1,720,994 research outputs found
Corrigendum to “A warmer climate impairs the growth performance of Central Europe's major timber species in lowland regions” [Sci. Total. Environ. Volume 941 (2024) Article Number 173665]
No full textA warmer climate impairs the growth performance of Central Europe's major timber species in lowland regions
No full texthttp://dx.doi.org/10.13039/501100020631 Bundesministerium für Ernährung und Landwirtschaf
Recent growth decline and shifts in climatic growth constraints suggest climate vulnerability of beech, Douglas fir, pine and oak in Northern Germany
No full textWinter and spring frost events delay leaf‐out, hamper growth and increase mortality in European beech seedlings, with weaker effects of subsequent frosts
No full textThe persistence of plant populations depends crucially on successful regeneration. Yet, little is known about the effects of consecutive winter and spring frost events on the regeneration stage of trees from different seed sources, although this will partly determine the success of climate warming‐driven poleward range shifts. In a common garden experiment with European beech ( Fagus sylvatica ) seedlings from winter 2015/2016 to autumn 2017, we studied how simulated successive spring and winter frost events affect leaf‐out dates, growth performance, and survival rates of 1‐ to 2‐year‐old seedlings from provenances differing in climate at origin. We further investigated the combined effects of successive frost events. The first spring frost after germination led to a mortality rate up to 75%, resulting in reduced seedling numbers but better frost tolerance of the survivors, as reflected in a weaker impact of the following winter frost event in the survivors compared to the non‐acclimated control. Final plant height was most strongly reduced by the spring frost in the second year. The winter frost event delayed leaf‐out by up to 40 days, leading to severe growth impairment in 2017. Our results indicate partly successful frost acclimation and/or the selection of frost‐hardier individuals, because the negative growth effects of consecutive frost events did not add up after exposure to more than one event. Both mechanisms may help to increase the frost tolerance of beech offspring. Nevertheless, mortality after the first spring frost was high, and frost exposure generally caused growth reductions. Thus, achieving higher frost tolerance may not be sufficient for beech seedlings to overcome frost‐induced reductions in competitive strength caused by winter frost damage and delayed leaf enfolding.Deutsche Forschungsgemeinschaft https://doi.org/10.13039/501100001659Open-Access-Publikationsfonds 202
Winter matters: Sensitivity to winter climate and cold events increases towards the cold distribution margin of European beech (Fagus sylvatica L.)
No full textAim The dominant forest tree in Europe, European beech (Fagus sylvatica L.), covers large areas of continental Europe and thus experiences diverse climatic conditions. In the face of predicted climate change and shifts of distribution ranges, it is important to understand the diverse climate–growth relationships towards distribution margins. Beech is generally reported to be sensitive to summer drought towards dry and continental regions; yet, few studies have investigated climate sensitivity towards the cold distribution margin of beech. We hypothesized that at colder sites (a) growth of beech is more sensitive to winter cold, (b) growth is less influenced by summer drought, and (c) stand‐wide growth reductions (negative pointer years) are related to extreme winter cold events. Taxon European beech (Fagus sylvatica L.). Location A large gradient of decreasing winter temperature (ΔT >4 K along 500 km) from Rostock (Germany) to Gdańsk (Poland). Methods We analysed climate–growth relationships and the nature of growth reductions of 11 beech stands from more central to cold marginal beech populations. Results Towards the cold marginal populations, growth became increasingly sensitive to winter cold (February temperature) and less sensitive to summer water availability (June precipitation). Likewise, negative pointer years coincided with winter cold anomalies at the colder sites and with summer drought anomalies at the warmer sites. Thus, over the studied gradient, the general sensitivity of beech to summer drought transitions into sensitivity to winter cold. Main conclusions A range shift of beech across the current cold distribution margin is often assumed to compensate for habitat and productivity losses of drought‐prone southern and central populations. With respect to the winter cold sensitivity found in our study, such assumptions should be taken with caution. Since winter cold events are predicted to persist with similar frequency and magnitude even during predicted climate warming, beech populations in the newly colonized habitat might be significantly sensitive to winter cold
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Root and shoot traits of two common herbs respond differently to drought and fertilization in a multifactorial global change experiment
No full textAbstract Background Plants must adapt locally to the recent global change, such as increasing drought exposure or altering nutrient availability. In ecological theory, all functional traits of the plant move towards strategies of stability and resource conservation. In particular fine roots are responsible for water and nutrient uptake and they are highly plastic to stress. In contrast to shoot traits, the dynamics of root growth and the relationship between root and shoot trait responses are still understudied and poorly understood. Methods Therefore, we investigated the shoot and root trait responses of two herbaceous plants, Plantago lanceolata and Rumex acetosa, growing in monoculture or in mixture in a drought x nutrient greenhouse experiment. Results Low-nutrient stress, more than drought stress, led to a strong carbon allocation to the roots, because the root–shoot ratio increased to compensate for stress with improved root development. Roots responded with a more conservative resource use strategy, e.g., an actually decreasing biomass and surface area to drought and, in contrast, unexpectedly with acquisitive strategy by strongly increasing the root–shoot ratio in nutrient-poor conditions. Classical shoot traits such as the decreasing specific leaf area (SLA) indicated a more resource-conservative strategy in response to any stressor. Conclusions Understanding whole-plant responses to global change scenarios urgently requires a much more specific exploration of the adaptation and acclimatisation potential of roots in the application of ecological research. In view of climate-smart land management, the study highlights the importance of maintaining species-rich ecosystems in face of increasing likelihood of global change-type droughts.
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