Monday, February 27, 2012

Saplings Tell the Story of Success

Measuring the transect area

As the song goes...From little things big things grow! It's all well and good knowing how many flowers are produced and how many fruits are eaten but it's what happens next that is crucial for the survival of the Virola species...Offspring. Progeny. Heirs to the forest throne. Seedlings. Saplings. Juveniles. Baby trees!

The next stage in our field research is to record how many seedlings are present around the trees. We take a 50m transect from the parent tree at a known compass bearing and record every seedling, sapling and juvenile tree that occurs along that transect up to 3m either side. Samples of the leaves are collected which will provide information on the genetic make-up of the seedling.

Rolling a leaf up for genetic sampling

This is fun work and generally involves Kate, Juan, Pablo and myself setting out early to track down a pre-selected tree. We quickly fall into our now well rehearsed roles. Pablo selects the bearing for the transect and heads off with one end of the 50m tape. We get our "equipment" together while we wait for him to return. The longer he takes the harder we know we're going to have to work as the terrain can be unforgiving to say the least! Then Juan and Pablo scout out the seedlings we're interested in. Apparently they're quite distinctive however I still struggle to identify them even when I know which one is the right one. My job is to record the information required - distance from parent tree and distance from transect midline, height of seedling, year of it's "birth" i.e. when it emerged from the seed, number of leaves and the species type. This is all conducted in Spanish which is easy enough as it's just numbers which both Kate and I have mastered! Kate's job is to take the leaf sample. She carefully cuts a section of leaf along the mid vein then tightly rolls this into a cigarette shape which is then handed to Pablo who carefully inserts it into an individual bag with silica beads. I provide a sticky label for the sample and we continue to the next seedling.

We usually take 3-4 transects for each tree and can find as few as 10 seedlings around a tree or as many as 35. The information will be mapped to provide a visual representation of where seedlings are located throughout the forest. In addition to this, seedlings will be selected for genetic testing to determine which trees are the parents. All the known male and female trees in the area have been sampled and their genetic fingerprint is known which means this can be matched to the seedlings.

One major draw-back to this element of the research is that it is very expensive. Although it is believed that the Virola trees are quite well suited to this type of genetic matching, the technique is not without limits and potential errors. However the results will provide a fascinating insight into the reproductive success of the Virola trees.

-Helen, GVI intern in Drake Bay