Works in Horse Close Wood

In a meeting with National Grid in early March this year it was agreed that the works area within the wood should have temporary fencing, which would serve to protect surrounding trees from damage.

At subsequent meeting in mid June it was again agreed that the fencing of the works area should be set sufficiently back from the edges of the Glade as to avoid inadvertent damage to the surrounding trees.

When I saw the preparation of the Glade for the works, I was happy that it had been cleared well, but didn't notice that the eastern edge of the glade was not fenced off. [I have edited my account here, as my recollection was that the eastern edge of the glade was fenced off. I was incorrect in that.] The sharp edge of the cleared area, nevertheless showed the edge of the woodland. On the 23rd July, However, work was in progress removing the underground cables at the Glade. I was disturbed to find that the huge amounts of excavated soil had been stockpiled within the part of the woodland behind two Small-leaved Lime trees at the woodland edge. This is entirely contrary to the agreeement reached in the meetings with National Grid and their contractors and cannot but cause harm to the wood.

The photographs below each show a Small-leaved Lime tree at the edge of the Glade which should have been protected by fencing. The high mound of soil is within the woodland behind the Limes.

View E to a Lime with a mound behind

View SE to two Limes and a mound behind

View NE to a Lime and a mound

Lake water mid July

I did my lake water sample on the 16th.

Over the previous month much Fennel-leaved pondweed had been removed from the lake and I found that a blue-green bacterium, Aphanizomenon flos-aquae, had come to dominate the open water.

This last happened in 2018, when the bacterium was so abundant that it made the water murky until late August. The Long-spined waterflea was absent when the bacterium dominated, but returned in late August. I speculated that the clearance of waterweed had disturbed the sediment on the lake bottom, increasing water fertility and leading to the bacterial growth. So I have been looking closely at water clarity this year. I was disturbed to find a decline in clarity in June, but pleased that this did not continue into July, as it did in 2018. Nevertheless, I found not a single waterflea this July, so there remains a risk that water quality will decline further.

This is not a trivial matter, as blue-green bacteria can be toxic and those doing water sports, and the anglers, could be at risk.

The chart below gives the water clarity for each of the last four years. It shows the drastic reduction in clarity between June and July 2018 and the arrested decline this year.

July 10th

Today I did the monthly bird count.

The Mute swans are now down to a pair of birds with their eight well-grown cygnets. The lake had a good growth of Fennel-leaved pondweed, despite much having been hauled out by the watersports people. This was being fed upon by the usual Coots. Sixty-five Coots was the third highest July number of the 35-year study, showing that the lake water quality remains good. Most of the 95 Canada geese and 90 Greylag geese were on the lake feeding on waterweed, showing that the grassland of the golf course and great field was not such attractive fodder this year. The Egyptian geese In July, Black-headed gulls that have been unsuccessful in breeding begin to return to the lake and there were 35 birds. Unusually, there was a recently fledged youngster, presumably reared in a nearby area, such as the Wetland Centre. I didn't spot the pair of Common terns, but they were seen regularly in the following days, so still claiming the lake as their territory.

There's now quite a long list of plants growing in the northern part of Horse Close Wood where the Ash trees were cut back in the winter, however the area is dominated by a thick growth of Bramble, Nettle, Hybrid bindweed and Ivy. In most places the other species were struggling for light. Several Ash trees have been coppiced successfully and are putting up vigourous growth, as are a couple of poplars, a few Hawthorns, Wild cherries, Elms and a Horse chestnut. I failed to spot the Hybrid hawthorn under the bindweed and there are no new Oaks to be seen. A Spear thistle and pair of garden escapes (an Argentine vervain and a Large-flowered evening primrose) added colour. Common figwort and Great willowherb were the only wetland species.

The Water-plantain in the brook

Watercress and Great willowherb were flowering in the upstream part of Wimbledon Park Brook, but the real news was in the brook downstream of the cafe. Looking upstream from the bridge, I saw a single plant of Water plantain, an uncommon plant in our area and the first sighting in the public park. It occurs in a few places on the River Wandle. Back before the public right of way across the golf course was closed off, I knew it from the ditches south of the lake. As far as I know it's not found on the golf course any more, but its arrival here suggests that the seeds have come downstream from the lake. Another new species for the public park was near the tennis courts in the far eastern corner: a single clump of the grass Crested dog's-tail. This species is indicative of high quality meadowland, but one plant doesn't prove anything!

National Grid's contractors were working in Revelstoke Road just outside the park entrance. I took a last look at The Glade in Horse Close Wood before National Grid's contractors get going on removing the cables there. I found two new species, bringing the cumulative total seen there since Summer 2016 to 125. These were single plants of the grasses, Tall fescue and Red fescue. Many of the species seen in earlier years have now gone, displaced by taller-growing vegetation. Because of this, the number of species seen in July was just 35 and the number seen at any time in 2020 was 48.

The park seems to have been opened at around 07:30, which is when I spotted the first walker. The two children's play areas had been opened a day or two ago and were now unlocked, although some out-of-date notices suggested not! The worst of the weeds had been cleared before the re-opening. Microbee Tree surgeons were working on the Lombardy poplars at the northern edge of the stadium. This is not best practice, as many bird species are still nesting and it's impossible to spot every nest in such situations.