Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2022
Sammendrag
Tree diameter increment (ΔDBH) and total tree height increment (ΔHT) are key components of a forest growth and yield model. A problem in complex, multi-species forests is that individual tree attributes such as ΔDBH and ΔHT need to be characterized for a large number of distinct woody species of highly varying levels of occurrence. Based on more than 2.5 million ΔDBH observations and over 1 million ΔHT records from up to 60 tree species and genera, respectively, this study aimed to improve existing ΔDBH and ΔHT equations of the Acadian Variant of the Forest Vegetation Simulator (FVS-ACD) using a revised method that utilize tree species as a random effect. Our study clearly highlighted the efficiency and flexibility of this method for predicting ΔDBH and ΔHT. However, results also highlighted shortcomings of this approach, e.g., reversal of plausible parameter signs as a result of combining fixed and random effects parameter estimates after extending the random effect structure by incorporating North American ecoregions. Despite these potential shortcomings, the newly developed ΔDBH and ΔHT equations outperformed the ones currently used in FVS-ACD by reducing prediction bias quantified as mean absolute bias and root mean square error by at least 11% for an independent dataset and up to 41% for the model development dataset. Using the revised ΔDBH and ΔHT estimates, greater prediction accuracy in individual tree aboveground live carbon mass estimation was also found in general but performance varied with dataset and accuracy metric examined. Overall, this analysis highlights the importance and challenges of developing robust ΔDBH and ΔHT equations across broad regions dominated by mixed-species, managed forests.
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Forfattere
Jutta KapferSammendrag
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Bjørn ØklandSammendrag
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Andrea Ponzecchi Emil E. Thybring Ramunas Digaitis Maria Fredriksson Sara Piqueras Solsona Lisbeth Garbrecht ThygesenSammendrag
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Forfattere
Philipp Lehmann Tea Ammunet Madeleine Barton Andrea Battisti Sanford D. Eigenbrode Jane Uhd Jepsen Gregor Kalinkat Seppo Neuvonen Pekka Niemelä John s. Terblanche Bjørn Økland Christer BjörkmanSammendrag
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 complex. We reviewed the effects of climate warming on 31 globally important phytophagous insect pests to determine whether general trends in their responses to warming were detectable. We included four response categories (range expansion, life history, population dynamics, and trophic interactions) in this assessment (Figure 1). For the majority of these species, we identified at least one response to warming that affects the severity of the threat they pose as pests. Among these insect species, 41% showed responses expected to lead to increased pest damage, whereas only 4% exhibited responses consistent with reduced effects; notably, most of these species (55%) demonstrated mixed responses. This means that the severity of a given insect pest may both increase and decrease with ongoing climate warming. Overall, our analysis indicated that anticipating the effects of climate warming on phytophagous insect pests is far from straightforward. Rather, efforts to mitigate the undesirable effects of warming on insect pests must include a better understanding of how individual species will respond, and the complex ecological mechanisms underlying their responses. Although not the focus of our review, the main conclusions we reach also should hold true for biological control agents and there is indeed evidence for phenological mismatch and other climate-change-related effects on biological control of varying magnitude among systems. At least some natural control agents seem to respond more positively to climate warming than their herbivore prey, and as such, one might expect better biological control in certain systems. One potential reason for these differences is that while both control agents and herbivores are affected physiologically by changing climate drivers, by for instance increasing development rate, the control agents in addition are affected behaviourally and, for instance, can increase foraging or searching rate. In addition, and specifically in relation to biological control, it is often crucial to achieve high synchronization between control agent and prey, which can be complicated by different response rates to winter temperature. This is something that has been observed with the chestnut gall wasp Dryocosmus kuriphilus (Hymenoptera: Cynipidae) and its parasitoid Proceedings of ISBCA 6 – D.C. Weber, T.D. Gariepy, and W.R. Morrison III, eds. (2022) page 3.19 Torymus sinensis (Hymenoptera: Torymidae) over the last years, as the gall wasp depends largely on the budbreak of the host plant while the parasitoid relies mainly on the air temperature for spring emergence. Figure 1. Four major categories of responses to climate warming. (a) Range changes include range expansions or shifts (latitudinal and/or altitudinal). (b) Life-history changes primarily consist of alterations to biological timing events or the number of annual generations. (c) Population dynamics reflect population size, and damage is expected to increase whenever temperature limits performance, but if threshold temperatures are reached, control and related feedback mechanisms may be triggered. Tpresent reflects current temperatures over a time period (e.g., a year or a day), whereas Tfuture reflects future temperatures over the same period. (d) Trophic interactions reflect temperature responses of organisms and trophic groups (plants = dashed green line, herbivores = solid red line, predators = dashed blue line). Because vital rates (i.e. rates of important life-history traits, such as growth, dispersal, and reproduction) may vary, climate warming could strongly affect trophic relationships. This is of direct consequence for the planning and efficiency of biological control programs.