Herbaria: science and specimens | University of Oxford
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Herbaria: science and specimens

Guest: Penny Sarchet

At 389 years old, the Curator of the Oxford University Herbaria is one of the oldest positions in Oxford. Its current holder, Dr Stephen Harris, curates a vast collection of plant specimens, archived and housed in the Department of Plant Sciences.

These specimens have been brought back to Oxford from all over the world since 1608. Stephen stresses, however, that old herbaria like these are of vital importance to 21st Century environmental research. In the face of climate change, plummeting biodiversity and habitat loss, historical plant collections have a lot to contribute when it comes to confronting today’s environmental threats.

The history represented within the Oxford Herbaria makes the collections a rich resource. Whilst herbaria were founded originally for the purpose of correctly naming plants and recording their geographical distributions, they now have a key role in telling us how human activities over the last 400 years have affected our planet.

‘We are essentially a repository of biodiversity,’ Stephen explains. ‘We provide the evidence that a particular organism occurred in a particular time and space.’

Data like these are invaluable for investigating how plant species, and the animal communities that depend upon them, have changed in abundance and location as a consequence of human trade, agriculture and resource exploitation. The information contained in the Herbaria archives not only show changes in biodiversity - the species richness of an area - but also can be used to monitor conservation, providing evidence of how plant populations change in response to different conservation methods.

Identifying patterns, threats
Within the University of Oxford, the specimens of the Herbaria are key to a large number of research projects:

For example, the archive of plant material is essential to scientists in the Department of Plant Sciences who want to study a plant which has gone extinct or resides only in a current war zone. Dr Robert Scotland, Reader in Systematic Botany, has been using the collections over the last fifteen years to put together a new ‘monograph’ (an exhaustive and detailed description) of the plant genus Strobilanthes.

Detailed taxonomic work like this is essential for determining the global patterns of plant species and discovering which plants are under threat; and with 400 different species of Strobilanthes spread across 40 different countries, an undertaking of this size would have been impossible without access to Oxford’s collections.

Meanwhile researchers from the Oxford Environmental Change Institute use pollen to monitor changes in climate. They extract pollen from specimens which have been collected from around the world and correctly identified by the Herbaria’s experts and use it to identify the species of pollen present in ‘cores’ of the Earth’s crust.

By digging deep down at a certain site, and identifying all the plant species that were present at a certain time - the deeper you go, the further back in time you can see - it is possible to deduce the environmental conditions that once existed at that place, based only on the knowledge of the plants that used to live there. Studies like these can show us how climatic conditions in specific places have been changing over time, and the impact that this has had upon what types of plant grow there.

Herbaria were originally founded as research and educational collections, and the roles of the Oxford Herbaria in education today are of key importance to fighting extinction. The United Nations declared 2010 the International Year of Biodiversity, in an effort to emphasise the importance of preserving biological richness and the health of our natural environments.

However, faced with climate change and resource exploitation, the ‘Taxonomic Impediment’ stands in the way of conserving what we have. The problem is that the correct identification of the vast majority of our planet’s species requires expert training and education, a detailed knowledge of the ever-changing official species names, and confidence in using the Latin naming system.

Conservation on the frontline
Whilst these are possible in the well-funded universities of the developed world, the world’s most biologically rich areas - referred to as ‘biodiversity hotspots’ - tend to be located in economically poorer countries and under threat from destruction through industries like mining. It is almost impossible to conserve and protect a species if you are unable to correctly identify it, and the most conservative estimates suggest that we have discovered and named less than half of the total species on Earth so far.

With habitat destruction and species extinction occurring at accelerating rates, it has never been more important to remove the taxonomic impediment to biodiversity conservation, and projects like the Virtual Field Herbarium (VFH), based in the Oxford Herbaria, are using the Internet to transfer knowledge from Oxford archives to local scientists in biodiversity hotspots like Granada, Cameroon, Ghana and Mexico.

Dr Will Hawthorne, founder of the VFH project, explains ‘in the developing world, herbaria tend to be low priority for funding. Traditionally the names are twenty to thirty years out of date, and they cannot afford to get all the scientific journals.’

Before Will set up the VFH, Internet herbaria did already exist, but they consisted of photos of old, dried, preserved herbarium specimens: ‘It’s like trying to identify the mammals of Britain based on road-kill. Yes, you can probably do it, but it’s much better to have a lovely picture of a fluffy squirrel rather than a squashed one.’

Oxford’s VFH therefore has an emphasis on live plants, growing in the field. This enables local academics worldwide to use colour and three dimensional shape - features which are typically distorted through the traditional preservation of plant material - to compare plants to the VFH’s photos and correctly identify their species.

The mission of the VFH does not stop there. Its founders and curators want local scientists in the world’s most biodiverse habitats to write books. ‘We didn’t just want people sitting here in Oxford writing field guides for the rest of the world, we wanted to empower people,’ Will explains.

Confronting the Taxonomic Impediment head-on, users of the VFH online can access a step-by-step guide to producing scientific field guides, reference a glossary of useful plant characteristics, browse the online images and access key scientific literature - all the ingredients required to easily construct your own, user-friendly, field identification guide for a specific area.

Providing people in developing countries with the tools to identify their local flora not only benefits conservation efforts, but also local economies. ‘There are lots of other uses to which biodiversity is put these days,’ says Will, as he shows me a field guide for Granada specifically written to encourage visits from ecotourists.

Mapping hotspots
Oxford Herbarium researchers have just received funding to take the Virtual Field Herbarium to a new level. Whilst the identification of ‘biodiversity hotspots’ is useful for focusing conservation efforts on the world’s most biologically rich areas, these designated hotspots often comprise very large geographical areas, like the Andes or the Congo Basin. The residents of these areas need to live off their land, and to completely protect such vast areas from agriculture, mining and human exploitation is impractical and unrealistic.

Over the next 5 years, Phase Two of the Virtual Field Herbarium will go out to biodiversity hotspots and use Will’s ‘Rapid Botanical Survey’ technique to gather detailed information about plant species and their exact location at lightning speed. Working with BRAHMS - a tool developed in the Oxford Herbaria by Denis Filer for the worldwide tracking of herbaria specimens, species name changes, and biodiversity research - the project will precisely map biodiversity levels within these hotspots.

The end product will enable users to zoom into biodiversity hotspots in their web browser and view the differing levels of species richness across the region. From here, users will be able to access species data previously collected at these areas and links to related Oxford Herbaria specimens. This new tool will enable people living within biodiversity hotspots to identify the less biologically important areas and to develop these for economic use, leaving the areas of high significance more likely to be preserved and protected.

Whilst the Internet-based projects of the ‘e-taxonomy’ movement have the potential to add real momentum to conservation efforts worldwide, these projects depend upon a strong foundation of detailed, ‘old-school’ taxonomy. The very concepts of biodiversity and hotspots rely upon an understanding of basic information about species - location, abundance, endemism...

Home-grown taxonomy
‘Herbaria are often seen as being repositories of something that’s over,’ says Robert, ‘but they are incredibly dynamic collections of data. Not just collections of dead specimens, they are the best evidence we have for biodiversity.’

In the UK, however, we are experiencing our own Taxonomic Impediment: The decline in fully-trained, professional taxonomists in Britain has been steep, with Robert being one of only a few full-time university taxonomists left in the country. With the science of species identification and classification being of such great relevance to preserving the environment, the pressure is on for those remaining within the field. Robert is currently launching a pilot project, using the genus Convolvulus to experiment with high-speed taxonomy.

This group of plants has not been monographed since the 19th century Swiss botanist de Candolle attempted to describe all the plant species of the world. Robert and his colleagues aim to revise this untouched monograph in only 6 months, through reducing the number of objectives and using new imaging technologies. This project will seek to describe all species in the group, develop classification keys, and list herbarium specimens, and spend less time on the more complicated aspects of traditional monographs, like the evolutionary relationships between all the species.

This project will require no field work - cameras will be sent to different herbaria, and photos sent back of Convolvulus specimens. ‘We are exploring new ways to monograph the world’s flora,’ explains Robert. ‘There are very few initiatives addressing how to do the science that underpins taxonomy in a new and relevant way.’

When Phase Two of the Virtual Field Herbarium is complete, it will exemplify botany in the 21st Century. The sophisticated software of BRAHMS will link together large datasets from Oxford, The Royal Botanic Gardens at Kew, and others in a user-friendly interface mapped onto Google Earth and Google Maps, and this rich data resource will be made available to taxonomists and researchers worldwide over the Internet.

Whilst modern technology provides the key to ease-of-use and accessibility, projects like these still entirely depend upon the centuries-old practices of expert surveying and, at the heart of it all, historical and well-kept herbaria.

The Internet will be a key weapon in fighting the Taxonomic Impediment but Denis stresses that ‘the IT tail shouldn’t wag the taxonomy dog’. Investment is being increasingly channelled into Internet-based branches of taxonomic research, but in today’s world of changing climates and natural habitat destruction, the more ‘old-fashioned’ methods of taxonomy, and the herbarium specimens they depend upon, have never been more vital.

Penny Sarchet is based at Oxford University's Department of Plant Sciences.