Botanical Notes, Ipsley Alders, Redditch, 4th August 2012
Ipsley Alders’ ecological interests were first recognised in the mid 1960s when Fred Fincher came across the site during his Ecological Survey for the Redditch Development Corporation. It has been reasonably well covered by survey work since, with fairly intensive botanical surveys in most subsequent decades.
Its principal interests lie in its soils, which include fen peat and the associated plant communities. Habitats and communities include open water, swamp, fen, wet grassland, unimproved mesotrophic grassland, alder carr and plantation woodland, all of which were sampled during the course of the field meeting. The flora is diverse and in the period 1966-2011 267 species were recorded.
The current survey recorded a total of 195 species of which 166 were of species already known from the site. This represents a 62% rediscovery rate. This is reasonable, given the extent of the survey and the time of year. Perhaps only 25-35% of the area was covered in the current survey and it largely avoided the peripheral woodland zones.
|Ipsley Alders||No of Species|
|4th August 2012||195|
|Species not refound||101|
|New species 2012||29||15% (day list)|
Table 1. Species numbers at Ipsley Alders
The jewel in Ipsley’s crown is its diverse calcareous fen community. The majority of the wetland is now dominated by a M22 Juncus subnodulosus-Cirsium palustre fen-meadow community. This is by a considerable extent the largest such fen community in Worcestershire. It has spread noticeably during the course of the past 30 years. Other scarce species of the fen, which occur here in some abundance, include Fen Bedstraw, Galium uliginosum and Brown Bent, Agrostis canina. The latter species had surprisingly not been recorded at Ipsley before. I suspect it was likely present in small numbers but overlooked. Within the fen there are extensive stands of Hemp Agrimony, Eupatoria cannabinum, which probably represents a community or sub-community not circumscribed within the NVC (National Vegetational Classification). Unfortunately for the entomologists, the peak flowering period of this rich nectar source was well over.
As Ipsley is a well recorded since the 1960s, it is worth comparing this survey’s results with past records. This enables insights into the ecological processes on site. Given the extent of the survey, any gains in species are potentially more significant than losses. For instance, amongst the 101 species not rediscovered, there is a vernal group of 24 species, which would have been missed in August.
|Habitat||pre-2012 only||2012 only|
Table 2. Habitats of Species either novel to the site or not rediscovered
|Bird food -berries||9||31%||8||1|
|Animal bodies incl. human||10||34%||1||9|
Table 3. Status and dispersal mechanisms of the species new to the site
Of the 29 new species to the site, 12 (40%) are either alien to Great Britain or are not native locally. The high proportion of alien additions is not unusual in habitats close to urban centres. Most of the additions into native habitats, as occurs here, tend to be either water plants or woodland species.
Grassland plants represent a large proportion of those not relocated. Even allowing for seasonality and grazing regime, the number and quality of the grassland species not rediscovered e.g. Sawwort Serratula tinctoria, Devils Bit Scabious Succisia pratensis and Sneezewort Achillea ptarmica suggests a possible deterioration in the grassland resource. Whilst some of the losses may be due to the spread of fen communities, the species loss is marked enough to indicate that a more thorough investigation of the situation should be undertaken.
The wetland/fen species assemblage seems fairly stable. The proportion of species acquired compared to those not rediscovered suggests a fairly stable assemblage. The acquisitions may indicate a strengthening of this resource.
The proportion of pond losses is very high. The pond was not surveyed with a grapnel so the losses may not be quite as dramatic as suggested. Despite this there have been significant losses but also moderate gains. Species turnover rate in ponds is often high. Despite this, the species variation here is much higher than I would anticipate for a pool of this size with a restricted and mainly unimproved catchment. Once again the figures suggest that a more thorough investigation of the losses here is warranted.
Woodland was the least surveyed habitat on the day in terms of time and area, so the high number of not found species is considered not significant. This is in marked contrast to a high acquisition rate of new species which should be considered a “real” phenomenon. Most of this group are genuine immigrants. Many of the species are plants of secondary woodlands and their acquisition here can be considered to be natural species accumulation as the peripheral woodlands (mainly 30-40 years old) age. Secondary woodland species tend by definition to be good dispersers. The majority take a ride on animals, including human footwear and clothing.
Species accumulation is however not confined to secondary woodland sites. I have witnessed high acquisition rates of woodland species in urban and urban fringe woods in Worcestershire on a number of studied woods. The phenomenon seems to relate to urban landscape management in the second half of the 20th century. The explosion in horticulture plus urban landscaping, particularly associated with new builds, over this period has brought considerable numbers of woodland species, very many of them alien to the British Isles into our built environments. Each generation of landscape architects has produced a new wave of fashionable species. Redditch exemplifies this phenomenon in extremis. The landscape architects of the Development Corporation inadvertently created a vast ecological experiment with the millions of alien woodland plants they introduced into a lowland farmed landscape. The accumulation of woodland species at Ipsley Alders is a part of the legacy. The end point of this massive inoculation is yet to be determined; we still lie close to the beginning of the experimental time line.
A common feature of this woodland species accumulation is the high number of berry producing plants involved. The vast majority of the dispersal here is by birds. Nine of the new species (31%) are berry producers and mostly alien. Berries for birds may be popular but it is having a knock on effect on our native woodlands. Those close to urban centres are most at risk but it is quite possible that in a couple of hundred years that the species assemblage of all Worcestershire woodlands may be quite different. I suspect that cotoneasters will be found in most Worcestershire woodlands before too long.
The most surprising addition was Thin-spiked Wood Sedge, Carex strigosa which is almost confined to ancient woodland sites in the county. It was growing in an area of secondary woodland by a path and judging from its size was a relatively recent colonist. There are a couple of locations in ancient woods in the Redditch area but there appears no natural mechanism for dispersal to Ipsley Alders. With no sign of recent disturbance (long buried seed) my best suggestion is a conservation workparty who had picked up seed on boots or tools at a Wildlife Trust ancient woodland reserve to be deposited here inadvertently.
The grassland acquisitions are likely to relate to animal husbandry. Yellow Rattle, Rhinanthus minor and Meadow Barley, Hordeum secalinum have most probably entered the site as hay, stock feed. Indeed in the case of the large heavy seeded Yellow Rattle it was the most significant dispersal agent in traditional farming.
Only one species, Greater Spearwort, Ranunculus lingua was considered a deliberate introduction. It is in my experience always a deliberate introduction. Some folk seem unable to throw aquatic species into the compost when clearing out ponds, always seemingly to prefer to give them a chance in the wild. It’s amazing just how quickly newly dug pools even in remote areas can acquire alien water plants.