Fig Stakes: Shoreline Restoration for a Costa más Rica

Andres Santana is the graduate program coordinator at the Organization for Tropical Studies. During a recent fieldtrip in southern Costa Rica, he and CCSD restoration ecologist Leighton Reid compared notes on using fig stakes for ecological restoration.

Tropical beaches are many things to many people. To plants, beaches are hot, sandy, and salty – complicating their restoration.

Costa Rica has 1228 km (763 mi) of coast line – including 1016 km on the Pacific side and 212 km on the Caribbean. Along Costa Rica’s northern Pacific coast, the beach forms the natural edge of the dry forest. Farther south the adjacent forest is more humid. Giant trees, 40 m or more in height, grow right up to the high tide mark, particularly along the Caribbean.

But as with so many tropical ecosystems, Costa Rica’s coastal forests have been subject to human impacts. Many shoreline forests were cleared for cattle ranching, and exotic grasses were introduced as forage. Some of these grasses are fierce competitors and prevent tree seedlings from establishing, even long after the pastures have been abandoned.

Playa Hermosa Antes y Despues

Playa Hermosa, before (left) and after (right) planting 2-m long cuttings of a coastal fig species (Ficus goldmannii).

In 2009, a small non-profit organization, Costas Verdes, was formed to restore coastal forests along degraded shorelines, particularly wildlife refuges. The restoration work was initially challenging; tree seedlings were hard to establish along the coast because of the harsh environment – high temperatures and salinity and lack of freshwater were among the most significant obstacles. Not to mention the invasive cattle forage grasses.

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Coastal restoration at Playa Hermosa

Playa Hermosa, a surfing destination on the Central Pacific coast, was among the most heavily deforested project sites. This area, part of a wetland and river estuary, was declared a national wildlife refuge in 1998. By 2009, very little forest had naturally regenerated. This led Costas Verdes to implement a restoration project at this beach. Planting plots were established where invasive grass was removed. In other areas, grasses left intact, as a comparison. It quickly became evident that tree seedlings were outcompeted by the grass. Those in the cleared plots grew better, but they still faced the other coastal habitat challenges.

Some native trees are resistant to hot substrates and high salinity, but these species were not available in tree nurseries, most of which focused on ornamental species. This meant that seedlings needed to come from locally collected and germinated seeds. We realized that this would take time to get going. Tree seedlings under 50 cm rarely survive, even if they have the proper coastal adaptations.

To accelerate the restoration, we decided to use tree cuttings rather than growing seedlings from seed. A colleague suggested Ficus goldmannii as a candidate species, so in 2011 we conducted a planting trial. We planted 225 2-m long cuttings. Of these, 195 (87%) survived their first year. By the second year all 195 survivors had become established and were quickly providing canopy cover and lowering the temperature of the sand.

Ficus

An established fig stake with a dense canopy. Note the weak, patchy grass below it.

Once fig stakes created some canopy cover, we brought in other tree species – mostly from the coastal tree nursery that we created. Shade from the fig canopy also began to inhibit the invasive grasses, which require high sunlight to photosynthesize efficiently. Reduced competition with these grasses allowed other tree seedling species to survive.

In this instance Ficus cuttings turned out to be useful in promoting restoration. We have since used cuttings for other plots with similar success.

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Coastal trees and shrubs growing below established fig cuttings at Playa Hermosa.

El Niño’d: tropical field research when climate won’t sit still

Steve Roels is a PhD candidate in the Department of Integrative Biology at Michigan State University. His research asks how trophic cascades interact with tropical forest restoration. When not in Panama, he enjoys documenting biodiversity and restoring native vegetation on his own 6.2 acres of Michigan.

Tropical field biology has a lot of uncertainty built into it. The scientific community is still barely scratching the surface of tropical biodiversity and the immense complexity of biotic interactions (relationships between organisms). Biologists, myself included, often get lulled into thinking of the tropical climate as a stable abiotic backdrop that lies behind the great drama of biotic interactions. But what happens when those abiotic conditions change abruptly and dramatically?

The current El Niño event in the Pacific is now regarded by meteorologists as one of, if not the, strongest El Niño events ever recorded. The North American media understandably focuses on how El Niños affect our continent; usually wetter West Coast winters and dryer, warmer Midwest winters. What many North Americans don’t realize is that El Niño events have their most profound effects on Pacific countries in the tropics.

El Niños are one extreme of a much larger climate pattern, the Southern Oscillation. The El Niño-Southern Oscillation (ENSO) is an erratic seesaw of Pacific surface water temperatures from warm to cool (La Niña events) and back again. Temperature swings from one extreme to the other occur every few years (on average about 5) and “the switch” is often flipped very abruptly, shifting ocean currents, air pressure, and precipitation throughout the eastern Pacific. It is important to keep in mind that ENSO events are not “bad” per se, just different, and that creates biological winners and losers.

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Strong El Niño conditions in the eastern Pacific during my field season. Image from: www.ncdc.noaa.gov.

In central Panama, where I research bird communities in forest restorations, El Niño conditions generally bring warm coastal waters and drought. I say “generally” because each El Niño is like a snowflake—there are some basic patterns, but every event is unique. This El Niño is sticking to the pattern: central Panama is currently experiencing a severe drought and creating headaches for many of my colleagues at the Smithsonian Tropical Research Institute (STRI). The drought has played havoc with the frog biologists, who are waiting for mating frogs, who have, in turn, often been waiting for rain. Coral researchers are scrambling as abnormally warm waters cause coral bleaching. However, some scientists view this El Niño as an opportunity because it could be considered a proxy for future climate. The El Niño is compounding the warming effects of global climate change, putting 2015 on track to be the warmest year on record. A friend of mine who studies tree physiology and water use in forest restorations says she is getting great data. After all, a key challenge for restoration ecology is deciding what we restore to. An ecosystem that tries to match what was formerly present? Or one that will continue to thrive in an uncertain future?

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The Agua Salud restoration site. The blocks of vegetation in the landscape are different experimental tree planting treatments. Lake Gatun, part of the Panama Canal, lies in the haze on the horizon. Lake levels are anticipated to drop to record lows this dry season.

The effects of current El Niño on my own research are difficult to assess. I study trophic cascades (basically, ripples in food webs) at STRI’s Agua Salud forest restoration project, especially focusing on birds, insects, and trees. I conducted an experiment this past July-August, which is normally the heart of the wet season, but was instead a historic drought. How this drought effected tree growth, insect populations, and bird behavior—all components of my study—is hard to say. Prior research on ENSO effects on trophic relationships is limited (it’s hard to plan research around an unpredictable and irregular event!) but some long-term studies have found large ENSO effects on food webs in Panama and Chile.

When I returned to the United States after my field season and talked with my research advisor about the uncertainty the El Niño brought to my study, she said, “You’re going to hate me for saying it…” I replied, “I already know what you’re going to say.” Maybe I need to do the experiment again next year.