Intense grazing of calcareous grasslands has negative consequences for the threatened marsh fritillary butterfly

Johansson, Victor; Kindvall, Oskar; Askling, Johan; Franzén, Markus

doi:10.1016/j.biocon.2019.108280

Cited by 19 publications

(67 citation statements)

References 40 publications

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“…Larvae feed and bask gregariously during sunny days until September, when they enter diapause in a collective nest (larval autumn nests). The species is very sensitive to grazing, and the number of autumn nests is on average 4.8 times lower in grazed compared to ungrazed habitat (Johansson et al, 2019).…”

Section: Methodsmentioning

confidence: 99%

“…Discrete patches were defined as habitat areas separated by >33.3 m of open habitat without the host plant, or >10 m with forest barrier. These threshold values were based on observed movements between patches from an earlier mark–recapture study (Johansson et al, 2019). In this way 256 separate habitat patches were identified within the study area (Figure 1c).…”

Section: Methodsmentioning

confidence: 99%

“…In the study area this means grazing from late May to late September with sheep or cattle (Angus and Charolais) with approximately 0.3 animals/ha on average. This is an intensity that is clearly too high for the marsh fritillary in the study area, and current grazing is therefore detrimental for the species (Johansson et al, 2019). It is likely that grazing becomes harmful already at low stocking rates, and due to the poor soil and slow accumulation of humus (Eliasson, 2008) the habitat will remain naturally open for decades without any grazing.…”

Section: Methodsmentioning

confidence: 99%

“…As explanatory variables we used patch area, connectivity, grazing and the mean GMI for the patch. Grazing was included as an adjustment of the ‘effective area’ of the patch (Moilanen & Hanski, 1998), as we earlier have shown that grazing reduces habitat quality (Johansson et al, 2019). Specifically, grazed areas were reduced 4.8 times and we then used this ‘effective area’ in the models (ungrazed areas remained unchanged).…”

Section: Methodsmentioning

confidence: 99%

“…Moilanen & Hanski, 1998), where a low‐quality patch has a smaller ‘effective area’ compared to an equally sized high‐quality patch. For example, too intense grazing may reduce the habitat quality, and thus the ‘effective patch area’, for many grassland butterflies (Johansson, Kindvall, Askling, & Franzén, 2019; Moilanen & Hanski, 1998). It is also possible that habitat quality is further affected by extreme weather, for example, due to changes in abundance or quality of host plants (Curtis, Brereton, Dennis, Carbone, & Isaac, 2015; Gutbrodt, Mody, & Dorn, 2011).…”

Section: Introductionmentioning

confidence: 99%

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Extreme weather affects colonization–extinction dynamics and the persistence of a threatened butterfly

Johansson¹,

Kindvall²,

Askling³

et al. 2020

Journal of Applied Ecology

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Extreme weather events can be expected to increase in frequency in the future. Our knowledge on how this may affect species persistence is, however, very limited. For reliable projections of future persistence we need to understand how extreme weather affects species' population dynamics. We analysed the effect of extreme droughts on the host plant Succisa pratensis, colonization–extinction dynamics, and future persistence of the threatened marsh fritillary Euphydryas aurinia. Specifically, we studied a metapopulation inhabiting a network of 256 patches on Gotland (Sweden), where the summer of 2018 was the driest ever recorded. We analysed how the frequency and leaf size of host plants changed between 2017 and 2019, based on 6,833 records in 0.5‐m2 sample plots. Using turnover data on the butterfly from 2018 to 2019 we modelled local extinction and colonization probabilities. Moreover, we projected future population dynamics with an increasing frequency of extreme years under three different management strategies that regulate the grazing regime. Our results show a substantial decrease in both frequency (46%) and size (20%) of host plants due to the drought, which taken together may constitute a 57% loss of food resources. The butterfly occupancy decreased by over 30% between 2018 and 2019 (from 0.36 to 0.27). The extinction probability increased with increasing ‘effective area’ of the patch (taking quality reduction due to grazing into account), and the colonization probability increased with increasing connectivity and ground moisture. Projections of future dynamics showed an increasing risk of metapopulation extinction with increasing frequency of years with extreme droughts. The risk, however, clearly differed between management strategies. Less grazing in years with droughts decreased the extinction risk considerably. Synthesis and applications. Extreme weather events can have profound negative impacts on butterflies and their host plants. For the marsh fritillary, an increased frequency of extreme droughts can lead to extinction of the entire metapopulation, even in a large and seemingly viable metapopulation. Increased grazing, due to fodder deficiency in dry years, may lead to cascading negative effects, while active management that reduce grazing in years with droughts can almost completely mitigate these effects.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Extreme weather affects colonization–extinction dynamics and the persistence of a threatened butterfly

Johansson¹,

Kindvall²,

Askling³

et al. 2020

Journal of Applied Ecology

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Strong isolation by distance among local populations of an endangered butterfly species (Euphydryas aurinia)

Pertoldi

Ruiz‐González

Bahrndorff

et al. 2021

Ecology and Evolution

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The marsh fritillary (Euphydryas aurinia) is a critically endangered butterfly species in Denmark known to be particularly vulnerable to habitat fragmentation due to its poor dispersal capacity. We identified and genotyped 318 novel SNP loci across 273 individuals obtained from 10 small and fragmented populations in Denmark using a genotyping‐by‐sequencing (GBS) approach to investigate its population genetic structure. Our results showed clear genetic substructuring and highly significant population differentiation based on genetic divergence (FST) among the 10 populations. The populations clustered in three overall clusters, and due to further substructuring among these, it was possible to clearly distinguish six clusters in total. We found highly significant deviations from Hardy–Weinberg equilibrium due to heterozygote deficiency within every population investigated, which indicates substructuring and/or inbreeding (due to mating among closely related individuals). The stringent filtering procedure that we have applied to our genotype quality could have overestimated the heterozygote deficiency and the degree of substructuring of our clusters but is allowing relative comparisons of the genetic parameters among clusters. Genetic divergence increased significantly with geographic distance, suggesting limited gene flow at spatial scales comparable to the dispersal distance of individual butterflies and strong isolation by distance. Altogether, our results clearly indicate that the marsh fritillary populations are genetically isolated. Further, our results highlight that the relevant spatial scale for conservation of rare, low mobile species may be smaller than previously anticipated.

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Negative impacts of future forest succession on three threatened butterfly species

Sunde,

Askling,

Kindvall

et al. 2024

Biodivers Conserv

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The dynamic interplay between anthropogenic activities and biodiversity conservation necessitates a nuanced understanding of habitat change, especially in contexts marked by transitions from grasslands to forested areas. This investigation utilised three threatened butterfly species—the Marsh Fritillary, Apollo, and Large Blue—as models to explore how grassland associated species respond to altered environmental conditions. The methodology encompassed extensive field surveys and statistical analyses with ecological niche modelling to determine their current and future distributions on the Island of Gotland. The species were surveyed under distinct years from 2017 to 2020 in a total of 3333 hectares in a 6000 hectare area—the Marsh Fritillary in 2017 (1232 hectares), Apollo in 2019 (2346 hectares), and Large Blue in 2020 (2256 hectares). Results revealed that the estimated current extents of suitable habitats were 49,104 hectares for the Marsh Fritillary (15.6% of the island), 45,646 hectares for Apollo (14.5%), and 33,089 hectares for Large Blue (10.5%). In general, increased forest and shrub cover and decreased heterogeneity negatively affected butterfly occupancy, but each species exhibited unique habitat preferences. The predictive modelling demonstrated that continued succession would reduce the amount of habitats predicted to be suitable and generated alarming forecasts—a twofold increase in forest and shrub cover suggests habitat declines of 41%, 47%, and 65% for the Marsh Fritillary, Apollo, and Large Blue, respectively. Given these findings, proactive measures are imperative for strategically managing these habitats to preserve landscape heterogeneity and accommodate diverse ecological needs. This study is important to conservation management providing, crucial insights amid anthropogenic and ecological changes.

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Intense grazing of calcareous grasslands has negative consequences for the threatened marsh fritillary butterfly

Cited by 19 publications

References 40 publications

Extreme weather affects colonization–extinction dynamics and the persistence of a threatened butterfly

Extreme weather affects colonization–extinction dynamics and the persistence of a threatened butterfly

Strong isolation by distance among local populations of an endangered butterfly species (Euphydryas aurinia)

Negative impacts of future forest succession on three threatened butterfly species

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