Naturalist Steve Backshall and Lost Gardens of Heligan co-founder Sir Tim Smit have called for more "greenlightenment" to put nature education at the heart of school curriculums.
The government has been consulting on a new natural history GCSE. Sir Tim called it a "seismic moment for British education", adding "a deep understanding of the natural world is fundamental to humanity's future".
Backshall, who hosted the Wild Heligan experience to excite young people about wildlife, said: "I see every day how nature revitalises, restores and fills people with joy."
A survey by Heligan of 1,004 parent and child groups across England found 55% of children had never climbed a tree.
Backshall said: "We can get so much from the wild world, but now more than ever the wild world needs us. Young people who are engaged with nature will be happier, healthier and more likely to take on our planet's problems."
Sir Tim said: "It is our responsibility to equip the next generation with the tools to protect nature so it doesn't become history." He added children had not lost their interest in nature but had lost opportunities to experience it.
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The survey found "ordinary contact with nature" was unfamiliar to many children. It also found 61% of children had never collected a conker or camped in a tent.
The research also found 34% of children asked said they would definitely choose the proposed natural history GCSE if their school offered it, with another 41% saying they probably would.
The government said, if brought in, the GCSE would "ensure that children are equipped with the highly sought after skills for the workforce of a changing world" and could help reduce the number of young people not in education, employment or training.
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