60 posts in the category

Miscellany

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Atlas cedar cone

Atlas cedar cone

Sometime last week I saw a conifer with these big solid looking cones. I was intrigued and plucked one off the tree. Fairly light but rock hard with a nice scent.

Atlas cedar cone in hand

But what kind of tree has these weird cones? The Atlas cedar (Cedrus atlantica) [aka (Cedrus libani var. atlantica)]!

close-up of Atlas cedar cone

It is a native of the Atlas Mountains in Algeria and Morocco and is apparently one of the most planted decorative conifers in Britain. Which makes it all the more surprising that I've never noticed one before.

top-down close-up of Atlas cedar cone


Posted in Miscellany





Ash at night, Edinburgh (10th April 2008)

ash tree silhouetted against night sky in Edinburgh

The view from my bedroom window at about half an hour past midnight on the morning of April the 10th. Well, actually all I could see was blackness and a crescent moon, but this was a fifteen-second exposure. The tree in the centre is an ash (Fraxinus excelsior).


Posted in Miscellany





treeblog: One-Year Anniversary

One year ago to the day, the first post appeared on treeblog. In it, I stated that the purpose of treeblog is to 'form a chronology of the development of a group of trees, right from being planted as seeds or nuts. To chart their development from germination to maturity… supposing that they don’t die before they get there'. So far treeblog has stuck to its purpose then. The first seeds were planted on the 28th of March 2007. This Set A consisted of cider gum, common alder and Scots pine seeds. Seedlings from all three species sprouted, and their progress has been tracked. It will continue to be tracked, and a new set of seeds will be added to treeblog in the spring!

Looking back over the first year of treeblog, I have picked out a selection of ten quite good posts that you may well have missed the first time around. Celebrate the anniversary and enjoy!

Mycorrhiza - a brief introduction
Sunday 11th March, 2007
Mycorrhizas! Those intimate mutualisms between fungi and plant root tissue.

Habitat fragmentation
Tuesday 13th March, 2007
Habitat fragmentation - a significant obstacle to the long-term conservation of biodiversity.

Branch shedding in mature beech trees
Thursday 3rd May, 2007
To live long, a tree must stay small...

The Plane Tree of Hippocrates
Friday 18th May, 2007
Is this the tree under which the great healer sat when he taught medicine to his disciples in the 5th century BC?

Scots pine (Pinus sylvestris) reproductive organs
Thursday 24th May, 2007
Flowers and cones.

Derwent Dam tree photographs
Saturday 16th June, 2007
During World War II, Derwent Reservoir was used for bombing practice by the RAFs 'Dambusters'...

Sweet chestnut - waiting for the nuts
Sunday 12th August, 2007
Unsuccessful attempts at getting sweet chestnuts for Set B.

Field trip to the Italian Alps (Part 1) and (Part 2)
Thursday 13th September, 2007 and Saturday 15th September, 2007
Learning about forestry in the Paneveggio Forest and spending time in the field collecting data.

Giant Yorkshire oak trees (1829)
Thursday 11th October, 2007
Massive oak trees, far bigger than any tree in Britain today!

Majesty, or the Fredville Oak (Kent, UK)
Friday 7th December, 2007
A stunning oak.

Okay, so that's eleven posts. But I'm counting the two Italian field trip posts as one. Why are there no treeblog seedling updates in that list? Because I plan to give Set A its own special list on its own one-year anniversary!


Posted in Miscellany





Nutters and nutting: illegal hazelnut gathering

Everyone is familiar with the term 'nutter', but I bet not many people know how the word originates. The book Sheffield's Woodland Heritage by Mel Jones explains (the context is woodland management from the Middle Ages to the 1800s):

There were particularly sensitive times of the year in the woods. In autumn when berries and nuts were ripe, and in winter, when firewood and food supplies were low, thefts were particularly common. The practice of collecting hazel nuts in local woods caused widespread damage to wood boundaries and the underwood and prompted the Pegges of Beauchief in 1809 and the Duke of Norfolk in 1812 to post warning notices around their estate and woodland boundaries.

The text below is included as a figure, labelled as 'Warning to hazel nut gatherers, Beauchief estate, 1809.'


WHEREAS,
The Woods and Wood-Fences,
IN THE LORDSHIP OF
BEAUCHIEFF,
Have for several Years past suffered great
Damage about this Season pf the Year,
from a set of idle People, who stile them-selves NUTTERS :
THIS IS TO GIVE NOTICE,
That if any Person or Persons are caught
Nutting, or pretending so to do in the
above-mentioned Woods, or Premises, they
will be prosecuted as the Law directs.
Beauchieff, August, 1809.

J. MONTGOMERY, PRINTER, SHEFFIELD.


Posted in Miscellany





Form: beech, horse chestnut, lime and willow

Look here. I've dug out some photos taken last year on February the 3rd. It was a lovely day with a beautiful clear sky. And some of the leafless trees in the Grange area of Edinburgh looked stunning against the wide blue yonder.

European beech

European beech (Fagus sylvatica). Smooth silver bark and fine, delicate branches.

horse chestnut

Horse chestnut (Aesculus hippocastaneum). Thicker twigs than beech. Notice how the branches droop downwards but have recurved tips.

lime

Lime (Tilia) - whether common, small- or large-leaved I do not know. Notice the dichotomy in size between the main branches and the finer twigs.

willow

Willow (Salix) - I think. I can't remember, but it sure looks like willow.


Posted in Miscellany





Happy New Year! New trees ahoy!

real Christmas tree

Happy New Year, dear reader. Let's hope it's a good one. Doesn't the tree above look great, all dressed up in Christmas lights? I took that about a year ago. I was just impressed. I mean, that's how you decorate a tree. And that's a fairly big tree.

It'll only be a few months before treeblog can look forwards to planting some more trees, the fabled Set B. What flavour trees shall B see? We're talking downy birch (Betula pubescens), European beech (Fagus sylvatica), weeping beech (a variant of European beech), dwarf pine (Pinus mugo), and sweet chestnut (Castanea sativa). The seeds and nuts are all collected (more on this later). Now all treeblog needs is time. And a bigger garden.


Posted in Miscellany





Marcescent oak leaves in Holyrood Park

I had a wee wander in Holyrood Park, Edinburgh, yesterday. And guess what I saw? Some marcescent leaves, of course.

marcescent oak leaves

Marcescent oak leaves.

dead oak leaves still on the tree

These dead leaves will probably spend the whole winter attached to the tree. I'll see if I can remember to go back and check in a month or two.

completely bare oak tree

But wait! Just a stone's throw away, this oak stands completely devoid of any leaves. Why?

the two oaks - not far between them

See how close the two oaks are? Only about ten metres. The marcescent oak is ringed to help distinguish it from all that gorse. Hunter's Bog can be seen in the centre of the picture.


Posted in Miscellany





Marcescence (winter retention of dead leaves)

marcescent oak leaves in spring

This photo also appeared in a treeblog post from the 29th of March with the caption "These oak leaves have doggedly remained on the tree all winter, but for how much longer can they hang on? It seems that oak and beech are always the last to lose their leaves.".

I have known for many years through personal observation that beeches and oaks often retain their withered leaves beyond autumn and sometimes all through the winter, whereas other species lose all of their leaves in autumn. Since reading this post over at Arboreality, I have been able to give a name to this phenomenon: marcescence.

Deciduous trees shed their leaves in autumn by the process of abscission. The Oxford Dictionary of Biology (fifth edition) gives the following definition:

abscission The separation of a leaf, fruit, or other part from the body of a plant. It involves the formation of an abscission zone, at the base of the part, within which a layer of cells (abscission layer) breaks down. This process is suppressed so long as sufficient amounts of auxin, a plant growth substance, flow from the part through the abscission zone. However, if the auxin flow declines, for example due to injury or aging, abscission is activated and the part becomes separated.

The following extract from a paper written by E. E. Berkley in 1931 (Botanical Gazette, Vol. 92, No. 1, pp. 85-93) explains marcescence and mentions some marcescent species (notes in square brackets are my own):

TISON observed both marcescent and deciduous leaves in Carpinus betulus [hornbeam], Fagus sylvatica [European beech], Quercus hispanica [Spanish oak], and Q. pedunculata [now Quercus robur, the common or English oak]. In the deciduous leaves the abscission layer was formed in the autumn… In the petioles of the marcescent leaves, only partially formed abscission layers were found… The marcescent leaves were abscissed the following spring…

...

In some instances development of the abscission layer in the autumn is arrested before it is completed, and the leaf may remain on the branch for some time after the other leaves have fallen. Leaves remaining on the trees later than January usually reveal little if any morphological evidence of the formation of an abscission layer.

Marcescent leaves, even on the same plant, do not all fall at once, but once begun, abscission proceeds rapidly and the fall is much more uniform than is the case with leaves falling in autumn. [Berkley goes on to list the order of leaf-shedding in the following marcescent oaks: Quercus coccinea (scarlet oak); Quercus velutina (black oak); Quercus marilandica (blackjack oak); Quercus rubra (northern red oak); Quercus alba (white oak).] Cursory observations were made on a few species in other genera, including Fagus grandifolia [American beech], Ostrya virginiana [American hophornbeam], and Acer saccharurn var. nigrum [black sugar maple]. The behavior of these is similar to that of the species of Quercus. The marcescent leaves of F. grandifolia remain on the branches long after the buds begin to swell, and in some instances until the new leaves have expanded. A single specimen of Acer saccharum var. nigrum was observed to retain its leaves until many of the new ones were almost fully expanded.


Posted in Miscellany





Traditional Highland uses of birch

The Highlanders of Scotland make everything from it, they build their houses, make their beds, chairs, dishes and spoons; construct their mills; make their carts, plows, harrows, gates and fences; and even manufacture ropes of it. The branches are employed as fuel in the distillation of whisky; the spray is used for smoking hams and herrings, for which last purpose it is preferred to every other kind of wood. The bark is used for tanning leather, and sometimes, when dried and twisted into a rope, instead of candles. The spray is used for thatching houses; and dried in summer, with the leaves on, it makes good bed when heath is scarce.

- J. C. Louden, An Encyclopedia of Trees and Shrubs, being the Arboretum Fruiticetum Britannicum, 1842 (London).


Posted in Miscellany





treeblog is back... with excuses

No, treeblog isn't dead. And I haven't forgotten about it. In fact, an extraordinary combination of circumstances have lead to treeblog being either offline or without an update for almost a month! A most shocking turn of events, I'm sure you'll agree, and please accept my apologies.

You see, I left sunny Sheffield for the Italian Alps on the 15th of August for a university field trip. So while I was enjoying myself in the forests of the Dolomites (and Venice) for a week and a half, treeblog was without an update. Not that I could have posted anything had I been home, seeing as how treeblog was probably offline for the time I was away! That brings me on to Problem Number Two: insufficient bandwidth. Since its inception, treeblog has been building in popularity. Yet an image-heavy blog combined with a meagre bandwidth allowance from my web host spells disaster. And thus when treeblog reached its bandwidth limit partway through the last couple of months, the host pulled the plug and the rest is history.

However, the bandwidth allowance is reset at the beginning of each month. So why no post on the 1st? Well, by that time, I was on another field trip. One that I only returned from on Saturday. And what with me being extrordinarily busy for the moment, coupled with living in a flat with no internet... that goes some way to explaining the lack of posts.

Until now.

I am back in the Scottish capital, and I am bringing treeblog back. I have sort of integrated Flickr with this blog, and that should solve the bandwidth problems for the time being. But enough excuses; this digression ends here.

I have so much to tell you, and so many pictures for your eyes to feast upon. The next few posts should be good, and best of all, they will be with you shortly!


Posted in Miscellany





treeblog visitors (30th July 2007)

a European Common Frog in a cider gum's pot

A European Common Frog (Rana temporaria) in a cider gum pot.

An earwig (Forficula auricularia) above the treeblog's seedling stronghold.


Posted in Miscellany





The Great Flood of 2007

I promised photos; here are a few I took myself:

nearby section of road / raging torrent

Part of a nearby road turned raging torrent.

another road / rapids

Taken close to the above photo. The red lines highlight the kerbs at either side of the road.

underwater roundabout

Under that brown water is a roundabout!

tree blocking road

This silver (or downy) birch fell across a main road into Sheffield. About a dozen people helped to saw it up and clear it out of the way in the space of about ten minutes. Large sections of this road were knee-deep in water and a bit has since slid into the adjacent river.

The above photos were taken on Monday the 25th of June and give only a small taste of the devastation caused by the floods. The following photograph was taken on Tuesday the 26th and shows the same section of road as seen in the first two photographs once the water had mostly subsided. This particular road was just an inch or so deep in water, yet it was flowing with such ferocity that over the course of only a few hours it ripped up an impressive amount of tarmac and carried away quite a lot of road base.

damaged road

The morning after. A gash approximately one metre wide.


Posted in Miscellany





Scots pine (Pinus sylvestris) flowers

I took the following photographs of the reproductive parts of the Scots pine yesterday near the little village of Bolsterstone. The accompanying information comes from Forestry Commission Booklet No. 15, Know Your Conifers, authored by Herbert L. Edlin, B.Sc. and published by HMSO in 1970.

Male flowers.

Male flowers... consist of clusters of golden anthers, set some way back from the tips of the twigs; they shed clouds of pollen in May, and then wither.

A click beetle (Athous haemorrhoidalis) close to a male flower. Adult click beetles feed on pollen, nectar and flower and leaf tissues, but they do not feed exclusively on Scots pine.

Female flower.

The female flowers appear at the same time [as the male flowers], at the very tip of a newly expanded shoot; they are tiny, crimson tinted globes. After fertilisation they grow into brown structures no larger than a pea; they need two years for full ripening.

Two-year-old unripe cone.

Mature cones... which are always "one whorl back" from the tip of the shoot, owing to its continued growth, are at first green with tightly-shut scales. [...] Their symmetrical, "pointed-cone" shape helps the tree's identification; each scale bears a knob, but no points. In spring they turn brown and the scales open, to release the winged seeds... As in all pines, the seed is lightly held in a curved "claw" at the base of the wing.

A ripe, woody Scots pine cone, open for seed dispersal.


Posted in Miscellany





Branch shedding in mature beech trees

I recently recieved an email with the following photograph of an old beech (Fagus sylvatica) attached.

beech near Burwash, E. Sussex (Tim Symonds)

The sender, Tim Symonds, included the following information:

The beech in the attached photo is near Burwash, East Sussex. It displays clearly how the beech can drop its branches if need be. This one is in clay soil, on a steep-ish slope, about thirty metres above a tiny brook. The Woodland Trust guessed it must be between 200 and 250 years old. It is 220 inches in girth at 5 feet.

A girth of 18 feet 4 inches (559 cm) would give the beech a diameter of appox. 178 cm (5 feet 10 inches)! This is much larger than the Loch Tay 'Mother Beech' which had a girth of 377 cm (12 feet 4 inches) and thus a diameter of approx. 120 cm (3 feet 11 inches).

But I digress, and let us get back to the beech in the photograph. Why would a tree want to lose its branches? It might seem like a ridiculous thing to do, considering the time and effort invested in growing them. Yet many biotic and abiotic stresses (e.g. water shortage or disease) may cause a tree to shed branches. However, given the size of this specimen, it is likely that simple old age is the causal factor - senescence. I believe the following article describes the whys and wherefores of geriatric branch shedding particularly well. I will reproduce it here in its entirety, but I found it here (FindArticles). The author is Peter Thomas (a lecturer in environmental science at Keele University (UK)), and the article originally appeared in the May 2002 edition of Natural History magazine.

To live long, a tree must stay small.

Old age is not the problem for plants that it is for animals. Being modular, plants can grow new limbs when old ones die off. More crucial to the longevity of a tree is its size. A tree reaches a stage when it cannot get taller, owing mainly to the difficulties of bringing water up from the roots, and when its side branches cannot grow longer, because they are too expensive to support. So the number of leaves a tree holds becomes more or less fixed, and this means that the tree's ability to produce food--the sugar made in leaves by photosynthesis--also levels off.

Yet each year the tree adds a new layer of wood under the bark, and the amount of wood needed to coat the whole tree increases, just as, in a set of Russian dolls, each new doll on the outside has to be bigger. As the tree grows, the amount of food needed for running it rises. The tree resembles a bank account whose income (sugary food) is fixed but whose outgo (respiration and new wood) keeps mounting. The tree compensates for a time by producing narrower and narrower rings, but there comes a point when a ring cannot get any narrower. Something has to give, usually the water-deprived top most branches. The result is a stag-headed tree, so named for the antlerlike dead branches sticking out of the top. A downward spiral begins: the loss of branches means fewer leaves, and fewer leaves means less new wood.

But many trees can slow the process. Some have buds in the trunk that sprout new branches. These may hold enough leaves to make up for those lost higher up, so the tree can keep the leaf area constant while cutting out the expensive-to-maintain upper trunk and its big branches.

Although these new trunk branches are fairly short-lived (a hundred years in oak, sixty years in hornbeam and beech, and less in birch and willow), an oak with plentiful trunk buds can stave off death for centuries. As the old saying goes: "Oak takes 300 years to grow, 300 years it stays, 300 years it takes to decline." Perhaps we should think of a stag-headed oak as merely entering middle age and, like many humans, just going a little bald on top.

A tree has no fixed life span. To live long, it must stay small. One way to do this is to grow slowly. Bristlecone pines are the supreme example: they live on poor soil in a dry, cold environment with a short growing season. One bristlecone in the American Southwest has been documented at three feet tall, less than three inches in diameter, and 700 years old! The other way to stay small and live long is, paradoxically, to be cut down repeatedly. (This strategy, of course, will work only for trees capable of regrowing when cut.) The ash Fraxinus excelsior normally lives for 250 years, yet Suffolk, England, hosts a coppiced ash with a stump almost seventeen feet in diameter. It is at least a thousand years old.

A tree's bank balance is also influenced by savings in the form of food reserves. As a tree gets bigger, however, it has less food left over. At the same time, the larder--the sapwood--gets smaller. Eventually, infections penetrate inner structures, and storage capacity is lost behind a barrier zone, a layer of new cells produced in the inner bark to seal off infected wood. The living part of the tree is walled into a thinner and thinner space under the bark. Part of the tree dies. New branches on the trunk can still save its life, but a large old tree is not good at producing new shoots, perhaps because it is running out of stored buds or because they are trapped behind thick bark. New sprouts on weak trees often die just when people think the tree is going to live. This may be because the barrier zone is missing or because there are too few reserves left for the tree to grow a strip of tissue from the new branch down to the roots. Either way, disease easily overtakes the tree, and the branch withers away. At this point, the tired old tree bows out gracefully.

COPYRIGHT 2000 American Museum of
Natural History
COPYRIGHT 2003 Gale Group


Posted in Miscellany





Tricotyledonous sycamore: first true leaves

Below is a photo of my tricotyledonous sycamore (taken by my father on Saturday), 23 days after I discovered it. Its first true leaves are now developing, and I am glad to see that there are three of them. As the tree develops, growth (branches, leaves and so on) will be trifurcate (in threes), as opposed to normal dichotomous (in twos) growth. Basically, this tricotyledonous sycamore is to a normal dicotyledonous sycamore what a four-leafed clover is to a normal three-leaved clover (Trifolium repens). I am interested to see whether or not its offspring will be tricotyledonous, although it's going to be quite a wait to find out.

tricotyledonous sycamore seedling with first true leaves – 28th April 2007


Posted in Miscellany





Tricotyledonous sycamore!

Aaah, the humble cotyledon. The Oxford Dictionary of Biology defines ‘cotyledon’ thus:

A part of the embryo in a seed plant. The number of cotyledons is an important feature in classifying plants. Among the flowering plants, the class known as Monocotyledoneae have a single cotyledon and Dicotyledoneae have two. Conifers have either two cotyledons, as in Taxus (yews), or five to ten, as in Pinus (pines). In seeds without an endosperm [*], e.g. garden pea and broad bean, the cotyledons store food, which is used in germination. In seeds showing epigeal germination e.g. runner bean, they emerge above the soil surface and become the first photosynthetic leaves.

[* The endosperm is a nutritive tissue that surrounds the developing embryo in a seed.]

The sycamore (Acer pseudoplatanus) is a non-native yet extremely common tree in Britain. It is dicotyledonous and undergoes epigeal germination.

Out walking on the 5th of April, I spied a sycamore seedling with three cotyledons. An amazing mutant tricot! This is the second time I have seen one of these; the first was on a field trip in spring 2005. Back then I was amazed by my lucky find. Although I took it home with me, it rapidly perished due to a long day in the field with no suitable way to preserve it. Back to the 5th of April… This particular day I was walking down a country lane with my friend, and noticing all of the newly germinated seedlings in the edge of the road, I was reminded of my encounter with the tricot. From time to time I would glance into the edge looking for another – and as luck would have it, I found one! I wasn’t taking any chances with this one, so I left it in situ, returning later in the day to collect it. Behold!

mutant sycamore seedling with three cotyledons – 7th April 2007

mutant sycamore seedling with three cotyledons – 7th April 2007


Posted in Miscellany





A lovely lichen

A lovely lichen (possibly a Xanthoria species) growing on an ash (Fraxinus excelsior) near Dungworth (close to Sheffield). Photo taken on the 1st of April, 2007.


* * * * *

treeblog news: Set A (Day 23)
No seedlings have germinated yet, unfortunately. Come on already!


Posted in Miscellany





Habitat fragmentation

Habitat fragmentation is a significant obstacle to the long-term conservation of biodiversity. Research and monitoring have revealed a continual decline in biodiversity, caused in part by decreasing habitat quality and increasing fragmentation. Models have predicted that fragmentation can increase the extinction threshold (the minimum population level needed to ensure survival) by up to 60–80%. As a result, greater amounts of habitat are required for population persistence in fragmented landscapes. Isolated woods often have a simplified structure with levels of biodiversity lower than would be expected if they formed part of a large, continuous forest.

The species most at threat have high area, specialist habitat requirements and low dispersal potential; for example, certain birds, wintergreens, orchids and detritivore invertebrates. Many species have already been lost from the British Isles, including the lynx, wild horse, moose, brown bear, beaver, boar, and wolf.

To reduce the fragmented nature of our woodlands without establishing continuous woodland cover across the UK (which is obviously unfeasible), habitat networks are being developed. Habitat networks are intended to reverse the decline in biodiversity by linking and expanding habitats to sustain a greater biodiversity. The Forestry Commission has worked on the recognition and development of forest and woodland habitat networks. Existing native woods (in particular ancient woods) are the main pool of native woodland biodiversity, and must therefore play a key role in the network system. The development of ecologically sustainable landscapes requires that patterns of future landscapes sustain the necessary ecological processes in the landscape. Habitat networking can help achieve this requirement. There is potential for the creation of networks for most habitats and species.

It must be borne in mind, however, that by creating woodland corridors and new areas of woodland, other habitats are becoming more fragmented. Take the figure below, for an oversimplified example. In panel A, the woodland is fragmented. In panel B, a woodland corridor has been established to form a habitat network. However, the moorland habitat has now become fragmented.

habitat network example

Connectivity can be defined as physical or functional. Physically isolated woodland fragments may be functionally connected. The permeability of the surrounding ‘matrix’ has a significant impact of functional connectivity for many species; semi-natural habitats are considered to be more permeable than land used intensively. It is possible to have high functional connectivity in a fragmented area of low physical connectedness. Matrix use is considered to be a predictor of species sensitivity to fragmentation. This assumes that ‘functionally connective zones’ of varying quality exist around woodland fragments. An example of two matrix types of different permeability are ‘willow thicket’ and ‘coniferous forest’ to certain taxa of butterfly; a study* has shown that conifer was 3-12 times more resistant than willow.

*Ricketts, T. H. (2001). The matrix matters: effective isolation in fragmented landscapes. The American Naturalist, 158, 87-99.


Posted in Miscellany





Mycorrhiza - a brief introduction

If you don’t have a clue what a mycorrhiza is, or if you have a vague idea but nothing substantial, then read on: I will do my best to edify you.

Simply put, mycorrhizas are intimate mutualisms between fungi and plant root tissue. Almost all higher plants are mycorrhizal, and those that are will be either obligative (the mutualistic species cannot survive if separated) or facultative (the mutualistic species can survive if separated, but mutualism is preferable). Trees are generally mycorrhizally facultative, whereas orchids are generally mycorrhizally obligative. ‘Mutualism’ is ecology jargon, but its meaning is fairly obvious – two organisms live in intimate association with mutual benefit.

With mycorrhizas, the host plant benefits by receiving nutrients from the fungal network that it is not capable of extracting from the soil itself. The mycorrhizal fungi benefits by receiving carbon from the plant in the form of photosynthate sugars. This mutualism is millions of years old, with the fossil record suggesting that the earliest land plants were heavily infected by mycorrhizal fungi.

There are a number of different types of mycorrhiza. When it comes to trees, two kinds are really important: arbuscular mycorrhizas and ectomycorrhizas. Arbuscular mycorrhizas are found in about two thirds of all plant species, particularly tropical trees and non-woody species. The fungi involved are not host specific, and there are only a few hundred known species. Ectomycorrhizal fungi generally are host specific, and there are about 6000 known species world-wide. They dominate in boreal and temperate forests.

What I find most interesting is that large (typically arbuscular) mycorrhizal fungal networks in forests often simultaneously colonise hosts of differing age and species. Even more interesting is the fact that nutrients can be exchanged between different tree individuals via the mycorrhizal fungi! A study* reported that "91% of paper birch and 56% of Douglas fir intermingled mycorrhizal roots examined were colonized by the same mycorrhizal fungi. In these tree species, a 4–7% net transfer of isotopically labelled carbon from birch to Douglas fir has been demonstrated". Amazing! Recently an ericoid mycorrhizal fungus (mutualistic with ericaceous plants such as heather) was shown to associate with Quercus (oak) roots. This suggests the possibility of some trees sharing nutrients with ericaceous plants!

* Durrell, D. M., Jones, M. D., Molina, R., Myrold, D. D., Perry, D. A. and Simard, S. W. (1997). Net transfer of carbon between ectomycorrhizal tree species in the field. Nature, 388, 579-582.


Posted in Miscellany





I love pine

In early February I stumbled upon Trees for Life's I love pine page. They had a competition running where they asked for a short answer to the question 'Why do you love pine?', with a winner and two runners-up selected each day from the 1st to the 14th of February. I won on the 6th of February with this tongue-in-cheek entry:

Because of the evocative aroma of its resin which conjures up memories of the Black Wood of Rannoch. Because of how sublime and majestic a mature pine appears when silhouetted against the setting sun. Because of the mesmerising nature of its wonderfully patterned bark. Because the incomparable experience of sauntering over the needle-carpeted floor of a pristine pine wood is undeniably divine. I love pine for all these reasons and more.

Here’s my prize:


This beautiful watercolour painting of a Scots pine tree in Glen Affric is by Joan Fairhurst, who has generously donated it to Trees for Life. This large, portrait-format print measures 40.5 x 51 cm. (picture area is 24 x 32.5 cm) and when framed will grace any wall with the beauty of the Caledonian Forest.

Thank-you, Trees for Life!


Posted in Miscellany





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