability and phase space topology. Various types of uncertainty plague climate change simulation, which is, in turn, a crucial element of Earth System modelling. Since the currently preferred strategy for simulating the climate system, or the Earth System at large, is the coupling of sub-system modules (representing, e.g. atmosphere, oceans, global vegetation), this paper explicitly addresses the errors and indeterminacies generated by the coupling procedure. The focus is on a comparison of forced dynamics as opposed to fully, i.e. intrinsically, coupled dynamics. The former represents a particular type of simulation, where the time behaviour of one complex systems component is prescribed by data or some other external information source. Such a simplifying technique is often employed in Earth System models in order to save computing resources, in particular when massive model inter-comparisons need to be carried out. Our contribution to the debate is based on the investigation of two representative model examples, namely (i) a low-dimensional coupled atmosphere-ocean simulator, and (ii) a replica-like simulator embracing corresponding components.Whereas in general the forced version (ii) is able to mimic its fully coupled counterpart (i), we show in this paper that for a considerable fraction of parameter- and state-space, the two approaches qualitatively differ. Here we take up a phenomenon concerning the predictability of coupled versus forced models that was reported earlier in this journal: the observation that the time series of the forced version display artificial predictive skill. We present an explanation in terms of nonlinear dynamical theory. In particular we observe an intermittent version of artificial predictive skill, which we call on-off synchronization, and trace it back to the appearance of unstable periodic orbits. We also find it to be governed by a scaling law that allows us to estimate the probability of artificial predictive skill. In addition to artificial predictability we observe artificial bistability for the forced version, which has not been reported so far. The results suggest that bistability and intermittent predictability, when found in a forced model set-up, should always be cross-validated with alternative coupling designs before being taken for granted

The Ursinus Weekly, March 15, 1943

Officers will begin Navy\u27s inspection of college Tuesday • Curtain Club\u27s opus grows in rehearsal • Bond queen race enters final week as Jean Haight leads Nancy Landis • Red Cross to sponsor campaign on campus • Treasury to back playwright contest for college bards • Three I\u27s of religion explained to vespers • Dr. Fulton encourages collegians to promote interdependent world • May queen\u27s election postponed until Tuesday of next week • College to claim students\u27 rations • Alumni receive bulletin on annual Founders\u27 Day • Pre-meds hear botanist • Brotherhood, Y\u27s to lead Lenten service each week • World federation speaker will address next forum • Y will hold shamrock shag • Jr. prom will not be offensive, despite its theme of offense • French Club hears resume of former premier\u27s talk • Classes to battle for campus crown • Coeds seek 6th win in clash Thursday with Chestnut Hill • All-stars trounce pre-flight school after losing to coast guards 54-31 • Lassies top Drexel 22-18 for fifth straight victory • Girls lose lead and bow 35-25 to unbeaten Temple • JV team tramples Drexel and Temple • 612 trips Sprankle 21-8 as Secor and Waltz star • Government offers technical positions in research work to science majors • Free French to show movieshttps://digitalcommons.ursinus.edu/weekly/1756/thumbnail.jp

Ice nucleation from aqueous NaCl droplets with and without marine diatoms

Ice formation in the atmosphere by homogeneous and heterogeneous nucleation is one of the least understood processes in cloud microphysics and climate. Here we describe our investigation of the marine environment as a potential source of atmospheric IN by experimentally observing homogeneous ice nucleation from aqueous NaCl droplets and comparing against heterogeneous ice nucleation from aqueous NaCl droplets containing intact and fragmented diatoms. Homogeneous and heterogeneous ice nucleation are studied as a function of temperature and water activity, <i>a</i><sub>w</sub>. Additional analyses are presented on the dependence of diatom surface area and aqueous volume on heterogeneous freezing temperatures, ice nucleation rates, ω<sub>het</sub>, ice nucleation rate coefficients, <i>J</i><sub>het</sub>, and differential and cumulative ice nuclei spectra, <i>k(T)</i> and <i>K(T)</i>, respectively. Homogeneous freezing temperatures and corresponding nucleation rate coefficients are in agreement with the water activity based homogeneous ice nucleation theory within experimental and predictive uncertainties. Our results confirm, as predicted by classical nucleation theory, that a stochastic interpretation can be used to describe the homogeneous ice nucleation process. Heterogeneous ice nucleation initiated by intact and fragmented diatoms can be adequately represented by a modified water activity based ice nucleation theory. A horizontal shift in water activity, Δ<i>a</i><sub>w, het</sub> = 0.2303, of the ice melting curve can describe median heterogeneous freezing temperatures. Individual freezing temperatures showed no dependence on available diatom surface area and aqueous volume. Determined at median diatom freezing temperatures for <i>a</i><sub>w</sub> from 0.8 to 0.99, ω<sub>het</sub><u>~</u>0.11<sup>+0.06</sup><sub>−0.05</sub> s<sup>−1</sup>, <i>J</i><sub>het</sub><u>~</u>1.0<sup>+1.16</sup><sub>−0.61</sub>×10<sup>4</sup> cm<sup>−2</sup> s<sup>−1</sup>, and <i>K</i><u>~</u>6.2<sup>+3.5</sup><sub>−4.1</sub> ×10<sup>4</sup> cm<sup>−2</sup>. The experimentally derived ice nucleation rates and nuclei spectra allow us to estimate ice particle production which we subsequently use for a comparison with observed ice crystal concentrations typically found in cirrus and polar marine mixed-phase clouds. Differences in application of time-dependent and time-independent analyses to predict ice particle production are discussed

Monitoring Low Density Avian Populations: An Example using Mountain Plovers

Declines in avian populations highlight a need for rigorous, broad-scale monitoring pro-grams to document trends in avian populations that occur in low densities across expansive landscapes. Accounting for the spatial variation and variation in detection probability inherent to monitoring programs is thought to be effort-intensive and time-consuming. We determined the feasibility of the analytical method developed by Royle and Nichols (2003), which uses presence-absence (detection-non-detection) field data, to estimate abundance of Mountain Plovers (Charadrius montanus) per sampling unit in agricultural fields, grassland, and prairie dog habitat in eastern Colorado. Field methods were easy to implement and results suggest that the analytical method provides valuable insight into population patterning among habitats. Mountain Plover abundance was highest in prairie dog habitat, slightly lower in agricultural fields, and substantially lower in grassland. These results provided valuable insight to focus future research into Mountain Plover ecology and conservation

Movements and Home Ranges of Mountain Plovers Raising Broods in Three Colorado Landscapes

We report movements and home-range sizes of adult Mountain Plovers (Charadrius montanus) with broods on rangeland, agricultural fields, and prairie dog habitats in eastern Colorado. Estimates of home range size (95% fixed kernel) were similar across the three habitats: rangeland (146.1 ha +/- 101.5), agricultural fields (131.6 ha +/- 74.4), and prairie dog towns (243.3 ha +/- 366.3). Our minimum convex polygon estimates of home-range size were comparable to those on rangeland reported by Knopf and Rupert (1996). In addition, movements - defined as the distance between consecutive locations of adults with broods - were equivalent across habitats. However, our findings on prairie dog habitat suggest that home-range size for brood rearing may be related to whether the prairie dog habitat is in a complex of towns or in an isolated town

Movements and Home Ranges of Mountain Plovers Raising Broods in Three Colorado Landscapes

We report movements and home-range sizes of adult Mountain Plovers (Charadrius montanus) with broods on rangeland, agricultural fields, and prairie dog habitats in eastern Colorado. Estimates of home range size (95% fixed kernel) were similar across the three habitats: rangeland (146.1 ha +/- 101.5), agricultural fields (131.6 ha +/- 74.4), and prairie dog towns (243.3 ha +/- 366.3). Our minimum convex polygon estimates of home-range size were comparable to those on rangeland reported by Knopf and Rupert (1996). In addition, movements - defined as the distance between consecutive locations of adults with broods - were equivalent across habitats. However, our findings on prairie dog habitat suggest that home-range size for brood rearing may be related to whether the prairie dog habitat is in a complex of towns or in an isolated town

New Dimensions for Wound Strings: The Modular Transformation of Geometry to Topology

We show, using a theorem of Milnor and Margulis, that string theory on compact negatively curved spaces grows new effective dimensions as the space shrinks, generalizing and contextualizing the results in hep-th/0510044. Milnor's theorem relates negative sectional curvature on a compact Riemannian manifold to exponential growth of its fundamental group, which translates in string theory to a higher effective central charge arising from winding strings. This exponential density of winding modes is related by modular invariance to the infrared small perturbation spectrum. Using self-consistent approximations valid at large radius, we analyze this correspondence explicitly in a broad set of time-dependent solutions, finding precise agreement between the effective central charge and the corresponding infrared small perturbation spectrum. This indicates a basic relation between geometry, topology, and dimensionality in string theory.Comment: 28 pages, harvmac big. v2: references and KITP preprint number added, minor change

An Assessment of Factors Affecting Population Growth of the Mountain Plover

Effective conservation measures should target the most sensitive life history attributes of a species, assuming they are responsive to potential management actions. The Mountain Plover (Charadrius montanus) is a species of conservation concern with a patchy breeding distribution in western North America. Plovers prefer areas with short vegetation, bare ground, and disturbance for nesting. Current management tools, including grazing and burning, have been used to attract plovers and enhance nesting success. We used a stage-specific matrix model to study the influence of vital rates, e.g., juvenile and adult annual survival, on population growth rate in the Mountain Plover at two breeding sites in Colorado, South Park and Eastern Colorado, and one breeding site in Montana, USA. Our analysis was motivated by a need to 1) better understand the relationship between demographic rates and population growth rate, 2) assess current management tools for the plover by exploring their effect on population growth rate, and 3) identify areas of the plover’s population biology where additional demographic work is needed. Stochastic population growth rate was most influenced by adult survival, especially in Montana and South Park, Colorado (elasticities \u3e 0.60), and was least influenced by first-year reproduction (all elasticities \u3c 0.20). The modeled relationships between lambda and each demographic rate were generally weak (r2 \u3c 0.30) with the exception of number of eggs hatched per nest in Eastern Colorado (r2 = 0.63), chick survival in South Park (r2 = 0.40) and Montana (r2 = 0.38), and adult survival in Montana (r2 = 0.36). We examined the predicted increase in lambda that would result from increasing each demographic rate from its mean to the maximum value observed in our simulations. Chick and adult survival showed the greatest increase in lambda while eggs hatched per nest produced the smallest increase. Our results suggest that future conservation efforts should favor ways to increase adult or chick survival over efforts to increase nest success. In particular, adult survival rates during the stationary periods, i.e., summer and winter, are relatively high, implying that efforts to increase adult survival rates may need to focus on the migratory periods. Increasing chick survival should be a priority for efforts that are restricted to the breeding grounds because this life history stage is relatively short (\u3c 3 mo) and it offers opportunities for targeted short-term management activities in breeding areas