I felt sad that there are four hemlock and one arbutus trees will be taken down due to the new house construction in Dunbar. Among those targeted trees, there’s one hemlock which I believe the age was over one hundred years old. I measured the largest tree’s circumference was 150 inches ( at approximately four feet height from the ground). My question is how can I guess the age of the hemlock tree?
By my calculations, that hemlock might be 100 years old if it were 60 feet tall and growing a conservative 20 inches a year. These trees can grow much faster than that however and you could make a rough estimate based on its height and growing conditions. See: Tsuga heterophylla - Wikipedia This tree looks like it was topped many years ago and then developed 3 trunks as a result. I suggest that it would be a good tree to take down proactively because of the danger multiple trunks creates together with the fact that Western hemlocks (Tsuga heterophylla) are often prone to suffer from windthrow because of their shallow rooting systems. To paraphrase something Judy Newton of UBC said many years ago - forest trees do not belong on city lots.
Even if the city lot used to be forest? I suppose once its supporting neighbours are gone, the remaining tree is less safe.
Not only are forest trees less safe growing singly on small city lots, their sheer size is overwhelming. A mature hemlock can have a canopy width that far exceeds the width of a typical 33 x 122-foot residential property. From an ecological and horticultural point of view, I think a variety of smaller trees, shrubs, perennials, annuals, groundcovers and bulbs provides equivalent or greater diversity and beauty. You can't have both once a tree grows large and it becomes almost impossible to get anything smaller to grow underneath.
Tree shown is a coast redwood. These often fork at our latitude. Otherwise: How Old Is That Tree? (conifers.org)
Agree with Coast Redwood for that tree. Probably not very old, given its fast growth rate, perhaps only 30-40 years. @Ron - "These often fork at our latitude" - any idea why? They hardly ever do so here even further north at 55°N; even single trees growing in fairly exposed sites usually remain single-stem, and when in plantations, certainly stay single stem.