Since September 2012 Anaité López (Instituto Nacional de Bosques, Guatemala), Tim Marks (Millennium Seed Bank) and Wolfgang Stuppy (Millennium Seed Bank, do visit his amazing blog) have been working at the Millennium Seed Bank to develop a long-term storage protocol for the seed of the Maya Nut tree (Brosimum alicastrum).

This is important because Maya Nut is a significant famine food for the rural poor in northern Central America and is being actively used in reforestation projects as it is fast growing and relatively tolerant of disturbance.  At the moment, however, it is not possible to store the seed for more than a couple of weeks making it very difficult to deploy seed as and when it is needed outside of the fruiting season.

Left: Maya Nut (Brosimum alicastrum) fruit - Fruit as it is when still on the tree

Right: Maya Nut (Brosimum alicastrum) seed - Seed once stripped of the fleshy outer layer by bats or birds (left), with both papery coverings removed (centre), with only the outer of the two papery covering removed (right)

The work involved collecting about 5,000 seeds from Maya Nut forests in the Peten of north eastern Guatemala. The seed was then shipped to the Millennium Seed Bank by courier where it was unpacked and studied by Anaité who had flown over from Guatemala for six weeks to undertake the work under the supervision of Tim Marks and Hugh Pritchard, specialists in seed research and storage. This was an opportunity for her to take back the skills and knowledge that she had learnt to Guatemala. The work has been funded by Defra through the Darwin Initiative (project 18-010) and is taking place incollaboration with the Maya Nut Institute.

A batch of Maya Nut seeds being germinated following controlled storage. Image courtesy of Anaité López.

Our plan was to devise a regime of cooling and drying the seed that would enable it to be cryogenically stored (frozen) and so stored for many years. To do this we needed to identify the best rate at which to drop the temperature and humidity whilst keeping the seed viable. This involved storing the seed at different temperatures and humidities and taking a batch out and germinating it every month.

Given that this seed does not survive for long in the wild and that it is protected by two very thin, papery coverings (see above) we expected it to be very prone to dessication and so sensitive to low humidity. In fact we found quite the reverse. Six months later we are still germinating seed that has retained most of its moisture after having being stored in a dessicant for all this time!

In order to understand how this could happen we contacted seed morphologist Wolfgang Stuppy, world expert on seed morphology. He made the following images of sections through the seed which show a thin but dense layer of cells that control waterloss from the seed:

Section through Maya Nut seed showing the dark outer layer that might reduce water loss. Image courtesy of Wolfgang Stuppy.

So we now have a partial explanation as to how the seeds can show such remarkable tolerance to drying out. It does, however beg two questions:

1. Why do seeds not survive under the conditions of the forest floor?
2. Why would a tropical tree that grows in the humid tropics develop such a remarkable resistance to drying out?

To be continued maybe...

I have just spent a week collecting samples of Brosimum alicastrum (Maya Nut) with colleague Tonya Lander in Panama. It was a bit scary at first as we were not sure that we would find it, or recognise it in the field. Although it is relatively common, tropical forests have a lot more different species of tree than you would find at home. It is not uncommon to find over 100 species of tree in a 100 m x 100 m patch of forest. Fortunately the leaves have quite distinctive venation (see below) and we were able to collect samples from most of the places that we went to.

Tonya and I are documenting geographical patterns in the populations of this tree across Central and South America with the aim of making reforestation with this species sustainable. We were especially keen to collect samples from both the Caribbean and Pacific coasts as further north in Mexico there appear to be physical differences in the bark and branching between these coasts. This involved a lot of driving, over 1,500 km and at one site in the Pacific province of Los Santos, avoiding a large number of crocodiles that were basking on the river bank close to which our tree was growing. Although to be fair to them they seem a lot more scared of us than we were of them!

Our last day in the mountains. Mixed emotions really. We have made some great collections, enjoyed each other’s company (I hope), learnt a lot, had great support from our porters and field team and have been very lucky with the weather. We are a bit tired though and beginning to lose some of our enthusiasm. I even caught myself not being amazed at seeing a Quetzal so it is probably time for us to head home.

Oak forest at 8 in the morning, light streaming through the foliage

For me the highlight of the fieldtrip has been camping on top of one of the Cerros Tararias, almost certainly the first Europeans to have made it to the top of one of these 200 m high blocks of gneiss rock each with its mini paramó atop. Not only did we get the first plant collections from here but we also enjoyed spectacular views between Cerros Kamuk and Fábrega and down the valley of the Río Jet. A completely unexplored part of the Park and the focus of another trip should we get the funds.

View of one of the Cerros Tararias and out across to the Río Jet valley

Carlos ‘Leña’ and his son Josué. Carlos has been our guide and lead porter for much of our work in La Amistad Binational Park and has been a key player in our exploration of the Park.

It has also been a real privilege to be able to share some of what we have done and seen with visitors to the Museum as part of the Nature Live programme. For that a big thank you should go to Stephen Roberts and Jo Kessler from the Museum’s Nature Live team, Lee, Adam, Alex, Eddie, Ken and Tony from our Special Effects Department and Erica McAllister and Gavin Broad from our Entomology Department.

Also to Tom Simpson, who although was of course very lucky to come with us and whose feet in no way smell (no really they don’t), was incredibly professional and did everything possible to make sure that the live video links went well and answered as many of the questions on the schools blog as possible. Last but not least Jon from our Interactive Media team who has been assembling and editing this blog and to Grace from our Learning Programme who set up the events for schools.

Tom uploading his blog from the base of the Cerros Tararias

Our camp at the base of the Cerros Tararias

The plan today was to walk from our main camp at the Albuerge (see the map on Tom's blog) at 2,500 m to a smaller one, Casa Coca, at 1900 m so that tomorrow morning we can get back to the park entrance in good time for the eight hour drive back to San José. It was a beautiful sunny morning, the light streaming through the trees as we set off.

The plan was to interrupt our walk and sneak in a sample point half way, in the Pacific drainage. It was really amazing how dramatically the forest changed once we had crossed the main pide between the Caribbean and the much drier Pacific, the understory becoming more open and the canopy lower, possibly because of less rain and more wind?

Holger at the Continental pide collecting a sneaky lichen from the back of the Park sign

Scientifically the trip has been a great success, Jo Wilbraham made about 340 moss collections, Holger Thues about 500 lichen collections and Daniel Santamaría (from Costa Rica), Neil Brummit and myself about 640 vascular plants collections.

I think that Holger has certainly been the most enthusiastic about his finds with new records not just for Costa Rica but the whole of Tropical America. We are quietly confident of having collected some new species but will need to wait until we get back to a herbarium to be sure. This highlights the importance of global reference collections, such as our own, to identifying new species.

Jo with the bulk of our collections, bagged up and ready to be transported
to the INBio herbarium for drying, sorting and identification

I have just finished doing a videoconference with a group of schools who will be following our field trip to the Talamanca Mountains in Costa Rica next week. It was really fun and as usual we had some very good (and difficult) questions.

The plan is that we will share our scientific field work, which to be honest is one of the must fun parts of our work at the Museum, with the public and a pre-arranged group of schools. We will be running Nature Live sessions from the forest using an Inmarsat video satellite link, which will let us talk to visitors in the Museum's Attenborough Studio.

As well as blogging about the trip we'll also be answering the questions of teachers and school children who have been invited to sign-up for our schools link. If you know any teachers who might want to get involved and get access then please get them to contact Grace from the Museum's Learning Programme by email (videoconferencing@nhm.ac.uk).

So, we leave here Monday morning and by Wednesday we should be collecting our first moss, lichen, algae and plant specimens!

In collaboration with the US NGO the Maya Nut Institute and women's cooperatives in Mexico, Guatemala, Honduras, El Salvador and Nicaragua, the Natural History Museum is hosting a project to produce tools for the sustainable use of the tropical forest tree Maya Nut (Brosimum alicastrum). A project funded by Defra through the Darwin Inititiative. This will involve providing training to cooperatives in the collection and interpretation of harvest data with the aim of helping them to calculate sustainable harvest levels, developing a protocol for the long term storage of the seed and discovering the genetic structure of this species with a view to supporting the sustainable reforestation using this species. Tonya Lander, formerly at INRA Avignon has joined the Museum to study the population structure of this species across Central America. Tonya has a background in population, landscape and pollination molecular ecology and we are very excited that she has joined us.

Tonya  on fieldwork in Chile	Maya Nut fruit