Controls on vegetation structure in southwestern ponderosa pine forests, 1941 and 2004

Long-term studies can broaden our ecological understanding and are particularly important when examining contingent effects that involve changes to dominance by long-lived species. Such a change occurred during the last century in Southwestern (USA) ponderosa pine (Pinus ponderosa) forests. We used five livestock grazing exclosures established in 1912 to quantify vegetation structure in 1941 and 2004. Our objectives were to (1) assess the effects of historical livestock grazing on overstory structure and age distribution, (2) assess the effects of recent livestock grazing and overstory on understory vegetation, and (3) quantify and explain changes in understory vegetation between 1941 and 2004. In 1941, canopy cover of tree regeneration was significantly higher inside exclosures. In 2004, total tree canopy cover was twice as high, density was three times higher, trees were smaller, and total basal area was 40% higher inside exclosures. Understory species density, herbaceous plant density, and herbaceous cover were negatively correlated with overstory vegetation in both years. Most understory variables did not differ between grazing treatments in 1941 but were lower inside exclosures in 2004. Differences between grazing treatments disappeared once overstory effects were accounted for, indicating that they were due to the differential overstory response to historical livestock grazing practices. Between 1941 and 2004, species density declined by 34%, herbaceous plant density by 37%, shrub cover by 69%, total herbaceous cover by 59%, graminoid cover by 39%, and forb cover by 82%. However, these variables did not differ between grazing treatments or years once overstory effects were accounted for, indicating that the declines were driven by the increased dominance of the overstory during this period. Our results demonstrate that historical livestock grazing practices are an aspect of land-use history that can affect ecosystem development. Grazing history must be considered when extrapolating results from one site to another. In addition, the understory vegetation was more strongly controlled by the ponderosa pine overstory than by recent livestock grazing or by temporal dynamics, indicating that overstory effects must be accounted for when examining understory responses in this ecosystem

Mapping Europe’s party systems: which parties are the most right-wing and left-wing in Europe?

Within individual countries there is usually a good understanding of how parties differ from one another on economic issues, but how do parties in different European countries compare? Would Angela Merkel’s Christian Democrats lie to the right of Mariano Rajoy’s People’s Party in Spain? Is the British Labour Party to the left of other centre-left parties in Europe? Based on data from expert surveys, Ryan Bakker, Seth Jolly and Jonathan Polk map the left/right positions of political parties from 14 eastern and western European countries. They write that while this comparison gives a good indication of party competition across Europe, future research will also allow for European parties to be compared on non-economic dimensions and with parties in other parts of the world such as North America

Integrated Al2O3:Er3+ zero-loss optical amplifier and power splitter with 40 nm bandwidth

A combined planar lossless optical amplifier and 1x2 power splitter device has been realized in Al2O3:Er3+ on silicon. Net internal gain was measured over a wavelength range of 40 nm across the complete telecom -band (1525–1565 nm). Calculations predict net gain in a combined amplifier and 1x4 power splitter device over the same wavelength range for a total injected pump power as low as 30 mW

Analyzing the cross-national comparability of Party Positions on the Socio-Cultural and EU Dimensions in Europe

Using survey vignettes and scaling techniques, we estimate common socio-cultural and European integration dimensions for political parties across the member states of the European Union. Previous research shows that economic left/right travels well across the EU, meaning that the placements of parties on that dimension are cross- nationally comparable; however, the social dimension is more complex, with different issues forming the core of the social dimension in different countries. The 2014 wave of the Chapel Hill Expert Survey includes anchoring vignettes which we use as \bridge votes" to place parties from different countries on a common social liberal/authoritarian dimension and a separate common scale for European integration. We estimate the dimensions using the Bayesian Aldrich-McKelvey technique. The resulting scales offer cross-nationally comparable interval-level measures of a party's social and EU ideological positions

Effects of long-term livestock grazing and habitat on understory vegetation

The herbaceous understory stratum contains most of the plant diversity in ponderosa pine (Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.) forests of the American Southwest and provides critical food and habitat for many wildlife species. During the last century, this stratum has been affected by livestock grazing and by increased dominance of overstory trees. We sampled a unique grazing exclosure to examine the relative importance of long-term livestock grazing (grazed or ungrazed) and habitat (park or tree) on the understory community. We sampled 3 plots of 192 contiguous quadrats (each quadrat 0.5 m2) in each of the 4 treatment combinations, for a total of 2304 quadrats. Species-area curves were generated by aggregating quadrats into nonoverlapping areas at grain sizes of 0.5 to 576 m2. The effects of habitat and grazing on species density were evident at very different scales. Species density was higher in park than tree plots at scales ≤32 m2 but did not differ between habitats at larger scales. Species density differed minimally between grazed and ungrazed treatments at small grains, but grazed plots contained more species than ungrazed plots at larger grains. Grazing treatments differed at smaller grains (to 4–8 m2) than did habitats (to 32 m2), with respect to density of native species and graminoids. Grazed plots had more exotic species than ungrazed plots at all grain sizes, though few exotics were present. Twenty-two species were identified as indicator species associated with habitats and/or grazing treatments. Evaluations of plant community response to treatments would be improved by accounting for the grain at which data have been collected and analyzed and by identifying indicator species associated with various treatments. These data would enable more-informed conservation and management decisions

The European Common Space: Extending the Use of Anchoring Vignettes

In this article, we combine advances in both survey research and scaling techniques to estimate a common dimension for political parties across the member states of the European Union. Most previous scholarship has either ignored or assumed cross-national comparability of party placements across a variety of dimensions. The 2010 wave of the Chapel Hill Expert Survey includes anchoring vignettes which we use as “bridge votes” to place parties from different countries on a common space. We estimate our dimensions using the “blackbox” technique. Our results demonstrate both the usefulness of anchoring vignettes and the broad applicability of the blackbox scaling routine. Further, the resulting scale offers a cross-nationally comparable interval-level measure of a party’s left/right ideological position with a high degree of face validity. In short, we argue that the left/right economic dimension travels well across European countries

Long-term vegetation studies in the southwest

In this paper, we describe several long-term studies in the ponderosa pine (Pinus ponderosa) forests of the American Southwest, focusing on the unique insights and contributions of these studies. Many of the studies that we discuss were established by staff from the Fort Valley Experiment Station (FVES; http://www.rmrs.nau.edu/fortvalley/)

The hill plots: a rare long-term vegetation study

One legacy of the Fort Valley Experimental Forest is the number and quality of long-term studies associated with it. One such study is the “Hill plots,” which began in 1912 and is still being actively studied. Livestock exclosures were built at five sites to examine vegetation recovery when protected from livestock grazing. Sites span a range of soil types and elevations. Materials associated with the Hill plots include historical data, plant specimens, and photographs. In this paper, we summarize the research that has occurred on the Hill plots, historical personnel who worked on them, threats they have experienced, ecological insights they have provided, and current research directions

Forest structure and tree recruitment changes on a permanent historical Cinder Hills plot over a 130-Year Period

We examined forest structure, tree recruitment, and spatial pattern over a 130-year period on cinder soils in northern Arizona. Data were collected from a 3.24 ha permanent, stem-mapped plot established in 1909. This site is unique in that it represents ponderosa pine (Pinus ponderosa Laws. var. scopulorum Engelm.) growing on black cinder soils, which are of limited extent in the Southwest. Tree diameter, tree density and spatial data reconstructed from 1874 and actual measurements from 1909 and 2004 were compared, and the current stand age-structure of living trees was examined. Unlike most studies of stand dynamics in the Southwest, this site has experienced little change in structure or spatial pattern between 1874 and 2004. This difference is thought to reflect the unique environmental conditions associated with black cinder soils

Multidimensional Incongruence, Political Disaffection, and Support for Anti-Establishment Parties.

To what extent do representational gaps between parties and voters destabilize party systems and create electoral opportunities for anti-establishment parties on the left and right? In this paper, we use multiple measures of party-partisan incongruence to evaluate whether issue-level incongruence contributes to an increase of political disaffection and anti-establishment politics. For this analysis, we use data from the Chapel Hill Expert Survey (CHES) for party positions and public opinion data from the European Election Study (EES). Our fi ndings indicate that multidimensional incongruence is associated with disaffection at the national and European level, and that disffected mainstream party voters are in turn more likely to consider voting for anti-establishment challenger parties. This nding suggests that perceived gaps in party-citizen substantive representation have important electoral ramifi cations across European democracies