The study shows that people in the US and other developed nations
are spending far less time in nature than ever before. Oliver and
Patty tested trends in nature participation in 16 time series in the
categories of visitation to various types of public lands in the US,
Japan, and Spain; number of various types of game licenses issued;
amount of time spent camping; and amount of time spent
backpacking or hiking.
 
The four activities with the greatest per capita particpation were
visits to Japanese National Parks, US State Parks, US National
Parks, and US National Forests, with an average individual
participating 0.74-2.75 times per year. All four are in downtrends
and are losing between 1% and 3% per year. The longest and most
complete time series show that these declines in per capita nature
participation typically began between 1981 and 1991, are losing
about 1% per year, and have so far lost between 18% and 25%. 

Oliver's and Patty's concern is that less contact with nature is likely
to translate to less support for the environment in future generations.