Jane Uhd Jepsen

Bio: Jane Uhd Jepsen is an academic researcher from Norwegian Polar Institute. The author has contributed to research in topics: Population & Arctic. The author has an hindex of 21, co-authored 55 publications receiving 4191 citations. Previous affiliations of Jane Uhd Jepsen include Norwegian Institute for Air Research & University of Copenhagen.

Climate change and outbreaks of the geometrids Operophtera brumata and Epirrita autumnata in subarctic birch forest: evidence of a recent outbreak range expansion.

Abstract: 1. Range expansions mediated by recent climate warming have been documented for many insect species, including some important forest pests. However, whether climate change also influences the eruptive dynamics of forest pest insects, and hence the ecological and economical consequences of outbreaks, is largely unresolved. 2. Using historical outbreak records covering more than a century, we document recent outbreak range expansions of two species of cyclic geometrid moth, Operophtera brumata Bkh. (winter moth) and Epirrita autumnata L. (autumnal moth), in subarctic birch forest of northern Fennoscandia. The two species differ with respect to cold tolerance, and show strikingly different patterns in their recent outbreak range expansion. 3. We show that, during the past 15-20 years, the less cold-tolerant species O. brumata has experienced a pronounced north-eastern expansion into areas previously dominated by E. autumnata outbreaks. Epirrita autumnata, on the other hand, has expanded the region in which it exhibits regular outbreaks into the coldest, most continental areas. Our findings support the suggestion that recent climate warming in the region is the most parsimonious explanation for the observed patterns. 4. The presence of O. brumata outbreaks in regions previously affected solely by E. autumnata outbreaks is likely to increase the effective duration of local outbreaks, and hence have profound implications for the subarctic birch forest ecosystem.

Complex responses of global insect pests to climate warming

Abstract: Although it is well known that insects are sensitive to temperature, how they will be affected by ongoing global warming remains uncertain because these responses are multifaceted and ecologically ...

Rapid northwards expansion of a forest insect pest attributed to spring phenology matching with sub-Arctic birch

Abstract: Species range displacements owing to shifts in temporal associations between trophic levels are expected consequences of climate warming. Climate-induced range expansions have been shown for two irruptive forest defoliators, the geometrids Operophtera brumata and Epirrita autumnata, causing more extensive forest damage in sub-Arctic Fennoscandia. Here, we document a rapid northwards expansion of a novel irruptive geometrid, Agriopis aurantiaria, into the same region, with the aim of providing insights into mechanisms underlying the recent geometrid range expansions and subsequent forest damage. Based on regional scale data on occurrences and a quantitative monitoring of population densities along the invasion front, we show that, since the first records of larval specimens in the region in 1997–1998, the species has spread northwards to approximately 70°N, and caused severe defoliation locally during 2004–2006. Through targeted studies of larval phenology of A. aurantiaria and O. brumata, as well as spring phenology of birch, along meso-scale climatic gradients, we show that A. aurantiaria displays a similar dynamics and development as O. brumata, albeit with a consistent phenological lag of 0.75–1 instar. Experiments of the temperature requirements for egg hatching and for budburst in birch showed that this phenological lag is caused by delayed egg hatching in A. aurantiaria relative to O. brumata. A. aurantiaria had a higher development threshold (LDTA.a.=4.71 °C, LDTO.b.=1.41 °C), and hatched later and in less synchrony with budburst than O. brumata at the lower end of the studied temperature range. We can conclude that recent warmer springs have provided phenological match between A. aurantiaria and sub-Arctic birch which may intensify the cumulative impact of geometrid outbreaks on this forest ecosystem. Higher spring temperatures will increase spring phenological synchrony between A. aurantiaria and its host, which suggests that a further expansion of the outbreak range of A. aurantiaria can be expected.

Drought-Induced Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009

Abstract: Terrestrial net primary production (NPP) quantifies the amount of atmospheric carbon fixed by plants and accumulated as biomass. Previous studies have shown that climate constraints were relaxing with increasing temperature and solar radiation, allowing an upward trend in NPP from 1982 through 1999. The past decade (2000 to 2009) has been the warmest since instrumental measurements began, which could imply continued increases in NPP; however, our estimates suggest a reduction in the global NPP of 0.55 petagrams of carbon. Large-scale droughts have reduced regional NPP, and a drying trend in the Southern Hemisphere has decreased NPP in that area, counteracting the increased NPP over the Northern Hemisphere. A continued decline in NPP would not only weaken the terrestrial carbon sink, but it would also intensify future competition between food demand and proposed biofuel production.

Tutorial on agent-based modelling and simulation

Abstract: Agent-based modelling and simulation (ABMS) is a relatively new approach to modelling systems composed of autonomous, interacting agents. Agent-based modelling is a way to model the dynamics of complex systems and complex adaptive systems. Such systems often self-organize themselves and create emergent order. Agent-based models also include models of behaviour (human or otherwise) and are used to observe the collective effects of agent behaviours and interactions. The development of agent modelling tools, the availability of micro-data, and advances in computation have made possible a growing number of agent-based applications across a variety of domains and disciplines. This article provides a brief introduction to ABMS, illustrates the main concepts and foundations, discusses some recent applications across a variety of disciplines, and identifies methods and toolkits for developing agent models.

Individual-based modeling and ecology

Abstract: Individual-based modeling is a new, exciting discipline that allows ecologists to explore, using computer simulations, how properties of populations and ecosystems might evolve from the characteristics and behaviors of individual organisms. Individual-based Modeling and Ecology, written by Volker Grimm and Steven F. Railsback, gives an excellent introduction and overview of this field. It should be read by everyone interested in individual-based modeling, and especially by anyone contemplating developing, or being involved with a group developing, an individualbased model.