South American timber used for Borders Railway bridges
Timber from South America was used to refurbish bridges as part of the Borders Railway project, BBC Scotland has learned.
Network Rail said it used sustainably sourced Greenheart wood for replacement decking on 12 bridges.
It has led to a call from the timber industry for more homegrown wood to be used in construction projects.
However, the rail firm said the hardwood was the "best option" to meet the requirements of the new railway.
Stuart Goodall, the chief executive of the Confederation of Forest Industries (Confor), welcomed the use of wood in refurbishing bridges.
He said it was a "very suitable material" with a "far stronger environmental footprint than the alternatives".
"However, we are concerned that local authorities are not making more effort to use wood produced in Scotland, or at least in the UK," he added.
Greenheart wood is said to be a very durable wood, mainly found in north-eastern South America.
Most of the timber produced in Scotland is softwood, and is considered unsuitable for bridge projects.
But Mr Goodall said: "We grow a wide variety of species of tree in Scotland and there are new engineered wood solutions that provide the means to bridge wide spans.
"Unfortunately architects and construction firms don't make the effort to explore new and alternative solutions when it comes to wood."
Earlier this year, it emerged the timber industry is worth £1bn to the Scottish economy.
Despite this, the UK is the world's third largest importer of timber, importing 80% of the wood it uses, according to Mr Goodall.
He said: "We need to plant more trees, of all types, to make it easier to source a wide range of timber produced domestically in the long term."
The Scottish government has set a target of planting 100,000 hectares of new woodland in the decade to 2022.
A Network Rail spokesman said the timber used on the Borders Railway project was subject to an independent audit to check it was sustainably sourced.
He added: "We regularly support British industry and products - 95% of our rails are made in the UK and stone for the Borders was sourced locally too.
"However, not all materials can be sourced from within the UK and in the case of timber used on these bridges, Greenheart was the best option to meet the durability and load-bearing requirements of the railway."