Changes in the cover of plant species associated with climate change and grazing pressure on the Macquarie Island coastal slopes, 1980-2009

• Published in: Polar Biology
• Main Authors: Scott, JJ, Kirkpatrick, JB
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer-Verlag 2013
• Subjects: Biological Sciences; Ecology; Terrestrial Ecology; Macquarie Island; Polar Biology
• Online Access: https://doi.org/10.1007/s00300-012-1243-y; http://ecite.utas.edu.au/80710

Climate change and alien species have affectedthe vegetation of subantarctic islands. Long-term monitoringof vegetation change on the steep coastal slopes ofsubantarctic Macquarie Island has allowed responses ofplant species to various disturbance regimes to be welldocumented, although, until recently, the confoundingeffect of feral herbivore disturbance obscured any responsesthat might be attributed to climate change. Theuncoupling of climate change from variation in feral rabbitnumbers allowed us to test whether any plant species wereincreasing or decreasing on the coastal slopes of the islandbetween 1980 and 2009, independent of rabbit grazingpressure. We used analysis of variance to test for differencesin species cover classes between four measurementtimes on each of 101 quadrats in each of 1980/1981, 1995,2003 and 2009. We had 54 quadrats on landslips and 47elsewhere. Approximately two-thirds of the species withsignificant temporal change exhibited changes that couldbe expected from variation in rabbit grazing pressure.However, approximately one-third of the species increasedin cover irrespective of grazing pressure. On landslips,variation in the cover of these increaser species was largelyrelated to time in a linear mixed model, whereas elsewherealtitude and time were both important. The increase in bothatmospheric dryness and episodic soil water-logging thathas been described for the island since 1980 may bestexplain the increaser species.