u/Petaaa

Yesterday I promised a post worthy update so here you go

In the 2010 Irish tree register audit the giant sequoia girth champion was found in Montalto estate with a whopping 8.55m girth at 1.5m and 39m tall

I managed to get a street view of it and its thinner but still very large siblings…and was able to get their coordinates

From the panorama I could apply tan method and use ref objects to get height. The ref objects can also give girth.

Now bear in mind the image was from 2020 so these trees are all bigger now

Champion tree girth 9.1m height 44m
Tree 2 girth 6m height 40m
Tree 3 girth 5.5m height 39m

https://www.monumentaltrees.com/en/gbr/northernireland/down/38897\_montaltoestate/

Ok now on to their cousins the taller coast redwood (120m potential) which was introduced to Ireland a good bit later, the reasons these are not topping our lists is that they have not been planted in groves (rather as individual specimens) however I know a few locations where they have been recently.

Kilbroney rostrevor
Hillsborough Castle (likely tallest grove)
Hillsborough Forest (by the wall on long trail)

And the one I have most data for sir Thomas and lady Dixon park Belfast
4 planted 14m tall in 2015
24m in 2026
Growth rate of nearly a metre a year (only eucalyptus matches this) could be up with our tallest trees in 20 years…

They aren’t the only trees growing rapidly there too… a caucasian fir, noble fir and two Norway spruce have overtaken the giant redwoods as the tallest trees in the park since the survey. One spruce is now 5m clear of the tallest redwood at 38m tall but is wind damaged.

https://www.monumentaltrees.com/en/gbr/northernireland/antrim/38922\_ladydixonpark/

Ok I got to briefly visit Belfast castle and could tell by sight that the “46m” redwood recorded in the Belfast tree survey was a typo it was certainly 36m then. Good news is thought the entrance coast and giant redwoods 38m entries were legit.

I want able to measure as was on tight schedule but can estimate that in 2019 (google street then applying tan method with coords from multiple points, plus reference object extrapolation ) that the entrance redwoods are now 43 and 41m with the giant now being taller than the coast (unusually). The misentered redwood I estimated the same way as 39.3m in 2019 imagery. So all are growing and all likely over 40m tall today. From my visit the entrance giant sequoia may well be 46m tall today. https://www.monumentaltrees.com/en/gbr/northernireland/antrim/38886_cavehillcountrypark/

Now our “giant sequoia forests “ what remote region do these exist you may ask. Well the less known areas of finaghy to hilden Lisburn and holywood to Bangor. The sequoias are up there with most common tree species in these areas and the 3d loader imaging has led to some extremely tall specimens in the hilden to finaghy stretch in particular. This also goes up the castle reach hills towards Drumbo. The reason I’m calling these forests is that they might be the a top3 most common canopy tree species and I am now seeing naturally germinated saplings of the species in these areas, which is something I’ve seen claimed is not possible in the uk as sequoias “need fire” to germinate, well I’ve germinated them at home as an experiment in natural ni conditions so that’s wrong…

The irony here is with their growth potential of 70-100m tall we may have a more impressive skyline in belfasts suburbs than the city itself.

Also the tallest trees in this band were 37m and 36m tall one by rathmore school and the other beside apartments in dunmurry however it had a thin top so are likely taller in reality due to what lidar can pick up… (for reference the mt Stewart redwoods that are 40 m plus show up as only slightly taller in lidar) for the holywood to Bangor band none exceed 32m bar the giants in Bangor castle is

Ok from using satellite data to track down the mt Stewart champion eucalyptus regnans I realised I could find and update giant trees measurements while not trespassing of using a tonne of fuel, that being said I did go to a few of these to verify my measuring methods

New estimation technique use google earth pro (on flat land the 3D models of the wider Belfast area and Derry are accurate bar missing some thinner tree tops)

This allowed me to verify my mt Stewart measurements and add a few more I couldn’t measure due to forest density (38m red cedar and another 41m doug fir discovered near the first one I measured). The data also made me revisit the redwood at the house. It came out as 40m tall a 2m increase to my first measurement (it was one of my first times using a climoneter so turns out I undersold it) https://www.monumentaltrees.com/en/gbr/northernireland/down/6636_mountstewartgardens/

Antrim castle a few trees approx 35m flagged, have visited found measured and identified two of the three. (One other side of park). First a very thin Douglas fir 37m and then nearby it a massive coast redwood 35m (biggest I’ve personally seen) https://www.monumentaltrees.com/en/gbr/northernireland/antrim/6595_antrimcastlegardens/

I’m going to have to visit Belfast castle as the trees on Google Earth are consistently 14m less than the survey. That being said it’s on a slope which supposedly breaks the model.

In Lisburn I have discovered a 36m giant redwood on bells lane with a potential 35m one around the corner from it.

I then remembered travelling to my grandparents house going past dunadry and templePatrick seeing a couple of big redwoods. Dunadrys is a private residence but Google Earth gave me a 34m get redwood and 34m Douglas fir. Templepatrick temple house had a 34m giant redwood as well

https://www.monumentaltrees.com/en/gbr/northernireland/antrim/hd1

At this time I noticed that Derry had 3d trees and realised how poorly it had been recorded. Brook hall arboretum looks awesome if you are up there. Sitka spruce of 39 and 35m, a silver fir 40m and 31 and 32m giant sequoia spotted. https://www.monumentaltrees.com/en/gbr/northernireland/londonderry/39453_brookhallestatearboretum/

This led me to investigate the county’s other big silver fir in fact the oldest on the island, however it did not have 3d coverage…but i found a solution (using my background in maths and tech). I had the trees rough coordinates and i gad goggle street view. Turns out some legend had shared pics of the tree plus its plus photos exact location to google with elevation data well covered I could estimate the trees height and girth with maths…it’s now over 40m again https://www.monumentaltrees.com/en/gbr/northernireland/londonderry/38950_theoaks/

This kind of ended up making a giant leap in documenting and updating trees…

It allowed to update tempo manor current tallest recorded tree in ni now 53.8m from an image in August 2025, It’s neighbouring spruces were 43.5 and 48m respectively and sequoia there also 43m clearly an amazing place https://www.monumentaltrees.com/en/gbr/northernireland/fermanagh/38880_tempomanor/

Unfortunately no images to use on Caledon
But there was on the Aughertaine spruce now 51m by 2025 images https://www.monumentaltrees.com/en/gbr/northernireland/tyrone/38895_aughertaine/

I then realised I had a lot of the coordinates for the tollymore arboretum trees and an image taken in the carpark that had all of them in view…
44-47m Douglas fir (maybe ni champion although plenty more unrecorded)
2 giant redwood 42-46m (twin pair)
One giant red wood 39m
Another 38m
Monterrey pine 42m (maybe a champion tree)
Forestry data also suggests Douglas fir and Sitka spruce on the river trail potentially over 40-50m tall

https://www.monumentaltrees.com/en/gbr/northernireland/down/6713_tollymoreforestpark/hd

I also have a Castlewellan giant Redwood update, the charity which is called friends of Castlewellan and Anglesey arboretum gave me the three latest measurements as of 2021 36m for the multi stem 39.9 and 42 for the twin pair. They are likely all a metre taller now,
I still suspect there are comparable trees around the lake forced to grow faster due to density, I know there are redwoods, Douglas fir and spruce there.

https://www.monumentaltrees.com/en/gbr/northernireland/down/7869_castlewellannationalarboretum/

So now the places to check are the actual forests of Castlewellan and tollymore, Hillsborough castles pinetum (densely planted so may have grown rapidly in last decade), colebrook estate, baronscourt estate, drum manor, glenariff gosford and most intriguingly Caledon estate who confirmed all three of their 50m plus tall trees still stand. Also less known forests that have not been recorded.