Baroness says she will be tied to tree to stop developer's axe

Spain's art magnate and former beauty queen Baroness Carmen Thyssen-Bornemisza has threatened to tie herself to one of the ancient trees that shade her museum in Madrid to stop them being chopped down for an urban renewal scheme.

Hundreds of trees planted in the late 18th century opposite the Thyssen-Bornemisza museum, which houses one of the world's finest private art collections, are to be felled and relocated in an ambitious remodelling of the adjacent Paseo del Prado boulevard.

"Everyone knows it's impossible to transplant trees of that age, and they will die," insists the baroness, fifth wife of Baron Hans Heinrich von Thyssen-Bornemisza, who died in 2002.

"I'll find other nature lovers and we'll attach ourselves to these beautiful trees to stop them being killed. I'll bring food and drink, and we'll see who will budge me," she said yesterday.

The high-profile renovation project, masterminded by the Portuguese architect Alvaro Siza, proposes to cut down or remove 700 trees of 40 species to widen the pedestrian area of the Paseo and improve traffic flow.

The baroness's intervention was crucial in persuading her husband to bring to Madrid the bulk of his fabulous art collection, rivalled only by that of Queen Elizabeth, which the Spanish state bought for around £210m in 1993. Parts of the late baron's collection remain in the family's palace in Switzerland, and part is in Barcelona.

Madrid's 19th-century Villahermosa palace, a few moments' walk from the Prado and Reina Sofia museums, was spectacularly restored by the Spanish architect Rafael Moneo to house the paintings. Last year a new wing opened to house some of the 700 works collected personally by the baroness. The revamped Paseo del Prado seeks to unite the three museums, which are separated by 11 lanes of traffic.

"They want to put a motorway past our door, and cut down this divine grove of trees," the baroness complained to El Pais newspaper. "Our visitors will be choked by carbon monoxide, and will fry in the summer with no shade. Many years of work and sacrifice have gone into this collection, and it grieves me greatly to see it so mistreated.I feel wounded, offended and angry."

Madrid city hall's opposition socialist leader, Trinidad Jimenez, said her party was considering "introducing some proposals to satisfy ecological concerns and those of the museum",

At present, vehicles thunder past the Thyssen while pedestrians cower on a thin strip of pavement, but even the proposed wider walkway does not please the baroness: she objects to plans to strew it with fine, golden sand known as albero.

"Albero is lovely in the bullring, but is dirty and uncomfortable to walk on," she said. "Ladies won't walk on it because they'll get earth in their sandals. People will come into the museum with their shoes full of sand."