The fagus turned early in Autumn 2015. King Billy pines and pencil pines produced masses of seed in the 2014-15 summer. So it seems, according to anecdotal observations. Is this unusual? Is it important?
People frequently remark on the timing of natural events and the apparent links to seasonal weather, particularly when things seem unusual. However without long-term data it is impossible to determine ongoing trends from natural variability.
The timing of events such as bird migrations and the flowering of plants is often closely linked to climate. Historical records of phenology (the study of the timing of periodic phenomena in the life cycles of plants and animals) over decades or centuries have proven useful for reconstructing changes in seasons in the Northern Hemisphere. Unfortunately, Australia has a very poor record of historical phenology.
ClimateWatch (link: http://climatewatch.org.au) is an Australia-wide initiative involving dozens of marine and terrestrial species including plants, birds, frogs, mammals and invertebrates. Around 80 of these target species occur in Tasmania. The species have been specifically chosen by scientists to bridge the information gap and better understand how climate change is affecting our natural environment.
Tasmania’s two endemic Athrotaxis species, pencil pine (link: http://climatewatch.org.au/species/plants/tasmania-pencil-pine) and king billy pine (link: http://climatewatch.org.au/species/plants/king-billy-pine), are target species for ClimateWatch. Public observations of the health, recruitment and seed production of these trees will be a valuable addition to the long-term program established by the DPIPWE to monitor the impact of climate change on these iconic conifer trees (link: http://dpipwe.tas.gov.au/conservation/publications-forms-and-permits/publications/montane-conifers-establishment-report). These species produce masses of seed every 5-6 years with few seed cones in intervening years; we don’t know why, though it’s likely to involve climatic cues.
A similar seed production pattern in another Tasmanian rainforest conifer, Huon pine (Lagarostrobos franklinii) appears to be linked to El Niño-Southern Oscillation (ENSO) cycles (link: http://www.researchgate.net/profile/Michael_Shawn_Fletcher/publication/273139940Mast_seeding_and_the_El_Nin_o-Southern_Oscillation_along-term_relationship/links/54fb94bc0cf20700c5e71700.pdf). With irregular seed production, very slow growth and sensitivity to hot and dry conditions the Athrotaxis stands are potentially highly vulnerable to climate change.
Many Tasmanians keep a close eye on the ‘turning’ of the deciduous beech or fagus (link: http://climatewatch.org.au/species/plants/fagus-or-deciduous-beech) (Nothofagus gunnii) in Autumn. As Australia’s only winter deciduous woody plant, it will be interesting to see if the timing of seasonal events such as bud burst and leaves changing colour is shifting, as has been observed in many Northern Hemisphere deciduous trees. If even a small proportion of the thousands of photos of fagus taken every year were added to the ClimateWatch database, with date and location, ecologists could answer these questions.
‘Nature’s Notebook’ collates citizen science phenology records in the USA (www.usanpn.org). A similar program in the UK launched over 15 years ago has recorded over 2 million observations (www.naturescalendar.org.uk).
Most long-term records for plant phenology from the Northern Hemisphere are consistent with observed recent climate change; that is an earlier arrival of Spring (typically 2-5 days earlier per decade) and a slight delay in Autumn events such as colouring and leaf drop of deciduous trees. The consequent lengthening of the growing season is likely to change the stability and functioning of ecosystems, particularly when combined with other climate-driven phenomena such as migration of species and changes in rainfall and snowmelt patterns.
Trends are not consistent across species, and even within a species observed changes in phenology may vary between sites, so it is necessary to collate a large number of observations over a long time to get a good picture of phenology. That’s where the citizen science comes in. Get involved and add your records to these ongoing projects.