Seminar at the Royal Botanic Garden Edinburgh on the nettle family

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View of the tropical glass house at the Royal Botanic Garden, Edinburgh

Last week I was lucky enough to be invited to present a seminar on  the nettle family, the Urticaceae at the Royal Botanic Garden Edinburgh. I have been working on this group of plants for over fifteen years with various collaborators  and am finally ready to publish a revised classification of the family. I had a good audience who asked some insightful questions as well as making some good suggestions for future research. You can see a pdf of my slides by clicking on the following link: Edinburgh Urticaceae 19-6. Afterwards I had a chance to talk to a number of colleagues that I would like to start collaborating with in the future.

Almacenamiento de semillas de Brosimum alicastrum (Ojushte, Rámon, Capomo)

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Frutos fresco de Brosimum alicastrum

Como parte de un proyecto financiado por la Iniciativa Darwin (18-010) para apoyar la recolección sostenible de Brosimum alicastrum tuvimos la suerte de trabajar con un equipo del Millennium Seed Bank de RBG Kew.  Anaïte López del Instituto Nacional de Bosques de Guatemala pasó un mes en el banco de semillas trabajando con Tim Marks, Wolfgang Stuppy y Louise Colville bajo la dirección de Hugh Pritchard, el jefe de investigación de semillas. Brosimum alicastrum es difícil de almacenar y esto ha impactado sobre su uso en reforestation en América Central. El equipo del banco de semillas emprendió una serie de experimentos para identificar las condiciones óptimas para el almacenamiento. La investigación involucró a varias conclusiones nuevas y emocionantes que estamos en proceso de publicar. Afortunadamente también identificó las condiciones que soportan almacenamiento de hasta un año.

Las condiciones óptimas de almacenamiento consisten en el mantenimiento de la semilla a 15 ° C y un límite superior de humedad del 75% RH. Sorprendentemente humedad puede ser mucho más baja sin afectar a la viabilidad de la semilla. El almacenamiento a 15 ° C impide la germinación y el daño que ocurre frío abajo de los 10 ° C, donde la posterior fuga de electrolitos anima a daños por hongos durante la fase de germinación.

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Sección a través de una semilla de Brosimum alicastrum fresco realizado por Wolfgang Stuppy del Millennium Seed Bank, Kew

 

Seed storage protocol for Brosimum alicastrum (Ojushte, Rámon, Breadnut, Maya Nut)

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As part of  Darwin Initiative grant (18-010) to support the sustainable harvesting of Brosimum alicastrum we were very fortunate in working with a team from the Millennium Seed Bank of RBG Kew. Anaíte López from the Instituto Nacional de Bosques in Guatemala spent one month at the Seed Bank working with Tim Marks, Wolfgang Stuppy and Louise Colville under the guidance of Hugh Pritchard, the head of seed research. Brosimum alicastrum is difficult to store and this has had an affect on its use in reforestation in Central America. The team at the Seed Bank undertook a range of experiments to identify the optimal conditions for storage. The research involved several new and exciting findings which we are in the process of publishing. Fortunately it also identified conditions which support storage for up to a year.

Optimal storage conditions consist of maintaining seed at 15°C and upper limit of humidity of 75% RH. Surprisingly humidity can be much lower without impacting on seed viability. Storage at 15°C  prevents most of the in-storage germination seen at higher temperatures, and the chill damage occurring at 10°C or below, where subsequent electrolyte leakage encourages fungal damage during germination phase.

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Section through fresh Brosimum alicastrum seed undertaken by Wolfgang Stuppy of the Millennium Seed Bank, Kew

 

Zonas de transferencia para Brosimum alicastrum en América Central

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Zonas de transferencia recomendadas. Al restringir el movimiento de las plántulas o semillas a dentro de cada zona no debería haber ninguna erosión de la diversidad genética de Brosimum alicastrum. Imagen hecho por Tonya Lander

Como parte de un proyecto de la Iniciativa Darwin del Gobierno del Reino Unido (# 18-010) hemos recibido fundos para proporcionar herramientas de apoyo a la reforestación sostenible con Brosimum alicastrum. Brosimum alicastrum, conocido como Ramón,  ojoche, ojite, ojushte, ujushte, ujuxte, capomo, mojo, ox, iximche, masica, uje o mojote, es un árbol común en América Central, y es bastante utilizado para reforestación. El objetivo de nuestro trabajo era de proteger la diversidad genética de la especie y el carácter distintivo genética de las regiones, mientras que al mismo tiempo permitir que sea utilizado en reforestación y restauración. Para esto hemos realizado un estudio genética de la especie a través de su rango de distribución con especial énfasis en América Central, donde la especie es más común y donde la demanda de su uso en la reforestación es mayor.

Tonya Lander analizo los datos genéticos y con el uso de técnicas estadísticas pudo identificar áreas que eran genéticamente distintas unas de otras. Estos se caracterizan por líneas negras gruesas en el mapa de arriba. Le recomendamos que las semillas y plantas no se mueve de un área o zona a otra. Si se mueven de una zona a otra, una vez que alcanzan madurarse,  comienzan a liberar polen y producir frutos, lo que erosionará el carácter distintivo genético de esta zona. Afortunadamente, dado el tamaño de las zonas que hemos delimitado no debería afectar en gran medida la reforestación con Brosimum alicastrum en América Central.

Las zonas identifacad son:
1) México, Guatemala, Belice, El Salvador, Honduras & Nicaragua,
2) Costa Rica, Panamá y Colombia,
3) Las Antillas,
4) América do Sur excluyendo a Colombia.

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Frutos de Brosimum alicastrum con la semilla saliendo. Normalmente pájaros y murcielogos comen la parte verde y solo cae las semillas por el suelo

 

 

Seed transfer zones for Brosimum alicastrum in Central America

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Recommended seed transfer zones. By restricting the movement of seedlings or seed for restoration to within each zone there should be no erosion of Brosimum alicastrum’s genetic diversity. Image: Tonya Lander

As part of a recent grant from the UK Government’s Darwin Initiative (#18-010)  to provide tools to support sustainable reforestation with Brosimum alicastrum, a common tree in Central America, we have identified safe zones for seed and seedling transplantation. The aim is to protect the genetic diversity  of the species and the genetic distinctiveness of the regions whilst at the same time allowing it to be used in reforestation and restoration. To do so we undertook a genetic survey of the species across it’s range but with special emphasis on Central America where the species is most common and where demand for its use in reforestation is greatest.

Tonya Lander analysed the genetic data and using statistical techniques identified areas that were genetically distinct from each other. These are marked by thick black lines on the map above. We recommend that seeds and seedlings are not be moved from one area or zone to the next. If they are moved from one zone to the next, then once they reach maturity and begin to release pollen and produce fruits, this will erode the genetic distinctiveness of this area. Fortunately given the size of the zones this should not greatly impact ongoing reforestation in Central America.

The zones identified comprise:
1) Mexico, Guatemala, Belize, El Salvador, Honduras & Nicaragua,
2) Costa Rica, Panama & Colombia,
3) the Greater Antilles, and
4) South America excluding Colombia.

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Fruits of Brosimum alicastrum showing the green fleshy sweet skin. Usually birds and bats eat the flesh whilst the fruit is on the tree causing the slippery seed to fall to the ground

 

Solving the mystery of Myriocarpa flowers


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Composite image of the base of a female flower showing what we now believe are bracts at the base. Note the small stalked glands spaced evenly along each bract. You can see each cell in the flower thanks to the amazing imaging facilities at the Natural History Museum.

For over a hundred years the genus Myriocarpa in the nettle family which comprises ca 15 tree species in South and Central America has been impossible to place within the family. This is largely because of the very unusual shape of the part of the female flower that receives pollen, known as the stigma (see image below) and the fact that neither of the two great experts could agree over whether the petal-like structures at the base of the flower were petals associated with the flower, or bracts associated with the stalk. Whilst this might not seem like the stuff to keep a botanist awake at night it has become of interest again as using DNA data we have identified as sister to another small group of trees, Gyrotaenia, found in Cuba, Hispaniola, Jamaica and Central America that has a flower which consists of the petals fused to form a tube which is fused to ovary.

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The tip of the female Myriocarpa flower showing the very unusual forked stigma, the part of the flower which receives the pollen. You can see that it is covered in multicellular hairs, which are characteristic of the nettle family, and serve to capture pollen form the air and guide it to the stigma.

I was therefore very curious to see whether Vladimir Blagoderov, Manager of the Museum’s Sackler Imaging Suite could help me generate an image that would help us resolve the mystery. He could! The two images above are each composed of about 20 images which ‘slice’ through the sample which was of young flowers collected in alcohol in Belize over 10 years ago. The resolution was amazing, each cell being visible. In fact you could even make out the rough crystalline structure on the surface of the hairs! Both of these images also helped us to answer the question, revealing that this flower does indeed consist of a tube composed of fused petals that is subsequently fused to the ovary. This we could see in both images where the clearly visible ovary is enveloped by another distinct tissue, as in the case of Gyrotaenia. It was also confirmed by the petal-like bracts at the base of the flower having stalked glands, structures not known to occur on the ovaries of Urticaceae. So a morning’s work and an idea of evolutionary relationships enabled me to answer a question that had been frustrating an albeit very small group of botanists for over 100 years!

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Photograph of the string-like flower clusters of Myriocarpa longipes taken in Panama where it occurs as a small tree growing near rivers in tropical forest. Each flowers cluster consists of thousands of tiny flowers

 

 

The future climate of Amazonia

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The cover of Antonio Nobre’s report, a copy of which in English, Spanish or Portuguese can be obtained by clicking on the image above

 

At the Intergovernmental Panel on Climate Change (IPCC) conference in Lima this December, Brazilian researcher, Antonio Donato Nobre published a synthesis on the most recent scientific data about the Amazon’s climate accompanied by an explanation of the the profound impact that the Amazon has on South America and how this is changing as a consequence of climate change and deforestation. Antonio Donato Nobre, a well-respected Brazilian scientist and brilliant science communicator (click here to see his Ted Talk) has been researching the Amazon’s climate for decades.

The synthesis introduces two concepts that were new to me: the first was the notion of the Amazon as a ‘Green Ocean’, the second that the Amazon functions as a biotic pump pushing ca 20 million tonnes of water into the atmosphere every day and in doing so drawing water vapour in from the Atlantic Ocean. The first idea of the Amazon as a Green Ocean is an important one as it gives a scale to the impact the Amazon has on the global climate, equivalent to one of the World’s Oceans. Conversely it also suggests the enormity of what we are doing to an ecosystem that is probably critical for our welfare. The second concept, not proven but for which there is mounting evidence, presents the Amazon as a vast community of ca 385 billion trees mutually interdependent with trillions of micro-organisms, insects and vertebrates functioning in concert as a water pump, extracting water from the ground, catalyzing its conversion to rain in the lower atmosphere and in doing so drawing water vapour in from the Atlantic Ocean and sending moisture to the grain belt of South America creating one of the most productive agricultural landscapes in the World.

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Diagram from Makarieva et al.’s article in the Journal of Hydrometeorology, 15, 411-426 (2014) summarizing the biotic pump, the product of the action of ca 385 billion trees. Precipitation in the lower atmosphere catalysed by volatile secondary plant chemicals released by leaves results in a drying of the air above which when rehydrated over the moist ocean carries water inland

 

The main points of Antonio’s report are that 1) the Amazon generates a climate that supports agriculture to its south, 2) deforestation will result in a climate that does no longer supports agriculture in southern South America, 3) that the nature of the Amazon’s impact on climate means that there is a point of no-return with respect to deforestation which once passed will lead irreversibly to desertification for much of southern South America, 4) that deforestation in the Amazon is already having an impact on the regions climate and that this could accelerate the impact of climate change on the Amazon, and lastly 5) it is not too late to reverse these impacts and that muscular actions to outlaw forest fires and deforestation coupled with a popularization of the scientific research on the Amazon cold avert the destruction of the Green Ocean. I can not recommend reading the report enough, it is engagingly and precisely written and will make you amazed at the impact forest have on our World.

Challenges of working with vulnerable rural communities

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Some of the Children of Pimpollo keen to show me their new school building. The Government of Bolivia provides all rural communities with a primary school and a teacher, no matter how remote they are. Click to see a clip of me introducing the project to the community

We have been working with the Pimpollo community for just over a year. It has been a real challenge for us, as well as for them. The community is formed of a group of ca 25 families  settled in the Amazon for less than two years and from three different parts of the Bolivian Andes. Life is very difficult for these communities. For a start they do not know each other very well and yet will depend on each other for their survival. This creates a number of tensions and in the last year of contact with Pimpollo we have seen an almost complete change in family composition with only three of the original families remaining. Secondly, Pimpollo is located over a 100 km, on dirt-track, from the nearest town, the last 30 km or so of which is semi-passable during the wet season. This makes access to medical care, schooling and security intermittent at best, especially considering that there is no phone coverage and all communication occurs through VHF radio. Thirdly, they are very poor and farming some of the World’s poorest soils. Having recently come from the relatively fertile Andes, this poses real challenges. It also makes it much harder for us to maintain contact.

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In answer to question from community members, Roman Velarde from Herencia explains some of the detail of the agroforest plot layout

Continue reading Challenges of working with vulnerable rural communities

Flooded forest agroforest plot five months after planting

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Forest Engineer Rolman Velarde standing between two rows of Inga saplings planted in the middle of May at our Palacios site. The site is on wha would be flooded or ‘varzea’ forest had it not been cut to grow rice. Click to see a clip of the site (in English)

Our plot at Palacios is located in seasonally flooded forest on the banks of the Tahumanu river. This meant that we had to plant our seedlings after the flood had receded as they would probably not have survived if completely immersed. The up-side of flooding though is that the soils are rich and the seedlings, although planted late, have grown well. When the next floods occur in February they will be tall enough not to be completely submersed and so should survive. It might seem strange that a slash-and-burn site on such rich alluvial soils should be abandoned and this was something I was keen to find out from the community. They explained that after a year or more weeds invade the site very aggressively and are very difficult to remove. We are hoping that Inga‘s rapid growth, spreading crown and large leaves should act as an effective weed-suppressant. It may be that weed control could be one of the main uses of Inga in the Amazon.

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The Palacios plot five months after planting. This plot is aimed at supporting the cultivation of annual crops, fruit trees and mahogany as timber. Growth has been strong but the plot needs weeding soon. Click to see Rolman Velarde talking about the site in Spanish.

The trees at Palacios have grown well, on average over 11 cm per month. Currently they range from 1.0-1.5 m in height at six months since planting. With the most intense rains to come they should increase this rate significantly over the next few months. They still need weeding, probably until after the next floods,. The community seem pleased with progress too and are planning another plot for after the next floods.

 

Agroforest plot on compacted bull-dozed site eight months after planting

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Eight-month old seedlings at our San José site planted on heavily compacted bulldozed land. Whilst over 3/4 have survived the site has suffered higher mortality and significantly lower growth rates than at other sites. Click on link to see clip.

Although the seedlings we planted at our San José site are growing poorly and about 1/4 of them have not survived, this is a strategically important site for us. This is because it represents a worst-case scenario in terms of land-use: top-soil removal combined with heavy compaction by a bulldozer. Compaction causes severe and long-lasting damage to soils that can take decades to recover from. The community of San José, by electing to establish an agroforest plot on this site, have given us an opportunity to gauge growth and mortality rates Inga edulis on such areas and so evaluate their potential with respect to restoring them to productivity.

Continue reading Agroforest plot on compacted bull-dozed site eight months after planting

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