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.
2020
Abstract
No abstract has been registered
Authors
Liv Guri Velle Siri Vatsø Haugum Pål Thorvaldsen Richard Thelford Bente Halvorsen Kristine Grimsrud Vigdis VandvikAbstract
The combined impact of climate and land-use change poses increasing threats to nature and nature's benefit to people. The LandPress project makes use of the severe Norwegian winter-drought in 2014 as a case study; and combines geographical, ecological and social science approaches to explore the drivers of ecosystem resilience to drought die-back, the ecological processes and implications of drought responses, and management options for mitigating damage and costs. First, by means of remote sensing, we assess the role of climate, environment and land-use in regulating resilience of Calluna heaths to drought die-back locally and along a biogeographic gradient. We find that drought-damage in heather varies across landscapes, and can be quantified by aerial photos, allowing us to establish that both environment (slope) and land-use (prescribed fire) influence ecosystem resistance to drought. Second, we conduct a drought experiment to understand and assess the impacts of severe drought events on coastal heathland ecosystem dynamics and functioning. After the three first years we find only weak effects on plant communities, but distinct responses in plant functional traits suggesting that ecosystem resistance to drought decreases with time since the last prescribed fire. Third, we experimentally assess whether prescribed burning can be used to promote Calluna's resilience after severe drought, and find that prescribed burning efficiently removes damaged heather, stimulating post-fire vegetation development and restore ecosystem functioning after drought. Finally, we conduct a cost-benefit analysis to understand the contribution of land management to the provision of ecosystem services, with focus on securing low fire-risk landscapes. We find that management has more benefits than food production; land-use can reduce the extent of extreme drought, reduce fire risk and help us keep the ecosystem functioning. Our project demonstrates the importance of understanding how interactions between climate-change and land-use and is crucial in developing new management strategies.
Abstract
There has been much recent research interest in the existence of a major axis of life‐history variation along a fast–slow continuum within almost all major taxonomic groups. Eco‐evolutionary models of density‐dependent selection provide a general explanation for such observations of interspecific variation in the "pace of life." One issue, however, is that some large‐bodied long‐lived “slow” species (e.g., trees and large fish) often show an explosive “fast” type of reproduction with many small offspring, and species with “fast” adult life stages can have comparatively “slow” offspring life stages (e.g., mayflies). We attempt to explain such life‐history evolution using the same eco‐evolutionary modeling approach but with two life stages, separating adult reproductive strategies from offspring survival strategies. When the population dynamics in the two life stages are closely linked and affect each other, density‐dependent selection occurs in parallel on both reproduction and survival, producing the usual one‐dimensional fast–slow continuum (e.g., houseflies to blue whales). However, strong density dependence at either the adult reproduction or offspring survival life stage creates quasi‐independent population dynamics, allowing fast‐type reproduction alongside slow‐type survival (e.g., trees and large fish), or the perhaps rarer slow‐type reproduction alongside fast‐type survival (e.g., mayflies—short‐lived adults producing few long‐lived offspring). Therefore, most types of species life histories in nature can potentially be explained via the eco‐evolutionary consequences of density‐dependent selection given the possible separation of demographic effects at different life stages.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Elena Albertsen Øystein H. Opedal Geir Hysing Bolstad Rocio Perez-Barrales Thomas F Hansen Christophe Pelabon William Scott ArmbrusterAbstract
No abstract has been registered
Authors
Elena Albertsen Øystein Hjorthol Opedal Geir Hysing Bolstad Rocío Pérez-Barrales Thomas F Hansen Christophe Pelabon William Scott ArmbrusterAbstract
Spatiotemporal variation in natural selection is expected, but difficult to estimate. Pollinator‐mediated selection on floral traits provides a good system for understanding and linking variation in selection to differences in ecological context. We studied pollinator‐mediated selection in five populations of Dalechampia scandens (Euphorbiaceae) in Costa Rica and Mexico. Using a nonlinear path‐analytical approach, we assessed several functional components of selection, and linked variation in pollinator‐mediated selection across time and space to variation in pollinator assemblages. After correcting for estimation error, we detected moderate variation in net selection on two out of four blossom traits. Both the opportunity for selection and the mean strength of selection decreased with increasing reliability of cross‐pollination. Selection for pollinator attraction was consistently positive and stronger on advertisement than reward traits. Selection on traits affecting pollen transfer from the pollinator to the stigmas was strong only when cross‐pollination was unreliable and there was a mismatch between pollinator and blossom size. These results illustrate how consideration of trait function and ecological context can facilitate both the detection and the causal understanding of spatiotemporal variation in natural selection.
Authors
Svenja B. KroegerAbstract
No abstract has been registered
Authors
Svenja B. Kroeger Daniel T. Blumstein Kenneth B. Armitage Jane Margaret Reid Julien G.A. MartinAbstract
No abstract has been registered
Authors
Magda Chudzinska Yoko L. Dupont Jacob Nabe-Nielsen Kate P. Maia Marie Vestergaard Henriksen Claus Rasmussen W. Daniel Kissling Melanie Hagen Kristian TrøjelsgaardAbstract
Understanding interactions between individual animals and their resources is fundamental to ecology. Agent-Based Models (ABMs) offer an opportunity to study how individuals move given the spatial distribution and characteristics of their resources. When contrasted with empirical individual-resource network data, ABMs can be a powerful method to detect the processes behind observed movement patterns, as they allow for a complete and quantitative analysis of the agent-to-environment relationships. Here we use the small-scale, within-patch movement of bumblebees (Bombus pascuorum) as a case study to demonstrate how ABMs can be combined with network statistics to provide a deeper understanding of the mechanisms behind the interactions between individuals and their resources. We build an ABM that explicitly simulates the influence of distance to the nearest flowering plant (allowing minimal energy expenditure and maximum time spent foraging), plant height and number of flower heads (as a proxy of food availability) on local foraging decisions of bumblebees. The relative importance of these three elements is determined using pattern-oriented modelling (POM), where we confront the network statistics (number of visited plants, number of interactions, nestedness and modularity) of a real B. pascuorum individual-resource network with the emergent patterns of our ABM. We also explore the model results using spatial analysis. The model is able to reproduce the observed network statistics. Despite the complex behaviour of bumblebees, our results show a surprisingly precise match between the structure of the simulated and empirical networks after adjusting a single model parameter controlling the importance of distance to the next plant visited. Our study illustrates the potential of combining field data, ABMs and individual-resource networks for evaluating small-scale, within-patch movement decisions to better understand animal movements in natural habitats. We discuss the benefits of our approach when compared to more classical statistical methods, and its ability to test various scenarios in a new or altered environment.