Foxley Wood

Yesterday we headed to Foxley Wood, which is about 30 minutes NW of Norwich, on an Ecology field trip. The purpose of our visit was to learn about coppicing as a management strategy, ancient woodland indicator species and to have a go at some plant identification. Unfortunately, we didn't do much of the latter due to the terrible weather.

Foxley Wood is Norfolk's largest remaining ancient woodland and over 350 flowering plants have been recorded on the site. This includes one of the UK's least known native trees: the Wild Service Tree Sorbus torminalis, which is rather inconspicuous for most of the year, until it becomes covered with white blossom in late spring and its leaves turn a coppery-red colour in autumn.

Coppicing is an ancient woodland management technique that is used extensively at Foxley Wood in order to maintain a matrix of woodland growth stages to benefit biodiversity. Coppicing involves felling the same stumps near ground level and then allowing shoots to regrow from that stump, whilst also leaving certain large trees (standards), typically mature oaks. Where coppicing occurs, the woodland is often divided into blocks and coppiced on a rotational cycle of about 15 years in order to maintain a variety of woodland ages. Historically, coppicing was used to produce numerous straight stems from each coppiced stump, which would then be used for posts, fencing and firewood.

Coppiced Hazel tree showing the numerous new stems
growing from the coppiced base.

During our wander around Foxley Wood, it was really interesting to see the different ages of coppice blocks and to be able to compare and contrast it with the ancient woodland and grazed areas. This allowed us to see first hand the effects of the different management practices and I found it particularly interesting to see the stark differences in the under storey between the coppiced areas and the ancient woodland, and also how the plant assemblages changed too.

Coppiced woodland with standards (left) compared to Ancient woodland (right)
Very different under storeys in the two areas with it being much denser in
coppiced areas and much thinner in the ancient woodland.

One of the main aims of our trip was to learn about ancient woodland indicator species (AWIs), and despite the weather, we managed to locate quite a few of the early flowering AWIs that are found at Foxley Wood. The term ancient woodland refers to land that has had continuous woodland cover since at least 1600AD, and AWIs are a group of species, typically vascular plants (but also some invertebrates and lichens), that are more common in ancient woodland than in recent sites and display a number of characteristics:

1. Rarely occur outside of woodland, and if they do, then they indicate a long temporal continuity of woodland cover.
2. Capable of growing in shade, though don't necessarily grow exclusively in shade.
3. Reliable indicators, in at least part of the region being surveyed.
4. Slow colonisers - normally have a small seed shadow, meaning that seeds don't disperse very far each year, so colonisation of new areas is slow.

There are approximately 100 plant species that are thought to be good indicators of a woodland's age, and when a woodland shows more than about 10 of these indicator species, it is likely that the wood has existed for a long time. AWIs vary between the different regions of the UK and finding one AWI species alone is not enough to determine a woodland's age, but finding combinations of AWIs suggests different things about the woodland's age.

A carpet of Honeysuckle (Lonicera periclymenum) - one of the 12 ancient
woodland indicator species that we were looking for.

While at Foxley Wood, we were on the lookout for 12 AWI plant species, and despite the dreary weather we managed to find 7 of them. One of the AWI species that we managed to find was Wood-sorrel Oxalis acetosella (also known as Common Oxalis). The Oxalis part of the binomial is due to the presence of oxalic acid within members of the genus, while acetosella is in reference to its sour taste. Wood-sorrel is a small plant that flowers between April and May. It has white flowers which droop down until the dappled sunlight reaches them, upon which the flowers tilt upwards. Each flower has 5 petals and tiny, purple veins. The leaves of Wood-sorrel are trefoil and fold down into a tent during the night, but flatten out again during the day.

Wood-sorrel leaves (left) - © Phil Dowling & Wood-sorrel in flower (right) - © https://bit.ly/2FmzKIV

Apparently, all parts of Wood-sorrel plants are edible, and the leaves (fresh or dried) are often used in alternative medicines. The leaves are said to have diuretic, antiscorbutic and refrigerant actions, and a decotion (an extract made by mashing, then boiling the plant) made from the pleasantly acidic leaves is used for high fevers, both to quench thirst and allay the fever itself. Although it may be consumed freely, excess consumption should be avoided as the oxalic salts are not suitable for all constitutions and may have unwanted effects.


Further reading:

• JNCC publication on "Coppiced Woodlands: their management for wildlife"
• English Nature "Ancient Woodland"
• Ancient Woodland Indicator Species

Dendrocoelum lacteum

Dendrocoelum lacteum is one of only 12 species of freshwater triclads found in Britain and Ireland.

The Tricladia are named as such due to the three main branches of the alimentary canal. Tricladia are a sub-order of the Turbellaria which sits within the phylum Platyhelminthes. Turbellaria are a globally widespread group, with new species continuing to be described. They also occur in such large numbers in some lakes that they are considered a significant components of aquatic communities.

Due to their dorso-ventral flattening, Triclads are commonly referred to as "flatworms". The adults range in size from approximately 8-15mm in length. All except one of the 12 British & Irish (B&I) species are normally found in the surface waters of lakes and streams, where they feed on a variety of prey species, including isopods (woodlice etc.), gastropods (snails and slugs) and oligochaetes (worms). Each species has its own realised niche though, which has evolved to allow coexistence. For example, D. lacteum feeds mostly on isopods, while Dugesia polychroa prefers snails and Polycelis nigra and Polycelis tenuis favour the oligochaetes.

Illustrations of 11 of the 12 species of triclad that have been found in Britain & Ireland.
Taken from "A key to the freshwater triclads of Britain & Ireland"
by T.B. Reynoldson and J.O. Young.

British freshwater triclads can be categorised into two groups: those that are found in lakes, and those that inhabit streams, however this distinction is not absolute. When they are found in lakes, triclads prefer sheltered, stony shores and are most abundant in shallow waters up to a depth of 30-35cm.

On the continent, stream-favouring species are spatially separated downstream, with Crenobia alpina (and sometimes Phagocata vitta) found near the source, with Polycelis felina occurring further downstream, followed by Dugesia gonocephala (not recorded in B&I). A similar pattern of distribution can also be seen in Britain, with P. nigra inhabiting the lower reaches of streams and rivers, however C. alpina and P. felina can cause complications as both occur along the length of short streams (although there is often spatial separation related to stream gradient).

P. nigra/tenuis (left) & D. lacteum (right) 

Triclads are interesting in terms of their reproduction, because different species reproduce either sexually, asexually (by fission & regeneration) or both! Asexual reproduction is though to have evolved secondarily in the Dugesiidae and Planariidae families, to allow reproduction even when food is limiting. Another interesting thing is that pseudogamic reproduction is common among several species. This is where sperm is necessary to stimulate egg development, but no male chromosomal material is incorporated into the egg nucleus!

Of the lentic species (those living in still waters such as lakes), there are two main types of life histories: D. lacteum, Bdellocephala punctata and Planaria torva are 'annuals' that die after their spring breeding season, meanwhile P. nigra, P. tenuis, D. polychroa and D. lugubris don't die after breeding. The latter group exhibit iteroparity, breeding numerous times during their lifespan, while the former group exhibit semelparity, which is where they breed once and then die. No one really knows why these two life histories have evolved, but there are many different hypotheses, including a relation to their feeding strategies or a reduction in interspecific competition.

Dendrocoelum lacteum showing the 2 'eyes' in the top left and the internal
structures throughout. Specimen collected from the River Yare.

According to the 2009-2011 Biodiversity Audit, 5 species of triclad have been recorded on the UEA campus. One of these is Dendrocoelum lacteum, a pale and fairly large species of freshwater triclad, and one that I recently found a specimen of in a still part of the River Yare. It is a lentic species which ranges between 14-25mm in length. In the UK, it is quite common and is most frequently found in productive lakes where the calcium concentration is at least 10mg per litre. D. lacteum predominantly feeds on Asellus isopods and the triclad's distribution is closely linked with that of its prey, providing D. lacteum with a "food refuge". In order to capture intact prey, D. lacteum moves faster than the Planariid species, and has a shallow anterior pseudo-sucker. Its distribution in Britain is mostly curtailed by interspecific competition and has not yet spread into northern Scotland or the western islands.

Further reading:

• "A Key to the Freshwater Triclads of Britain and Ireland with notes on their ecology" by T.B. Reynoldson and J.O. Young - https://bit.ly/2FcoUVV

Marchantia polymorpha subsp. ruderalis

Liverworts are non-vascular plants which, along with the mosses and hornworts, make up the bryophyte group. Of the different bryophytes, there are 763 species of moss, ~300 species of liverwort and just four species of hornwort in Britain and Ireland. Liverworts are split into two main groups based on their structure: leafy liverworts, which have leaves and a stem, and thallose liverworts, which don't have leaves or a distinct stem, but have flattened, lobed, leaf-like bodies called thalli.

Hornworts are superficially very similar to the thallose liverworts, and are often regarded as 'honorary liverworts', however they differ slightly to liverworts in their reproductive methods and structures, whereby asexual reproduction occurs primarily via fragmentation as lobes separate off from the main part of the thallus. In hornwort sexual reproduction, archegonia (female part) and antheridia (male part) are produced in rows just beneath the upper surfaces of the gametophytes and the sporophytes grow into long, horn-like structures, with the sporangium located at the tip. These sporophyte 'horns' are very long lived (unlike liverwort sporophytes) and can grow quite long. Hornworts are also distinguished from liverworts by the presence of stomata and cuticle, which is also seen in the mosses.

The hornwort Anthoceros agrestis © Štephán Koval (2010) - https://bit.ly/2r7UuzU

In liverworts and hornworts, reproduction occurs via the alternation of generations where the gametophyte stage is dominant (unlike other plants such as clubmosses and ferns which have dominant sporophyte stages) reproduction can occur sexually or asexually. The way in which liverworts reproduce also depends on whether they are leafy or thallose. The sexual reproduction of liverworts occurs predominantly during the winter months when conditions are wetter. This is because their spore dispersal is water dependent.

Leafy liverworts always have two rows of partially overlapping 'leaves' which don't have midribs, but do often have folds and lobes (unlike the 'leaves' of mosses). Rhizoids are present on the underneath of some underleaves, which help anchor the plants. The male and female reproductive structures (archegonia and antheridia) of leafy liverworts are inconspicuous, and are produced in cup-like structures made out of some modified leaves on separate plant bodies. At maturity, the sporophyte capsule is pushed out from among the leaves as the seta (stalk) elongates.

Sporophyte development in leafy liverworts.
Illustration © Mosses & Liverworts of Britain & Ireland/British Bryological Society

Some of the best-known species of thallose liverworts are in the Marchantia genus. Asexual reproduction in thallose liverworts occurs via a rather cool system, in which structures called gemma cups form on the top of the liverwort gametophyte (thallus). These gemma cups colonially produce identical 'leaflets' (gemmae) within them, which are then dispersed into the wider environment via rain splashes - raindrops may splash the gemmae up to 1m away! While the gemmae are in the gemma cups, lunularic acid inhibits their further development, but each gemma remains capable of growing into a new thallus as soon as it leaves the cup.

Asexual and sexual reproduction in thallose liverworts
(© Plant and Microbe Diversity by Harriet Jones and Anthony Davey)

In the sexual reproduction of thallose liverworts, there are two types of gametophores (umbrella-like structures on stalks which arise from the thallus): the antheridiophore (male gametophore) and the archegoniophore (female gametophore). The two gametophores are shaped differently, with the male 'umbrellas' being disc shaped and the female receptacles shaped like miniature palm trees.

Reproductive structures of thallose liverworts.
Illustration © Mosses & Liverworts of Britain & Ireland/British Bryological Society

Fertilisation causes the development of sporophytes anchored to the underside of the archegoniophores. Meiosis occurs in certain cells within the sporophyte, creating haploid spores, but the rest of the cells do not undergo meiosis, instead remaining diploid and developing into long, pointed elaters with spiral thickenings. The elaters are hygroscopic and therefore change shape in the presence of water. This causes the elaters of Marchantia to rapidly twist and untwist, causing the  spores to be shaken out of the sporophyte, ready to be dispersed by water.

Marchantia polymorpha is a large, thallose liverwort that is widely distributed around the world, and is also found on the UEA campus. It is very variable in appearance and has several subspecies, 3 of which are found in Britain and Ireland. The subspecies I found at UEA is Marchantia polymorpha subsp. ruderalis (aka the Common Liverwort). As with all liverworts, M. p. ruderalis has a horizontal growth structure and no vascular network to transport water or nutrients, instead relying on its large surface area and preference for damp conditions. Due to the changeability of environmental conditions, liverworts are well adapted to tolerate desiccation; their flat structure maximises photosynthetic abilities and they minimise water loss by only having pores (for respiration and photosynthesis) on their upper side.

Marchantia polymorpha subsp. ruderalis with numerous
gemma cups present on the upper-side of thallus.
Found on the UEA campus 03/02/18.

Holly Leaf-miner

Leaf mines are mainly caused by species of Lepidoptera (moths), Diptera (flies), Hymenoptera (sawflies, bees, wasps & ants), and a few Coleoptera (beetles), whose larvae feed within the leaves of plants. As the larvae feed and grow, they move throughout the leaves, creating mines. The mines created by these species are often very distinctive and, coupled with the fact that leaf-mining species tend to be restricted to a certain range of host plants, it is often possible to identify mines to an individual species.

The first step in working out a miner's identity is correctly identifying the host plant. Doing this normally narrows down the possibilities quite a bit and then you can identify which type of insect (order) the miner is from:

• Lepidoptera normally make full depth galleries or blotches with single lines of frass (droppings).
• Diptera mines are either lower- or upper-surface (or a mix of both), their larvae are maggots and they characteristically make twin trails of frass.
• Hymenoptera mines are blotches rather than galleries and characteristically have extensive amounts of dark frass (compared to diptera mines). The larvae of Hymenoptera also have visible legs.

Phytomyza ilicis is a species of fly (diptera) whose larvae mine the leaves of Holly (Ilex aquifolium). P. ilicis is incredibly common and is the only species to mine Holly in Britain, making it very easy to spot and identify! It is abundant on the UEA campus, with P. ilicis mines visible on just about every Holly bush you come across.

Phytomyza ilicis leaf mine on holly

Snowdrops

The appearance of Snowdrops (Galanthus nivalis) in January is one of the first signs that Spring is just around the corner.

Snowdrops are a perennial flower in the Alliaceae family, alongside the garlics and daffodils. They can grow up to 25cm tall and are found in a range of habitats, including damp woodlands, hedge banks, churchyards. Although many people think of Snowdrops as a native wildflower, it is now believed that they were in fact introduced to Britain in the early sixteenth century.

Snowdrops are pretty neat little things and have a surprising range of uses too, including agricultural and medicinal applications...

Snowdrop lectin (carbohydrate-binding proteins) is an effective insecticide against species of Coleoptera (beetles), Lepidoptera (butterflies and moths) and Hemiptera (true bugs), and some research has suggested that introducing Snowdrop lectin to genetically-modified crops may increase the resistance of GM crops to insect pests. Snowdrop lectin is also being investigated due to its potential activity against HIV.

Galanthamine is an alkaloid found in Snowdrops which has been approved for use in a number of countries for assisting with the management of Alzheimer's disease, as well as being used in the treatment of traumatic injuries to the nervous system.

These delightful little plants are fairly numerous around the UEA campus, and are especially abundant underneath the conifers near the Sainsbury Centre.

Some of the Snowdrops (Galanthus nivalis) near the UEA Sainsbury Centre

Diurnea lipsiella

Diurnea lipsiella (aka the November Tubic) is a micro moth in the Chimabachidae family. It is locally, but widely distributed across the UK, with Oak (Quercus spp.) and Bilberry (Vaccinium myrtillus) being the preferred larval food plants. As with other members of the Chimabachid moths, the females are brachypterous and therefore flightless. The males however, have a forewing length of 10-12mm and are on the wing in October and November (hence their very imaginative vernacular name).

Distribution map of Diurnea lipsiella using the 292 records from the NBN atlas (https://species.nbnatlas.org/species/NHMSYS0021142565)

Whenever the weather has been suitable this semester, we have tried to run two moths traps on the UEA campus. On the night of 31st October we set two traps as usual: one with an actinic bulb and one with a mercury vapour bulb. When we checked the traps in the morning, there were quite a few moths in and around the traps, including 26 November Moth agg. (Epirrita dilutata agg.), four December Moths (Poecilocampa populi), two Sprawlers (Asteroscopus sphinx), two Feathered Thorns (Colotois pennaria) and singles of Diamond-back Moth (Plutella xylostella) and Red-green Carpet (Chloroclysta siterata). Also in the trap was one Diurnea lipsiella, a new species to me, and apparently a new species for the UEA campus too!

Absolutely shocking iPhone photo of Diurnea lipsiella.

The Sprawler

The Sprawler (Asteroscopus sphinx) is a species of resident macro-moth found throughout most of England and Wales, although it is more common in the South. It can be found in broadleaved woodlands, and other well-wooded ares, including some gardens.

It is one of the later-flying species to be found in Britain, with adults being on the wing from mid-October to early December. The species frequently comes to light, with males usually arriving from midnight onwards, and females arriving earlier.

This species only has one generation each year and survives the winter by overwintering as eggs, which are laid in small crevices on the trunks of trees. The eggs hatch in April and the larvae feed nocturnally on a variety of tree species, including Pedunculate Oak, Blackthorn and Small-leaved Elm until early-June when they pupate in a cocoon beneath the soil surface.

The Sprawler (Asteroscopus sphinx)

The larvae have a habit of throwing their head back as a defence mechanism, and this behaviour is where the English name 'Sprawler' comes from.

It is classed as a UK Biodiversity Action Plan species in England due to an 83% decline in its UK population over a 35 year period (1968-2002) and its use as an indicator species for the winder environment.

Over the last two weeks I have been helping run a few moth traps on campus. Considering the time of year we have done quite well for variety, and in 3 nights of trapping with both an actinic and MV bulb a total of 87 individuals of 16 species have been caught. So far, seven of the species caught have been new to me which is very nice, taking my moth list up to 597 and PSL total to 1186. I'm hoping to reach 600 moths and 1200 overall by the end of 2017 so I have my work cut out a bit, but hopefully a few outings around Norfolk and Hampshire over Christmas will easily take me up to my targets.

Relative frequency of species on three trapping dates at the same site.
Cumulative totals of individuals from both an actinic robinson
trap and an MV robinson trap run simultaneously.

If you want to find out any more information about The Sprawler, or moths in general, these websites are a mine of information:

http://www.ukmoths.org.uk/species/asteroscopus-sphinx/adult/
http://www.hantsmoths.org.uk/species/2227.php
https://www.norfolkmoths.co.uk/index.php?bf=22270
http://jncc.defra.gov.uk/_speciespages/2067.pdf