Working with Royal Botanic Gardens, Edinburgh student Jia Dong and plant anatomist Louis Ronse De Craene has resulted in some exciting and thought-provoking images of nettle flowers. The aim of our collaboration is to understand how nettle flowers develop and in the process work out what parts they have in common and which they don’t. The samples used were from living collections at Edinburgh and RBG Kew, together with my own collections in alcohol made over several years. The results are some beautiful and very informative scanning electron micrographs which show that the part of the female flower which recieves pollen (stigma) and conducts it to the egg (style) is characterised by two classes of hairs, one comprising defensive tusk-like hairs (above) and the other receptive tubular like hairs (above & below).
Tubular hairs associated with the stigma are characteristic of all nettle flowers. They also appear very early in development. Combined this makes us think that they might have a role in pollination. Specifically in the reception of pollen. Being wind-pollinated, nettles don’t have a lot of control as to whose pollen reaches their female flowers and so there needs to be a way for them to control which pollen grains develop and fertilise the single egg. It seems likely that these hairs play a role and hopefully Jia will be able provide some more great images to test some hypotheses about this.
As part of my job I give talks to students or colleagues on aspects of my research and botany. Generally the less scientifically literate the audience the better and more insightful the questions. For this reason I was a little nervous and excited at meeting two classes at the St Keyna Primary School in Keynsham near Bath. I had been invited by my old friend Larissa Roberts who works at the school. After over 20 years working for a major museum I was also very honoured to be inaugurating their natural history museum! It might seem a poor use of resources for scientists to go and meet schoolchildren half way across the country and we struggled to find any resources to support for my visit. For me though it is very important. Botany is rarely taught in UK schools, there is no university degree in Botany in the UK anymore (imagine if that was the case for zoology or paleontology) and so the routes for recruiting young enthusiastic people from a variety of backgrounds into botany are somewhat limited. If visits such as mine inspire just one pupil to consider a career in botany then it would have a tremendous impact on our discipline.
Some of the questions were quite a challenge. Mainly because although I should have I had not thought about them before. I was almost thrown by questions such as, ‘what is the rarest plant that you have collected?’, ‘what is the oldest plant that you have collected?’ and ‘how many new species have you discovered?’. On the basis of my answers I am not sure how well I would fair in a job interview. I was very pleasantly surprised to meet so many children with a spontaneous enthusiasm and interest in natural history and plants! I was also very impressed with how friendly and polite the children (and staff) were and of how well supported learning seemed to be at St Keyna’s. So all in all a very positive experience that I would gladly repeat.
Dos años después de plantar nuestra primera parcela en Motacusal, la comunidad acaba de terminar la primera poda de los árboles. El denso follaje de los árboles de Pacay (Inga) se ha reducido a una capa vegetal y los tallos sacado para servir de leña, dejando aproximadamente 1/3 hectárea de terreno fértil para cultivos anuales como maíz, arroz o frijoles. Es la culminación de más de dos años de trabajo y testimonio del esfuerzo de nuestro equipo de campo, dirigido por Ingeniero Forestal, Rolman Velarde.
Dejaremos la hojarasca pudrirse un mes antes de sembrar las primeras cosechas. Gestión de la parcela de Motacusal está siendo supervisado por los niños de la comunidad a través del programa ‘Bosque de los Niños‘ lo que significa que pueden elegir lo que van a sembrar. Esto es importante para la participación de los niños, y también para la comunidad, uniendo nuestras parcelas con su recurso más valioso y llevarlo a buen término es un poderoso símbolo. Los niños han experimentando con diversas semillas para plantar como parte de su currículo productivo y estoy entusiasta de saber lo que han sembrado en siguiente mes. Sin embargo quedan algunos desafíos, por ejemplo el tiempo anómala asociada con El Niño podría dañar las cosechas o al Inga.
Se utilizó la oportunidad de que sea la primera parcela que se podado para invitar a representantes de las otras comunidades participantes: Palacios, San José, Jerico y Monte Sinaí. Esto nos permitió formarlos en la poda, también para ellos era una oportunidad para tener una idea de como sus parcelas agroforestales se verá en más o menos un año.
Two years after planting our first plot at Motacusal, the community has just completed the first pollarding. The dense canopy of Inga trees has been reduced to a green mulch and the main stems taken away to be stored for fuel wood leaving about 1/3 ha of fertile ground for growing annual crops such as maize, rice or beans. The pollarding is the culmination of over two years work and testimony to the skills and hard work of our field team, lead by Forest Engineer, Rolman Velarde. We will leave the mulch to rot down a little and in a month the first crops will be sown.
Management of the Motacusal plot is being overseen by the communitie’s children through the ‘Bosque de los Ninos‘ programme which means that they get to choose what will be sown. This is not just important for the engagement of children but also for the community as a whole, linking our demonstration / trial plots with their most valued resource and bringing it to fruition is a powerful symbol. The children have been experimenting with growing various seeds for planting as part of the ‘productive’ part of their school curriculum and I am keen to see what has been planted in a month’s time. There stil remain some challenges though. The anomalous weather associated with El Niño could lead to the crops failing or to the pollarded Inga not recovering as planned.
We used the opportunity of this being the first plot to be pollarded to invite representatives from the other particpating communities: Palacios, San José, Jerico and Monte Sinai. This enabled us to train them in pollarding but also for them to get an idea as to what their agroforest plots will look like in a year or so.
Desde julio los árboles de Inga (pacay) en nuestra primera parcela que plantamos al finales de febrero 2014 son bastante grande para podar. Pero no los hemos podado porque las condiciones no son buenos para hacerlo. Como explicó Dr. Terry Pennington, experto sistemas agroforestales con Inga, no debe podar árboles durante la estación seca y el mejor momento para hacerlo es un par de semanas en la temporada de lluvias. La razón de esto es que cuando se quita todas las hojas y las principales ramas de un árbol, la pérdida por encima del suelo se refleja por debajo del suelo. Es decir que cuando podas un parte de las raíces mueren lo que va disminuir la capacidad del árbol a conseguir agua . Durante la estación seca, hay poca agua en el suelo y si ha podado el árbol se queda sin bastante raíces para sobrevivir.
Por la Amazonia la estación seca empieza por abril / mayo y termina por octubre / noviembre. Este año ha sido muy seco por el fenómeno de El Niño entonces hemos tenido que adelantar de podar nuestros arboles. Después de podar necesitas dos meses de lluvia. Ya estamos por febrero entonces es possible que no va alcanzar el tiempo para podar antes de la llegada de la estación seca otra vez.
Por una otra parcela, Palacio, también es importante seleccionar un buen tiempo para podar. La razón es que este sitio se inunda por un par de semanas cada febrero. Entonces tenemos que asegurar que los arboles tienen el tiempo para brotar o el menos que se podan arriba del nivel del agua. Estamos descubriendo que puede se algo complicado ubicar un buen tiempo para podar!
I first came these majestic and mysterious forests in 2003 whilst collecting on the summit of Cerro Fabrega in Panama. We had hiked through montane tropical forest and cloud forest and suddenly we came into a forest consisting almost only of massive oak trees, covered in dark maroon liverworts and bright red bromeliads. It was a magical and unexpected experience. I had no idea that there were oak forests in the wet tropics and whilst I had seen small oak trees growing in semideciduous forests in Belize and El Salvador they could not be said to constitute a forest. Later on subsequent expeditions we came across these forests at between 1,900 and 3,100 m in Costa Rica and Panama, always characterised by tall trees festooned with epiphytes and very quiet. Indeed an oak forested portion of the La Amistad World Heritage site is known as the ‘Valley of Silence’.
What surprised me about these forests was their stature growing at such high altitudes, well above the stunted and gnarled cloud forests below them. Secondly, they have a rich diversity of plants associated with them, we documented over 500 species. Thirdly, in Latin America, they are restricted to mountains in Costa Rica, Panama and Colombia. They are also relatively unknown, both amongst botanists, ecologists and conservationists. Having done some more work analysing the patterns of species in these forests with Nadia Bystriakova and discussions with Dutch ecologist Maarten Kappelle we are planning a research programme on these high elevation oak forests. One which will seek to document and establish their importance as a source of plant diversity, both for conservation and science but also to evaluate the threats they experience across their range.
I first went to the Pando in the Bolivian Amazon in 1988 as a young undergraduate. Returning in 2013 as a middle-aged botanist it was a pleasant surprise to find that although the capital Cobija had grown a lot much of the forest remained and that sustainable Brazil nut harvesting remained the major source of income for rural communities. It also remained one of the forests with the highest diversity of primates in the World. A single locality having up to thirteen species of monkey! That all looks about to change though as a triple whammy of semi-legal gold-mining, oil exploration and road building took off in 2015 and which by 2018 will have completely transformed the infrastructure, economy and likely the social fabric of one of the least deforested parts of the Amazon.
Asphalt roads are clearly of benefit to Amazonian communities, providing improved access to healthcare, education and markets and assist with the seasonal Brazil nut harvest. Roads also, however push back the frontiers of the forest and facilitate currently unsustainable agriculture, such as slash-and-burn, cattle-ranching or intensive soya / oil-palm production. Finding a balance between the opportunities and risks posed by asphalt roads is very difficult and rarely achieved. Oil extraction and transportation will also have an impact, changing the economy of the Pando and possibly replacing natural forest with its Brazil Nut and rubber trees as a major souce of employment and incomes. It also of course brings with it the risks of any large mining operations.
The rapid growth of semi-legal artesanal gold mining in the Pando could have a far greater impact. The mercury used to separate gold from the river sediment has profound health risks for those mining but also for the whole ecosystem downstream, and for decades to come. Artesanal gold mining also attracts people desperate for money, from all over South America, together with many other strands of the black economy leading to social and political instability.
In addition to getting the timing right it is also important to pollard at the right height, point on the stem and using the right tools. Pollarding involves cutting the top and branches off of a tree. Normally this is done to promote resprouting at the top of the stem but in the case of our agroforest system we want to allow light into our plot for the cultivation of annual crops or fruit trees. This means that we need to cut the stem at the right height so as to shade the crops below and to give them enough time to grow and be harvested before the branches have regrown to their original length. For this purpose we are aiming to pollard at approximately 1.30 m in height, the height of somebody’s chest.
The best place to cut the stem is a couple of centimetres above or below a branch or branch scar. The reason for this is that new branches will sprout from these points. If you cut through the branch point or scar then the tissue from which new branches will develop will be damaged and new branches will be generated at the nearest point above or below it, meaning that it will be higher or lower than desired. The choice of implement is also important. Whilst it is much quicker and more natural to want to use a machete, this is not the ideal way to cut the branch. The reason for this is that it is hard to get a clean clut with a machete as Inga wood splits very easily and the split wood is vulnerable to insect and fungal infections.
The Inga trees in the first plot that we planted at the end of February 2014 have been big enough to pollard since July. We have not pollarded, however, as the conditions have not been right to do so. As Dr Terry Pennington, Inga agroforest expert explained, you should not pollard trees during the dry season and the best time to do so is a couple of weeks into the wet season. The reason for this is that when you remove all of the leaves and main branches of a tree, the above-ground loss is mirrored below ground. That is the roots die back comensurate with what was lost above. During the dry season there is little water in the soil and the tree needs all its roots to obtain the moisture it needs. Therefore if you have pruned during the dry season, the tree is left without enough roots to survive.
In the case of the Bolivian Amazon, the dry season normally runs from April/May to October/November. This year has been particularly hot and dry, possible a consequence of the El Niño phenomenon, and so pollarding our plot would likely kill all of the trees. We will therefore wait until the middle of November when the rains should have started before pollarding.
At another of our sites, Palacio, the timing of pollarding is also important. The reason for this is that it is a site which floods for a couple of weeks each February. We therefore have to be careful that we leave enough time between pollarding and the floods. Or at least make sure that we pollard high enough so that the new shoots emerge above the floodwaters. So here again the timing of pollarding and the associated planting of crops needs careful thought!
One important task for specialists in a particular plant group, in my case nettles, is to visit national or regional collections and not just rely on the collections of our own institutes, no matter how good they are. As part of a conference and field trip I have just spent a couple of days in the La Paz herbarium. My colleague Nicholas Hind will spend three weeks there identifying plants from the daisy family (Compositae) and running an identification course. There were 92 boxes of unidentified Compositae waiting for him when we arrived!This herbarium was founded by German botanist Stephan Beck in 1984 and currently houses over 400,000 herbarium specimens. The reason why such visits are important both for the specialist but also for the herbarium are that although there is an active inter-herbarium loan system for plants it relies on material being accessioned, mounted and identified. This can be a real challenge to achieve in a country where there are few funds and even fewer botanists. The visit of a specialist allows material that has not been mounted or accessioned, together with unidentified material, to be reliably (one hopes) identified and so used as reference for future identifications. Continue reading Herbarium visit to La Paz (LPB)→
Alex Monro's blog about the documenting and conservation of biodiversity