We are meeting more people and slowly learning more Spanish. Ruby and Sarah are playing with an Orchestra at one of the local middle schools so they are meeting some friends. In fact, they have gone to one of their fellow strings player's house today to spot the toucans in their backyard. I have heard lots of howler monkeys and now even seen some. The butterflies are amazing in number and variety.
Work
After two months I feel I have achieved several things with results being collected and am at the stage where I need to take stock and see what else needs to be done in the coming months to complete some things.
The bags made last month have been successful at collecting the Guinea grass seed — need to design the experiment to test their germination. I have also harvested some pollen excluded
Saccharum spontaneum seed — will test if this germinates. The level of germination has been low and variable from site to site. However, repeated sampling from the same sites is consistent. I have just started re-assaying samples.
One of the existing data sets I have been exploring is the 20 years of seed collection data that Joe Wright has. On Barro Colorado Island (a hill top made an island with the creation of the canal) is a 50 ha plot where every stem over 5 cm is recorded to species and a new census taken every five years. This is one of several now around the world that are the cornerstones of tropical ecology. In this plot there are 200 seed traps (mesh forming a basket) that are emptied every week and every fruit, flower and seed collected is identified to species level.
I have been analysing the data for
Saccharum spontaneum. Significant in itself as the seed is not produced on the island and so gives some indication of the distance the seed can travel. I am looking at this data in relation to the weather records. It is not staightfoward as the year to year variation in timing and amount is a product of both seed production and dispersal and capture on the island. These two things may depend on different things. My assessment of germination data will be helpful to them as well because part of the assessment of their and related work is working out how big gaps have to be in the forest before
S. sponataneum can invade. Part of this will be seed deposition but knowing the fraction that is viable is another important parameter.
Well we have viable seed and in an experiment set up last week have demonstrated that it can germinate in the environment — so we will be following the fate of these seedlings over the next few months. Re the vegetative reproduction,
S. spontaneum seems to be able to withstand drying of the stems a lot more than elephant and guinea grasses, the other introduced competitors. My four weeks of drying treatment gets planted tomorrow.
I have taken the bee observations reported last month a step further, caught some bees and given my colleague Kristin the pollen mass that they adhere to their legs to see if we can identify S.spont DNA in the pollen mass. There are too many of them spending too much time on the flowers for them not to collecting the material. The anthers are very easily accessible as they protrude from the spikelets. The bees have been identified by Simon Tierny, a fellow Australian. It is good to see something making good use of the spont — if in fact they are. Whether they are aiding pollination at all is another matter.
PHOTO CAPTION:
Deanne and I have made polyester bags to exclude pollen from developing inflorescences of S. spontaneum and smaller ones to collect the seed of Guinea grass, it shatters at maturation. More from Graham in the next issue of eNews.