Ecological anachronisms in the recruitment of temperate light‐demanding tree species in wooded pastures

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<jats:title>Summary</jats:title><jats:p> <jats:list list-type="explicit-label"> <jats:list-item><jats:p>Light‐demanding trees and thorny shrubs in temperate plant communities may reflect adaptations to now‐extinct large grazers, such as aurochs and tarpans, rendering these adaptations ecological anachronisms.</jats:p></jats:list-item> <jats:list-item><jats:p>We explored the ecological functions of plant traits of <jats:italic>Quercus robur</jats:italic> and <jats:italic>Prunus spinosa</jats:italic> in areas grazed by cattle and horses, the domesticated descendants of aurochs and tarpans. Specifically, we tested the hypothesis that grazing induces a shifting mosaic of grassland, shrub thickets and woodlands through the key process of associational resistance: the protection of palatable young trees by thorny shrubs.</jats:p></jats:list-item> <jats:list-item><jats:p>An exclosure experiment with transplanted <jats:italic>Q. robur</jats:italic> seedlings revealed that <jats:italic>Q. robur</jats:italic> grew best in grassland exclosures and on the edge of thorny shrub thickets, which may be viewed as an optimal balance between sufficient protection from large herbivores and sufficient light availability.</jats:p></jats:list-item> <jats:list-item><jats:p>A cross‐site comparison of four floodplain woodlands in north‐western Europe showed that <jats:italic>Q. robur</jats:italic> can regenerate in the presence of large herbivores through spatial association with <jats:italic>P. spinosa</jats:italic>. However, we found that expansion of <jats:italic>P. spinosa</jats:italic> shrubs and <jats:italic>Q. robur</jats:italic> coincided with periods of low rabbit abundance and not with livestock density. From this, it appears that the process of associational resistance does not work with rabbits.</jats:p></jats:list-item> <jats:list-item><jats:p> <jats:italic>Synthesis and applications</jats:italic>. With extensive grazing by large (domesticated) grazers in temperate floodplains, a shifting mosaic of grassland, shrubs and trees may develop that has high conservation value. Palatable, light‐demanding <jats:italic>Q. robur</jats:italic> seedlings can successfully regenerate in spiny <jats:italic>P. spinosa</jats:italic> shrubs through associational resistance. This process does not offer protection from abundant small herbivores, such as rabbits, that can inhibit the recruitment of shrubs and trees in this mosaic vegetation. In floodplain meadows frequent flooding may be an efficient way to reduce rabbit populations, with dry conditions in summer and wet in winter. When floodplain meadows are combined with adjacent higher grounds, large herbivores can escape the floods through migration.</jats:p></jats:list-item> </jats:list> </jats:p>

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