Epiphytic bryophytes near forest edges and on retention trees: reduced growth and reproduction especially in old-growth-forest indicator species
Article first published online: 28 SEP 2012
© 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society
Journal of Applied Ecology
Volume 49, Issue 6, pages 1334–1343, December 2012
How to Cite
Löbel, S., Snäll, T., Rydin, H. (2012), Epiphytic bryophytes near forest edges and on retention trees: reduced growth and reproduction especially in old-growth-forest indicator species. Journal of Applied Ecology, 49: 1334–1343. doi: 10.1111/j.1365-2664.2012.02201.x
- Issue published online: 29 NOV 2012
- Article first published online: 28 SEP 2012
- Manuscript Accepted: 8 AUG 2012
- Manuscript Received: 24 MAY 2012
- Bjurzon's fund
- Swedish research council Formas
- councils VR and Formas
- buffer zones;
- canopy openness;
- edge effect;
- edge orientation;
- transplantation experiment;
- tree retention;
- Epiphytes are an important component in many forest ecosystems. The proportion of threatened epiphyte species is high, and the impact of clearcuts on key demographic processes via edge-influence is still poorly understood. There are few studies on epiphyte growth, and even less is known about how reproduction is affected by proximity to forest edges. For retention trees, demographic studies are even scarcer.
- Based on the results from a 6-month transplant experiment and a 3-year study of natural colonies, we modelled growth and reproduction of epiphytic bryophytes used as indicators of old-growth forests and widespread epiphytes in relation to distance from the forest edge. We also modelled growth and reproduction on retention trees within the clearcut. Species responses were linked to variation in canopy openness.
- Unlike the widespread species, the old-growth-forest indicators grew exponentially with distance from the edge, and this response was more pronounced at the south-east than north-west forest edge. In one red-listed species, reproduction was thoroughly inhibited near the edge, whereas the reproductive rate of the widespread species tended to increase. However, the widespread species also showed reduced shoot lengths on the retention trees.
- Reduced growth and inhibited reproduction of sensitive epiphytes near edges decrease the number of dispersing diaspores and may, in combination with lower local connectivity and increased tree fall rates close to edges, increase the risk of metapopulation extinction.
- Synthesis and applications. Two general management implications for boreal forests are drawn. First, retention trees may not have the capacity to act as a ‘lifeboat’ for epiphytic bryophytes and support their populations during the regeneration phase. Second, the creation of buffer zones is a useful conservation strategy for bryophytes. The exact width of zones depends on the forest structure and should be orientated in relation to the requirements of the most sensitive species. For the rather dense experimental forest, a width of at least 30 m was required for the south-facing buffer, whereas for the north-facing buffer 10 m was sufficient.