The fire started at 12:28 on Friday, and was still raging on Monday morning.
English Nature site manager Simon Nobes had initially reported that 90% of Thursley Common National Nature Reserve was devastated by the flames. But on Monday, he discovered that 40% of the heath still survives in islands of greenery.
Mr Nobes said: “We’re working quickly with a local bulldozer owner to create fire breaks around the islands of green that will form relic building blocks for the future.
“We’re still at risk of small hot spots flaring up again in the windy conditions, but the fire is no longer a solid wall of flames advancing across the heathland.”
At one point, 120 fire-fighters were working to douse the flames, aided by an English Nature team.
Wildlife sheltering in the surviving pockets of heath will be used to repopulate the land. There are also signs that rabbits have survived by hiding in their burrows.
English Nature has not released any information on how the fire was started, but a 52 year-old man has been arrested on suspicion of arson and released on bail pending further investigations.
Gretchen Hendriks