Bats and Forest Structure (B5)

Bats and Forest Structure (B5)

B5) Landscape-moderated use of forest structures by bats

Veronika Braunisch (1,2), Marlotte Jonker (1,3) & Ilse Storch (3)

(1) Forest Research Institute of Baden-Württemberg (FVA), Department of Forest Conservation

(2) University of Bern, Faculty of Science, Department of Biology, Institute of Ecology & Evolution, Division of Conservation Biology

(3) University of Freiburg, Faculty of Environment & Natural Resources, Institute of Forest Sciences, Chair of Wildlife Ecology and Management

Background and state of research

Bats are considered as indicators of forest structural complexity and are frequently selected as target species for conservation programs integrating key structural elements in forest management. Forest-dwelling bat species use old and dead trees as roosting sites, and forest gaps and linear elements for foraging and commuting.

Retention of old-growth structures may be beneficial, yet, as recent studies indicate, their use and usability by bats may strongly depend on the landscape context(1,2). Species-specific association of bat occurrence with forest structures has been shown at plot scale(3) (1 ha), yet minimum landscape-scale requirements for abundance and distribution of such structural elements are lacking.

Study questions and hypotheses

For the 135 ConFoBi plots, B5 will relate bat diversity, activity, and type of use to forest characteristics and landscape heterogeneity, expecting that:

  1. The species-specific use of structural elements at the local scale – and thus the effectiveness of retention measures – will be modulated by the surrounding landscape.
  2. Overall bat activity at the plot scale will increase with matrix heterogeneity, permeability and linear connecting structures.
  3. Diversity of species and functional guilds will increase with heterogeneity at both the forest stand and landscape scale.
  4. The use by foraging guilds will be related to the surrounding forest matrix, with a decreasing amount of gaps and open structures shifting the community towards clutter-tolerant species.
  5. The relative abundance and diversity of forest-specialists will increase with the abundance of old forest (habitat trees) and dead wood in the surroundings.

Approach and methods

Forest structure and landscape patterns are assessed by remote sensing complemented with plot-scale terrestrial mapping. LiDAR-information capturing the 3D-characteristics of sub-canopy space may predict bat occurrence at the stand scale(3). Using bat-loggers allows species identification as well as distinguishing hunting from commuting bats(4).

Capturing of bats with mist nets complements and refines species identification. Assessment of food availability (with B3) allows elucidating functional patterns. By relating bat presence and diversity to structural characteristics quantitative threshold values for integrative forest management are derived.

Outputs

B5 provides bat data to the ConFoBi database, and uses structural data from A1 and A2 and moths data from B3.

Further reading

  • Duchamp & Swihart 2008. Shifts in bat community structure related to evolved traits and features of human-altered landscapes. Landscape Ecology 23:849–860.
  • Kalda et al. 2015: Multi-scale ecology of woodland bat the role of species pool, landscape complexity and stand structure. Biodiversity and Conservation 24/2:337-353.
  • Jung et al. 2013. Moving in three dimensions: effects of structural complexity on occurrence and activity of insectivorous bats in managed forest stands. J Applied Ecology 49:523-531.
  • Walters et al. 2012. A continental-scale tool for acoustic identification of European bats. J Applied Ecology 49:1064 – 1074.