tree spread

Mid to late 20th century expansion of Dracophyllum scrub into tussock grassland on subantarctic Campbell Island has been attributed to the collective effects of global warming, cessation of farming in 1931, and continued grazing by feral sheep. To determine the importance of these, we dated the timing of scrub expansion by aging 241 Dracophyllum plants in 17 plots chosen to sample the range of environments this shrub/ small tree occupies on Campbell Island.

Mycorrhizal colonisation of Douglas-fir and Corsican pine seedlings in soil from kānuka and mānuka dominated shrublands in Canterbury was studied using a bait plant technique. Soil cores were collected from 10 sites of each shrubland, transferred to a glasshouse, and sown with seed of both tree species. Mycorrhizal colonisation was examined after 19 weeks’ growth. Overall, seedlings of Douglas-fir were larger than those of Corsican pine, but the amount of Corsican pine seedlings that were colonised (56%) was about twice that of Douglas-fir (29%).