Nearly half of Sherwood's remaining oak trees are dead or dying and the rate of death is accelerating from an average of one a year for the past 20 years to five a year now mainly because of old age. 
Forest rangers predict that this rate could double in the near future.  When Robin Hood hid out there with his band of men in the early 13th century the forest was dense. 
Now less than 1,000 oaks remain -- some of which would have been saplings in Hood's era -- and most are between 300 and 800 years old because of a planting hiatus that lasted between 300 and 150 years ago.
In a bid to rectify the problem, the management at Sherwood just north of Nottingham in central England is bidding for 50 million pounds from a national lottery fund for a replanting programme to revitalise the woodland and bring back tourists.