Sammendrag
Conserving semi-natural grasslands, a threatened habitat type in European landscapes, is increasingly recognized
as a measure to conserve pollinators. Our aim was to test if (a) prediction maps of solitary bee species richness
could be used to rank semi-natural grasslands in terms of their potential for supporting wild bees, and (b) if such
predictions extend current assessment criteria that determine which grasslands are eligible for being listed under
habitat conservation schemes. We sampled wild bee communities in 52 semi-natural grasslands in southeast
Norway. We conducted an across-year validation, using data from 2019 (32 sites) to model bee species richness,
and used data from 2020 (20 sites) to validate predictions. We then conducted a leave-one-out cross-validation,
iteratively using data from 51 sites to parameterize our model, and validating predictions on the withheld site.
Finally, we used data from all 52 sites to update the model and tested if predicted species richness within the
1075 grasslands in our region was reflected in current assessment criteria scores assigned to those grasslands.
Models from across-year, and leave-one-out cross-validations, predicted 39%, and 43% of bee species richness in
semi-natural grasslands, respectively. Model predictions and current criteria of semi-natural grassland quality
were not strongly related (R2
adjusted = 0.01), suggesting that prediction models can add a valuable extra
dimension when prioritizing between semi-natural grassland for pollinator habitat conservation. Our findings
illustrate how spatial prediction models can provide management authorities with a valuable tool for prioritizing
where to direct habitat enhancement schemes in order to improve conservation effectiveness.
Pollinators
Bees
Grassland
Semi-natural
Management
Conservation
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