Canopy cover and understory composition determine abundance of Vaccinium myrtillus L., a key plant for capercaillie (Tetrao urogallus), in subalpine forests in the Pyrenees

Abstract

Background: The dwarf shrub Vaccinium myrtillus – with high cover, height, and fruit production – benefits capercaillie (Tetrao urogallus).

Aims: Our aim was to quantify landscape (e.g. elevation, geographic location, and precipitation), site (e.g. overstorey cover and stoniness) and very fine scale factors (e.g. spatial associations in the understorey) that affect cover, height, and fruit production of V. myrtillus in subalpine forests in thePyrenees, with understorey usually dominated by Rhododendron ferrugineum.

Methods: We sampled 155 plots (0.5 m × 5 m) in six sites. For each plot, in the understorey layer, we assessed species cover, height for R. ferrugineum and V. myrtillus, number of total fruits in V. myrtillus, and spatial associations among V. myrtillus and the remaining cover types.

Results: Overstorey cover negatively influenced V. myrtillus cover, its height, and particularly, the number of fruits, which was also negatively influenced by R. ferrugineum cover. Associations between R. ferrugineum and V. myrtillus were site dependent, while V. myrtillus showed mostly positive associations with grasses and mosses.

Conclusions: Reducing overstorey and R. ferrugineum cover has the strongest positive effect on increasing V. myrtillus fruit production, but with additional positive effects on V. myrtillus cover and height. Increases in grass and moss coverage could favour V. myrtillus.

Keywords:

• bilberry
• habitat management
• Rhododendron ferrugineum
• pine overstorey cover
• pine forest understorey
• spatial associations
• Vaccinium myrtillus

Acknowledgements

The authors thank the Alt Pirineu Natural Park, the DARPAMN-Generalitat de Catalunya offices in Alt Urgell and Pallars Sobirà, CEINR and FORCAT. The authors also thank the participation of G Barengueras, A Barons, G Boixadera, S Busquet, F Cano, J Canut, P Casals, A Domingo, C Fañanás, S Farriol, J Faus, J Fernández, O García, D García-Ferré, M Garriga, J González-Carrato, A Ivars, E Ménoni, M Martí, R Martínez-Vidal, C Novoa, S Navarro, P Omedes, M Puig, E Rifà, A Rom, X Roqué, M Sala, S Sánchez, D Schönig, A Tamás, J Tristany and P Vericat. This work was supported by the EU (Project POCTEFA) under Grant no. EFA 81/08 (2008-2012), ‘Reseau pyreneen de galliformes de montagne GALLIPYR’.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Francesc Montané

Francesc Montané is post-doctoral researcher; his research focuses on how environmental changes impact carbon cycling.

David Guixé

David Guixé is a researcher; his research interests can be found at http://baclab.ctfc.cat/?p=29&lang=en.

Jordi Camprodon

Jordi Camprodon is a researcher; his research interests can be found at http://baclab.ctfc.cat/?p=37&lang=en.