Andalucia 2000: A report of the Course 35 Field Trip
hosted by Reading University
23rd March – 6th April 2000
by Christopher Weddell
Shortly before Easter 2000, and with the majority of the Diploma Course completed, ten members of the course set out with Reading University to participate in a field study course to look at the Mediterranean flora of Andalucia, Spain. While this trip was a welcome break from both the Kew weather and the pressures of the course, it was also a great opportunity to study the flora, habitats and environment of southern Spain. Though to keep our minds sharp, two projects had to be completed for the Diploma Course.
The two stated aims of the trip were to learn about the flora and physiology of the Mediterranean climates, and to enhance theoretical botany courses with hands-on practical experience. These aims were completed by undertaking practical field studies and by carrying out a series of surveys to assist with ongoing studies of rare and endangered Spanish flora. The projects consisted of creating individual plant lists as assigned by Dr. Steven Jury, and undertaking and compiling a small group project as assigned by Dr. Jim Ross.
The Plant List Project, tutored by Dr. Steven Jury, enabled the participants to concentrate on certain categories of plants. These included bulbous plants, parasitic plants, cacti and succulents, Liliaceae, aromatic plants, crops and trees. The group projects included a survey of areole production on Opuntia ficus-indica, an investigation into the uniformity of Ceratonia siliqua beans, a report on Chamaerops humilis, and the effects of Thymus vulgaris and Lavandula multifida on the surrounding vegetation. A summary of the projects is included at the end of this report.
Initially, the trip was based at Las Negras, a small fishing village on the south eastern coast of Spain. The first couple of days were spent on treks along the coast and up the numerous dry ramblas (seasonal waterways). Here it was possible to see many food crops growing in the small fields and back yards in and around the village, as well as some of the flora being exploited by the farmers for feeding the numerous goats and sheep. Abundant here were Opuntia ficus-indica, Agave americana, Arundo donax, Phragmites australis, Ceratonia siliqua and Hyparrhenia hirta, all indicators of the arid thermo-mediteranean climatic zone. Also noted were Ophrys lutea, Genista umbellata and Lobularia maritma.
Over the next few days the trip started to move inland and to higher altitudes to look at the transition zones between the thermo-mediterranean and the meso-mediterranean. With further distances to cover, much of the travelling was done by coach with short forays by foot being completed at noted locations. When the coach ascended to around 1,000m in the hills there was a noticeable change in vegetation as we moved out of the thermo-mediterranean and into the meso-mediterranean zone. The common thermo-mediterranean indicators switched to extensive open forests of Quercus ilex and along the roadsides were dense populations of Narcissus cantabicus. Before the trip moved to its final location and a change of hotels, three days were spent on group projects, some of which left off where previous groups had finished the previous year, and others were carried out due to group participants’ interest.
The second area the trip visited was high in the Alpujarras near the small town of Lanjaron. Here we had left the thermo-mediterranean well behind, and were deep in the meso-mediterranean zone. Walking through deciduous woodland it was interesting to note Quercus faginea, Q. robur, Castanea sativa and Melissa officinalis.We were also able to see natural regeneration of the flora after summer fires the previous year. The most dominant plant on the landscape was Asphodelus cerasiferus, followed by vast numbers of Cistus albidus and Lavandula stoechas seedlings, as well as resprouts of both Quercus ilex and Q. coccifera.The regrowth of Thymus vulgaris was especially fragrant.
Course 35 would like to thank all the tutors and staff of Reading University and the Royal Botanic Gardens, Kew, who assisted in the field course, and the Kew Guild for part-financing the trip.
A summary of the projects
A survey of areole production on Opuntia ficus-indica
It is hypothesised that plants such as Opuntia ficus-indica do not invest great amounts of energy in defence unless required to do so. Thus, after disturbance by foraging animals, there should be a notable increase in areole numbers. The investigators counted areole numbers of 100 undamaged cladodes arisen from damaged cladodes from five unique populations, and 100 undamaged cladodes that had arisen from undamaged cladodes within the same five populations. Results indicated that new cladodes growing from damaged cladodes displayed a 21.53% increase in areole numbers over undamaged ones. This agreed with the hypothesis although many other uncontrolled variables may have contributed to the results.
Worth their weight in gold: Exploring the uniformity of Ceratonia siliqua beans
Measurement relies on the uniformity and integrity of the measuring tool. For the beans of the carob, Ceratonia siliqua, to have been the basis of the jeweller’s measurement, the weight beans would have to be fairly uniform, and difficult to adulterate without external signs. While the results of this study showed that the average weight of a ripe Ceratonia siliqua bean was close to the modern jeweller’s weight of 0.200g, the study was statistically inconclusive because of the inaccuracy of the means of measurement.What the study did reveal was that beans are easily adulterated, becoming lighter or heavier depending on the treatment of drying or wetting. This means that as a measurement, Ceratonia siliqua beans were not tamper-proof and could be weighted in the owner’s favour.
Report on Chamaerops humilis, Las Negras, Spain
Chamaerops humilis is the only native European palm, although its natural range is restricted to small areas in the thermo-mediterranean region around the Mediterranean Sea. Whilst it has been in cultivation for many years, very little is known about this species. The project aimed to investigate a population growing wild around Las Negras, southern Spain, to plot their distribution and sex, and to make observations on the size and maturity of the individuals.
The effects of Thymus vulgaris and Lavandula multifida on the surrounding vegetation
The investigators tested the hypothesis that Thymus vulgaris and Lavandula multifida secrete substances which inhibit plant growth in their direct surrounding area. This hypothesis was suggested several years ago for plants that secrete volatile oils. It was seen as a kind of chemical control against surrounding plants, competing for water, nutrients and space. The results of the project clearly show that this was not the case, because the control measurements did not differ significantly from the plants under investigation. Furthermore, Thymus vulgaris seems to act as a `nurse-plant’ for the establishment of a range of other plant species that grow on the site.