Population fluctuations of moths and small rodents in relation to plant reproduction indices in southern Norway

Selås, Vidar; Kobro, Sverre; Sonerud, Geir A.

doi:10.1890/es13-00228.1

Cited by 19 publications

(16 citation statements)

References 55 publications

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“…space, time) and complexity of ecosystems, such studies are challenging to design (Underwood, 1999). Nevertheless, there are some studies that show close correlations between bilberry production and local population sizes of both insects and large herbivores known to feed on bilberry (Selås, 1997(Selås, , 2000(Selås, , 2006Selås, Kobro, & Sonerud, 2013).…”

Section: Multiannual Ramet Interactionsmentioning

confidence: 99%

Multiannual effects of induced plant defenses: Are defended plants good or bad neighbors?

Benevenuto

Hegland

Töpper

et al. 2018

Ecology and Evolution

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Defenses induced by herbivore feeding or phytohormones such as methyl jasmonate (MeJA) can affect growth, reproduction, and herbivory, not only on the affected individual but also in its neighboring plants. Here, we report multiannual defense, growth, and reproductive responses of MeJA‐treated bilberry (Vaccinium myrtillus) and neighboring ramets. In a boreal forest in western Norway, we treated bilberry ramets with MeJA and water (control) and measured responses over three consecutive years. We observed the treatment effects on variables associated with herbivory, growth, and reproduction in the MeJA‐treated and untreated ramet and neighboring ramets distanced from 10 to 500 cm. MeJA‐treated ramets had fewer grazed leaves and browsed shoots compared to control, with higher effects in 2014 and 2015, respectively. In 2013, growth of control ramets was greater than MeJA‐treated ramets. However, MeJA‐treated ramets had more flowers and berries than control ramets 2 years after the treatment. The level of insect and mammalian herbivory was also lower in untreated neighboring ramets distanced 10–150 cm and, consistent with responses of MeJA‐treated ramets, the stronger effect was also one and 2 years delayed, respectively. The same neighboring ramets had fewer flowers and berries than untreated ramets, indicating a trade‐off between defense and reproduction. Although plant–plant effects were observed across all years, the strength varied by the distance between the MeJA‐treated ramets and its untreated neighbors. We document that induced defense in bilberry reduces both insect and mammalian herbivory, as well as growth, over multiple seasons. The defense responses occurred in a delayed manner with strongest effects one and 2 years after the induction. Additionally, our results indicate defense signaling between MeJA‐treated ramets and untreated neighbors. In summary, this study shows that induced defenses are important ecological strategies not only for the induced individual plant but also for neighboring plants across multiple years in boreal forests.

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Section: Multiannual Ramet Interactionsmentioning

confidence: 99%

Multiannual effects of induced plant defenses: Are defended plants good or bad neighbors?

Benevenuto

Hegland

Töpper

et al. 2018

Ecology and Evolution

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“…While frugivorous species may eat a significant number of berries (Cadieux et al 2005), they have little impact on plant integrity. On the other hand, moth outbreaks were found to reduce seed crop (Selas et al 2013) and microtine grazing may remove up to 40% of bilberry phytomass during pre-peak winters (Andersson and Jonasson 1986). Semi-domesticated reindeer herds have significant impact on the vegetation in northern Fennoscandia; however, studies suggest that the cover of ericoid shrubs is not strongly affected by reindeer trampling and grazing (Br athen et al 2007, Kumpula et al 2011.…”

Section: Introductionmentioning

confidence: 99%

Climate and herbivore influence on Vaccinium myrtillus over the last 40 years in northwest Lapland, Finland

et al. 2017

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Abstract. Annual fluctuations in the abundance of wild berries have repercussions on animals and humans who depend on this important resource. Although studies have tried to disentangle the effect of climate and herbivores on inter-annual berry yield, there are still many uncertainties as to which factors are driving productivity. In this research, we evaluated the effect of climate and predation by rodents and moths on the abundance of bilberry (Vaccinium myrtillus) flowers and berries at the Kilpisj€ arvi Biological Station in northwest Finnish Lapland. The data were collected from 1973 to 2014 in a forest and an alpine site, both undisturbed by human activities. This dataset is unique due to the length of the sampling period, the availability of flower, berry, and rodent abundance data as well as the undisturbed nature of the habitat. Previous summer temperatures, the abundance of rodents, and the presence of a moth outbreak were complementary factors explaining the abundance of flowers. Herbivores had a larger impact on flower production than climate, but both variables were important to understand reproductive effort. Contrary to results from experimental studies, warmer winters did not significantly influence reproductive success. The abundance of fruits was strongly correlated with pollinator activity; the forest site, with a larger pollinator network, had a higher reproductive success and spring conditions were linked to inter-annual variability in fruit production. Our results illustrate the importance of the location of the population within the species distribution range to understand plant sensitivity to climatic fluctuations with fruit production only influenced by current year summer temperatures at the alpine site. Finally, we observed a general increase in flower and fruit production at the alpine site, which was driven by large yields since the early 1990s. Fruit production at the forest site was comparatively stable throughout the study period.

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“…Forest-dwelling ungulates such as red deer (Cervus elaphus) and moose (Alces alces) feed on bilberry, particularly in winter when other food sources may be scarce (Hjeljord et al 1990;Hegland et al 2005). Several studies by Sela˚s and colleagues (Sela˚s 1997(Sela˚s , 2000(Sela˚s , 2006Sela˚s et al 2013) have, for example, shown close correlations among bilberry production and population sizes of both invertebrate and vertebrates herbivores known to feed on bilberry. Recent increases in wild ungulate populations have created concerns about the impact of such high population densities (Coˆte et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Can browsing by deer in winter induce defence responses in bilberry (Vaccinium myrtillus)?

Hegland

Seldal

Lilleeng

et al. 2016

Ecological Research

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Wild ungulates are key determinants in shaping boreal plant communities, and may also affect ecosystem function through inducing the plant defence systems of key plant species. We examined whether winter browsing by deer could increase the resistance of bilberry (Vaccinium myrtillus). We used three indicators of induced bilberry defence: reduced growth (a), reduced reproduction (b) and decreased insect herbivory (c) in focal plants. In a field experiment, using a randomised block design, we exposed half of plants twice in winter to exogenously applied methyl jasmonate (MeJA) and crossed this factor with randomly selecting browsed and unbrowsed plants. We predicted that MeJA-plants would have significant lower growth, reproduction and insect herbivory than Control plants. We also expected that Browsed plants would experience similar negative effects and that there would be an interaction between MeJa and Browsed indicating a possible additive effect. Growth, flowering and insect herbivory were significantly lower in MeJA than in Control, as expected. We did not find the same reduction for Browsed and no significant interaction between factors. The combined treatment, unexpectedly, flowered more and showed higher levels of insect herbivory than MeJA. Our study showed that defence responses of bilberry may be induced by exogenously-applied MeJA in winter. Our study could not confirm whether winter browsing by deer can induce the same defence responses.

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Population fluctuations of moths and small rodents in relation to plant reproduction indices in southern Norway

Cited by 19 publications

References 55 publications

Multiannual effects of induced plant defenses: Are defended plants good or bad neighbors?

Multiannual effects of induced plant defenses: Are defended plants good or bad neighbors?

Climate and herbivore influence on Vaccinium myrtillus over the last 40 years in northwest Lapland, Finland

Can browsing by deer in winter induce defence responses in bilberry (Vaccinium myrtillus)?

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