Sussex ecologist’s orchid study helps find new clues on climate change

University of Sussex ecologist Mike Hutching’s study of rare orchids has provided a powerful source of data for studying climate change, according to new research.

Professor Hutchings’ collection from the Castle Hill National Nature Reserve was used in research published today (Wednesday 22 September 2010) in the British Ecological Society’s Journal of Ecology.

The scarcity of reliable long-term data on phenology - the study of natural climate-driven events such as the timing of trees coming into leaf or plants flowering each spring - has hindered scientists’ understanding of how species respond to climate change.

But ecologists from the University of Sussex, the University of Kent, the University of East Anglia (UEA) and the Royal Botanic Gardens, Kew have found that plants pressed by collectors up to 150 years ago tell the same story about warmer springs resulting in earlier flowering as field-based observations of flowering made much more recently.

The team examined 77 specimens of the early spider orchid (Ophrys sphegodes) collected between 1848 and 1958 and held at the Royal Botanic Gardens, Kew and the Natural History Museum in London. Because each specimen contains details of when and where it was picked, the researchers were able to match this with Meteorological Office records to examine how mean spring temperatures affected the orchids’ flowering.

They then compared these data with Professor Hutchings’ field observations of peak flowering of the same orchid species in the Castle Hill National Nature Reserve, East Sussex, from 1975 to 2006, and found that the response of flowering time to temperature was identical both in herbarium specimens and field data.

In both the pressed plants and the field the results are first direct proof that pressed plants in herbarium collections can be used to study relationships between phenology and climate change when field-based data are not available, as is almost always the case.

Professor Hutchings says: "Scientists have long suspected that these dusty archives might help us understand the effect of climate change on plants and this is the first study to prove that hypothesis. The great thing about this is that we can now predict flowering times more reliably and subsequently predict the activity of pollinators. Ultimately this discovery will help us to know whether we will be able to grow food in the same way in the future."

The study opens up important new uses for the 2.5 billion plant and animal specimens held in natural history collections in museums and herbaria. Some specimens date back to the time of Linnaeus (who devised our system of naming plants and animals) 250 years ago.

It is hoped that similar principles could be extended to museum collections of insects and animals.