MSPs are to hear calls for tougher controls on the number of deer in Scotland.
Evidence on the subject is being heard by Holyrood's Rural Affairs, Climate Change and Environment Committee.
The damage caused by Scotland's large deer population has been described by environmentalists as the country's "most pressing conservation issue".
Many of the deer are on privately-owned sporting estates which operate a voluntary system of deer management.
Scottish Environment Link, which represents the country's biggest environmental organisations, claims the population of red deer alone has increased from 150,000 in the 1960s to about 400,000 today.
Those figures are disputed by land managers.
The Association of Deer Management Groups said the population had declined in many areas and was now less than 300,000.
'Wildfire' riskThe environmental groups, which include the John Muir Trust, the Scottish Wildlife Trust and RSPB Scotland, argue large areas of the country's uplands and native woodlands have been "ecologically impoverished" due to the large number of deer on Scotland's sporting estates.
They are calling for major changes to the present voluntary system and want to see a new statutory system which would require private landowners to meet deer cull targets set by Scottish Natural Heritage.
In its submission to the committee, the Association of Deer Management Groups said new regulations would fail to resolve disputes over deer numbers, while increasing bureaucracy and costs.
The association also highlighted the economic benefit of deer stalking to Scotland's rural economy.
Stalking is estimated to be worth £105m and to support the equivalent of more than 2,500 full time jobs.
Land managers also believe undergrazing may become a problem if deer numbers are heavily reduced, leading to the loss of species-rich grassland and an increased risk of wildfires.