The NSW Scientific Committee has made the first step in upgrading the vegetation's status from ``endangered'' to ``critically endangered'' under the Threatened Species Conservation Act.

There is only 9per cent of the woodland left from what was estimated to have covered 1250 square kilometres of the Sydney Basin before European settlement.

In Camden, an estimated 35 square kilometres of the woodland survives.

Leonie Kelly, from the Macarthur Greens, wants the State Government to ensure its survival.

The Department of Environment and Climate Change said a draft plan was expected to be released by the middle of the year.

Ms Kelly said even more of the woodland would be compromised with the development of the South West Growth Centre.

``A lot of people think the Greens are totally against development in green spaces, but we would like it to be sensitive to these types of vegetation so as much as possible can be saved,'' she said.

About two-thirds of the 20 square kilometres of woodland in the North West and South West Growth Centre areas is expected to be lost over the next 30 years.

To offset that, the State Government will buy and protect just over six square kilometres of the best quality vegetation in those centres.

A State Government spokeswoman said the planning process would establish precisely where the vegetation would be protected .

Another 13 square kilometres of lower quality

vegetation would be retained in the growth centres while 23 square kilometres will be protected outside the centres through reserves or private conservation agreements.

Ms Kelly, who volunteers at Mount Annan Botanic Garden, said it was not too late for the remaining woodland. She said segments being regenerated were proving to be very resilient.

``We rarely have to plant anything because there's an incredibly rich bank of seeds in the soil,'' she said.