Someone once told me that the best way to collapse a powerful social movement is to tell them they won. In 2001, a 30-year campaign to protect old-growth forests in Western Australia’s south-west escalated into a spectacular confrontation with the state-backed logging industry. If you’re familiar with the tall eucalypt forests in Tasmania or the east coast but haven’t yet visited the west, you’re in for a treat.

The south-western tip of this old continent catches enough winter rainfall to support cathedral-like stands of giant hardwood trees that exist nowhere else on earth. Tingle, karri, marri, jarrah, tuart and wandoo, and complex tiers of understorey plants have grown and diversified in magnificent isolation since the breakup of East Gondwana more than a hundred million years ago. Today this global biodiversity hotspot is home to unique creatures like western ringtail possums and Baudin’s cockatoos, embedded within the rich cultural heritage of the Wardandi, Kaneang, Pibelmen and Minang Nyoongar people for at least 45,000 years.

This stunning part of the world is in deep trouble. More than half the forested area of these bioregions has been levelled since colonial occupation began in 1826. Even today, land-clearing for agriculture, mining and city-building is wiping out roughly 38,500 hectares of forest and woodland every year, injecting feral animals, weeds and pests into these ecosystems even as the slow-burn impacts of climate change are sending rainfall and fire regimes into uncharted territory.

The most immediate threat to the tall forests however, remains the one that many people thought had been resolved: native forest logging. The story reads like a textbook grassroots campaign: local people allied with scientists, city-based environmentalists and an ever-widening circle of supporters, taking on one of the most powerful industries in the state. These things take time, and there are heartbreaking losses along the way. In the mid-1970s, state government contractors began erasing whole landscapes with 200 hectare karri clearfells, leaving scorched earth and converting the bulk of the felled trees into low-value woodchips. Spindly monocultures were seeded in the wake of the destruction. Over time, forest protection campaigners won important concessions: adding forests to national parks and restricting the clearfell areas to 80 hectares in 1994 and down to 40 hectares in 2004, but each of these gains was hard fought.

An increasing number of people have accepted that 2001 was an important turning point, but that the future of the wild south-west is not yet won

In the late 1990s, a critical mass of community organisers wove together an unstoppable campaign of legal and political pressure, backed by spectacular nonviolent blockades and tree-sits that caught the imagination of the whole state. The 2001 state election was defined by this flashpoint campaign: the Greens and eventually Labor in opposition, demanding an end to logging in old-growth forests, with the incumbent Court government caught badly exposed to surging community anger. Incoming premier Geoff Gallop rode this wave all the way into office, and in the years immediately after the election established a number of important new national parks, protecting 300,000 hectares of old growth karri and jarrah forest from destruction.

It felt like the win this movement had been working towards for decades. Campaign groups dispersed, people got on with their lives. As the chainsaws fell silent in Wattle, Swarbrick and Jane forests, the action moved from the front lines to the fine print, and in the intervening years something has gone terribly wrong.

It hinges, as you might have guessed, on the legal definition of old growth; and how that definition might be carefully distanced from the reality of ecosystem function and form. If a hectare gridded in some consultant’s database shows evidence that a tree was removed by hand with a crosscut saw in the 1920s, that hectare is no longer considered old growth. In the anodyne language of the industry, it has been “previously harvested”. It now forms part of an ambiguously defined “two tier” forest category, and around 10,000 hectares of karri forest by this definition are presently slated for destruction. Other abstract technicalities lurk in the rulebook, which are exploited by the Western Australian Forest Products Commission (FPC) to allow small or irregularly shaped patches of untouched old growth forest to be wiped out.

While a core of the Western Australian forest movement has held its ground in documenting and occasionally protecting new high conservation value areas, the industry has regrouped and enrolled an important new ally: the international certification network established to guarantee that wood products are not sourced from destructive forestry operations.

Next time you’re buying paper towels or office copy paper, look on the packaging for a Forest Stewardship Council logo: a little green tree with a tick-mark. This tells you, among other things, that old growth or high conservation value forests are not being flattened and burned in order to make whatever it is you’re about to throw in the shopping trolley. Until native forest logging is banned worldwide, such schemes will be an important interim measure to help guide people toward products sourced from well managed plantation operations. As you’d imagine, these schemes only work if the rules are watertight and set by independent organisations at arms-length from industry.

And this is where the tragedy unfolding across the south-west comes into sharp focus: the FPC has persuaded the Forest Stewardship Council to at least grant it the half-way certification of so called “controlled wood” status. This falls well short of full certification but was still intended to guide the industry toward protection of high conservation value forests and upholding the rights of Aboriginal people to maintain the cultural integrity of these landscapes.

And yet, even with this additional layer of bureaucracy and oversight, in May 2018 the Commonwealth Threatened Species Scientific Committee was compelled to list the Baudin’s cockatoo as endangered, and the western ringtail possum as critically endangered. Populations of these creatures are in a state of collapse, and even in the cautious language of these expert assessments, the daunting slide towards extinction is undeniable. In both instances, native forest logging is listed as a factor in their precipitous decline.

Forest campaigners argue that the FPC has successfully gamed the Forest Stewardship Council’s ruleset in order to drive logging operations into areas that should urgently be included in the conservation estate. The industry has ambitions to expand woodchip milling and begin feeding logs into biomass power plants; anything to keep native forest logging going. This poses intolerable risks to these species and many others, but it also threatens to undermine public support for environmental certification schemes and the carefully curated reputation of the Forest Stewardship Council.

Local environmental campaigners have been reluctant to pull the pin and launch an all-out campaign against the Forest Stewardship Council, preferring to work within its internal appeal processes in order to have the FPC’s certification immediately withdrawn.

Jess Beckerling is convenor of the WA Forest Alliance, who has been on the front lines in the south-west for more than 20 years. She said,

“Carbon-dating has shown that karri trees up to 600 years old are being logged and trucked directly to the woodchip mill. These are the world’s only karri forests, spectacular ancient forests that are critical habitat for a number of unique wildlife species and they’re being levelled almost entirely for woodchips. It’s disgraceful for FSC, which is supposed to be the gold standard in forestry certification, to have their logo on karri clear-fells. It’s undermining FSC’s credibility and enabling the destruction of these irreplaceable forests.”

As evidence of cascading extinctions within native forests grows more somber by the day, an increasing number of people have accepted that 2001 was an important turning point, but that the future of the wild south-west is not yet won. As a new generation of forest protectors bear witness to the continued destruction of places their parents and grandparents thought they’d saved, time is against them. The big winner from this contest will be a sustainable plantation industry, if the campaigners have their way. Now, finding themselves in the unexpected position of fighting for their forests as well as for the reputation of well-meaning certification bodies, something has to give.

• Scott Ludlam is a Guardian Australia columnist