By Tim Hirsch BBC environment correspondent

Forest: Scarred by ranchers, who clear land to graze buffalo

But that is what environmental groups are doing on the Atlantic coast of southern Brazil, as part of a project to restore a damaged forest rich in unique wildlife.

And it is funded by three major corporations seeking to offset some of their greenhouse gas emissions against the carbon dioxide which will be soaked up by the new trees being planted here.

The future of this kind of scheme is being decided this week thousands of kilometres away in Milan, Italy.

Here governments from 170 countries are finalising the rules which will cover "carbon sinks" under the Kyoto climate change agreement - if, that is, the UN protocol ever comes into force.

The coastal strip east of the city of Curitiba includes the largest remnant of the Brazilian Atlantic Forest - home to some 20,000 unique plant species, as well as jaguars, monkeys and at least 15 varieties of globally threatened birds.

Before we watched the environment being destroyed, but [this project] is not only restoring the environment, it is also showing that you can do this and still we can keep our jobs, keep our livelihoods Lidia Mendes Plant nursery worker

Barely 7% of the original forest remains, and even this protected area has suffered serious damage in recent years from ranchers who have cleared trees to graze imported Asian buffalos - scarring the lush landscape and badly eroding the soil.

Nearly 20,000 hectares of this pasture land has been bought on behalf of a local environmental group which is painstakingly recreating the forest which once stood here.

The buffalo themselves have also been purchased to ensure they are not simply moved elsewhere to cause more damage.

Boost to nature

Making a rainforest is not just a matter of putting a few seeds in the ground and hoping for the best.

In a clearing next to the existing forest, the Curitiba-based Society for Wildlife Research (SPVS) has set up a special nursery where thousands of seedlings are planted and nurtured in tubs by local people.

Andre Ferretti of SPVS explains: "The idea is to go into a degraded area and look what kind of natural regeneration is occurring, look at the species which are naturally restoring the area.

"We try to produce seedlings of these species to plant in other areas where nature doesn't have the same power to do it faster."

They start with "pioneer species", trees which grow quickly and form a canopy of leaves which provide shade, allowing other forest plants to colonise the area and fight the alien grasses that have taken over the landscape.

A few kilometres down the red dirt road heading towards the coast, we looked at one area where this technique was begun three years ago.

In that short time, a new forest is starting to take shape on former pasture land, with some trees already more than six metres (20 feet) high.

And the wildlife is starting to return - we saw the tracks of a jaguar leading into the embryo forest.

Long-term investment

The funding for this project - nearly $20m - comes from three corporations: Texaco, General Motors and American Electric Power. So what's in it for them?

They hope that the extra carbon dioxide which will be absorbed by the restored forest will earn them "carbon credits", counting towards their future requirements to cut greenhouse gas emissions produced by burning oil and coal.

But this is no quick fix - it will be at least 15 years before the newly planted areas start to take significant amounts of carbon dioxide out of the atmosphere.

Miguel Calmon of the US environmental group The Nature Conservancy (TNC) is responsible for calculating the climate benefits from the project over its 40-year period.

These seedlings will take 15 years to begin to absorb CO2

He fears that the rules now being finalised at the UN conference in Milan could deter companies from making long-term investments like this, in favour of quick-growing plantations of eucalyptus or pine trees which do little for wildlife.

Mr Calmon said: "What we are concerned about is these plantations can start occupying important areas for biodiversity and not really bring anything to communities in those areas.

"I think this kind of project can bring much more for the communities, and for the long term, than a plantation."

A key part of the Guaraquecaba scheme is its commitment to local people. The money is also used to provide employment, education and eco-tourism opportunities for nearby communities.

One of the workers at the nursery, Lidia Mendes, said: "Before we watched the environment being destroyed, but SPVS is not only restoring the environment, it is also showing that you can do this and still we can keep our jobs, keep our livelihoods. So it's been getting better since the project started."

A key question in Milan is whether companies will have to show they are providing social and environmental benefits before they can earn credits from forest projects in developing countries.

With the right safeguards, the argument is that the value to the world's climate of tropical forests can help lever much-needed funds into conservation.

The fear is that the system will instead be used to provide cheap alternatives to cutting emissions - doing nothing to recreate the lost habitats for species threatened by deforestation.