Ash – Grantham Ecology

2017 in Trees

December 22, 2017Grantham Ecology1 Comment

The darkness of the winter is always a good time to reflect on a year passed, not only to appreciate what you’ve seen and experienced but to look forward to the treasures which await the eager explorer in the year ahead.

As always, I find trees feature strongly when I look back at the photos I’ve taken. There is much to appreciate in the natural world and each element has its own pleasure and essence. Trees feel like communing with the elders (no pun intended!) – even a stand of spindly silver birch will have been alive almost as long as I have and some of the trees you meet allow you to reach back through the generations, to the limits of living memory and far beyond. Here are a just a few such encounters from this year.

Clumber Park

Clumber has much to offer at any time of year – the double lime avenue on the entrance just keeps rolling the trees before you like an unfurling scroll as you drive in, and the old parkland has many veterans to tell you their tales. This photo was taken across the lake, as the sun sunk low on a Sunday afternoon in January, lighting the trunks and stretching the reflections out across the water.

Grantham

This tree sits proudly on top of the hillside overlooking Grantham and I pass it most days on my lunchtime walk. It is a sycamore and sits at the end of an incongruous line of old oaks, beeches and other sycamores which speak of an older time. A friend refereed to it as ‘that amazing oak’, assuming the species from its stature and prowess. I wonder if she’ll read this… Stretching out below is the course grassland and gorse of Harrowby Hill and above it lies the Hills and Hollows where barn owls and short-eared owls hunt through the winter months and marsh orchids nestle in the summertime.

Hatfield Forest

We went with some friends to listen to Sam Lee’s ‘Singing with Nightingales‘ at Fingringhoe Wick in spring, and took the opportunity for a walk around Hatfield Forest. Hornbeam was growing in the woodlands with a frequency and regularity I never see here in the Midlands, but this particular specimen was exceptional. This is an old hornbeam pollard where the heartwood had rotted away and the tree split into two live, healthy halves which were easily large enough to walk through.

Treswell Wood

Treswell Wood is a very special place – Nottinghamshire Wildlife Trust’s first reserve, it is an ash dominated ancient woodland in the north of the county which now plays host to the successfully reintroduced dormouse populations as well as supporting a whole range of other species. Springtime sees the trees burst into an abundance of fresh green leaves and creamy white blossom and this photograph of the mixed canopy captures this exuberance for me.

Muston Meadows

Muston Meadows is an ancient haymeadow in Leicestershire – it’s deep ridge and furrow grassland supports an exceptional population of green-winged orchid as well as a burnet, pignut, cowslip, quaking oat grass and meadowsweet. This photograph of the oak and ash within the boundary hedgerow was taken as a starlapse at midnight under moonlight in the springtime. I love to be somewhere that allows you to feel such a strong connection to the past, I imagine scenes from D. H. Lawrence’s works where the haymaking in these meadows was a time of great importance for sustenance and survival, as well as opportunities for intrigue and romance.

Bedford Purleius

The light filtered through a thousand leaves has subtleties of which vary from species to species, from place to place and from month to month. There can be few however to match the soft light of sunshine through newly unfurled beech leaves, as this stand in Bedford Purleius. Later in the season, the ground beneath these trunks will support helleborines which flower in mid-summer.

Millstone Edge, Derbyshire

Leaving the twisted, gnarled oak woodland of the valley beside the Burbage Brook, you turn onto an entirely different scene – one of light and green and air. This edge is populated almost entirely by silver birch with sketch a monchrome array between the greens of foliage above and grassland below.

Robin Hood’s Bay

This was an opportunistic photograph of the sunlight playing through woodsmoke from a bonfire in the clearing below. It’s not often that mist and fog will persist long enough through the day to allow such vertical shafts of light in a woodland scene, so I took advantage of serendipity to catch a shot which reminds me more of rainforest than an English woodland.

Quantocks

The Quantocks has become one of my favourite places to visit – the different characters of the trees and woodland set within an ancient landscape are irresistible. You can read more in this blog post from the autumn, but below are a couple of my favourites.

First is the gnarled oak woodland crowding the road which ventures up over the wooded hillside from Nether Stowey towards Crowcombe.

Next is the massed boughs of the coppiced beeches which line the Drove Road – a prehistoric track which runs across the ridge of the hillside above Crowcombe.

This photograph is perhaps my favourite of this year – it shows the woodland closing over the road with Tolkinesque grandeaur. If these were ents which came to life, I wouldn’t be so very surprised…

Cambridge Botanic Garden

This shows the beautiful soft browns of the autumn needles of swamp cypress – an evergreen conifer – against the backdrop of yellow maple leaves. I was in Cambridge for a meeting and had an hour before catching my train which gave a perfect opportunity to explore the botanic gardens which were conveniently close to the station. As well as the stunning floral displays and specimens, they have some beautiful trees and it’s a great spot for autumn colour!

Wappenbury Wood

Small-leaved lime used to be the key component of the woodlands around the midlands, before the clearance of the wildwood and the generation of the stands we see today. They still occur if you know where to look – Steve Falk‘s guides can help if you’re lucky enough to be in Warwickshire – and these old coppice stools within Wappenbury Wood are a fine example of a tree with which we should all be more familiar. Coppicing was the ancient practice of cutting the tree down to a bole, from which new growth would appear and could be substantially harvested without ever killing the tree. On the contrary, some of the oldest trees you can find are coppices and pollards, including small-leaved lime coppices in Westonbirt Arboretum thought to be over 2000 years old. This photo shows the tall, straight trunks of the regrowth many years after their last cut.

Bottesford Church

This photograph was taken at a local churchyard one frosty morning on Novembe. The night had turned the grass and gravestones to white whilst the sunrise caught the embers of autumn leaves on this beech and ignited them into a celebration of orange, umber and yellow. It was only a few more days before the leaves fell, but this was a moment when autumn had not yet given way to winter and the right morning can provide you with the best of both.

Staverton Park

I was very pleased to find myself within a few miles of this woodland in November, and took the opportunity to explore one of the most impressive assemblages of ancient trees in the country. You can read more in my blog post, but here area couple of my favourites.

The path through The Thicks wound its way between trees and shrubs, but split around this majestic old oak which stood in the centre of the path and demanded all that pass must pass around it.

This photograph was taken at sunrise, of one of the idiosyncratic old oaks on the edge of the parkland. The ground layer beneath is dominated by bracken, and I thought the frond and the tree made a nice contrast against the morning sky.

Whatton-in-the-Vale

Grantham Road is a bypass to the old road, which was subsequently bypassed again by the new A52 which avoids the village altogether. The road now links the two parts of the village and, though less than 100 years old, is bestowed an authority and antiquity by the double-line of planes which enclose it. The houses at the end are where the Griffin’s Head pub once stood. I liked the way the glow of life and civilisation lay at the end of the imposing avenue against a starry sky, like coming out of the woods into the safety of a home.

Millstone Edge

Back once more amongst the silver birches of Millstone Edge – their black and white stems through the snow transports you to another country, to Russia or else eastern Europe.

Bedford Purleius

With the seedheads of the helleborines still standing, this was the last view I had of these beech trees in 2017. I love the softness of the light which seems to remain as a memory of those leaves from early springtime.

Vegetation Layers in an English Woodland

September 5, 2017Grantham Ecology1 Comment

The different layers within a woodland are one of those classic illustrations from ecology textbooks – usually a cartoon graphic showing how the structure changes as you move from the ground up to the canopy. The distinctions are indicative – there is often plenty of overlap between the layers – but these are a useful way of thinking about the woodland in terms of its ecological function beyond what simply meets the eye. Helping you to see the wood for the trees, if you will!

We undertake tree climb and inspect surveys for bats in a variety of settings – from individual trees in gardens to well-spaced parklands and dense woodlands. Each of these gives a different insight into vertical variation but a recent climb in an oak and ash woodland gave a nice opportunity to illustrate how this changes in a typical ancient woodland habitat.

English Oak Woodland Structure — Photographs taken at 2m (bottom), 6m (middle) and 12m (top) in an English oak and ash woodland to illustrate the variation in spatial structure.

The number of ‘layers’ and their distinctions vary between sources and across countries – I’ve seen three defined layers, nine defined layers and every number in between delineated in various graphics. I’m going to keep this simple and focus on the three broad categories which are shown in these photos:

Field Layer – taken at 2m height

This photograph encapsulates what could be considered the field layer, the ground layer or the forest floor depending on which divisions you use. Broadly, this is the view from the ground – the most apparent vista for most visitors to the woodlands but the scene varies greatly as the year progresses. In secondary woodland or more botanically diminished sites, this can be a mass of ruderals such as nettles, cow parsley and bramble whilst some plantation woodlands can be head-high in bracken. In ancient woodland – such as this – springtime sees a flush of ancient woodland species which time their flowering early in the season before the canopy closes overhead. As May arrives and the trees and shrubs come into leaf, the main event on the forest floor is already coming to an end. Some species flourish later in the season but in September, the vegetation has largely died back often leaving a relatively bare floor. The dominant vegetation remaining is therefore the trunks of the trees and the shrubs which rise above the field layer to leaf and flower higher.

Scrub Layer – taken at 6m height

This could be described as the under-canopy, the scrub layer, the shrub layer or the under-storey layer. This is the level at which the shrubs flourish – those smaller woody species which often include hawthorn, blackthorn, hazel, holly, dogwood and elder, amongst others. These shrubs can often form such a dense canopy that the view to the treetops above can be quite obscured – something of an issue when you’re searching for bat roosts! In this instance, hazel and hawthorn dominate and as the photograph shows, they form a dense and highly cluttered environment some 6m above the ground.

Canopy Layer – taken at 12m height

This is up at the top of the trees, where the taller trees branch and close their canopies to claim first use of the sunlight available. I’m not right in the canopy in this photograph – the trees did not require us to climb to the peaks – but this nicely illustrates the shrub layer below with the high canopy of the oak and ash above. In some forests, the species composition includes a sub-canopy of smaller trees – such as rowan, silver birch and field maple – which form a layer between the lower shrubs and the taller climax species. This photograph nicely illustrates how much of a space can open up between distinct layers within the higher reaches of the forest structure.

Why does it matter?

An appreciation of how the character and conditions of a woodland change on a vertical plane are just as important, although a little harder to appreciate, than the variation on the ground. The illustrations above are for just one section of just one woodland and each type of species composition but they help to give a visual idea of how this works.

One example of how this type of variation is important is when considering how bats might use a habitat. Different species of bat have different hunting characteristics and habitat preferences, and this often relates to how open or cluttered a habitat is. Species such as brown long-eared are highly maneuverable and will glean insects from leaves so a reasonably cluttered woodland environment suits them perfectly. At the other end of the spectrum, a noctule hawks in open space, often flying over fields and catching its prey on the wing. Species such as pipistrelle are typically characterised as edge specialists which forage along woodland edges, hedgerows and other similar environments.

Pipistrelle bats are typically described as ‘edge’ species which forage along the edges of vertical features, such as a woodland edge

The field layer of the woodland looks ideal for a species such as brown long-eared but you might think that it would be too cluttered and enclosed for other species. However an insight into the structure above the shrub layer reveals a mosaic of open space and leaf cover which provides perfect ‘edge’ habitat for a hunting pipistrelle, and the voids between the trees would be perfectly navigable for a noctule in search of a roost. This was the subject of a talk by Ian Davidson-Watts at a recent BCT Bats and Woodland conference which you can read more about in this blog post here.

If you’re looking for tree climb and inspect surveys for bats, do check out this page for further details!

Ash dieback disease – do you know what to look for?

February 26, 2013Grantham Ecology1 Comment

I noticed that the buds of the hawthorn at the back of my garden are starting to break – always an early starter but a good omen of spring just around the corner. With the return of the leaves to the trees, now is a good time to familiarise yourself with the symptoms of ash dieback ready for the spring as it could well be that 2013 is the year that this disease is really going to take hold in the UK. With so many trees in so many locations across the country, the best chance for monitoring the spread is for people who walk, work and live in the countryside to be vigilant. There are a number of locations in East Anglia where the disease is confirmed which makes the risk of cases around Grantham a real possibility.

Ash is a widespread species in the UK – as an ecological surveyor I have been to many sites in the east midlands and beyond and it is very rare that any broad leaf woodland doesn’t have a component of ash – it is the third most common UK tree species.

Ash is the first species I learnt to ID in the winter as it really is so distinctive, the buds are jet black and triangular in shape. The bark is smooth and ash (!) gray in colour. The leaves are pinnate – that is the leaflets come off a central stem in pairs.

Ash whips within grassland - note the black buds! — Ash whips within grassland – note the black buds!

You come across large impressive old trees within hedgerows and older woodlands, they also have a strong presence within secondary woodlands where they can be the dominant tree – there are some good examples of this type of woodland just down the road in Oakham. You can also come across them invading fields in the first wave of succession from grassland to woodland, here they grow as single stems, “whips”, a very appropriate name if one snaps back and cracks you across the leg! It is therefore quite diverse tree – they can be a constituent of a climax community, they grow quickly enough to gain dominance within a woodland after only 50 years or so, but they can also be the first woody species to stake its claim on a woodland-to-be.

Ash trees are prevalent in and around Grantham, older specimens can be found in Belton House and around the town close to the river, whilst newer specimens form part of the planting at the Woodland Trust’s Londonthorpe Woods.

Chalara fraxinea (the second part of the latin relating to the ash genus – Fraxinus) is the fungus which causes ash dieback. It is thought to have come from nursery stock brought across from the Netherlands, a location which instantly brings to mind the Dutch elm disease which decimated the English elm in the middle of the last century. It spreads by spores which are tiny airborne particles which means that it is easily spread by the wind within a certain radius, up to around 10 miles. Over longer distances, it is thought that the movement of diseased material such as nursery trees is likely to be the main cause which is why import and movement was banned in the UK at the end of October in 2012.

The disease can be detected even now, in the winter and spring, but becomes more obvious when the trees come out of dormancy and the leaves are in evidence. The Forestry Commission has a very thorough guide on how to recognise which I would urge everybody to read so that you know the symptoms. There are other diseases, pathogens, fungi and environmental impacts which can cause an ash tree to be in poor condition – this guide should help you to spot the distinctive signs of this particular disease.

The Dutch Elm epidemic in the 1970’s did not kill every elm tree and a small number still stand around the country – only a tiny fraction. It is assumed that these trees have immunity to the disease and, on this basis, The Conservation Foundation has begun a project of collecting cuttings from these trees, propagating them and distributing them to schools and other locations all around the country. This was begun in 2009 so it is too soon yet to know whether this is to be a success but, because the cutting method ensures that the derived seedlings are clones of the original tree, there is every reason to think it will be and hopefully, one day, English elm will be a common sight in our countryside once more.

Based on the existence of some similarly disease resistant trees in Denmark, there is a NERC funded project currently under way to sequence the ash genome and try to identify the genetic basis for immunity. This would put us in a position where the lost ash trees (and it is almost inevitable that at least a proportion will be lost) can be replaced with disease resistant trees. The strong hope is that these resistant trees will be identified in the UK so that any replacement planting programme will not require stock from abroad but will remain of British origin.

What can you do to help?

Familiarise yourself with the symptoms of ash dieback here or watch the Forestry Commission produced video so that you know what to look for when out and about;
Report any findings, or suspicions of chalara to the Forestry Commission using their Tree Alert form here – they will want to know the exact location of the tree, the symptoms noted and any other information which will help them to find it. Photographs are also very useful and there is a chance to upload these;
Install the Tree Alert app on your phone to issue reports when you’re out and about – link here for android or iOS

The brown hairstreak is a butterfly which uses ash trees as 'master trees' where the males and females gather to mate before the females descend down lower to lay their eggs on the larval foodplant, blackthorn. They are one of the species which might be impacted if chalara has a serious detrimental impact on the UK ash population. — The brown hairstreak is a butterfly which uses ash trees as ‘master trees’ where the males and females gather to mate before the females descend down lower to lay their eggs on the larval foodplant, blackthorn. They are one of the species which might be impacted if chalara has a serious detrimental impact on the UK ash population.

Lichens on ash trees at Londonthorpe Woods

February 3, 2012Grantham EcologyLeave a comment

When I went to Londonthorpe to look at the winter buds, I noticed how well lichens had already established on some of the ash trees. These are often overlooked but well worth further investigation, especially if you have a little hand lens to help you out!

Definitive identification often involves recourse to complex keys involving chemical tests and microscope work. But don’t let that put you off, the more common species are often identifiable using a simple guide such as the ones produced by the FSC. These show you some of the species you often encounter along with the places you are likely to find them. For example, all three species shown below are found on the ‘Lichens on twigs’ laminated sheet.

Lichens are quite unusual in that they are a symbiosis between a fungi and an algae which are in entirely separate kingdoms – the plant and the fungi. They grow on trees, on stone, on sawn wood and bricks and even at the edge of the pavement where feet rarely tread.

A common myth is that lichens only grow where the air is clean. Whilst it is true that many species are very sensitive and can be used to indicate the quality of the air, there are also species which are quite tolerant of poor air quality and will thrive in fairly grim conditions. This is evidenced by the number of lichens you can find on trees in the busy London parks. All three of the species described below are fairly tolerant of nitrogen and acid pollution so we can’t use them to make any great claims about the cleanliness of Grantham! These are common species and are often the first to colonise new trees, especially smooth barked species such as the ash.

There is lots of terminology associated with lichens – the Natural History museum website has a good glossary. I will introduce a few of the key terms here which we can hopefully expand on with different species in a later post!

Lichens can be categorised as crusteose, those which form a crust upon a surface, foliose which are leafy in nature and fruticose which you could describe as shrubby. The three below show examples of crusteose and foliose species. I will try to add a fruticose specimen in a later post!

Xanthoria parietina

The xanthoria genus of lichens may be the ones you are most familiar with – you can find them in a variety of habitats and they are quite common. This species, Xanthoria parietina, is a foliose lichen and is a good model on which to show the difference between the main body of the lichen, the thallus, and the fruiting bodies, the apothecia. The fruiting bodies in this species are of the ‘jam tart’ variety, named because of their shape. These are where the spores, the reproductive seeds of the lichen, are produced.

Leacanora albella

Leacanora are crusteose lichens and are another fairly common group of species which you are likely to come across. This one is differentiated from the very similar Lecanora chlarotera by the colour of the fruits which are white rather than buff. Again, you can see the jam tart like fruiting structures and you can see the difference between this crusteose lichen and the much leafier foliose Xanthoria parietina.

Lecidella elaeochroma

You might have to look a little more carefully to spot this one, another crusteose species. Depending on the tree you find it on, it may only be the black fruits which give it away – these are often called wine gum fruits. If you look carefully though, you’ll see plenty of established specimens of this lichen on the ashes throughout the plantation, as well as tiny patches which are only just beginning to establish and where only a few black dots are apparent.

Amandinea punctata on ash — Amandinea punctata

Winter Buds ID Part 1 – Londonthorpe Woods

January 26, 2012Grantham Ecology1 Comment

Tree identification in the winter isn’t so difficult as you might think! Broadleaf trees lose their leaves in the autumn and develop buds which remain throughout the winter and these make it very easy to work out which species is which. The Woodland Trust have produced a very handy guide to some of the most common species which shows photographs side-by-side for comparison. If you want to identify them in a little more detail, this little booklet is invaluable and provides a few more diagnostic characteristics such as the architecture and bark types. It even has a handy key which takes you step by step towards the correct identification!

Of course, one drawback of relying on the buds to identify the tree is getting to the buds in the first place, which can be a long way off the ground depending upon the tree in question. So Londonthorpe Woods seemed like an ideal place to begin.

Londonthorpe Woods is located just off Londonthorpe Lane as you leave Grantham to the north-east. The wood was created by the Woodland Trust who planted thousands of trees on the 56ha arable site between 1993-1995. The Woodland Trust continue to own and manage the site.

As the site is so large, I concentrated on the first area you arrive at if you step through the gate from the car park. This area has been planted with a number of our native species which will one day develop into a woodland much more natural in character than it may appear at present. Alder (Alnus glutinosa) and willow (Salix spp.) will grow quickly but remain smaller, as will the silver birch (Betula pendula) and cherry (Prunus spp.). The English oak (Quercus robur) on the other hand will grow slowly and steadily to rise to prominance above the canopy one day, with ash (Fraxinus excelsior) close behind. Finally there are hazel (Corylus avellana), hawthorn (Crataegus monogyna) and blackthorn (Prunus spinosa) shrubs which will form an understorey, along with dog rose (Rosa canina).

Londonthorpe Woods Map — Map of the plantation behind the main carpark of Londonthorpe Woods (courtesy of Google Maps).

Each of the species is described briefly below, along with a photograph of the buds to show you what to look for! Click on any of the photos for a larger image.

Alder

Alder buds are red and vaguely conical and remain quite close (appressed) to the stem. They are alternate – each bud is present as an individual rather than a pair and they alternate as you look along the twig, one to the left, then one to the right.

Alder is one of the more helpful tree species in that it often provides extra clues in the winter – the cones are generally present right through until spring time.

Willow

Willow’s are a variable bunch and as well as having several species native to the UK, they hybridise so there is even greater variety than you might expect. I think that this example might be goat willow (Salix caprea) – it will be easy to check when the buds break – goat willow produce fantastic flowers so watch this space! The buds are alternate again, lime green with redness towards the tip.

The presence of both the willow and the alder in this plantation suggests that the ground may be damp – both species are most commonly found along river banks or in other damp conditions. Like the hazel (see below for more details), the willows have been coppiced in this site.

Silver birch

Now this is a species which few will need the buds to identify – the distinct silver banded bark is visible behind the buds in this photograph!

The buds themselves are alternate and on small stems which protrude from the main twig.

Silver birch grow quickly but are relatively short lived – they are often one of the first pioneer species in a new woodland but soon become out-competed by larger, taller trees.

Cherry

Cherry is another difficult species as there are so many ornamental and hybrid varieties to choose from. The buds are alternate and dark brown with scales visible. Cherry is another species where the bark is very useful in the winter – the lines which look almost like horizontal cracks in their shiny bark are called lenticels and these are quite characteristic of cherries.

Although it is difficult to be sure of the exact species, it is likely that the Woodland Trust would have planted one of the native varieties – wild or bird cherry. Of the two, this one looks more like wild cherry (Prunus avium). Again, we can return to check this in the spring or summer!

English oak

The oak has tight clusters of buds especially at the tips. The buds are brown and have lots of scales.

One day this tree will probably tower above the others – think of the Major Oak in Sherwood Forest. For an example closer to home, there is a beautiful mature oak specimen along Belton Lane which you will probably pass on your way to Londonthorpe Woods – more on this magnificent tree in a later post!

Ash

The ash has one of the most distinctive buds – they form jet black pointed cones which really can’t be confused with much else. If you find buds of a similar shape but a different colour, such as grey, think of one of the other ashes which we sometimes encounter such as manna ash.

Hazel

Hazel buds are a greenish red in colour – a little like a red and green apple. They are alternate along the twig which itself is often hairy. Hazel provides a few extra clues in the winter time – the catkins (the male flowers) are often visible and if you look very carefully, you can see the tiny red female flowers on the same branch.

Another clue, depending on the management, is the growth form of hazel. It is often coppiced – that is cut down to the ground – and from here it sends up lots of new shoots which are often allowed to grow for several years before being cut back. The hazels in this plantation have been coppiced.

Hawthorn

The spiky shrubby hawthorn bush is fairly distinctive, even in the winter time. The spikes are generally quite visible and the buds compete with these along the twig. The buds are alternate and a similar dark reddish colour to the twigs.

Blackthorn

Blackthorn buds, by contrast with the hawthorn, are tiny little red dots which appear along the stem. The twigs are often long spikes and the buds appear along these. The colour of the bark of blackthorn is, as you might imagine quite dark, a blackish grey perhaps.

Dog Rose

Another species which you are unlikely to confuse with many others. Native roses grow lower to the ground than the other species in this plantation but can develop quite a shrubby form. The curved rose thorns, like a hawk’s talon, are quite distinctive and the rose hips, still present in January, are another key clue. The buds themselves are a slightly lurid red and grow alternately up the twig, alongside the thorns.