At the end of a long tropical rainy season in 2010, a once-in-a-century monster storm dropped 760 mm (30 inches) of rain in the upper reaches of the Chagres River, the biggest Panama Canal tributary. For only the fourth time in 100 years the canal, a $2 billion business run on fresh water, suspended ship transits, opening locks to ease the burden on spillways roiling with café-con-leche-colored runoff. People called the storm La Purísima, the colloquial name given to deluges falling during the December celebrations of apparition of the Virgin of Guadalupe and Panamanian Mother's Day.
...NOR ANY DROP TO DRINK
Ironically, though the rains continued, the storm left nearly a million people in the Panama City metropolitan area without drinking water for almost two months. The city's main potable water treatment plant ceased to operate, overwhelmed by sediments from some 500 landslides in the upper Chagres, which STRI staff scientist and U.S. Geological Survey hydrologist, Bob Stallard documented with aerial photographs.
La Purísima underscored the need for better scientific understanding of environmental threats to canal infrastructure posed by extreme weather. In 1998, during a the worst El Niño-related drought in canal history, water levels in the main channel fell six meters (20 feet) below the normal level. The Canal Authority imposed draft restrictions forcing some shipping companies that could not lighten their loads to reroute vessels through the Suez Canal or to use multimodal train routes across the United States.
Climate change models forecast more extreme, unpredictable events.
GRASS OR TREES?
As news of the Panama Canal’s $5.25-billion expansion rippled out, ports across the U.S. eastern seaboard uncorked billions more to deepen ports to accommodate the bigger post-Panamax ships scheduled to transit the waterway by 2015. The expansion also generated an increasingly acrimonious debate about how land use in the canal watershed would affect the resource that keeps the canal afloat: water. Do the forests between central Panama’s two city centers simply pump valuable water out of the watershed into the air, or are they vital for the health of the waterway?
THE SPONGE EFFECT
Preliminary results from one of Stallard’s experiments indicated that the soils in the canal watershed might behave like soils in some temperate forests, storing water during the rainy season and releasing it during dry periods, thereby creating a “sponge effect.” The study suggests forested land better supplies the canal’s dry season water needs than pastureland. But it raised a number of doubts, including whether exotic species like teak (which dominated reforestation projections at the time) was the best choice for converting landscape from pasture to forest.
But the only way to get solid answers about how regenerating forests restore ecosystem services would be by establishing a decades-long, landscape-scale experiment. This gave rise to the Panama Canal Watershed Experiment, a STRI collaboration made possible by a $4 million grant from HSBC bank and two private donors who purchased 700 hectares (2.7 square miles) for the study. The project was critically backed by the Panama Canal Authority and Panama's environmental authority, ANAM.
The land was mostly low-productivity cattle pasture lying on highly degraded landscapes between the 300-year-old forests of Soberania National Park, which was protected in 1980, and the Transisthmian highway that connects Panama’s Pacific and Atlantic coasts. In other words, it was a perfect place for the project.
NOT ALL TREES ARE EQUAL
Even before the project began, putting teak plantations on ground compacted by years of cattle ranching seemed, to many, like a poor replacement for lush lowland tropical forest native to the region, home to jaguars, howler monkeys and an occasional harpy eagle.
“In 2003 researchers predicted that most of this area would be reforested by 2020,” explained Jefferson Hall, director Agua Salud. “But it’s already 2015, and we’re not seeing that happen. People aren’t stupid. They won’t give up their farms to plant teak on infertile soils.”
So what’s the alternative? Teak is Panama’s most popular plantation tree. One investment website touts a $520,000 profit for sales of teak logs from a 5 hectare plot. On the best soils in Panama, a hectare of teak trees can reach full market value after 20 years. Based on earlier native tree species studies by Yale University and STRI, scientists set out to compare teak and native alternatives. Seven years into the project, Agua Salud has already demonstrated that some native trees can produce more timber, in less time and with less initial investment, and restore more lost biodiversity.
Experiments by STRI staff scientist Klaus Winter’s former post-doctoral fellow Lucas Cernuzak showed that cocobolo, Dalbergia retusa, also used water very efficiently, at least in a small-scale greenhouse experiments. Katherine Sinacore, doctoral student at the University of New Hampshire is comparing water use by teak, amarillo and cocobolo in the field.
Hall expects these results — which are backed by data generated from some 140,000 planted trees — to create some excitement in local timber markets.
“Terminalia amazonia (amarillo) grows fantastically well on our low-nutrient status soils, and a back-of-the-envelope calculation for a 20-year-old cocobolo stand based on its reported market price of up to $5,000 per cubic meter suggests it could be worth up to $200,000 per hectare," said Hall. "Imagine if rural farmers could get even half of that on degraded soils?”
Hall’s team has extended the experiment along the Transisthmian highway where Argos, S.A. the fourth-largest concrete producer in Latin America, faces important decisions about how to manage land near a cement plant the firm recently purchased. “This is a company that can afford to invest in reforestation and biodiversity conservation, and they can probably pay for it through carefully designed harvests and sales of the timber that is already there now,” said Hall.
Not long ago, as Hall drove home after giving an evening lecture to a group of graduate students funded by the US National Science Foundation, a jaguar crossed the road, caught in his headlights. Jeff continues to be hopeful about the prospects for understanding the tradeoffs between water use, carbon storage and biodiversity conservation in Panama.“Based on more than a century of Smithsonian science in Panama, we’re in the position to let nature show us the best course to take as we reforest and restore degraded lands—and we’re calling that Smart Reforestation™.” said Matthew Larsen, STRI director. "We’re hoping that people put the information we’re generating into practice for sustainable management of the Panama Canal watershed and in land use planning throughout the tropics.”
THE PRICE OF WATER
$2 billion [general revenue of the Panama Canal per year] divided by 2.6 km3 [the amount of water it takes to run the locks] = $ 0.003 per gallon
from Bob’s presentation: 2.6 km3 per year to run the locks
There are 2.6417 x 1011 gallons in a km3