SCORES of landowners could be left with unpaid leases on land covered with worthless trees if managed investment scheme companies go under.

Some analysts say an acute lack of export facilities at the Port of Portland could be the killer blow for two MIS giants, Timbercorp and Great Southern.

The region known as the green triangle, where both companies own massive tracts of plantations, will produce four million tonnes of bluegum annually this year, but the port's annual capacity is less than one million tonnes.

The port plans to expand, but has not obtained finance, cannot say when it will, and says construction will take at least a year when it does.

Edenhope landowner Malcolm Warner said if the company he has leased land to folded, it would not be under any obligation to pay out the lease.

"We'd have to clean them (the trees) up, it would be a nuisance," Mr Warner said.

Meanwhile, landowners in southwest Victoria said prime land taken by timber plantations could go to waste if MIS companies did not secure markets.

The Weekly Times understands contracts typically entered into between MIS companies and landowners do not require trees to be removed from the landowner's property if the company goes under. Timbercorp communications manager Matt Trewin denied the port situation signalled financial trouble for the company.

"The majority of our revenue is generated by ongoing management fees we receive from our investors," Mr Trewin said.

"There could be other ways of exporting."

Analysts say the lack of export infrastructure could also endanger Timbercorp's attempts to sell 40,000ha of plantation timber as it attempts to reduce its $500 million debt.

Late last year, Timbercorp issued a warning that if asset sales and debt reduction did not proceed as planned, there would be "material uncertainty in relation to the group continuing", and Great Southern issued a very similar warning.

Portland Port Authority chief executive Scott Paterson was worried about the port's throughput.

"If someone else bought the companies, or they went into administration, they don't necessarily have to honour contracts - that raises doubts," he said.

Glenelg Shire Mayor Geoff White said the harvest delay meant the 1000 jobs promised by the MIS companies were also delayed.

Great Southern corporate affairs manager David Ikin said income from the sale of the trees belonged primarily to investors. The company would push its harvest back to 2010, he said.