2018 in Trees

It might sound simple, but trees are without doubt one of the things which makes me happiest in this world. Their architectural limbs during winter; that joyous first flush of green in the springtime; the cacophony of life they support in the summer and the glowing hues of autumn – all through the year they can lift the spirit into their boughs. Here are a few of my favourite photographs from 2018.

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This photograph shows the veins in a lime seed wing with the tree in the background – I love the echo beteen the parent tree and the wing which will take its tiny progeny to a new place to germinate.
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We walked the Peddar’s Way in spring this year – from Thetford all the way to the coast at Holme next the Sea. The green tracks with overarched by mature trees were a joy to walk beneath.
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Another photograph taken along the Peddar’s Way – I love the imagery of the broadleaf trees with lances drawn against the arrayed army of conifers in the plantation; however these are more likely a stress response to the intense shading of the industrial plantation.
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Scilly is one of the places in the UK where elms have held out against Dutch Elm disease – likely primarily due to their relative isolation from the mainland. This was taken of young growth in the centre of St Mary’s
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This photograph was taken in mid-summer but the fallen lime wings made it look as though autumn had come early. This green arched footpath leads down towards Sedgewick Meadows in Grantham
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Limes seem to have figured highly in my photographs this year – this is a lime avenue in a Northamptonshire Estate where we undertook tree climb & inspect surveys one misty morning in autumn
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One of my favourite trees in Richmond Park which brings back memories of my dissertation there many years ago – the Royal Oak is estimated to be 750 years old!
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The silver birch is a typical pioneer tree species of Sherwood, well suited to the sandy, heathy soils. These were taken as the bracken leaves browned in November.
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Whilst obviously not a fan of the inert conifer plantations which pass for ‘woods’ in too many places, there is an undeniable beauty to their straight, uniform structures especially when the light is right!

 

 

Thermal Imaging footage of Honeybees and Bumblebees

Thermal imaging technology works by recording the infra-red energy emitted from surfaces – this doesn’t rely on a light source like typical infra-red photography, but instead measures the radiation given off by both living an inanimate objects. The camera can measure the temperature of these items and display a ‘thermal’ image which shows the gradation and variation between different objects within the field of view. In simple terms – it can show a hot object as white/red whilst cooler objects would be shown as green or blue.

In mid-summer, social bees produce a high density of very busy insects in the nest, so it was no surprise that they stand out a mile on a thermal camera! It was also exciting to be able to understand what individual bees had been doing – for example their temperature signature differentiated those who had recently returned to the nest from those who were standing guard and checking in new arrivals.

Wild Honey Bee Nest

We often encounter honey bees when out looking for tree roosting bats in woodland and this was a prime example! Whilst honey bees are often kept in hives, they can establish wild colonies in features such as this.

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Showing the tree cavity feature where the honey bee nest was located

I took the following images around sunset so the tree itself was cooling but you can immediately see just how hot the inside of this tree cavity is compared with the surrounding wood. The temperature reading inside the nest was 33 degrees Celsius, whilst the surrounding tree barn dropped to around 25 degrees.

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A still photograph of the bees within the nest – you can see the differential in heat between the nest itself (yellow) and the outer wood (black). You can also see a recently-returned bee glowing white hot!

Even at sunset, honey bee workers were still returning to the nest and you can see the white-hot glow of these warmer bees compared with the much cooler bees at the entrance. What is also interesting is the pattern of heat in these recently-flown bees – the flight muscles are in the thorax where the wings are attached and this part is much hotter than the abdomen as you can see more clearly in the video below.

The thermal image gave a nice opportunity to watch guard behaviour in action – some honey bees will take the roll of guarding the nest entrance, positioning themselves on the edge and checking returning bees to ensure that they are welcome. The thermal footage clearly differentiates those bees who have recently flown from those which have not, and you can see the much cooler guard bees intercepting the warmer returning workers as they pass by.

If you’re interested in guard behaviour, you might also like this post from a couple of years ago regarding this behaviour in hornets!

Bumblebee Nest

These images and videos come from a bumblebee nest which was situated underneath a loose cobble in the courtyard of our office.

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The stone beneath which the bumblebee nest is situated

I think the bumblebees are either white-tailed (Bombus lucorum) or buff-tailed (Bombus terrestris) bumblebees – this photo shows one of the worker bees returning with well laden pollen baskets.

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Bumblebee worker returning to the nest with well-laden pollen baskets.

The thing that I found most surprising on the thermal footage to see just how hot this cobble got compared with those around it, even though the nest is buried beneath! I assume this is due to the heat rising with the warm air from the next and heating the stone as it passed by.

As with the honey bees, you can see how much warmer the active bumblebees are compared with their environment. Bumblebees have a good degree of control over their temperature. The hairs on their body provide some insulation and they can use their flight muscles – uncoupled temporarily from their wings – to warm themselves up before taking off. This uses the same technique as they use for buzz-pollination of some flowers. This video gives an idea of just how much heat these muscles can generate, allowing some bumblebees to remain active through the winter, flying at temperatures of just 10 degrees Celcius. You can read more about bumblebee thermoregulation here!

Vegetation Layers in an English Woodland

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.

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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

Ground Layer
Photograph taken at 2m showing the field or ground layer in an English oak and ash woodland

 

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

Shrub Layer
Photograph taken at 6m showing the hazel-dominated shrub layer in an English oak and ash woodland

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

Canopy Layer
Photograph taken at 12m showing the space between the shrub layer and the woodland canopy in an English oak and ash woodland

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.

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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!

 

2016 in trees

Looking back through the photographs I’ve taken in 2016, it’s striking how many trees there are! As with the small things such as wildflower ‘weeds’, it’s easy to take for granted these enormous beings which grow amongst us. The sheer scale of a mature oak or beech is far beyond our magnitude of experience, as is the timescale they can span which numbers many of our lifetimes combined.

Here are just a few of my favourite encounters from 2016.

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These snow-lined branches were in the mountains above Freiburg at the beginning of the year – we took the cablecar from the grey countryside below up into a winter wonderland of freshly fallen snow. I liked the way that the snow outlines the curved architecture of the branches.
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Part of my job involes climbing trees to inspect them for roosting bat potential. On my way up this field-edge tree, the sun came out and I couldn’t resist a quick shadow-selfie!
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This photograph was taken for the Woodland Trust – this is one of the Verdun Oaks which grew from acorns brought back from Verdun after the First World War and planted in towns and cities as a commemoration to the fallen. In the background is Lichfield Cathedral. The Woodland Trust are tracing these trees as part of the commemoration of the First World War – you can read more about these pieces of living history on their website here.
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I spotted this tree sillouetted against the sunrise on a drive across to Norfolk one morning and had to stop off to get a photograph. The tree was in the middle of a field which was not publically accessible, so I only have the shape to go off but this looks like a poplar tree to me – perhaps a black poplar?
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This is the view up to the canopy at Treswell Wood in North Nottinghamshire. This is a Notts Wildlife Trust site which has a precominantly ash canopy. Unfortunately, Ash Dieback was confirmed in one corner of the woodland and targetted trees were felled in an effort to stop the disease spreading. Ash trees are a characteristic part of the British Countryside and one of the most common species in our landscape – it would be a tragedy if they were to go the way of the English Elm.
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I love being out in the countryside at night – we spent much of the summer watching trees to survey for emerging bats so this scene feels very familiar to me. I took a walk out past this tree near Harlaxton one night when the skies were very clear to capture a starlapse with the North Star centred above the dead crown of this oak.
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This is a slightly boosted photograph in terms of colour saturation, but is otherwise untouched. This was a starlapse of a meadow oak but the quirks of lighting led to this rather psycadelic image. The tree and the hillside to the left were occasionally lit by car headlights from the road behind me, and the background cloud was illuminated by the light pollution of Nottingham in the distance. Not your typical tree image but I rather liked the effect!
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These beautiful old beech trees line a trackway which forms part of the Laurie Lee Wildlife Way in Slad. I love trackways which are overarched by tree canopies, and I especially like the idea that Laurie would have walked these tracks. The book Cider with Rosie is a favourite of mine, especially the descriptions of the Gloucestershire vally in which he grew up, so there is a real feeling of walking somewhere familiar, even when exploring this landscape for the first time.
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This is a photograph taken in Wyndham Park in Grantham. The autumn leaves of a beech provide a frame for the Hand and Apple sculpture which commemorates Isaac Newton’s connection with the town of Grantham – he went to school at King’s Grammar which is just beside Wyndham Park, and lived at Woolesthorpe Manor just down the A1 from the town, where the famous apple tree can still be seen today.
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These two majestic field trees stood like sentries on either side of the gateway. This was on a walk in Somerset which explored an ancient landscape full of both recent history – including an old lead working now rewilded as a nature reserve – and ancient history including a number of monuments, burial mounds and barrows.
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This photograph was taken on a farm track footpath which leads to Muston Meadows, an old haymeadow now designated as an NNR. I wanted to try to capture the essence of mid-December in the Midlands – to me that is muddy walks, early sunsets and skeletal trees.
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This photograph was one of several I took of bark patterns in a veteran oak we were climbing to look for potential evidence of bats. This deadwood can be very stable, remaining as a component of the tree for decades after the wood has died, and the patterns etched into the wood represent to the various conditions and experiences which the tree has gone through.
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This photograph neatly finishes where this summary started – back in the mountains above Freiburg. This was taken just before Christmas where we had the magical opportunity to rise up above the clouds and see the sun setting. The fog and cloud was rolling up the valleys, obscuring and revealing treelines, and the sunset coloured the fog in pinks and oranges.

2016 in Wildflowers

Every week this year, with just one or two exceptions, I’ve taken part in the excellent #wildflowerhour on twitter where people across the UK share their sightings for the week between 8-9pm each Sunday – an excellent way to draw a weekend to a close.

Many of these photos made an appearance at some point but this is a run-through a few of my favourite wildflower finds or photos from 2016. The absence of orchids can be explained by a whole post all of their own from earlier this week – take a look here!

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Tree flowers are some of the first to make their appearance each year and this set shows a few of these in silhouette against a white February sky. The photo on the left is the male catkins of alder whilst the right two images are the female flowers of two different willow species. Many of these early tree species have both male and female flowers. Some, such as the hazel and alder, have both male and female flowers on the same tree. Others, such as these willows, have male trees or female trees which produce just one type of flower.
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An early-morning walk in May treated me to these frosted flowers in Muston Meadows NNR. The sward was still low, with many of the larger, later meadow species such as salad burnet and meadowsweet still to appear, and these smaller early-summer flowering species were the stars of the show. Clockwise from top left are bulbous buttercup,  cuckooflower, green-winged orchid and cowslip.
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Spring sandwort is a member of the campion family and I came across these cushions of flowers at a disused leadworking site in Derbyshire. It is quite a scarce plant across the UK but frequents these old spoil heaps – such is its connection that  leadwort is another name for this flower. I like that this species has specific habitat preferences which are far from the pristine grasslands and woodlands which are associated with the conservation of many species.
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This is another example of where a closer look rewards the curious – this is a view down the spadix of an arum lily – also known as Lords and Ladies. This reminds me of one of the plasma balls I used to see in Science Museums when I was younger!
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It would be difficult to exclude bluebells from this selection as the sight of a good bluebell wood, with wood anemone, primrose, violets and yellow archangel mixed in, is one of those sights which is profoundly uplifting after a long winter. Many species begin to flower before these, but the bluebell season marks a threshold between the sparsity of spring and the abundance of summer which is just on the horizon. I like the lightness and delicacy of this shot – taken at the Notts Wildlife Trust site – Treswell Wood.
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Another photograph from Treswell Wood. I’m not sure I’ve ever seen such an abundance of greater stitchwort than at this site this year – glades were filled with the snow-white flowers of this native woodland specialist.
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This is another photograph from Muston Meadows NNR – this time at sunset. I liked the moody, hazy feel of this photograph with buttercups and grass flowers against a darkening sky.
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This set was taken on my birthday this year – we were camping just below Old Sarum outside Salisbury and woke up early to climb the old hillside and watch the sun rise. The fields and landscape below were misty and I liked the contrast of these wildflowers against the sunrise haze.Clockwise from top left is dock, cow parsley, nettle and bulbous buttercup.
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Smooth tare is a member of the pea family with these tiny white flowers with delicate purple veining. Easily overlooked in a grassland sward, I like the way that they stand out against the soft greens of the surrounding vegetation when you get low enough to appreciate them!
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I took a treacherous walk up to the Hills and Hollows on the outskirts of Grantham one very stormy lunchtime in June – somehow these ominous heavens never opened but gave a nice opportunity to capture some common wildflowers against a dark sky. Clockwise from top left is white campion, poppy, white clover and hogweed.
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I have a real soft spot for arable weeds – modern farming works hard to eradicate competition from arable fields but many species still find a way to brighten a dull monoculture. This flax field was quite an amazing sight in itself with its array of ripe seeds, but flecked throughout where the glaucous green and delicate mauve of fumitory which scrambled up and through the crop.
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Harebells are common in more acidic conditions but can pop up in a variety of habitats. I found them for the first time in the grasslands above Grantham this year, nestled in amongst the Hills and Hollows, but this photo was taken on the Laurie Lee Wildlife Walk in Slad this autumn. You have to get down low to see inside these little flowers, and when i did, I was surprised to find two invertebrate residents settled in for the day. I guess a downwards-facing bell makes perfect cover for a snail to wait until nightfall!
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The Longshaw Estate in Derbyshire comes brightly to life with the purple wash of heather in August and this photograph was taken on one of my favourite walks which cuts across this land. The bell heather was frequented by the beautiful heather colletes bees which emerge to coincide with this floral abundance each year, feeding on the flowers and making their nest holes in the sandy soils beneath the roots.
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Another from the Peak District – this time the coconut-scented flowers of gorse against a backdrop of heather. The old saying goes, ‘when gorse is out of flower, kissing is out of fashion’ because you can find this species flowering pretty much anytime throughout the year. There are many fewer pollinators at work during the winter, but when a warm day awakens a hibernating bumblebee, it can be fairly sure of a nectar source amongst a stand of gorse.

 

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Whilst I doubt this will be my last wildflower photo of 2016, it seems a nice place to end – a common mallow flower with ice crystals taken on my walk to work in December. A bitterly cold morning, the white edging brought a nice contrast to the deep purple of this flower. Many wildflowers of late-summer will continue flowering until the first hard frosts of winter finish them off so this might perhaps signal the end for this individual!

If you are interested in commissioning botanical surveys in the midlands, you can check out Landscape Science Consultancy’s website here!

Three trillion answers to a single question

On the last day of November, the decadence of summer is long gone. The flowers and leaves, butterflies and bees were so easy to take for granted until autumn and then winter take them from us. But every season has its own treasures and the wind-whipped, leaf-stripped trees are on glorious display across the countryside.

One thought which always strikes me when I see winter silhouettes, is how amazingly adept trees are at achieving their structure in an infinite number of ways. A line of trees planted together will each grow to maturity in a different form. The form will be dictated by species, by sub-species perhaps, by individual genetic variation, phenotypic plasticity to adapt to the conditions, defense responses to biotic attack or abiotic damage such as frost and wind, competition avoidance strategies and more besides. There are as many answers as there are trees to the simple question of how to be upright. And whilst the tree is growing, the process is never complete as the tree grows adaptively to maintain its balance and posture with continual interaction with their environment.

One recent 2015 study put an estimate of 3 trillion on the number of trees in the world. The mind boggles to even begin to comprehend the variety and scale which this number encompasses, but here are nine examples from my walk near Muston Meadows at dusk this evening.

Mink climbing a tree

I wanted to share a rather unusual video clip which I captured on a trailcam recently. I know mink to be good swimmers but I did not realise they were tree climbers! Various sources suggest this is a known behaviour, with some suggesting they climb regularly whilst others suggest rarely. One website states that they frequently climb to escape predation although there is nothing to suggest that this was the case in this video.

One of the best applications of a camera trap is when it allows you to observe something unusual or unexpected which could not otherwise be obtained without hours of watching and waiting. I think this clip is a perfect example!