Thursday, 10 October 2019

Goldsmith Street: an Environmental Beacon of Hope?

Yesterday came the news that a social housing development in Norwich had won the prestigious RIBA Stirling prize. Goldsmith Street is a mix of 105 dwellings from 1-bed flats to 4-bed flats built to the iconic “Passivhaus” standard.

 The BBC website described it thus:
Riba said the estate's environmental credentials made it a "beacon of hope" and highly unusual for a mass housing development.

However, there is more to “environmental credentials” than heating energy required. There is also ecology. I noted in the background of photos accompanying the BBC article what looked like American paper birches, Betula papyrifera. B. papyrifera is a stock tree for developers, and a species that causes ecologists to grind their teeth. Unlike the native silver birch Betula pendula, B. papyrifera has essentially zero ecological value. This is because native aphids do not colonise it, which in turn eliminates an important source of food for urban birds like blue tits. You might as well (and I am almost serious) plant a plastic tree instead. 

Moribund paper birch at Goldsmith St

I walked over to have a look yesterday to confirm my suspicions. Sure enough, there are plenty of paper birches around, particularly in the central communal area described by the chair of the prize judges as “lushly-planted.” (Quoted in the EDP). I would instead describe it as a monosward of rye grass, apparently moribund trees of zero ecological value, and a token flower bed (I did see a honey bee visiting a ?Heuchera? – that was the only non-human animal life I saw on my visit). Elsewhere there were field maples, which do have a good ecological value. It is notable that the original ecological appraisal for the development (Wild Frontier Ecology 2014; available after much digging on the Norwich City Council planning portal, case 15/00272/F) nowhere invites the use of B. papyrifera.

The same article in the EDP gives the cost of the development at £17 million, for 45 1-bed flats, 40 2-bed houses, three 2-bed flats and five 4-bed flats, for a cost of about £112 grand per bedroom. (Apparently adding up to 103, not 105.) At such cost, there ought to be a few quid spare for wildlife.

Final observation, not ecological: I could not help but notice that, a day after taking the prize, the mortar was already crumbling out of several of the windows. Mix too sandy perhaps? Who knows. Such trifles obviously don’t concern the wise minds at RIBA.

Mortal mortar

Tuesday, 14 May 2019

Norfolk Big Fields 1

The first in a (hopefully) occasional series.

Question: how many metres of hedgerow were lost in the making of this nearly 100-acre field?

Bonus question: how many trees were lost in the process?

Whenever you see odd-shaped fields, there is a good chance you are looking at what was once several smaller fields. Thankfully with the excellent resource at Norfolk County Council's mapexplorer it is possible to warp back in time to see whether your suspicions are correct. Here's the first edition OS map (1879-1886):

You can see the outline of the modern field easily enough, & a quick count shows that it was originally 12 fields. Actually if you go back to the 1840 Tithe map you can see a further 5 field divisions (not shown here, but drawn in later...). Fast forward to 1945:
The field boundaries are the same as in the OS1 map: usefully, individual trees are also visible. But by 1988, the hedgerows and trees have been removed:
In the following map I've drawn the lost hedgerows back in. (Note: some of these may have been banks only. It's hard to be sure. The shadows on the RAF photograph are a useful clue.)

The hedgerows marked in blue were removed between 1840 and OS 1st edition in 1879-1886. The pink hedgerows were removed between 1945 and 1988. The yellow hedgerow was added between 1840 and 1879-1886, but was removed between 1945 and 1988.

Finally, the trees visible on the 1945 RAF aerial have been drawn in too. These were probably mature oaks.

And so it is now possible to tally everything up. Between 1840 and OS 1st edition, 950 m of hedgerows were lost, with 150 m gained, for a net loss of 800 m. From 1945 to 1988, 3070 m of hedgerows were lost. The total over the mapped period lost was 3870 m, not including the 150 m added and subsequently removed.

Bonus answer: the number of trees, probably all oaks, lost was, by my count, 26.