- Overgrazing and the construction of a highway, in addition to more severe and extreme droughts and cold spells, have significantly impacted the delicate ecosystem of Bolivia’s Cordillera de Sama Biological Reserve.
- Water is the most affected resource, even though the reserve is protected and an internationally important wetland.
- Concerns remain that the changes could irreversibly alter the ecosystem.
“This year there was a hailstorm which ruined our garlic crops,” says Hilda.
A resident of the community of Pasajes in the southern Bolivian department of Tarija, Hilda says the hail destroyed the plants, and what little could be saved was unfit to sell. Juvenal Galéan, from the Vicuñayo community nearby, says the recent cold weather is the worst the area has seen.
Pasajes and Vicuñayo are part of a wider ecosystem served by the Cordillera de Sama Biological Reserve, home to two permanent and 18 seasonal lakes. The 1,085-square-kilometer (419-square-mile) reserve also hosts the Tajzara basin, declared a Ramsar site 18 years ago in recognition of its importance as a wetland. Cordillera de Sama was designated a reserve in 1991 primarily to protect these water sources, which feed the department of Tarija and the Tarija central valley.
The reserve ranges between elevations of 2,000 and 4,700 meters (6,600 15,400 feet) above sea level. This variation in altitude makes the reserve a unique natural space, endowing it with different climates, landscapes and ecosystems.
But the reserve faces a medley of threats, from loss of land to grazing and highway construction, to climate change, which is bringing about more frequent instances of extreme weather events, ranging from hailstorms to increasingly severe droughts.
In 2017, lakes in the Tajzara basin dried up, including its largest — one of the two permanent lakes that feed the wetlands. Authorities attributed this to climate change.
The impact was far-reaching: the lack of water meant that the horned coot (Fulica cornuta), an Andean bird species, was unable to migrate, resulting in the deaths of hundreds of the birds.
“When the lakes dry up there are no reeds, which … birds use to make their nests and feed on. This causes large numbers of birds to die,” including 400 in 2017, says Alba Gareca, former environmental monitor for Bolivia’s National Protected Areas Service, known by its Spanish acronym, SERNAP. Gareca says she hopes to see the area’s bird populations recover as the lake’s water levels improve and its reeds start to regrow.
The droughts have also had a severe impact on livestock. Hilda, who asked to be identified only by his first name, says he lost five cows and several sheep. “They went to the lake to look for water, and they became stuck in the marshes and died there.”
The management plan for the Cordillera de Sama Biological Reserve, which runs until 2026, notes that the effects of climate change on the reserve are “disheartening.” It says the variations in the climate are now more intense at the higher elevations.
“Before, the rains usually started in October and lasted until March or April, but now they don’t start until December or even January,” says Claudia Oller, manager of protected areas for the environmental organization PROMETA. “Not only is the rainy period shorter, but the rain itself is more aggressive: There are storms, rains that cause floods, followed by long dry periods.”
Another key threat to the fragile ecosystem is that from overgrazing by livestock, says biologist Gonzalo Torrez from the Tarija Animal Protection Society.
The breeding of sheep, llamas and cows was initially introduced as a way to combat poverty in Tarija’s highlands. But now these herds are exerting heavy pressure on the reserve’s vegetation.
“In the high area, llama breeding has been encouraged for wool production, without realizing that the [animals] would eat the little flora [that is] available,” Torrez says. “The cows eat everything and more than any other species, while sheep eat what they like and are homogenizing the [wild plant] species, since they leave what they don’t like, which is causing certain imbalances.”
Gareca says one potential solution would be to introduce Andean highland forage. But she adds that the priority for now should be on building mechanized irrigation infrastructure to optimize the use of water.
Torrez says the livestock herds also damage the topsoil. “They flatten the soil and leave it unprotected, without vegetation, which then leads to erosion,” he says.
All of these threats are related, Torrez adds. “When added together, the droughts could have a great impact and something to do with the changes observed,” he says.
For this reason, he says, it’s important that technologically sound projects are implemented to address these issues.
A third threat is the construction of a highway through the region, which Gareca says flouts existing environmental regulations for the conservation of protected areas.
The Copacabana-Iscayachi-Yunchará dual-carriage highway is slated to cross the Tajzara basin, but the work required to preserve the ecosystem hasn’t been done, nor has the corresponding environmental assessment, and it’s affecting the hydrology of the area, Gareca says.
“The road has not been finished, and much less has been done regarding the environmental [requirements], which consists of restructuring the land,” she says. “To build a road, sometimes parallel roads are made so that vehicles can still travel, which means taking soil from places or piling it [in] one area. Cleaning must be done to restructure the land so that it is how it was before the project, but this has not been done.”
Those living in the area have noticed other impacts the construction is having on the reserve. Armando Condori, a resident of Copacabana, says that before the road was there, they frequently saw vicuñas, a llama-like species prized for its wool. “But now you can’t see them,” he says.
“Where [have] they gone?” he adds. “They’re taking their time returning, and they’ve already gotten used to other places.”
The vicuña is native to Cordillera de Sama. Before the creation of the reserve in 1991, it was among many of the area’s animals under threat, alongside deer and condors.
“By creating the reserve, the animals have been monitored to see how they are developing, hunting has been banned, and the increase in vicuña has been exponential,” Gareca says.
But in recent years, the vicuña population hasn’t increased, she says. Farming and the construction of roads and bridges have reduced their habitat, preventing the population from growing.
“Before the highway, the vicuña moved through this wildlife corridor when it was a dirt path,” Gareca says. “Now this path has a deep cut through it preventing the vicuña from crossing.”
She says the authorities aren’t controlling or monitoring the construction. In many cases, businesses pay little heed to environmental requirements and prefer to simply pay for violations after the fact.
Alfonso Blanco López, director of the government’s Integral Water Management Service, says his office has been analyzing problems created by the Copacabana-Iscayachi-Yunchará highway for three months, and that the environmental assessment required is still incomplete. Blanco, who has discussed the issue with SERNAP officials, tells Mongabay Latam that his office hasn’t set a date yet to respond to SERNAP’s concerns.
Banner image courtesy of SERNAP.