This is the central question in Richard Louv's book, "Last child in the woods," and this concern is shared by the broadcaster Sir David Attenborough.  As Attenborough says, "all children start off being interested in the natural world, it's deep in our instincts...".    Children may have theoretical knowledge but not touchy-feely experience. As Louv explains, " children today are aware of global threats to the environment but their physical contact, their intimacy, with nature is fading."

Nature-deficit surveys
Natural England did a survey recently in which they examined changing relationships with nature across generations and they found that fewer then 10% of children now play in natural places (such as woodlands and heathlands) compared with 40% of today's adults who did so when they were young.  The BBC Wildlife Magazine carried out another survey which found that many children now cannot identify common species such as bluebells and frogs. Other surveys show that this is not just a British problem: the American Journal of Play, surveying thousands of mothers across the world, discovered that the number of those reporting their children "exploring nature" were lowest in China, Brazil and Indonesia.  Playing in wild areas has been shown to have a positive psychological impact - a National Trust survey of 3,000 adults revealed that their most prominent happy memories were of being outdoors in the natural world and a large number cited building dens as a particularly happy memory.

Causes of children being "stuck inside"
Computer games and TV are often blamed for children staying indoors but there are other factors - for example being driven to school rather than walking keeps children from the outdoors and the almost obsessive fear of abduction, which many parents have, often stops children being allowed outside.  It may also be that pressure to do more and more with school and outside means that there is less genuinely free time for children when they have to make their own entertainment.  At a recent woodlands.co.uk conference of owners of small woodlands it was suggested that owners should think of things for their children to do in woods, but one of the participants pointed out that once in a wood children will find their own activities and this process of discovering what's interesting and what there is to do is itself important.  Let them discover nature rather than spoon feed it to them was the message of that discussion.

What are the consequences of a "nature deficit"?
"Keeping an eye on children" is all very well but it has left a whole generation more ignorant of what goes on in the natural world and out of the habit of exploring and discovering.  This has consequences for them personally including much higher rates of obesity, suffering form attention disorders and more likely to experience depression.  In a bigger-picture way, though, it will surely have enormous consequences for their attitude towards nature when they grow up - if they haven't experienced the miracles of the world around them they will be less likely to make sacrifices to preserve woodlands and wild spaces.
But all this assumes that the nature deficit is limited to children - adults surely suffer from it too.  Many, many or our buyers of small woodlands give as driving motivation that they want to "get away from the screen" and get "back to nature".

What can be done about it?
It's hard to know how to persuade the nation as a whole to move towards more outdoor play, but individually families can choose more activities in woodlands and wild areas.  There are many structured activities which get people into woodlands such as Centre Parcs holidays and "Go Ape" walkway adventures.  Recent excitement about the Forestry Commission woodlands shows how much people value public spaces, even those who don't visit very often.  The threat of wholesale sell-offs has made everyone focus on how important woodlands are for our wellbeing, so hopefully the recent publicity will make people spend more time in open woodlands - whoever owns them!