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)→
I feel as if I have shed my youth and if I’m honest, early middle-age too, as I leave the Natural History Museum and move to Kew Gardens. I leave with no ill-feeling or sense of regret as I enjoyed over two decades working with some of the most amazing people in one of the great British and scientific institutions. My experiences in the field and working on the collections have made a deep impression on who I am and the science that I try to do, if fitfully and in a slightly uncoordinated manner. I also leave behind several thousand herbarium specimens that hopefully should still be in use a long time after I am no longer around.
But things change, as they should do and always will; the Museum is moving away from taxonomy, the science (& art?) of classification, into more derived collections-based sciences. The emphasis is less on generating new collections and more on synthetic analyses of what they have. It therefore feels like a very natural transition and of course a massive privilege to be moving to the Royal Botanic Gardens, Kew, another great British and scientific institution to continue the eclectic mix of taxonomy, fieldwork and conservation focussed science that have got me this far.
Como parte de nuestros esfuerzos para fortalecer el impacto de nuestro proyecto Futuros Forest hemos sido muy afortunados de asociarnos con la Fundación innocent para expandir nuestro componente agroforestal con una mejor incorporación de árboles frutales. Fondos de la Fundación innocent nos están permitiendo incorporar tres comunidades adicionales, construir viveros de árboles frutales y desarrollar la capacidad dentro de cada comunidad para germinar, crecer y gestionarlos. Como es el caso de las otras acciones de nuestro proyecto comenzamos conversaciones con cada comunidad, atravez del ONG Herencia, sobre cómo esta adición podría encajar en sus planes de desarrollo. También tienen que pensar en qué tipo de frutales quieren producir: la cantidad para consumo personal y para vender. Si sienten que encaje dentro de sus objetivos luego de pasar a la fase más sencillo de construir los viveros y la obtención de semilla.
We believe that the introduction of new approaches to land use needs to be done as part of a broader and integrated plan for a community. It would make little sense for a community to plant an agroforest plot unless they had considered the costs and long-term benefits of doing so. The reason for this is that at several stages in the process there will be challenges and decisions to be taken that will need require the community to remain motivated and able to evaluate the pros and cons of persisting with the system or abandoning it. Given the general lack of success of previous agroforest initiatives elsewhere we feel that this will be the key to our success. As part of our efforts to strengthen the impact of our Forest Futures project and with the support of the innocent Foundation, our main partners Herencia, have been working with three Amazonian communities: Remanzo, Jerico, Monte Sinai, to develop medium to long-term management plans into which agroforest for fruit and annual crops will be integrated.
We established our first Inga agroforest plot just over 17 months ago. Since then the seedlings have grown into 5 m tall trees, their crowns touching and shading out any potential weeds. They have captured the site meaning that it no longer needs any maintenance, allowing farmers to choose when to pollard (prune) at a time that best suits them. In the Bolivian Amazon the best time of year to sow plants is at the beginning of the wet season in October and so we are planning to return to complete this last step in the process.