Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2021
Abstract
Across North America, forests dominated by Quercus rubra L. (northern red oak), a moderately shade-tolerant tree species, are undergoing successional replacement by shade-tolerant competitors. Under closed canopies, Q. rubra seedlings are unable to compete with these shade-tolerant species and do not recruit to upper forest strata. In Europe, natural regeneration of introduced Q. rubra is often successful despite the absence of fire, which promotes regeneration in the native range. Considering that understorey light availability is a major factor affecting recruitment of seedlings, we hypothesized that Q. rubra seedlings are more shade tolerant in the introduced range than in the native range. Morphological traits and biomass allocation patterns of seedlings indicative of shade tolerance were compared for Q. rubra and three co-occurring native species in two closed-canopy forests in the native range (Ontario, Canada) and introduced range (Baden-Württemburg, Germany). In the native range, Q. rubra allocated a greater proportion of biomass to roots, while in the introduced range, growth and allocation patterns favored the development of leaves. Q. rubra seedlings had greater annual increases in height, diameter and biomass in the introduced range. Q. rubra seedlings in the introduced range were also younger; however, they had a mean area per leaf and a total leaf area per seedling that were five times greater than seedlings in the native range. Such differences in morphological traits and allocation patterns support the hypothesis that Q. rubra expresses greater shade tolerance in the introduced range, and that natural regeneration of Q. rubra is not as limited by shade as in the native range. The ability of Q. rubra seedlings to grow faster under closed canopies in Europe may explain the discrepancy in regeneration success of this species in native and introduced ranges. Future research should confirm findings of this study over a greater geographical range in native and introduced ecosystems, and examine the genetic and environmental bases of observed differences in plant traits.
Authors
Christel C. Kern Laura S. Kenefic Christian Kuehne Aaron R. Weiskittel Sarah J. Kaschmitter Anthony W. D'Amato Daniel C. Dey John M. Kabrick Brian J. Palik Thomas M. SchulerAbstract
We compiled data from several independent, long-term silvicultural studies on USDA Forest Service experimental forests across a latitudinal gradient in the northeastern and north-central U.S.A. to evaluate factors influencing aboveground live-tree carbon sequestration and mortality. Data represent five sites with more than 70,000 repeated tree records spanning eight decades, five ecoregions, and a range of stand conditions. We used these data to test the relative influence of factors such as climate, treatment history (uneven-aged or no management), species composition, and stand structural conditions on aboveground live-tree carbon sequestration and mortality in repeatedly measured trees. Relative to no management, we found that uneven-aged management tended to have a positive effect on carbon sequestration at low stocking levels and in areas of favorable climate (expressed as a combination of growing season precipitation and annual growing degree days > 5 ◦C). In addition, losses of carbon from the aboveground live-tree pool due to tree mortality were lower in managed than unmanaged stands. These findings suggest that there may be conditions at which rate of sequestration in living trees is higher in stands managed with uneven-aged silviculture than in unmanaged stands, and that this benefit is greatest where climate is favorable.
Authors
Harri Mäkinen Helena M. Henttonen Ulrich Kohnle Christian Kuehne Pekka Nöjd Chaofang Yue Joachim Klädtke Jouni SiipilehtoAbstract
The maximum size-density relationship describes site carrying capacity, i.e., the maximum number of trees of a given size that can be stocked per unit area (self-thinning line). We analysed whether the self-thinning lines of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) have remained unchanged over time in South Germany, Norway and Finland, i.e., over a wide climatic gradient from Central Europe up to the Arctic circle. The analyses are based on long-term growth and yield experiments measured on individual tree basis over several decades, the oldest experiments established during the early 20th century. The stochastic frontier analysis was used to analyse changes in the species-specific self-thinning lines. The results show that the self-thinning lines have shifted upwards over time in all the regions. Thus, currently stands sustain higher stand densities than in the past. The increase of the maximum density for a given average stem size was more pronounced for pine than for spruce, but similar in all studied geographical regions. In addition, increasing site index was associated with increasing site carrying capacity for spruce and pine in all regions. The results imply that environmental changes have altered site properties in similar fashion across the whole study region. In practical forestry, increased site carrying capacity will reduce mortality and loss of growing stock.
Lecture – Dead wood dynamics in old boreal forests: importance for carbon cycling
Jogeir N. Stokland
Authors
Jogeir N. StoklandAbstract
No abstract has been registered
Authors
Jogeir N. StoklandAbstract
No abstract has been registered
Authors
Jogeir N. StoklandAbstract
This study documents volume increment and natural mortality in 1379 old boreal forests plots during four consecutive inventory cycles in the Norwegian national forest inventory. The stands age up to 100 years beyond recommended rotation length (close to economical optimal rotation length) and comprise a wide range of site productivity classes in both pine- and spruce-dominated forests. The annual gross volume increment was stable and nearly constant up to 50–100 years beyond economically optimal rotation length. In parallel, there was very low natural mortality (0.22–0.66% of standing volume) with minimal risk of stand collapse. Stands with satisfactory stocking had volume increment equal to or higher than the reference volume increment in managed stands harvested at recommended rotation length, while poorly stocked stands had inferior volume increment. From a climate change mitigation perspective, it seems to be a good strategy to extend the rotation length beyond what is currently recommended, provided that the stands have satisfactory stocking.
Authors
Ingmar R. Staude Henrique M. Pereira Gergana N. Daskalova Markus Bernhardt-Römermann Martin Diekmann Harald Pauli Hans Van Calster Mark Vellend Anne D. Bjorkman Jörg Brunet Pieter De Frenne Radim Hédl Ute Jandt Jonathan Lenoir Isla H. Myers-Smith Kris Verheyen Sonja Wipf Monika Wulf Christopher Andrews Peter Barančok Elena Barni José-Luis Benito-Alonso Jonathan Bennie Imre Berki Volker Blüml Markéta Chudomelová Guillaume Decocq Jan Dick Thomas Dirnböck Tomasz Durak Ove Eriksson Brigitta Erschbamer Bente Jessen Graae Thilo Heinken Fride Høistad Schei Bogdan Jaroszewicz Martin Kopecký Thomas Kudernatsch Martin Macek Marek Malicki František Máliš Ottar Michelsen Tobias Naaf Thomas A. Nagel Adrian C. Newton Lena Nicklas Ludovica Oddi Adrienne Ortmann-Ajkai Andrej Palaj Alessandro Petraglia Petr Petřík Remigiusz Pielech Francesco Porro Mihai Puşcaş Kamila Reczyńska Christian Rixen Wolfgang Schmidt Tibor Standovár Klaus Steinbauer Krzysztof Świerkosz Balázs Teleki Jean-Paul Theurillat Pavel Dan Turtureanu Tudor-Mihai Ursu Thomas Vanneste Philippine Vergeer Ondřej Vild Luis Villar Pascal Vittoz Manuela Winkler Lander BaetenAbstract
Species turnover is ubiquitous. However, it remains unknown whether certain types of species are consistently gained or lost across different habitats. Here, we analysed the trajectories of 1827 plant species over time intervals of up to 78 years at 141 sites across mountain summits, forests, and lowland grasslands in Europe. We found, albeit with relatively small effect sizes, displacements of smaller- by larger-ranged species across habitats. Communities shifted in parallel towards more nutrient-demanding species, with species from nutrient-rich habitats having larger ranges. Because these species are typically strong competitors, declines of smaller-ranged species could reflect not only abiotic drivers of global change, but also biotic pressure from increased competition. The ubiquitous component of turnover based on species range size we found here may partially reconcile findings of no net loss in local diversity with global species loss, and link community-scale turnover to macroecological processes such as biotic homogenisation.
Authors
Lise Dalsgaard Lars Vesterdal Inge Stupak Arezoo Taghizadeh-toosi Lars Elsgaard Jørgen E. OlesenAbstract
No abstract has been registered
Authors
Mari Mette TollefsrudAbstract
No abstract has been registered
Authors
Michal Hájek Borja Jiménez-Alfaro Ondřej Hájek Lisa Brancaleoni Marco Cantonati Michele Carbognani Anita Dedić Daniel Dítě Renato Gerdol Petra Hájková Veronika Horsáková Florian Jansen Jasmina Kamberović Jutta Kapfer Tiina Hilkka Maria Kolari Mariusz Lamentowicz Predrag Lazarević Ermin Mašić Jesper Erenskjold Moeslund Aaron Pérez-Haase Tomáš Peterka Alessandro Petraglia Eulàlia Pladevall-Izard Zuzana Plesková Stefano Segadelli Yuliya Semeniuk Patrícia Singh Anna Šímová Eva Šmerdová Teemu Tahvanainen Marcello Tomaselli Yuliya Vystavna Claudia Biţă-Nicolae Michal HorsákAbstract
Water resources and associated ecosystems are becoming highly endangered due to ongoing global environmental changes. Spatial ecological modelling is a promising toolbox for understanding the past, present and future distribution and diversity patterns in groundwater-dependent ecosystems, such as fens, springs, streams, reed beds or wet grasslands. Still, the lack of detailed water chemistry maps prevents the use of reasonable models to be applied on continental and global scales. Being major determinants of biological composition and diversity of groundwater-dependent ecosystems, groundwater pH and calcium are of utmost importance. Here we developed an up-to-date European map of groundwater pH and Ca, based on 7577 measurements of near-surface groundwater pH and calcium distributed across Europe. In comparison to the existing European groundwater maps, we included several times more sites, especially in the regions rich in spring and fen habitats, and filled the apparent gaps in eastern and southeastern Europe. We used random forest models and regression kriging to create continuous maps of water pH and calcium at the continental scale, which is freely available also as a raster map (Hájek et al., 2020b; https://doi.org/10.5281/zenodo.4139912). Lithology had a higher importance than climate for both pH and calcium. The previously recognised latitudinal and altitudinal gradients were rediscovered with much refined regional patterns, as associated with bedrock variation. For ecological models of distribution and diversity of many terrestrial ecosystems, our new map based on field groundwater measurements is more suitable than maps of soil pH, which mirror not only bedrock chemistry but also vegetation-dependent soil processes.