How do different competing species influence the response of Betula pubescens Ehrh. to browsing?

• Published in: Basic and applied ecology 2006-01, Vol.7 (2), p.123-132
• Main Authors: Millett, J., Hester, A.J., Millard, P., McDonald, A.J.S.
• Format: Article
• Language: English
• Subjects: Above-ground plant interactions; Betula pubescens; Browsing; Calluna vulgaris; Cervus elaphus; Competition; Forest regeneration; Herbivory; Molinia caerulea; Semi-natural woodland
• ISSN: 1439-1791
• DOI: 10.1016/j.baae.2005.05.004

When attempting to expand existing woodland through natural regeneration, herbivory and competition from the existing vegetation may impede the regenerating saplings. This work addresses how browsing and competition with other vegetation interact to drive sapling growth and morphology of the widespread tree species Betula pubescens. We took above-ground morphological measurements of B. pubescens saplings within an intimate mosaic of Calluna vulgaris and Molinia caerulea, comparing saplings growing with each of the two plant species under three different red deer ( Cervus elaphus) densities, allowing comparison of different levels of both past and present levels of browsing damage. Saplings growing in M. caerulea-dominated vegetation responded to reduced browsing with faster growth than those growing in C. vulgaris-dominated vegetation. However, we found that when natural browsing levels were high, browsing masked any differences in inter-specific interactions between plant species. We propose that, in regeneration schemes where deer densities are reduced, these differences should confer a competitive advantage to saplings growing with M. caerulea over those growing with C. vulgaris. Additionally, our results highlight the importance of browsing history, rather than just current browsing levels, in determining sapling growth responses under different herbivore management regimes. This study highlights the importance of multi-factor interactions in determining plant growth and morphology under different conditions. In particular we identify the prevalence of interactions between competition, herbivory and time, as determining the potential growth and morphology of B. pubescens saplings in regeneration areas. This has important implications for the management of sites where browsing impedes the natural regeneration of trees and shrubs, or where herbivore densities have been reduced to encourage woodland regeneration. Bei dem Versuch, vorhandene Wälder durch natürliche Regeneration zu vergrößern, könnte Herbivorie und Konkurrenz durch die bestehende Vegetation die regenerierenden Schösslinge behindern. Diese Arbeit beschäftigt sich damit, wie die Beweidung und die Konkurrenz mit der übrigen Vegetation miteinander interagieren und dadurch Schösslingswachstum und –morphologie der weitverbreiteten Baumart Betula pubescens steuern. Wir nahmen die oberirdischen, morphologische Maße von B. pubescens-Schösslingen innerhalb eines engen Mosaiks mit Calluna vulgaris und