Twelve Extinction Rebellion activists who scaled trees in the Colne Valley nature reserve in west London to prevent HS2 operatives from chopping them down are claiming victory after the tree cutting did not go ahead.

The activists spent about 10 hours in the trees, joining forces with Stop HS2, Green party campaigners and local residents to raise concerns about the destruction they claim the HS2 development is causing to the environment.

The Colne Valley Park in Hillingdon is home to rich biodiversity including a string of wetland habitats. It is an area where a variety of wildlife, including bats, owls and ospreys, live and thrive.

Extinction Rebellion activist Sian Cox, 54, said the protest had achieved its aim of preventing the trees from being cut down. “It’s the first time I’ve been up a tree since I was 10 years old,” she said.

She had been driven to get involved in direct action protest because of the severity of the environmental crisis facing the planet. “This is a victory. It felt good being in the tree, very meditative. I was in the tree for 10 hours and was well looked after and fed and watered throughout the day.”

Extinction Rebellion activist up tree in Colne Valley in protest against HS2. Photograph: Joe Rukin

Environmental activists have staged protests at the site before and have previously temporarily halted work on the site. They have established a camp close to where the HS2 development works are taking place. But campaigners say that Saturday’s direct action represents a new phase in their protests against the controversial high-speed rail link. This is the first time a group of Extinction Rebellion activists has scaled trees en masse to prevent them being chopped down.

HS2 operatives applied for and were granted a permit to close Harvil Road, close to the nature reserve, in order to carry out the mass tree felling on Saturday. The road was due to close at 8am so that 16 mature trees – including willow, field maple, oak and hawthorn – could be felled. But the activists got to the site before HS2 staff, and scaled the trees at 6am.

Joe Rukin, the campaign manager of Stop HS2, said the action could be the first of many of its kind along the HS2 route. HS2’s work in the Colne Valley is further advanced than along other parts of the planned route, and Rukin said activists were watching developments at the nature reserve closely.

He said concerns about the damage the HS2 development was causing to the environment were so strong that other direct actions could follow.

Facebook Twitter Pinterest Joe Rukin, the campaign manager of Stop HS2. Photograph: Jon Super/JON SUPER

Activists say that 22% of London’s drinking water comes from Colne Valley and they fear the HS2 development under way will damage the quality of this water. They estimate that about 2,000 trees have been chopped down at the site and made into woodchips in recent weeks.

Rukin said: “Today’s protest is potentially the first of many up and down the HS2 route. Things have been going well and so far today we have achieved what we set out to achieve – the trees have not been chopped down. HS2 has not yet been given notice to proceed with their work, and so we are calling on them to immediately halt the work they are currently doing in places like Colne Valley.”

An HS2 Ltd spokesman said: “HS2 aims to be one of the most environmentally responsible infrastructure projects ever delivered in the UK, and managing our impact on the environment during construction is a high priority.

“HS2 will create extra capacity on our transport network, taking cars and lorries off the road. The project will also deliver a new green corridor made up of more than 650 hectares of new woodland, wetland and wildlife habitats alongside the line.

“More than 7m new native trees and shrubs will be planted to help blend the line into the landscape and leave a lasting legacy of high-quality green spaces all along the route. HS2 Ltd is working closely with the Environment Agency and Affinity Water to ensure construction activities do not adversely affect the flow, level or quality of surface waters and groundwater in the Chilterns-Colne Valley area.”