I’ve always felt a deep connection with trees and have often turned to them in challenging times. In October 1998, I was 25 and living in Humboldt County, California, doing side jobs while studying at the state university. My safe haven was an 80-acre grove of giant redwoods in Freshwater Creek Forest, a place I’d go for peaceful contemplation.

One evening, I noticed some trees had been marked with orange paint. The Pacific Lumber Company had stepped up its operations in the area, devastating old growth forest. Whenever I’d seen trees marked in this way, they disappeared within weeks. Many trees were already occupied by activists – Julia “Butterfly” Hill was part-way through a tree sit that ended up lasting more than two years.

I was on a construction job when my friend Roger said: “Hey, Nate – I don’t want to bum you out, but they’re going to cut that grove today.” I wanted to drive over straight away, but decided to wait until after work, in the hope that the loggers would have left for the day.

I’d already chosen three trees I particularly wanted to protect. When we arrived that evening, only one was still standing. I later called her Mariah, after the song They Call The Wind Mariah from the musical Paint Your Wagon. She was 12ft in diameter and 200ft high – even her lowest branches were 80ft from the ground. Luckily, smaller trees had sprouted off her main trunk at the base and I was able to work my way up using those. I used a 10ft length of twine to haul my supplies up after me and kept climbing until I found a growth of branches 130ft up where I was able to make a rudimentary nest – and that’s where I spent the first night. It was drizzly and my feet were cold, but I was able to rest, at least.

Before dawn, Roger returned with more food, a 50ft rope, a sleeping bag and a tarpaulin. The loggers had already arrived. At first, their hostility was aimed at one of their own: “Ah, Joe! You got hippies in your tree again – why is it always you?” But soon an argument started over whether they should carry on cutting regardless. They felled a nearby tree, which came close enough for some of its branches to whip through Mariah’s. When I felt chainsaw vibrations, I thought my time was up, but it was all for show – they were only cutting through the sprout trees at Mariah’s base.

Things remained pretty heated during the first couple of months. Sometimes the abuse came from less identifiable sources. Once, someone drove by and fired shots, seemingly in my direction; another time, a visiting friend found her car rolled over a cliff. By then I’d established more permanent living quarters about 160ft up, and was able to take in regular provisions, brought in by local residents.

Nature also provided some intimidating episodes. I experienced heavy rain and winds that whipped Mariah back and forth, 20ft in either direction. Eventually, I built a platform 40ft lower down, where things were calmer. As the months passed, I watched ravens raise their young in a tree opposite and a family of bears collecting acorns in an oak.

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Guests would climb up using my ropes and abseil back down again. I accepted a cellphone for calling in help and a laptop that I used to finish my degree. Occasionally someone would even look after Mariah while I went for a bath. But the company sometimes sent hired climbers to perform “forcible extractions” and during one of these, a colleague fell and was lucky to escape with her life. Wary of putting anyone else at risk, I vowed to go it alone. That led to my longest stretch in the tree without touching the ground – more than six months.

Finally, I learned Pacific Lumber was to stop its harvesting plan. I descended in mid-October, just over two years after my first ascent. The transition was difficult at times – I’ve never felt more alive than I did during my time looking after Mariah.

For the next few years, I planted trees and later acquired a 45-acre virgin forest, saving it from destruction. I sit on a steering committee for The Lost Coast League which works to stop logging in nearby Rainbow Ridge. I drive past Mariah from time to time and occasionally visit. The new landowners have a policy not to cut trees of her stature, so in theory she is safe. It has been 20 years and she’s still standing, touch wood.

• As told to Chris Broughton