Plant succession on Greywacke gravel and scree in the Subalpine Belt in Canterbury, New Zealand

Abstract

Summary Transects to measure changes in plant cover over a 10-year period were laid out on recently deposited river gravel and along the margins of a scree. On the former, Epilobium melanocaulon and the mat plant Raoulia tenuicaulis increased most rapidly and provided most of the cover. Under most circumstances, much slower-growing but longer-living species could be expected to replace these pioneers to form a stony herbfield, although in this particular instance the presence of seedlings of Nothofagus solandri var. cliffortioides indicator that the succession would be to beech forest. Margins between scree and stable vegetation proved to be remarkably permanent, although in most of the transects there was a transitional zone with a sparse cover of rhizomatous plants, usually Muehlenbeckia axillaris. The largest linear gain by vegetation at the expense of scree (19 cm) was by the prostrate shrub Podocarpus nivalis.