Demography of treeline mountain beech as a guide to lahar events

Mountain beech (Nothofagus solandri var. solandri) trunk diameters were measured in each of two catchments, a control, and a stream catchment (a putative lahar path), to assess the vulnerability of a hut sited on the Wakapapaiti Stream, Tongariro National Park, to disturbance events. Beech forest margins were more abrupt, terraced, and were adjacent to rocky areas in the stream catchment, while high altitude forest lacked sapling classes, but had a higher density of seedlings. Erosive events appear to have occurred in the stream catchment in the past 100 years, indicating the hut site may be vulnerable to future disturbance. The most recent large past disturbances appear to have been flood events, and the site may be vulnerable to large lahar events flowing in unusual paths.