LTERN Data Portal

Following the International Tundra Experiment (ITEX) protocol (Molau and Mølgaard 1996; Jarrad et al. 2009; Wahren et al. 2013), four open-heathland ATEX field sites, two burnt and two unburnt, were established in the Rocky Knobs area (36.90ºS, 147.27ºE) on the Bogong High Plains in 2003. The burnt and unburnt sites were ca. 1.7 km apart while within burn-type, each of the sites were separated by approximately 0.5 km. At each of the two unburnt sites, 26, 1 m2 plots are located along permanently marked transects. Transects are 10 m apart, 50 m long, and are marked with sturdy, red gum end-pegs. At each unburnt site, 13 of the plots are covered by a hexagonal open-topped chamber (OTC; base diameter 168 cm, top diameter 110 cm) and the remaining, control plots are uncovered. At each of the two burnt sites there are 14, 1 m2 plots, seven of which are covered by an OTC, and seven of which are uncovered, controls.

The OTCs, which increase ambient temperatures inside the chambers at these sites by about 2 – 2.5°C, are constructed from lightweight, shatter-resistant fibreglass with high light transmittance (86%) and low transmittance of infra-red (<5%). The OTCs for this project are about 50 cm tall, with 110 cm diameter open-tops, and bases 170 cm wide. This size is large enough to accommodate all species to be monitored, without influencing growth habits or reproductive structures via, e.g. edge effects..

Every second snow free season vegetative growth is recorded in seven species by measuring of growth amounts and converting measurements into a relative rate (i.e. relative rate of growth = (ti +1 – ti)/ti, where ti = measurement at time i). Measurements of selected species involved leaves of Carex breviculmis, Poa hiemata (Graminiods) and Celmisia pugioniformis, Erigeron bellidioides, and Plantago euryphylla (Forbs), and stems of Asterolasia trymalioides and Pimelea alpina. By using the relative rate of growth, the effect of initial size on measurements is removed. At the beginning of each growing season, plants are selected randomly for monitoring at every sub-plot within all ATEX plots. The first measurements are taken as soon as the snow melts and sites can be accessed in October or November, the second measurements is taken mid-season in January, and the final measurements is taken in March, the end of the active growing season. For the graminoids and C. pugioniformis, leaves are gathered and the longest live leaf is measured to the nearest 0.25cm for three random individuals of each species per plot.

For the forbs, two random leaves on three random individuals of each species per plot are measured for length (from base to tip, excluding petiole) and width (at the widest point) to the nearest 1mm. Older leaves at the base of the rosette are avoided, as they have already grown to their full length. For the shrubs, the lengths of three random new shoots are monitored on three random individuals of each species per plot. The ITEX protocol recommends a variety of vegetative measurements (Molau and Mølgaard 1996), from which a subset of measurements are selected that are appropriate for the species in this study. Further details are in Jarrad et al. (2009).

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Every second year vegetation is sampled by point quadrats using a 4 mm diameter steel pin, inserted vertically at 10 cm intervals within a grid of 100 points defined by a 1 m2 point-frame. At each point the top, intermediate and bottom species; canopy height; and condition of ground surface (bare soil, attached live or dead vegetation, loose litter) are recorded.