The NSW deputy premier threatened to blow up the Coalition: was it really all about koalas?

The threat to quit the Coalition and move to the crossbench came because the Liberals want to protect koalas. Is that it?

No. Resentment from the Nationals over some government policies has been building over time, including over plans to cull feral horses in the high country and, in the previous parliament, the withdrawn ban on greyhound racing.

The Nationals have also felt under siege since losing four seats to the Shooters, Fishers and Farmers and Labor at byelections and last year’s state election, and have been straining to prove their independence. Aggravation over koalas, while real, was just the trigger.

What are the changes that have set this dispute off?

At the heart of it is an updated koala habitat protection state environmental planning policy (Sepp) that came into force in March but had been proposed for more than three years.

Barilaro has claimed the changes his government introduced six months ago “attack the property rights of landholders [and] do absolutely nothing to support koalas”.

In reality, they won’t mean much to the everyday business of the Nationals’ traditional farming constituency. The state’s native vegetation code, which has allowed an upswing in land-clearing in recent years, is unaffected. Regular jobs such as building fences or removing trees or vegetation from around homes can be carried out as before.

Related: NSW Nationals ditch threat to quit Coalition as John Barilaro's leadership condemned as 'untenable'

The changes apply to developments on properties larger than a hectare and that require an application to be lodged with a local council. It means it could affect proposals to change land use, for example turning an agricultural area into a residential subdivision. Some Nationals MPs own properties in affected areas.

These sorts of proposals require a koala plan of management to be included. This isn’t new – it was already the case under the previous Sepp – but the description of koala habitat has been updated.

In what way?

The number of tree species listed as koala habitat has been increased from 10 to up to 65 in any one region, based on fresh scientific advice (the original list was from the 1990s).

The definition of “core koala habitat” has been clarified. Before it was based on the proportion of tree species in an area and whether there were breeding female koalas. The government says this was impractical to assess.

The new version is simpler: an area of land where koalas are present, or an area in which they have been present in the past 18 years and that has been found to be highly suitable for them. The government has also released maps designed to make it easier for councils and landholders to identify potential koala habitat without having to carry out new surveys.

But the new definition of core habitat kicks in only when a landowner is required to apply for a permit under existing local government laws – and even then it does not act as a block on development.

Developers can still clear koala habitat but may be required to “offset” what has been lost. As government audits have found, environmental offset programs in Australia have often been ineffective and worsened the plight of endangered species, rather than improving it.

Requirements of how offsets are carried out have not been toughened under the Sepp changes. In NSW, it can just involve paying an additional sum to get the development approved.

Why do koalas need protection?

They’re in trouble in NSW. Koalas are listed as vulnerable in the state but recent evidence has suggested this may underestimate the seriousness of the situation.

A multi-party parliamentary inquiry found in June they were likely to be extinct in the state by 2050 unless there was urgent government intervention to prevent habitat loss.

The koala population has been in decline for decades, with the federal threatened species scientific committee estimating numbers in NSW and Queensland fell 42% between 1990 and 2010.

Government estimates suggest there are 36,000 koalas in the state but the parliamentary inquiry found this was out-of-date and unreliable. It said habitat loss was the biggest threat facing the species, yet land-clearing and logging continued.

Previous government reports have spelled out the extent of this. Land-clearing has increased 60% since 2017, when the Coalition relaxed native vegetation laws.

The habitat loss had been compounded by last summer’s devastating bushfires, which are estimated to have hit a quarter of koala habitat across the state and up to 80% in some badly affected areas.