Very good news from the population of Festuca altissima, Wood Fescue, at Forge Dam, Porter Valley, Sheffield, UK. For the first time since 2013, many plants flowered this year.
The flowering status of this population prior to 2013 is not known, in 2013 and 2014 the counts were zero and in October 2015, I observed 13 flower heads. This is a fantastic increase, likely to be the result of the conservation efforts by the Friends of Porter Valley.
I reported in a previous post how they cleared the site from encroachment by cherry laurel, Prunus laurocerasus. I really hope to report similarly good news in a years time and if the management proves successful in the longer term, we ought to consider reducing even further the cherry laurel on this bank in order to promote Wood Fescue at the site.
Pictures of Festuca altissima, wood fescue, at Forge Dam, Porter Valley, Sheffield, UK, with inflorescences – apologise for the quality of the photography, it was a windy day! Wood fescue is the scruffy looking grass, by the way.
Urban flora fascinates me. One of the reasons is that the exceptional floristic diversity found in urban habitats challenges my ideas about wildlife and conservation. We tend to think of urban development as intrinsically adverse to biodiversity, however, re-colonisation can be quick and novel habitats can be rich and surprisingly biodiverse.
This positive aspect needs of course to be weighed up against irreversible loss of some habitats such as nutrient poor mires that can disappear and are never replaced.
But I also enjoy urban floras because so many unexpected plants turn up! and because it transforms my weekly trips to the supermarket into genuine botanical expeditions. Above and below are pictures of Filago vulgaris, the common cudweed, in a waste ground in (SK337889) Walkley, Sheffield, UK, near home. I had spotted the hundreds of tiny rosettes early this spring but couldn’t work out whether it would turn out to be a Filago or Gnaphalium uliginosum, the marsh cudweed.
Last August, I was fortunate to be shown several ponds near Catcliffe and Treeton, East of Sheffield, UK, by Bob Croxton, form Sorby Natural History Society. The area is full of history and is a fascinating example of nature recovering following industrialisation.For instance, one of the ponds visited was formed in a lost piece of land amongst spoil heaps and three railway line! At this site Persicaria maculata and Nymphoides peltata were in full bloom (see picture) and two Potamogeton species were observed, now confirmed as P. pectinatus and P. pusillus. However only one shore was prospected and other nice aquatic plants are likely to be present in the rest of the pond.
On the whole, too many of the water bodies in the area were absolutely dominated by Elodea nuttallii, an invasive species that colonised the UK from the 1970s. It’s phenomenal spread in Britain and Ireland is summarised in a paper by Simpson that can be read from the BSBI archives. It remains unclear whether this spread has caused arm to aquatic biodiversity or whether it was simply facilitated by degraded habitats.
“As a contribution to the South-west Yorkshire (v.c. 63) Vascular Plant Red Data List, a population of Festuca altissima (wood fescue) was re-found at Forge Dam in the Porter Brook Valley, Sheffield, UK.
This population was first observed in 1991, when it was seen on “On steep shady bank by path” by Ian Rotherham with the grid reference SK303849. This record for F. altissima had remained overlooked by O. Gilbert who completed ecological work in the valley (Gilbert, 2001; 2003) as well as during the field recording undertaken in the area for the South Yorkshire Plant Atlas by Wilmore et al. (2010)(Ken Balkow, personal communication, 2013).
F. altissima is a rare grass in South-west Yorkshire where it is only know from four other sites, one in the same valley, two in the Sheffield area and one between Sheffield and Barnsley (Wilmore et al 2010).
It is not rare nationally but restricted in distribution by its narrow ecological preferences. It grows exclusively on steep slopes in shaded valleys on neutral to mildly alkaline soils and is believed to regenerate very slowly, i.e. to be sensitive to mechanical disturbance (Cope and Gray, 2009; Richards, 2013).
The Porter Dam population is located in or adjacent to SK30378492, on the South bank of the Porter Brook. There are approximately 40 individual plants, large and small, suggesting a healthy and dynamic population but, unfortunately, there is no indication of abundance associated with the 1991 record and as a consequence, it is not possible to ascertain any population dynamic through time.
The 40 plants are split equally into two groups by a large specimen of Prunus laurocerasus (Cherry Laurel) and there is no regeneration under the canopy of this shrub. Cherry Laurel appears to increasingly encroach this bank of the river, potentially threatening the local population of F. altissima.
In order to minimise the risk of extinction for this localised population, I contacted the concerned environmental stakeholders, the Sheffield City Council Ecology Unit and the Friends of Porter Valley. As a result the Friends of Porter Valley have volunteered to cut back the encroaching Cherry Laurel and monitoring will be undertaken in the coming years by myself.
The rest of the valley has not been searched for systematically for other populations of F. altissima and it cannot be excluded that other locality will be found in the future. The picture below shows the vegetative diagnostic character for the identification of F. altissima. These reduced leaf blades called cataphylls are of variable length and can be observed towards the base of the stem. Please refer to Cope and Gray (2009) or to Hubbart (1986) for a full description of the plant.
I am very grateful to John Poland, BSBI (Botanical Society of Britain and Ireland) referee for vegetative identifications, to confirm the identification of the plant material sent and to Ziggy Senkar and Ann Le Sage for taking interest in this botanical findings.
References cited in the text:
Cope, T. & Gray, A. (2009) Grasses of the British Isles, BSBI Handbook no. 13, Botanical Society of the British Isles.
Gilbert, O.L. (2001). Ecological survey of the Porter Valley. Sheffield : Friends of the Porter Valley.
Gilbert, O.L. (2003). Plants in the Porter Valley and their Ecology. Sheffield : Friends of the Porter Valley.