Yesterday (17/1/15) we visited the Agua Salud Project. Agua Salud is an experimental forest alongside the canal where researchers are studying forest dynamics and hydrology. While Jefferson Hall was giving us a tour of the area I was struck by the differences between Agua Salud and Barro Colorado Island, both in terms of methodology and scientific impetus. Agua Salud is designed to study how the Canal Zone can be managed in a way that is beneficial to humans and the environment, as well as how forests change over time. BCI is used as a study area to intimately understand how organisms interact on one island. It demonstrates how different motivations can affect what questions scientists ask and how we try to answer those questions.
One of the major goals of the Agua Salud Project is to study how vegetation can be used to control water dynamics in the Panama Canal. The idea is that forested areas will absorb water during the rainy season, which will help to prevent the canal from flooding. Forested areas also have the potential to facilitate the release of water during the dry season, which can help fill the canal when water is more limited. Together, these processes are known as the “sponge effect” and are driven by soil properties and evapotranspiration. Just a few years ago a severe flood threatened to demolish the dams that control the canals water level, a disaster that would have implications for the global economy and cost Panama a lot of money to fix. Experiments at Agua Salud are looking at what species of trees can be grown along the Canal Zone that will facilitate the sponge effect while also providing other benefits to the community. Most of the trees that are being examined will be sustainably harvested and sold as timber. If reforestation can be shown to be an economically feasible venture, then people will have an incentive to invest in reforesting much of the area. This sort of experiment differs markedly from much of the work we have seen at Barro Colorado Island. At BCI, experimental manipulations are usually prohibited and work is being done to answer questions about maintenance of diversity, animal behavior, and any number of biological processes. To me, both of these experiments are fascinating and relevant. It is interesting to think about the motivation behind these different questions and how the balance between them might switch in the future.
Not all work at Agua Salud is centered on management practices and some experiments seek to answer questions similar to those being examined on BCI. In addition to studying the effects of timber farms on hydrology, experiments are also being conducted to measure dynamics of forest succession across the Agua Salud forest. This is done by setting up many plots across the island and monitoring the relative success of trees grouped into categories ranging from early to late successional. Researchers are looking at how nutrient availability, specifically nitrogen, affects forest succession. These questions are similar to some of the questions that are being looked at in one 50ha plot on BCI, where researchers have measured and mapped every single tree greater than 1cm in diameter over the past 30 years, allowing them to look at forest dynamics with incredible spatial resolution. At Agua Salud, Jefferson Hall explained that they chose to look at more plots with less resolution so that they could control for heterogeneity across the landscape. I think that it is important to think about the tradeoffs between these two approaches and how they contrast and compliment each other. This is definitely relevant to us young scientists as we design our own research projects to carry out over the next few months.