African Forage Invades Brazilian Pampas

African lovegrass has taken the place of native forage plants in several Brazilian states, and has spread to Uruguay and Argentina. Agronomists are experimenting with using buffalo to control it.

RIO DE JANEIRO - The transfer of plants and animals to new ecosystems can present unknown dangers, turning into a biological invasion with heavy environmental and economic costs. Such is the story of lovegrass, or ox grass, an African forage plant that found its way to the Brazilian pampas.

Known in Brazil as 'capim annoni' (Eragrostis plana Nees), the grass is native to southwestern Africa. It arrived in southern Brazil 50 years ago as seed mixed with other forage plants purchased by a rancher. Its development and resistance to cold won him over, and the rancher then disseminated the plant throughout the area.

Later, it was found to be too fibrous for the cattle, which did not eat it -- but by then it was too late.

The invading lovegrass became known in Brazil by the surname of the man who introduced it in this country, Ernesto Annoni. In 1974 it covered nearly 20,000 hectares in the state of Rio Grande do Sul, and by 1997 spread to 500,000 hectares, says Rogerio Coelho, an expert from the governmental Brazilian Agricultural Research Agency (EMBRAPA).

This expansion indicates that "nothing was done" to control the invasion, a lack of action even by the ranchers, despite the "incalculable losses" they suffered, Coelho told Tierramérica.

Lovegrass destroys the vegetation around it through allelopathy, in other words, by releasing chemical substances into the soil. It works as an herbicide because it inhibits the germination and growth of other forage plants, turning itself into a monoculture, explained the agronomist.

A species is considered an invader when "it adapts, reproduces and spreads in the new environment where it was introduced, and it displaces native species," says Silvia Ziller, president of the non-governmental Horus Institute for Development and Environmental Conservation, which specializes in preventing and reversing this biodiversity-destroying phenomenon.

'Capim annoni' possesses all of the traits that favor invasion, Ziller, who holds a doctorate in nature conservation, told Tierramérica.

Each plant produces 500,000 tiny seeds, which are dispersed by the wind, animal feces, and by trucks and other vehicles. Furthermore, the plant likes compacted, dry and acidic soils, which is why it spreads along roads and thrives at stock fairs and on ranches.

It has spread throughout Brazil's southern states and can even be found in downtown Brasilia, and in neighboring countries Argentina and Uruguay, according to the Horus Institute.

The preferred environment for the invader are the pampas, the plains of southern Brazil, especially the open areas that have been degraded by extensive farming, or that serve as pasture, or which have been burned to clear the land for cultivation.

Lovegrass, says Coelho, can be controlled by rotating farm and ranching activities and applying herbicides.

There is also the innovative approach that agronomist Fabio de Oliveira Rosa came up with. "I found that the buffalo has a greater digestive capacity than cattle and is able to digest lovegrass," said Rosa, head of the Institute for the Development of Alternative Energy and Self-Sustainability (IDEAAS).

His model for controlling the plant entails dividing pastures into small areas, then allowing the buffalo to graze in each one for 18 to 20 days. That is the period in which the lovegrass sprouts but does not flower.

In this way, the plants are eaten before they can produce seed, and in a rotational process can be eliminated from an area within five to seven years, Rosa told Tierramérica.

The divided areas are separated by solar-powered electrical fences, which cost less than barbed wire, he said.

Conservationist Ziller noted that southern Brazil does not have a history of raising buffalo, but its milk is in growing demand.

Furthermore, it is a means of eradicating the lovegrass and being productive at the same time, Rosa said.

But, admitted the agronomist, while this approach contains the invasion within a specific property, "it is not enough to resolve the problem."

The challenge is that the plant has already established itself along rural roads and other public areas.

What is needed is a public policy with rules as strict as those for fighting hoof and mouth disease, such as washing down farm vehicles as they leave areas where the lovegrass is found and making cattle fast 36 to 48 hours before they are moved, so that they do not carry the seed in their digestive tracts, he said.

"I cleared a ranch of the plant between 1993 and 1998" in Rio Grande do Sul, but "lovegrass grows along the entire stretch of road between the property and the city," said Rosa.

In 1978 the Brazilian government banned the sale of lovegrass seed, but did not take action to contain the spread of the plant.

Other invasive species -- plants and animals -- are establishing themselves in Brazil. Among the exotic forage plants, Rosa pointed out the 'brachiaria', also native to Africa.
"We are going to see another process of destruction of native species," he predicts.

* Mario Osava is an IPS correspondent.