Woodland restoration on mineral extraction waste tips: a comparison of tree performance over eight years

Woodland restoration on hard-rock waste tips is often unsuccessful because of inappropriate species selection for planting and poor growth of planted trees after initial establishment. In this study we monitored the growth of three native (Betula pendula, Sorbus aucuparia and Quercus petrea) and one exotic (Alnus cordata) tree species planted in a restoration scheme on slate-waste tips in North Wales. The objectives of this study were to: (i) investigate the relationship between the relative performance of planted species, and the species’ relative success in natural regeneration at the same site; and (ii) investigate how well early performance is correlated with the subsequent success of the species. The growth of the native species did reflect the extent of their natural regeneration at the site (B. pendula > S. aucuparia = Q. petraea). However, while not present as a natural coloniser, A. cordata was the best performing species. Species’ relative growth performance after eight years was predicted by that during the first few months after planting, suggesting that short-term monitoring has value in predicting longer-term establishment success. Of the species studied A. cordata is recommended for planting on slate waste. However, B. pendula is the best of the native species studied.