Thursday, 27 November 2014

A Special Day for A level Geographers

The Botanic Garden competes with many other providers of science enrichment activities for schools.  Teachers are bombarded with offers from museums, science centres and departments within the University.  Science Oxford trains a huge team of STEM ambassadors that are willing to take their research into schools.  Getting an audience for secondary science activities can be difficult.  The opportunities for geographers are much more limited.  If geography teachers take students out of the classroom it tends to be for fieldwork.

Over the summer Sarah Lloyd met with researchers from the University's School of Geography, the Department of Earth Sciences and local geography teachers to plan special events to support the geography curriculum.  The first A level geography day took place in October with 170 attendees from 10 local schools.

The format for the day was quite similar to A level days for other subjects areas with a programme of talks, workshops and self-led activities.

Speakers included:

  • Dr. Sallie Burrough from the School of Geography, who talked about some of the world's best known deserts and the way they are explored using new tools and technologies.
  • Prof. Paul Smith described Arctic processes, landscapes and ecosystems and the impact of climate change on fragile Arctic environments.
  • Kevin Wheeler from the School of Geography talked about the formation of rivers and described the complex historical and contemporary issues surrounding the Colorado River and the Nile.
  • Professor David Pyle from the Department of Earth Sciences spoke about the challenges of living on or around active volcanoes.

Later in the day students had the opportunity to play a game based on the impact of climate change on farming.  This game was developed by the Environmental Change Institute, the Red Cross Climate Centre (University of Reading) and the Africa Climate Exchange.  Dr. Jeannie Scott from the School of Geography also led a role-play activity based on the impact of volcanoes.

Students also visited the Botanic Garden. They discussed biodiversity, production of food, ecosystems and invasive species using a number of structured activities.

Comments from teachers were positive and constructive, and the two comments below give a flavour of the feedback they gave.

Superb introduction to University experience.  Reinforced information to year 13, good experience for year 12.  Level of lecture challenging but not pitched too high.  What is the date for next year?!!

Excellent day.  Informative and content linked to student's exams as well as giving them an insight into geography careers.  Keep me posted with dates for next year.

Friday, 21 November 2014

Arboretum Update

Over the past month an awful lot of work has been done at the Arboretum.  Our work to open up planting areas and thin the collection continues.  We have just removed five large birch trees from around the barn.  In this process we have opened up a young Metasequoia glyptostroboides and Pinus heldreichii, and the removal of Rhododendron from around the base of these trees also really shows them off.  To do this we had the help of the Botanic Garden’s enthusiastic trainees, Tonia and Virginia who really got stuck in. This was a good opportunity to get them using the chipper and also a chance for them to see some tree felling.  Whilst working in this area we have also created a new path leading up to the barn allowing easier access from the all-weather path. 

  Metasequoia glyptostroboides in newly cleared area

Another task that is being undertaken is the continuing classification of the trees in the collection. To do this we are working with the curator of the University Herbarium Dr Stephen Harris.  Over the last year we have gone through most of the collection looking for flowers and cones to find out exactly which species we have in the collection. This time of year there are few cones and flowers so it gave us a chance to start working through the specimens to verify them and to make sure that their accession labels are correct. 

It has also been a very wet month; this affects the ability to move machinery around the site without causing damage to the land. This not only gives us a chance to keep up to date on machinery maintenance, it has also meant that we have had a chance to modify the tractor shed and install an airline system. This means that in the future we have the right tools in place to carry out the correct maintenance to machinery. 

 New path near the Woodland Barn

Monday, 10 November 2014

Autumn Light

In autumn, the changes of light levels and temperature give the signal to deciduous shrubs and trees to respond to the season. The leaves of some trees turn bright or dark yellow, orange, brown, red and pink. The leaves of others stay green until they drop, and I was surprised to learn that according to a study of deciduous shrubs and trees in various temperate regions, that's most of them. Only 12.1% turn red, 15.8% turn yellow, the rest remain green until they fall.

Parrotia persica

Why? The pigmentation changes due to chemical processes with physiological and biological functions. The green pigment, chlorophyll, can be found in the chloroplasts of leaves. It absorbs the energy of the light in the process of photosynthesis and converts it into energy which enables the plant to grow. In summer, chlorophyll is continuously produced and broken down when the light levels are high and the temperature is warm and the leaves look green. As the days get shorter, photosynthesis gradually decreases, and trees re-absorb essential nutrients like nitrogen and phosphorus from the leaves to store them in twigs and branches during dormancy. Less and less chlorophyll is produced, while more and more chlorophyll gets broken down. 

Liriodendron tulipifera

The yellow/orange pigments, carotenoids, become visible as in the Liriodendron tulipifera in the walled garden. The pigments have been there all along, but were hidden by the dominant chlorophyll. The trees will loose the nutritional value of carotenoid pigments, but keep the more essential nutrients. Other trees like Alnus glutinosa in the lower garden- this genus lives in symbiosis with nitrogen fixing bacteria - loose their leaves at the moment they are still green.  

The pigment anthocyanin, giving the leaves of most trees red to purple colouration, is actively produced. It is generally not present when the leaves are still green, however in the early process of anthocyanin production, before chlorophyll is completely broken down, it may mix with anthocyanin to produce a brownish colour. One currently supported theory documents the red colour as a signal to insects like winged aphids to stay off the tree, as a protective mechanism to prevent aphids laying their eggs on the tree, thus making it also less vulnerable to viral or bacterial pathogens, which can be transmitted by aphids.

Prunus x subhirtella 'Autumnalis'

There are other pigments giving leaves a bright yellow colouration, such as 6-hydroxykynuric acid in Ginkgo biloba.

Ginkgo biloba

That's only a small insight into the mechanisms deciduous, woody plants have adapted as a response to their interactions with insects, organisms and weather conditions in temperate climates.

Tonia Friedrich, Trainee Botanical Horticulturist.

Wednesday, 5 November 2014

Autumn work in the glasshouses

Autumn is a busy time for us in the glasshouses. One of the main jobs is the annual clean for the display glasshouses. Before any cleaning can begin we have to do some serious pruning as the plants have flourished in their enclosed space and many need to be brought back to a more manageable proportions. This pruning will also reinvigorate plants so that they can put on fresh growth in the spring and improved flowering. Other plants may have simply have become too old and woody and it is time to replace them and so are removed, cuttings or divisions having been taken earlier. The optimum time for fresh planting will be in the spring as the days become longer and it warms up. By pruning and cleaning more light gets into the glasshouses, which is essential during the short, dark days of winter, as well as removing pests that may be lurking. So, once the pruning has been done, the power washing takes place removing dirt from inside and outside where we can and we have clean glasshouses once again.

Power washing in the Fernery

Another job that has taken place recently is the potting up of bulbs for forcing. Forcing is a method of growing a plant so that, in our case, it flowers earlier than it might do if allowed to grow naturally. Plants are also forced to give a vegetable or fruit crop earlier than normal. We do this by growing plants warmer than they would normally be, but you do not want to grow them too warm too soon. So, at the end of September the Narcissus Paperwhites and N Chinese Sacred Lily bulbs were potted up, closely followed by the hyacinths at the beginning of October. These were then plunged in beds of compost outside in the frames with several centimetres of compost over the top of the pots to exclude light. Once the bulbs have shoots of about 5cms, they are taken out of the frames and moved to a cool and bright glasshouse. The earliest bulbs to flower will be the Narcissus Paperwhites, which will flower before Christmas and these along with the other forced bulbs will be displayed in the Conservatory, bringing a splash of colour on a dull winter day.
Lucinda Lachelin

Hyacinths in the Conservatory