They're designed by Nigel Ross and this is what he says on his website:
The love of the outdoors led me to working in various forestry related employment and eventually running my own fencing dyking and forestry business on Arran.
My art developed from this background with the rhythms and energy of nature being an inspiration and by the mid-nineties I was working fulltime as a sculptor and maker.
I sculpt from lengths of fallen trees creating abstract forms sometimes with a functional element. The sculpture, sculptural benches and furniture, bridges etc are situated in woodlands, parks, gardens, schools, hospitals, gardens, and new developments across Britain, Europe and USA.
It's a good thing these pictures have come out so small because really you need to go to his website and admire properly. The twist in the snow in particular.