Biological Indicators of Climate Change and Historical Phylogeography

Phenological shifts and climate change – Fran MacGillivray

Shifts in phenology provide a reliable signal for the early detection of change in biological systems. However, the long-term data sets required to determine the nature and magnitude of climatic impacts are very limited in Australia. Current research incorporates an interrogation of archival records to redress this important issue. Herbarium collections, with their broad temporal, geographic and phylogenetic representation, provide a unique and readily accessible source of data, independent of season. However, such records are often variable, discontinuous, and incomplete, and research so far has generally been restricted to dates of full flowering of species represented in arboretum plantations. The impact of rising temperatures is highly significant in the northern hemisphere, but the non-uniform periods of warming which have occurred throughout the 20th century pose a particular challenge when linear regression analysis is used for the reconstruction of trends. In Australia, other climatic factors such as rainfall and periods of drought take on greater relative importance, and natural variation across sites, including local microclimatic conditions, genetic differences and other non-climatic factors contribute to the uncertainty. This project is investigating possible non-linearities between herbarium records and climate.

MacGillivray F, Hudson I, Lowe AJ (2009) Herbarium collections and photographic images: Alternative data sources for phenological research. In: Phenological Research: Methods for environmental and climate change analysis (Eds. Keatley MR, Hudson I). Chapter 19. pp 425-461. Springer.

The presence of refugia was important to the adaptation, diversification and persistence of native biota during the evolution of Australia's inland arid ecosystems. During times of climatic extremes, these refugia constituted places where populations could contract, and then expand from when conditions once again became favourable. It is however, unlikely that historic refugia alone will be sufficient to protect species from future climate change. Land uses have changed the quality of and access to local refugia as evidenced by local extinctions of birds in Australia's rangeland bioregions, and may further limit the availability of refugia in the future. Understanding how contemporary land uses leads to habitat fragmentation and its impact on metapopulation structure, will be critical to assessing a species' ability to navigate unsuitable habitat to locate their habitat envelope and seek out refugia as climatic conditions shift.

Ground-dwelling birds, such as the southern scrub-robin (Drymodes brunneopygia), appear particularly vulnerable to agricultural changes in their habitat because they feed, nest and seek camouflage on the ground. With a view to inform future management of priority refugia, we are seeking to undertake a genetic analysis of the southern scrub-robin in mallee habitat of eastern South Australia. We will assess the impact of agricultural practices on the quality of, and access to climatic refugia by investigating population demography across an ecotone between high vegetation remnancy north of the Murray River (where grazing dominates), and relictual habitat south of the river due to broad acre cropping.

Our objectives are

• Describe its "habitat envelope" at sites of intact and relictual mallee vegetation

• Understand historical and contemporary demographic dynamics (including dispersal)

• Using this information, predict future refugia and identify new management guidelines new management guidelines"