The charity has spent £42,596 on clearing up 196 incidents of fly-tipped waste this year, bringing the overall bill for dealing with litter in its woodlands to around £354,000 in 2016.
Costs are up substantially on last year, when the trust spent £31,360 on tackling fly-tipping, as part of an overall waste clearance bill of £192,000.
Since 2010, the charity’s total rubbish clear-up bill, including routine litter picking and dealing with fly-tipping, has reached more than £1.2 million - money which it says would be better spent on creating new woodlands or protecting ancient woods.
Some of the more bizarre items found fly-tipped include a snooker table, exercise bike, paddling pool, scooters, kitchen worktop and a burnt out wheelie bin.
In one urban woodland, Windmill Hill, near Runcorn, some 280 bags of rubbish have been collected since January, along with bulky items such as mattresses, a fridge and garden fence panels, at a cost of nearly £6,000.
A young woodland, orchard and wildflower meadow planted by members of the local community at Theydon Bois, Essex, a site that is thought to have once been part of Epping Forest, has been blighted by a huge pile of fly-tipped rubbish.
Just one fly-tipper was taken to court this year by the Woodland Trust, in what is the only known instance of a fly-tipper being tracked down in the 44-year history of the charity.
The culprit was ordered to pay £200 compensation for dumping a coffee table, mattress, bed frame and children’s playhouse at Little Wold Plantation, Yorkshire.
The Trust said it finds it hard to tackle the problem because of the cost of CCTV and the scale of the land it owns, with more than 1,000 woods covering 55,600 acres across the UK.
Norman Starks, Woodland Trust UK operations director, said: “It’s worrying to see in a world where our woods face constant threats from disease, pests and development that we also have to deal with the actions of mindless individuals.
“Each year we are spending thousands of pounds clearing up other people’s waste, which could otherwise go towards creating new woods or protecting ancient woodland.
“At the end of the day fly-tipping is an illegal activity, and people need to understand and remember that it has numerous implications for our woods and wildlife.
“We all need to care for our natural environment or risk ruining it forever.”
It is not just fridges and mattresses that cause problems, with the Woodland Trust Scotland warning that even “green fly-tipping” has become a problem.
Near Livingston, West Lothian, alone, five Trust sites have seen a deluge of garden waste such as grass clippings, hedge trimmings, weeds and leaves.
Dumping green waste may seem harmless but can damage the balance of UK habitat with additional nutrients and introduce non-native species, the charity said.