Movement and habitat use of the pool frog (Pelophylax lessonae) in Sweden: gaining ecological insights to improve forest management practices

Date:
2018/06/14

Time:
11:00

Room:
K308 Cabinet

Movement and habitat use of the pool frog (Pelophylax lessonae) in Sweden: gaining ecological insights to improve forest management practices

(Oral)

Lina Widenfalk
lina.ahlback@slu.se

Greensway AB and Swedish University of Agricultural Sciences, Sweden
,
Gustav Wikström
Uppsala University, Sweden
,
Frauke Ecke
Swedish University of Agricultural Sciences, Sweden
,
Anton Hammarström
Greensway AB, Sweden
,
Simon Kärvemo
Uppsala University, Sweden

DOI: 10.17011/conference/eccb2018/107619

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The pool frog (Pelophylax lessonae) has a limited distribution in Scandinavia and is red-listed in Sweden. Most of the ~120 Swedish localities are concentrated along a limited coastline in south-central Sweden. The major threat to the species is loss of suitable habitat, e.g. due to forest drainage ditching and clear cutting. Understanding important pathways between local subpopulations (ponds) is important for conservation and landscape management. To improve forest management practices around populated ponds, knowledge on habitats used for dispersal and hibernation is crucial.

We conducted a landscape connectivity analysis for the main region of the Swedish populations, based on presence/absence data on populated ponds from a survey in 2009; and a cost raster based on habitat data, forest data and a wetness index. To verify these theoretical dispersal routes, we performed radio-telemetry tracking of 43 individuals around four ponds, during the summer and autumn of 2017. As most frogs did not move away from the pond, translocations 500 m into localities connected with the ponds were conducted for 20 individuals. Six individuals were followed to their hibernation sites. Home range of individuals was estimated by utilization distributions which were calculated with the assumption of biased random walks. We determined habitat use preference with GLMMs of usage/available habitat using forest data and wetness indices.

Most individuals moved according to theory, in distinct moves along the wet habitat strings predicted from connectivity analysis. Translocated individuals moved quickly to suitable water bodies and remained there, often showing homing behavior. Habitat use of these individuals showed preference for open water bodies and open wetlands. Pine forests were avoided, while proximity to streams and distance from forest favored habitat usage. The theoretical dispersal routes (in low cost areas from the connectivity analysis) were used more often than high cost areas, verifying their relevance for conservation planning and landscape management. Hibernation sites were not located in burrows, as previously suggested, but instead directly in litter on the forest floor. All individuals hibernated on solid ground, within 250 meters from breeding ponds.

To maintain functional connectivity we suggest that also stream networks that interconnect neighboring ponds and have low presence of pine, should be preserved as dispersal corridors. Around the breeding ponds, hibernation sites at up to 250 meters should be considered during management activities. This project exemplifies the potential of combining theoretical analyses and practical field studies to improve our understanding of the requirements of a threatened species. Furthermore, it shows how an adaptive management approach and cooperation between forestry owners and managers, authorities, nature conservation consultancies and researchers may improve management and conservation practices.

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INTRO:
A landscape connectivity analysis for habitat of the pool frog in Sweden including general imnear mixed effects modelling for habitat preference.
MERITS:
Fundamental habitat and connectivity knowledge gained for a red-listed species
CRITIQUE:
From the abstract it isn't clear how the results could impact forest management practices, for example there are no managment recommendations presented.
DISCUSSION:
Interesting study. I would hope to see how changing management practices could benefit the species and how likely any changes would be from the management authority.

- - -
INTRO:
This study investigates habitat use during dispersal and hibernation of the pool frog, Pelophylax lessonae, to better predict what constitutes suitable habitat patches, and how these patches are connected in the landscape.

They use population data and a suite of habitat variables to make predictions about what landscape features are important for enhancing connectivity, and they test these predictions by radio tracking individuals moving through the landscape.

The aim is to identify those locations and habitat types most important for the conservation of the species, and to use this information to inform forestry management practices.

Concerning dispersal movements, they found good agreement between model predictions and telemetry data, showing the importance of wet corridors in linking habitat patches.

More surprising were their findings regarding habitat use during hibernation, where rather that utilising burrows individuals hibernated directly in the leaf litter.
MERITS:
The applied nature of the study means that the findings have important implications for management practices in forestry that promote the conservation of this threatened species. Their findings are also likely to have wider applications beyond the location of the study site.

The combination of modelling landscape connectivity and validating these model predictions through telemetry is a real strength of the study, particularly when considering the similarity in findings from the two methods.
CRITIQUE:
For a study with such clear applications for management practices I would have liked to see some more explicit suggestions for potential changes to management, and which findings necessitate such changes.

I found the methods section a bit unclear at times. I would like to know what the population data used for the landscape connectivity analysis consisted of. I was also unclear on a couple of occasions as to which results came from which method. Maybe reworking the methods such that it is clear which specific question was answered by each piece of analysis - the link between the methods and results will then be easier to follow.
DISCUSSION:
I would be fascinated to hear how each of these interesting findings could be combined to inform a comprehensive plan for forest management at a landscape scale. In particular, how understanding the difference in habitat use for these distinct behaviours (hibernation vs. dispersal) that take place over different spatial scales might help to inform the creation/maintenance of networks of suitable habitat patches that are well connected by movement corridors.

Movement and habitat use of the pool frog (Pelophylax lessonae) in Sweden: gaining ecological insights to improve forest management practices

Date:2018/06/14

Time:11:00

Room:K308 Cabinet

Movement and habitat use of the pool frog (Pelophylax lessonae) in Sweden: gaining ecological insights to improve forest management practices

(Oral)

Lina Widenfalk lina.ahlback@slu.se Greensway AB and Swedish University of Agricultural Sciences, Sweden, Gustav Wikström Uppsala University, Sweden, Frauke Ecke Swedish University of Agricultural Sciences, Sweden, Anton Hammarström Greensway AB, Sweden, Simon Kärvemo Uppsala University, Sweden

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Date:
2018/06/14

Time:
11:00

Room:
K308 Cabinet