Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation
Lycaena helle is an endangered butterfly that is mainly threatened by habitat degradation and fragmentation. For all species with a fragmented distribution, knowledge about mobility, habitat requirements and connectivity is key to developing successful conservation strategies. This study was conduc...
| Autor principal: | |
|---|---|
| Formato: | H2 |
| Lenguaje: | Inglés sueco |
| Publicado: |
SLU/Dept. of Ecology
2018
|
| Materias: |
| _version_ | 1855572252489154560 |
|---|---|
| author | Modin, Hanna |
| author_browse | Modin, Hanna |
| author_facet | Modin, Hanna |
| author_sort | Modin, Hanna |
| collection | Epsilon Archive for Student Projects |
| description | Lycaena helle is an endangered butterfly that is mainly threatened by habitat degradation and fragmentation. For all species with a fragmented distribution, knowledge about mobility, habitat requirements and connectivity is key to developing successful conservation strategies. This
study was conducted close to Östersund, in central Sweden, and aimed to investigate the mobility of L. helle, identify remote-sensed predictors of L. helle occurrence, examine the relationship between L. helle density, the abundance of its host plant and vegetation height and to classify local
populations according to their importance for the connectivity on a regional level.
A mark-recapture study was performed, which found that L. helle is extremely sedentary, faithful to its habitat and appears to be reliant on females for long-distance dispersal. The recorded flight distances were in
most cases longer than what has been found in Central Europe. A resource selection function was used to identify important predictors of L. helle occurrence among five variables computed from remote-sensed data;
vegetation height, variation in vegetation, solar radiation, slope and aspect.
Solar radiation and slope can be recommended for inclusion in future models. Probability of occurrence of L. helle increased at higher solar radiation, as L. helle is dependent on high insolation. helle. Slope had a
negative effect and is hypothesized to act as a proxy for wetness, as L. helle is strongly linked to wetland habitats and as low-gradient areas gather water
whereas steep areas shed water.
Host plant abundance and vegetation height were inventoried and tested for correlations with L. helle density. There was a significant but weak positive correlation between the abundance of the host plant and the density of L. helle. The weak correlation implies that L. helle is either primarily limited by something else than its host plant or that it can only use the host plant when it grows under certain conditions. L. helle density was negatively correlated with vegetation height, likely caused by the late succession stage of most habitat patches in the study area, which induces selection for lower vegetation heights.
The connectivity analysis identified so-called stepping stones, i.e. populations that are particularly important from a connectivity perspective and to which conservation efforts should be directed. Retained or improved
connectivity is stressed as fundamental for the conservation of the species.
Dispersal corridors improve connectivity and are suitable as habitat patches in themselves, meaning that they merit conservation efforts. The timing and frequency of the maintenance of dispersal corridors is crucial and there is a
need for better communication with the parties responsible. To improve the long-term viability of the studied metapopulation, it is recommended to
make a dispersal corridor to suitable habitats in Tysjöarna nature reserve to increase the extent of the metapopulation. With the onset of climate change, retained connectivity is yet more important since large networks of populations are more viable and have a higher adaptability to new
environmental conditions. |
| format | H2 |
| id | RepoSLU13488 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2018 |
| publishDateSort | 2018 |
| publisher | SLU/Dept. of Ecology |
| publisherStr | SLU/Dept. of Ecology |
| record_format | eprints |
| spelling | RepoSLU134882020-05-20T10:53:37Z Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation Modin, Hanna Lycaena helle violet copper Lepidoptera Lycaenidae mobility dispersal resource selection function habitat selection connectivity metapopulation stepping stone Lycaena helle is an endangered butterfly that is mainly threatened by habitat degradation and fragmentation. For all species with a fragmented distribution, knowledge about mobility, habitat requirements and connectivity is key to developing successful conservation strategies. This study was conducted close to Östersund, in central Sweden, and aimed to investigate the mobility of L. helle, identify remote-sensed predictors of L. helle occurrence, examine the relationship between L. helle density, the abundance of its host plant and vegetation height and to classify local populations according to their importance for the connectivity on a regional level. A mark-recapture study was performed, which found that L. helle is extremely sedentary, faithful to its habitat and appears to be reliant on females for long-distance dispersal. The recorded flight distances were in most cases longer than what has been found in Central Europe. A resource selection function was used to identify important predictors of L. helle occurrence among five variables computed from remote-sensed data; vegetation height, variation in vegetation, solar radiation, slope and aspect. Solar radiation and slope can be recommended for inclusion in future models. Probability of occurrence of L. helle increased at higher solar radiation, as L. helle is dependent on high insolation. helle. Slope had a negative effect and is hypothesized to act as a proxy for wetness, as L. helle is strongly linked to wetland habitats and as low-gradient areas gather water whereas steep areas shed water. Host plant abundance and vegetation height were inventoried and tested for correlations with L. helle density. There was a significant but weak positive correlation between the abundance of the host plant and the density of L. helle. The weak correlation implies that L. helle is either primarily limited by something else than its host plant or that it can only use the host plant when it grows under certain conditions. L. helle density was negatively correlated with vegetation height, likely caused by the late succession stage of most habitat patches in the study area, which induces selection for lower vegetation heights. The connectivity analysis identified so-called stepping stones, i.e. populations that are particularly important from a connectivity perspective and to which conservation efforts should be directed. Retained or improved connectivity is stressed as fundamental for the conservation of the species. Dispersal corridors improve connectivity and are suitable as habitat patches in themselves, meaning that they merit conservation efforts. The timing and frequency of the maintenance of dispersal corridors is crucial and there is a need for better communication with the parties responsible. To improve the long-term viability of the studied metapopulation, it is recommended to make a dispersal corridor to suitable habitats in Tysjöarna nature reserve to increase the extent of the metapopulation. With the onset of climate change, retained connectivity is yet more important since large networks of populations are more viable and have a higher adaptability to new environmental conditions. Violett guldvinge, Lycaena helle, är en starkt hotad fjärilsart som i Sverige främst förekommer i Jämtlands län, med traditionellt hävdad jordbruksmark och rikkärr som främsta habitat. Utbredningen har minskat drastiskt i takt med att jordbruket har förändrats och är idag mycket fragmenterad. För fragmenterade arter är det extra viktigt med kunskap om mobilitet, habitatpreferenser och konnektivitet för bevarandearbetet. Denna studie undersöker spridningsförmågan hos violett guldvinge, identifierar fjärranalysbaserade variabler som kan förutsäga dess förekomst, undersöker relationen mellan täthet av fjärilen, förekomsten av dess värdväxt och vegetationshöjd samt klassificerar populationerna i Jämtland utifrån hur viktiga de är för en bibehållen konnektivitet i länet. En fångst-återfångst-studie genomfördes utanför Östersund och visade att violett guldvinge är extremt stationär, habitattrogen och verkar vara beroende av honor för långdistansspridningar. Spridningsavstånden var i de flesta fall längre än de som har uppmätts i centraleuropeiska studier. Vilka fjärranalysbaserade variabler som kan förutsäga fjärilens förekomst identifierades genom att variablerna inkluderades i modeller och värderades utifrån hur väl modellerna fungerade. De variabler som ingick var solstrålning, lutning, vegetationshöjd, variation i vegetationshöjd och riktning. Solstrålning och lutning var viktigast och kan rekommenderas för inkludering i framtida modeller. Stark solstrålning ökar sannolikheten att fjärilen ska förekomma då den är starkt beroende av solsken. Ökad lutning minskar sannolikheten att fjärilen ska förekomma och kan ha fungerat som ett mått på fuktighet i marken, då violett guldvinge är starkt knuten till fuktiga marker och platta områden samlar mer fukt än områden som lutar. Förekomst av värdväxt och vegetationshöjd inventerades i fält och testades för korrelationer med täthet av violett guldvinge. Värdväxten och fjärilen var svagt positivt korrelerade, vilket innebär att fjärilen påverkas positivt av förekomsten av dess värdväxt men att den antingen begränsas av något annat än sin värdväxt eller att den bara kan nyttja värdväxten när den växer under vissa förhållanden. Fjärilen var svagt negativt korrelerad med vegetationshöjd, sannolikt på grund av att majoriteten av habitaten i studien har hög vegetation och violett guldvinge måste söka sig till områden med lägre vegetation inom habitaten. Konnektivitetsanalysen identifierade populationer som är extra viktiga för konnektiviteten i länet och som alltså bör prioriteras i bevarandearbetet. Bibehållen eller förbättrad konnektivitet är väsentlig för artens fortlevnad. Spridningskorridorer både förbättrar konnektiviteten och fungerar som habitat i sig själva, vilket innebär att åtgärder i dessa habitat bör prioriteras. Tidpunkt och frekvens för underhållsarbetet i dessa habitat är av stor vikt och bättre kommunikation med ansvariga aktörer behövs. För att förbättra den långsiktiga livskraften hos de studerade populationerna rekommenderas etablerandet av en spridningskorridor till lämpliga habitat i Tysjöarnas naturreservat. Ett klimat i förändring innebär att bevarandet av nätverk av populationer är fundamentalt för artens överlevnad, då de är mer livskraftiga och har högre potential att anpassa sig till nya förhållanden. SLU/Dept. of Ecology 2018 H2 eng swe https://stud.epsilon.slu.se/13488/ |
| spellingShingle | Lycaena helle violet copper Lepidoptera Lycaenidae mobility dispersal resource selection function habitat selection connectivity metapopulation stepping stone Modin, Hanna Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title | Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title_full | Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title_fullStr | Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title_full_unstemmed | Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title_short | Mobility, habitat selection and population connectivity of Lycaena helle in central Sweden : implications for conservation |
| title_sort | mobility, habitat selection and population connectivity of lycaena helle in central sweden : implications for conservation |
| topic | Lycaena helle violet copper Lepidoptera Lycaenidae mobility dispersal resource selection function habitat selection connectivity metapopulation stepping stone |