Mountain beech seedling responses to removal of below-ground competition and fertiliser addition

We examine the height growth, diameter growth and below-ground allocation responses of mountain beech (Nothofagus solandri var. cliffortioides) seedlings to the experimental removal of root competition through root trenching and the addition of fertiliser within relatively intact-canopied mountain beech forest in the Craigieburn Range, Canterbury. Trenching and trenching combined with fertiliser increased relative height and diameter growth of mountain beech seedlings above that of controls. Trenching and trenching combined with fertiliser also increased the root:shoot biomass ratio of seedlings above that of controls suggesting rapid root proliferation to maximise short-term nutrient uptake. Our results are consistent with an increasing number of studies that show that on infertile soils under intact canopies seedlings of ‘apparent’ light-demanding species can respond to the removal of root competition. Because New Zealand indigenous forests usually occur on infertile soils, we conclude that root competition may be particularly important.