Faculté des sciences

Safe sites for tree regeneration in wooded pastures: A case of associational resistance ?

Smit, Christian ; Béguin, Daniel ; Buttler, Alexandre ; Müller-Schärer, Heinz

In: Journal of Vegetation Science, 2005, vol. 16, p. 209-214

Question: Are tree saplings in wooded pastures spatially associated with specific nurse structures or plants that facili-tate tree sapling survival? Location: Wooded pastures in the Jura Mountains, Switzer-land. Methods: In two sites, 73 km apart, we sampled 294 plots of4 m², systematically distributed on 1 ha. We recorded number and height of all established Picea abies... More

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    Summary
    Question: Are tree saplings in wooded pastures spatially associated with specific nurse structures or plants that facili-tate tree sapling survival? Location: Wooded pastures in the Jura Mountains, Switzer-land. Methods: In two sites, 73 km apart, we sampled 294 plots of4 m², systematically distributed on 1 ha. We recorded number and height of all established Picea abies saplings (> 1 a of ageand up to 40 cm in height), and visually estimated cover of rocks, shrubs, tree stumps, overhanging tree branches and unpalatable plant species. Results: Despite differences in site characteristics, we found overall positive effects of cover of unpalatable plants, rocky outcrops and tree stumps on the density of Picea saplings. Plots with tree stumps and higher cover of rocky outcrops and unpalatable plants were more likely to contain Picea saplings. Conclusions: Unpalatable plants, rocky outcrops and treestumps seem to form safe sites for Picea saplings in this grazed system, improving their establishment and survival. Our find-ings support the idea that associational resistance drives thedynamics of wooded pastures, but experimental evidence forthis hypothesis is still required.