Large-Scale Throughfall Measurement System Installed at Agua Salud

by Frank Base

Following the long-term approach of the Agua Salud Project, researchers recently installed three automatic-logging trough systems to measure throughfall in a 5-year-old secondary succession forest at Agua Salud. The purpose of the permanent trough system is to document the temporal changes in throughfall as the secondary forest grows and develops.

Juan Carlos Briseño, technical assistant, finishing one of the new trough systems. Photo by Frank Base.

The trough systems consist of 32 three-meter open tubes (troughs) connected like feathers on the wings of a bird. One wing spreads over an area of 9 m x 3 m. The system in total has an opening of about 12 m². At the center of the construction, a logging tipping bucket catches all drained water and has a capacity of 3 L per tip. Within one hour, 2160 L can be measured. This capacity equals a rain intensity of 195 mm/h, which is sufficient for the strongest rain events in the Agua Salud area based on data from 2008-2010.

Before installing the system, Agua Salud researchers had been using 100 funnels to measure throughfall manually since 2008. The new automatic system now provides continuous measurement of throughfall over the course of the year, enabling us to characterize variations over time and correlate them with rainfall intensity.

Measuring throughfall with trough systems is not new, however. Cuartas et al. (2007) used a trough system covering 1.8 m² with 6-m troughs and a tipping bucket capacity of 125 ml per tip in central Amazonia, Brazil. And McJannet et al. (2007) used 6-m long troughs in a star formation covering an area of 2.4 m² - 3.6 m² in an Australian tropical rainforest. Their tipping buckets had a capacity of 1.8 L - 2.1 L per tip.

Scale is the main difference between the systems used in Brazil and Australia and the one at Agua Salud. We have built, as far as we know, one of the biggest trough systems in the world. Such a large measuring system is necessary to reduce the effect of throughfall on spatial variability caused by extreme structural differences in the canopy of secondary forests. By sampling such a large area, we hope to smooth out the variation caused by canopy structure.

Literature
Cuartas, LA, J Tomasella, AD Nobre, MG Hodnett, MJ Waterloo, and JC Munera. 2007. Interception water-partitioning dynamics for a pristine rainforest in Central Amazonia: Marked differencesbetween normal and dry years. Agricultural and Forest Meteorology 145: 69-83.

McJannet, D, J Wallace, and P Reddell. 2007. Precipitation interception in Australian tropical rainforests: I. Measurement of stemflow, throughfall and cloud Interception. Hydrological Processes 21: 1692–1702.

Students Study Secondary Forest Succession in Panama Canal Watershed

by Dylan Craven

Enmeshed in a mosaic of land uses, young secondary forests provide vital ecosystem services to the cities of Panama City, San Miguelito, and Colón, as well as to the Panama Canal. Under the auspices of the Agua Salud Project, a collaborative research project of the Smithsonian Tropical Research Institute sponsored by the HSBC Climate Partnership, a group of students from Yale and Harvard spent the summer investigating plant functional traits, functional diversity, and community assembly processes in the young secondary forests of the Panama Canal Watershed.

An extensive series of 0.10 ha transects (10 ha in total) has been established across this human-dominated landscape, where all trees, lianas, and palms have been inventoried yearly since 2008 (~450 tree species, ~150 liana species). Using demographic information from these transects, Dylan Craven (Yale F&ES), Grant Tolley (Yale F&ES), and Julian Moll-Rocek (Harvard) identified and sampled 56 of the most abundant tree species, which represent approximately 75% of basal area of transects between 0 and 20 years old. By looking at varying aspects of species-specific plant function – leaf morphology, physiology, and nutrient content – in combination with abundance and mortality data, these students hope to gain insights about how habitat filtering, niche differentiation, and functional diversity vary with secondary succession.

For more information, please contact Dylan Craven at dylan.craven@yale.edu.

University of Wyoming Ecosystem Services Field Course at Agua Salud

by Trey Crouch

A group of students and professors from the University of Wyoming’s Environmental and Natural Resources Department traveled to Panama at the end of July for a four-week ecosystem services field course. The group included seven students and professors Scott Miller and Fred Ogden, the latter one of four principal investigators on the Agua Salud Project. The course took advantage of the Agua Salud experimental landscape and study sites to provide the students with field and laboratory experience related to tropical forestry and hydrology and involve them in research on the connections between hydrology, geochemistry, and land cover.

PHOTO: (l-r) Brie Richardson, Nathalie Macsalka, Nibret Abebe, Aaron Rutledge, Bob Stallard, Ryan Anderson, Nathaniel Hadley Dike, and Scott Miller. By Trey Crouch.

The students participated in various hydrological activities, including two geophysical electrical tomography experiments, installation of shallow groundwater-monitoring wells, and collection and lab analysis of water samples taken from the various Agua Salud stream networks. They also participated in forestry fieldwork by taking crown and DBH measurements in the teak and secondary-growth catchments.

PHOTO: (l-r) Conducting the geophysical tomography tracer experiment in the native species plantation. By Trey Crouch.

Planting Trees to Celebrate World Environment Day 2010

by Jefferson Hall

The headlines are not good. A massive oil spill continues to foul the waters of the Gulf of Mexico, and negotiations to curb the increase of carbon dioxide and other greenhouse gasses in the atmosphere are in disarray. However, on World Environment Day 2010, we remembered the old environmental movement call to action “Think Globally, Act Locally.”

Photo: HSBC volunteers in Panama joined STRI and the Panama Canal Authority (ACP) on World Environment Day (5 June) to plant 2,500 trees over 2 hectares of land in Soberania National Park, Panama. HSBC-Panama CEO Ernesto Fernandes (center) and Arturo Cerezo (green shirt) from ACP were among the volunteers. Photo by Gian Montufar, STRI.

Despite the headlines and daunting environmental challenges the world faces, we need to remember that global action to address environmental problems starts with individuals and local groups. So on World Environment Day, we chose to do our part for the environment by planting trees. Our partners in the effort were 125 HSBC Bank employees in Panama.

As part of the Agua Salud Project—an ecosystem services research partnership between the Panama Canal Authority, the National Environmental Authority of Panama, HSBC Bank, and the Smithsonian Tropical Research Institute (STRI)—we enjoyed a day outdoors, doing something positive for the environment. To help control the spread of aggressive invasive canal grass (Saccharum spontaneum) and restore tropical forest within the boundaries of Soberania National Park, we planted 2,500 trees of native species over 2 hectares of land.

Will it work? No one can tell for sure, but in a six-year-old forest planted by STRI’s PRORENA project, we’ve seen the return of countless species of birds, species of primates, and even footprints of a very large cat believed to be a Jaguar—none of which would be there without the forest.