That entails eradicating pests and weeds, developing tracks, and labelling more than 140 trees to make the walks educational for visitors.
"The early settlers had the vision and wisdom to set aside this valley and leave the bush untouched because they considered it to be an ideal water catchment for the growing village," Steve said.
A keen hunter, tramper, and nature enthusiast, he said the reserve was unlike anywhere else.
"I've been in a lot of forest in New Zealand and this would have to be the most diverse and beautiful forest I've ever been in."
He credits the Department of Conservation for allowing the community to establish pest-control lines to help eradicate possums, feral cats, hedgehogs, rats, stoats, weasels and fallow deer.
Today the results of this work can be heard through the explosion of bird song echoing across the valley.
Mary said the chorus of birdsong came from tūī, pīwakawaka (fantail), riroriro (grey warbler), kererū (wood pigeon), korimako (bellbird), miromiro (tomtit), ruru (morepork), kōtare (kingfisher), pīpīwharauroa (shining cuckoo), waxeye, chaffinch, the Australian import the eastern rosella, magpies, thrushes, blackbirds and the distinctive call of the New Zealand kārearea (falcon), high above the forest.
Other unique elements throughout the bush include the different tree species that grow close together.
"We are so proud of this bush," Steve said.
"The community is right behind us.
"We have the time and experience to carry out this work.
"I know a lot of farmers don't have the time but they are supporting, helping and encouraging us."
He said they are motivated to help leave the bush in pristine condition for future generations to enjoy.
"This bush belongs to New Zealanders.
"The future belongs to our kids and grandkids and everyone can come along to this bush.
"You don't need any permission and it is not land-locked, you just come through and enjoy it.
"That's the magic of it, it is forever."
There is a Rangiwahia Scenic Reserve Givealittle page. https://givealittle.co.nz/cause/rangiwahia-scenic-reserve
For more information on the area visit irongates.co.nz and ManawatuNZ.co.nz