Science Spin March 2008

Tracking Nature's Calendar

Any society that realises its survival depends on an acute understanding of the interrelationships in nature must bestow great importance on this understanding. For 50,000 years before European man set foot in Australia (1788) the Aboriginals had incorporated this understanding of nature into their culture.

Rather than define seasons by a rigid calendar that is based on the rotation of the planet around the Sun, or to the 24 hours of a day (Earth's rotation on its own axisthey chose instead to use the cycles of events noticed in the local flora and fauna and climatic events such as prevailing winds. With such a dynamic 'phenological' calendar, they mapped out the year with between 5 and 10 seasons. For example, the Fruiting season or Midawarr lasted eight weeks for the Yolngu tribe. This is often equivalent to our March and April. The prelude to its onset was the arrival of a north-westerly wind.

Phenology

Such a variable definition of the seasons does not fit comfortable with our western scientific tradition. It was inevitably pushed aside by modern phenological recording practises. Modern phenological recording in Australia began as late as 1856 under the British regime. The Government employed the German botanist Baron von Mullen. In more recent decades Australia's phenological research has become fragmented in duration and spread across many different sciences such as agriculture, ecology, entomology, human health and fisheries. No doubt, the Yolngu tribe still know when their fruiting season is about to begin.

Phenology is the study of the 'show' or appearance of biological events that arise periodically. More specifically it involves looking at the seasonal reactions of our flora and fauna to climatic conditions, specifically temperature. Traditionally the terms seasonal and periodic are frequently treated as similar or interchangeable, but phenologists retain the word seasonal for non-biological events such as the amount of sunlight falling on an ecosystem at a particular time of the year. In its popular form it is referred to as 'Nature's Calendar', ''Spring Watch' or other descriptive phrases.

Almost every biological event is influenced by the weather, particularly temperature. The migration of birds, the tinting of leaves in autumn and the arrival of mackerel around our coastline are some obvious examples of phenological events. Synchronicity, a much understudied aspect of ecosystems, is tightly bound to phenology. Flourishing ecosystems work because they have achieved a perfectly harmonized syncronosity.

Ireland's climate, since the last Ice Age, has stabilized to give us our much spoken about temperate climate: not too much of a difference between Winter and Summer temperatures and an even distribution of rainfall throughout the seasons. Perhaps this is about to change. Although physical data, such as our mean temperature or precipitation data, collected and collated by Met Éireann, may be seen as delivering a more immediate indication of climate change, phenological studies reveal the affect of such changes on individual organisms. The behaviour of an individual organism may be critical in the maintenance of an ecosystem.

Phenological studies worldwide have enhanced our understanding of how ecosystems work. The most prominent work in phenology has come from workers in forestry and agriculture. From the point of view of observation, phenology is as old as agriculture itself; however, as a science it is a relatively recent study. Despite the fact that some countries have been collecting phenological data for several hundred years it is only in the last 30 years that this data has been examined scientifically to look for signs of climate change.

Worldwide

Since around 1850, the scientific community in a number of places around the world has made several attempts to embrace phenological observations and to create a science by building up databases of measurable phenological events.

Outside of Europe, China was one of the first countries to take phenology seriously. In 1931 Dr. Kezhen Zhu in China summarised 3,000 years of phenological observations. His own scientific data collection began in 1921. In 1934 he set up China's first phenological network of gardens using observation principles developed in Europe during the 1860s. Although interrupted by war, the studies were re-established in 1963 and ran consistently until 1996.

The renewed interest in climate change and the scientific recognition that phenology can make significant contributions to ecology and climate studies brought about resumption of the studies again in 2003. The current studies use both herbaceous and woody plants. Fauna includes bees, swallows, martins and cuckoos. Agricultural plants include rice, corn, wheat, peanuts, potato and millet.

Japan set up its phenological studies in 1953. Initially it had over 100 stations taking event observations. The data was published regularly. Unfortunately, increasing population and urbanisation in Japan has made observations unreliable. Flora and fauna close to buildings often behaves in an unpredictable way. Despite this, Japanese scientists have issued many reports based on phenological data. For example, Shigehara et al. (1991) showed that Prunus yedoensis (the wonderful flower-cherry that we associated with Japan) flowered later by between 0.6 to 1.8 days every 10 years from 1953 to 1987. The data showed that every 1º C drop in temperature delayed flowering by 4 days.

It is almost inexplicable as to why phenological observations were not to the forefront with the early European colonisers of North America. Surly, being in a new land, it was imperative that an understanding of the seasons be quickly established. This is not to say that phenological events were not monitored at all, it is just that they were very haphazard and local, often made by individual nature lovers. In 1845, Henry David Thoreau moved from Concord, Massachusetts, to live near Walden Pond. There he made many phenological observations. Even today, despite efforts made by meteorological stations, observations are haphazard.

One possible explanation for all this is the formulation of the Bioclimatic Law developed by Andrew Delmar Hopkins in 1938. Hopkins stated in very general terms that Spring developed from south to north in the temperate regions of North America, and for every degree north in latitude, or five degrees longitude in an easterly direction and 400 feet in altitude, Spring was four days late. With a law as seemingly clear as this, why bother making any further phenological observations?

The varied and harsh climates of parts of Canada lead to a long history of phenological observations. In modern times fur traders and missionaries kept nature's calendar diaries to increase their catch and make their day's hunting more efficient. Today, Canada runs extensive 'nature watch' programs. Ireland needs to increase its awareness of phenological events.

Europe

Phenological data of scientific value has been collected in Europe for several hundred years. In the early days these recordings were often made by landowners. One of the longest records was maintained by the Marsham family in Norfolk, England, between 1736 and 1947.

In 1957 the IPG, or International Phenological Gardens, were established in an effort collate the collection of phenological data in Europe. To date there are 50 phenological collecting points or gardens throughout Europe. Data is sent to their centre in Humboldt University in Berlin.

In Germany the phenological data is collected by Deutscher Wetterdienst, the National Weather Service. National Weather Services also run and collate data in Austria and Switzerland. Poland has 70 phenological recording stations, again collected and collated by the meteorological services. The Spanish Meteorological Institute has collected an enormous amount of data from a large number of stations. Estonia has been recording systematically since 1869 and is currently the leader in data collection in Europe. Despite efforts to set up phenological networks in Europe the total number of collecting stations or gardens has dropped from around 500 in the 1970s to around 50 at the time of writing.

The current popularity of Spring Watch or Nature's Calendar in the UK may be traced back to the autumn of 2000 when the Woodland Trust and the Centre for Ecology & Hydrology joined forces to bring phenology to the UK public.

Ireland

Ireland's interest in phenology started in 1966 with recording stations set up at Venetia, Co. Kerry, JFK Arboretum in Co Wexford and the National Botanic Gardens, Dublin. Johnstown Castle joined the group in 1967. The data collected at these five stations is collated by Met Eireann before being dispatched to the IPG in Berlin.

Attempts have been made to obtain data from the Irish public with the establishment of a schools monitoring program by the Native Woodland Trust. Phenological data resides with various wildlife groups in Ireland, including Bird Watch Ireland, The Dublin Naturalists' Field Club, The Heritage Council and the wonderful A Donegal Hedgerow web site run by Stuart Dunlop.

In 2005 Biology.ie (www.biology.ie) set up an interactive web site to try and attract records from the public. This more recent attempt, aided by Web technology using attractive interactive maps has a small but consistent group of recorders. The EPA part funded a pilot project for 70 secondary schools on Biology.ie in 2007.

This may be extended further for Spring 2008. Involvement of schools, garden centres and avid gardeners is imperative if Ireland is to build up a database of phenological events that can be used by the scientific community. Most scientists agree that 20 years of data is needed before any respectable conclusion can be drawn from it.

Government buildings such as Garda Stations, schools and other institutions should be made available for recording phenological events. With the aid of a Wildlife Grant for the Heritage Council in 2007, Biology.ie developed its Nature's Calendar project. The survey continues in Spring 2008. Biology.ie gives some guidelines on how to observe phenological events. Events include the appearance of first flowers (Alder, Hawthorn, Purple Lilac, Primrose and Wood Anemone); budburst (the first opening of leaf buds in Alder, Ash, Elder, Horse Chestnut, Oak, and Silver Birch); other species include the first swallows and the hearing of the first cuckoo.

Check it out on www.biology.ie and click on the tab marked Nature's Calendar.