Pseudosclerotic plates of Kretzschmaria deusta

On a red horse chestnut (Aesculus x carnea) that was felled today, I had the opportunity to look at the pseudosclerotic plates of the Kretzschmaria deusta colonisations around the base. As expected, they were certainly rather beautiful, and I have included a few images below to show exactly this. The black lines signal the extent of specific mycelial colonies within the wood structure, and as a group they are quite sublime. Natural art!

Pseudo-sclerotic plate Kretzschmaria 1
Colonising right up to near the periphery of the available wood substrate. The chestnut has not at all compartmentalised the decay, which is still in its early stages.
Pseudo-sclerotic plate Kretzschmaria 2
A view of the near the centre of the tree, around 50cm up from the base. Looks like part of a world map!
Pseudo-sclerotic plate Kretzschmaria 3
A closer look at the fictitious counties of the country of Kretzland.
Pseudo-sclerotic plate Kretzschmaria 4
A few isolated areas of more sound wood, amongst a sea of decaying wood. Perhaps other fungi already exist in those areas.
Pseudo-sclerotic plate Kretzschmaria 5
A lovely flower!
Pseudosclerotic plates of Kretzschmaria deusta

Canada and trees – the early 20th century

For this post, I’m doing something a little different – I’m quoting directly from a source, extensively. The reason for this is that the publication I am quoting from is the 1930 publication entitled “Canada: Descriptive Atlas“, which was issued by direction of Hon. Robert Forke, who was, until 1929, Minister for Immigration and Colonization in Canada. If you’re wondering where I obtained it, I was lent this publication by an old lady who had kept hundreds of old publications, ranging from old Post Office magazines to World War I and II publications. This text was among them all.

Canada Descriptive Atlas 1930
Here be the publication!

The publication is split into sections for each region of Canada, and I have picked out parts that relate to trees and have included them below, though within their wider context – I have not cut out any parts of the sub-sections quoted, and instead they are quoted in full (this means some bits aren’t directly related to trees). I may do them over the course of a few posts spanning a few days, as there is a lot to write! All below images are taken from the publication, and the captions below are the same as in the publication itself.

The Dominion of Canada

On lumbering: “The forests of Canada are among the largest in extent in the world, and are a correspondingly great source of wealth. When the early French explorers first sailed up the St. Lawrence River and endeavoured to penetrate the interior, they found the surface of the country virtually a huge forest, and rivers were the only routes into its vast recesses. Much of the forest, especially in the southern section, has been cleared away to make homes for the settlers, and still greater areas have been destroyed by fire, but sufficient still remains to make Canada one of the greatest potential lumber producing countries. Not only are those forests great for the lumber and pulpwood they contain, but they are also of immense importance in supplying fuel, in tempering the climate, and in conserving the water supply. For these reasons they are carefully guarded against fire and wanton destruction, and reforestation is being conducted in a scientific manner. Large areas in almost all the Provinces has been set apart as forest reserves, those in the hands of the Dominion Government alone, including parks, amounting to 43,710 square miles. With proper care, there is no danger of the forest wealth of Canada being depleted for centuries to come.

Government House, Ottawa, Canada, 1930
Government House, Ottawa, the residence of the Governor-General in Canada.

The production of pulp and paper is the most important manufacturing industry in Canada. It leads in gross value and also in the amount of wages paid. Canada produces more newsprint paper than any other country. The latest available figures show that 2,360,000 tons or about 990,000 tons more than the United States, the next largest producer.

The lumber industry is the fourth most important industry in gross value of products. It ranks first in the total number of employees, second in wage and salary distribution and third in value of capital.

Prince Edward Island

On industry: “As there are no minerals and no large forests in Prince Edward Island, neither mining nor lumbering is carried on. Manufacturing is connected chiefly with the preparation of foods, such as butter and cheese. Port-packing and lobster-canning are large and growing industries.

Prince Edward Island landscape 1930
Prince Edward Island is known as a Million Acre Farm or “The Garden of the Gulf”.
Prince Edward Island landscape 1930 (2)
Farm and Meadow mingle in a Charming Way on Prince Edward Island.

Nova Scotia

On climate: “The climate of the Province is remarkably healthy and invigorating. The sea modifies the temperature both of summer and winter. Lack of extremes of heat and cold tend to the rapid growth of vegetation. The rainfall is abundant, averaging about 44 inches a year.

On agriculture: “Agriculture is a leading industry of Nova Scotia, the annual value of the production being over $40,000,000 (£8,000,000). Along the northern side of the Province, a valley, 100 miles in length, yields one of the best apple crops in the world, while peaches, pears, plums, and cherries are also grown. The dyked lands are exceedingly rich and produce enormous crops of hay and cereals. Oats is the leader followed closely by wheat and barley. All root crops in the Province are healthy, the potato far outranking the other both in quality and quantity.

Nova Scotia rural landscape 1930
The beauties of Nova Scotia were sung by Longfellow in his “Evangeline”. Above is a picture of the Experimental Farm at Kentville, which is greatly aiding agriculture.

Along the southeastern shore of the Bay of Fundy is a range of hills. Sheltered between these hills and the central heights of the Province lies the famous Annapolis Valley, which, with its continuations, is about 100 miles long, and is sometimes as much as 10 miles wide. Here the early French immigrants planted their apple trees, and laid the foundation of Nova Scotia’s famous apple industry. This great industry supplies about half a million barrels of apples every year to the British Isles, besides a very large quantity the the apple-consumers nearer home. The apple is the king of fruits in Nova Scotia, where indeed it grows to a high standard of perfection. Plums and pears grow exceedingly well also; and at Digby, in the southwest corner of the Province, the cherry orchards in blooming time are a delight to the eye, and in picking time an enrichment to the pocket.

Nova Scotia apple orchard 1930
The Nova Scotia Apple is known the world over.

Dairying is becoming an important industry. Travelling dairy schools supported by the Provincial Government visit all parts of the Province to give instruction to the farmers. The hilly country ensures good pasturage, and the products from the dairy industry have an annual value of over $10,500,000 (£2,100,000). This does not include the large quantity of domestic butter produced on the farms. Stock farming is also receiving a great deal of attention, and by the importation of better breeds of cattle and horses promises to take a leading place in the agricultural interests of the Province.

Agricultural education is receiving stimulus from various agricultural societies, which provide addresses by experts at the meetings of farmers, and devote much attention to improving the standards of stock. The Provincial Government has established thirty-five model orchards throughout the Province. At the Provincial Agricultural College, Truro, practical training in all departments of farm work may be obtained.

On lumbering: “Pine has practically disappeared from Nova Scotia, but there still remains much larch, spruce, and fir, as well as beech, ash, birch, and maple. It is estimated that the Province now has about 12,000 square miles of good timber land, well looked after by a thorough system of fire protection. A large export trade is carried on with Great Britain, the United States, the West Indies, and South America.

More to come in the following few days, in separate posts!

Source: Anon. (1930) Canada: Descriptive Atlas. Canada: Houses of Parliament.


Canada and trees – the early 20th century

Relics of the past in the urban streetscape

Our urban areas were once not urban areas, but expanses of countryside that, over time, were built upon, sprawled outwards, and ate up even more countryside on the ever-growing periphery. For this reason, we can certainly come across mature and veteran trees, which signal previous landscape character and use. In the UK, where much of the landscape was cultivated for crops and converted for livestock, it is of little (but still nonetheless welcome) surprise when we spot the occasional lapsed pollard, or even an avenue of trees.

Earlier today, whilst out having a look at the same oak apple cynipid I posted about here, I paid a visit to a nearby street that is home to a very majestic lapsed oak pollard. Other old oaks are dotted about the landscape, and with a long line of very old oaks nearby (around 5 or 6), I suspect that this is, along with the others, a retained tree from an old hedgerow, field boundary, or pasture.

It’s funny, really. I do wonder sometimes whether people along that road realise what they’re looking at. The tree is, after all, a window into the past. Granted, it’s a tree that blocks out light and drops leaves, but more importantly than that it’s a relic of what used to be, and therefore has significant landscape value (ecologically and historically, in particular). Protecting such old trees, even in urban areas, is, at least in my opinion, critical.

lapsed oak pollard urban street 1
A lovely lapsed oak pollard. The stort trunk is very large – this image doesn’t quite capture the size.
lapsed oak pollard urban street 2
From the other side, we can appreciate its presence a bit more.
lapsed oak pollard urban street 3
And in a wider shot, we can see houses on both sides of the street. No doubt that this is a very important tree.
Relics of the past in the urban streetscape

Ceiba trees and the Mayans

Most cultures will have their important trees. Historically, perhaps more so, as cultures are so diluted today that the only thing worshipped with any ferocity is money and power (a generalisation, yes). An interesting relationship of trees and a culture is that of the ceiba tree and the Mayans (in the Mayan language, the ceiba was called the ‘yaxche‘, which translates to ‘the first [blue-green] tree’), and thus we have to go back a good few thousand years for this factoid.

We must first understand that, back in time, trees were so critically important. They provided food for humans and livestock, shade and protection from the harsh elements of nature, had medicinal properties and were thus used to treat illnesses, and were harvested for their timber, which could be used for construction (or burned as firewood). Therefore, there was a very strong connection between man and trees, and this was the case for the Mayans and the ceiba tree. The ceibas provided food through their edible fruits, of which the fine silk-like thread from the mature fruits could be harvested and spun into cloth, and the seeds crushed to make oil. The species also had wood soft enough to carve into canoes, and, in addition, numerous parts of the tree could be harvested for their medicinal benefits. For example, the leaves of the ceiba could treat skin burns, swellings, and rashes, whilst the bark could heal ulcerations, encourage ‘menstrual flow’ and expel placentas, amongst other more earthly ailments such as treating gonorrhea. The sap was also used as a weight-gainer (quick, someone inform the supplement industry!).

parakeet ceiba fruit
A parakeet feasting upon the fruit of the ceiba. We can also see the silky threads that would have been spun to make cloth. Source: The Internet Bird Collection.

The ceibas were also important for locating water sources. In dry regions, ceibas were found where there was water near to the surface, and therefore their presence indicated that sustaining a human population nearby was at least somewhat feasible. Often, settlements were built around the ceibas, meaning the trees had a particular status, which obviously fostered the relationship they had with the Mayans. Beyond growing in arid regions, their abundant presence in the forest was also a reason for them being so revered – their commonality is probably a factor that allured the Mayans into worshiping the tree. In fact, in forest settings, other trees would be cleared and ceibas retained, sometimes also the younger ones, and settlements were constructed around them.

The Mayans revered the ceibas so much that they made stone carvings of the trees (known as tree stones or stelae). Where these tree stones were placed in temples, they were situated in the central regions atop the pyramid, and around the tree stone would, at times, sit four ceiba trunks. In this sense, the tree stones and surrounding trunks suggested great power and status (in the religious and political sense). Despite this (arguably very masculine) power display, the ceibas were actually considered to be quite feminine. The trees had maternal characteristics, such as how it was seen to care for deceased children by feeding them milk from its fruits, which actually resembled female breasts (in the eyes of the Mayans). The swollen trunk of the ceiba, particularly when growing within the forest, also had similarities to a pregnant woman. Some Mayan groups also claimed to be descendants from the ceiba tree.

There is also cross-over (pardon the pun) with the Mayan view of the ceibas and Christianity. In Mayan culture, the ceiba was sometimes depicted as a cross (usually in a green colour). When the Spanish invaded the Americas many centuries ago, this depiction actually enabled for the ‘easier’ conversion of Mayans to Christianity.

ceiba cross
The ceiba cross, green in colour. Source: Travelblog.

In modern times, whilst the culture has been diluted, ceibas are still respected. Generally only much older trees are revered in modern day, whilst younger ones are ignored. Unfortunately, however, even at times the older trees are ignored. For those communities situated within the lowlands, the ceiba is more respected than it is in the highlands. Despite this, young ceibas are still felled in the lowlands to allow for agricultural practices to take place – an act that may have been hugely frowned upon (or perhaps banned) in historic times. The link with Christianity still exists, too, as the ceiba is linked with the Catholic Church and can therefore be found within the grounds of churches across the land (a bit like yew trees in churchyards across the UK).

Source: Anderson, K. (2003) Nature, culture, & big old trees: live oaks and ceibas in the landscapes of Louisiana and Guatemala. USA: University of Texas Press.

Ceiba trees and the Mayans

Wood pastures and society – changing times and changing desires

Man has always had a direct link to the landscape, though that link, whilst it is always there, may not be in the form that it once was. Keeping with the wood pasture theme, which I am really enjoying learning about through books and journal articles, I thought we’d look at how the manner in which we approach the ecosystem has changed over the centuries (quite briefly). Of course, what is written below doesn’t stop just at wood pasture – it has cross-over to other ecosystems, where the reasons for interaction with the landscape have altered through space and, more pertinently, time.

Historically, wood pastures were managed for economic purposes. The grazing of animals on grasslands containing trees (and the feeding of the livestock with cuttings from pollarded trees, and a tree’s fruit crop), such as cattle and pigs, was for the direct benefit of communities, who relied upon the produce of the livestock (milk, meat, and so on) in order to make a living, and to generally therefore survive. Of course, the wood pastures needed to be conserved, so that they did not disappear, due to over-grazing. In this sense, they were actively conserved (by replanting dying and dead trees, and limiting grazing intensity), though largely because, without actively conserving them, the livelihood of many tens of thousands of people would be challenged. A by-product of this conservation of wood pastures, for the benefits created from grazing livestock, was that the sites were very rich in biodiversity – birds, fungi, insects, and plants, for example. The complex mosaic of niches within the wood pasture, ranging from open and disturbed soils through to the (perhaps sizeable) groves surrounded by the mantle and fringe vegetation, meant that a large number of organisms could viably frequent the site. However, for all of the biodiversity present as a result of the careful management and conservation of wood pastures throughout history, biodiversity was not the reason for management – until recently.

The shift, in Europe, probably begun when wood pasture became disliked (for hope of a better word), during the 19th-20th century (varies depending upon the country). Foresters wanted to maximise output from the trees (coppice – sometimes with standards), and farmers wanted to maximise agricultural output. Therefore, the two practices, initially married, were divorced from one another (somtimes farmers were forced to stop grazing their livestock in wood pasture!). Wood pastures were thus either cleared of trees entirely, or alowed to regenerate into forest. With this came a decline in the richness of biodiversity and, eventually, this loss of biodiversity caused a rather evident of panic amongst conservationists. Ironically, therefore, the rationale behind creating and maintaining wood pasture became largely ecologically-driven, in place of economically-driven (though, particularly in Spain and Romania, wood pastures remain, are these are generally economically viable). Regardless of reason however, the status of wood pastures essentially went full-circle.

wood pasture estonia
A fantastic wood pasture in Estonia. Source: Ideas for Sustainability.

Of course, this new found love for wood pastures does not necessarily mean that they can ever exist in the manner in which they did before. First and foremost, wood pastures are extensively grazed, and thus, for operations to be self-supporting financially, they must cover large expanses of land (unless the wood pasture is maintained for subsistence purposes, or grants are provided as a means of financial support). As farmers in Europe are generally in ‘the game’ for profit (they must make a living), managing livestock in wood pastures is probably not going to be all too popular, as it’d probably signal a marked drop in profits and / or a marked increase in labour input (at least, initially). Scope does exist to harvest edible mycorrhizal mushrooms from the wood pasture, such as truffles, though this is a specialised pursuit that is far from the current farming status quo of Europe.

Furthermore, European culture has changed. Gone are the days of communities being self-sufficient, and instead many Europeans now work a job (that they may even hate) and buy their food from the supermarket (or even order it online). Therefore, is there even the desire to re-introduce wood pastures, for anything other than ecological reasons, or to supply the market with a niche animal product (such as Iberian ham from the black Iberian pig, in the holm oak dehesas of Spain). With this change in culture there has also been a change in learning priorities, and unfortunately many today seem to be fixated with knowing pointless facts about sports teams and celebrities. Functional and practical knowledge is largely gone. As a consequence, the management of wood pastures will be left to an expert few, where knowledge has either been gained academically, or via being passed-down through the generations (usually limited to rural areas where grazing still takes place). However, as more people now live in cities than in rural areas, and this trend will likely continue as rural areas are swallowed up by urban sprawl, or people move into cities for economic reasons, this tradition of passing practical knowledge on and keeping up the family tradition of extensive livestock grazing within wood pasture may very well become ever more the stuff of legend.

black iberian pig dehesa
The black Iberian pig grazing amongst a landscape of holm oak, in a Spanish dehesa. Source: Andrew Petcher.

Society is simply in a different place than it once was. For this reason, the conservation of wood pasture is to be far from mainstream. People are certainly aware of nature (of which wood pastures feature), though more and more awareness comes from watching on the television and less from direct experience, and with this comes a discord. There is less emotional and cultural attachment to nature, and as a result, less of an impetus to associate with nature. Why help with the recreation of wood pasture when you can watch about its conservation on television, utter some lamentations, and then switch the channel and soon relegate it to a mere memory? That’s even assuming people watch such programs, in large numbers, in the first place.

This probably turned out far more dystopian than I ever intended for it to come out as, though hopefully this illustrates how social changes have led to landscape management changes, with specific focus upon wood pastures in Europe. This is obviously applicable to other landscape types as well, of course. The principle generally carries across.

Source (of inspiration): Hartel, T. & Plieninger, T. (2014) The social and ecological dimensions of wood-pastures. In Hartel, T. & Plieninger, T. (eds.) European wood-pastures in transition: A social-ecological approach. UK: Earthscan.

Wood pastures and society – changing times and changing desires

Book review: Grazing Ecology and Forest History

In a world that is being so markedly impacted by human activity, it is of little wonder that ecosystems are collapsing. In response to such a collapse however, conservationists have sprung up to safeguard remaining ecosystems (or at least try to), and create the conditions to improve them and enable them to expand in size. With regards to trees within landscapes, which oft (but not always) form a basis (wholly, or in part) of landscapes, the general understanding, historically, has been that high forest was the norm, and man’s activities in the arable and pastoral sense have facilitated in the enrichment of the landscapes, which has been of huge benefit to many organisms. For example, the grazing of livestock in wood pastures is seen to have been important for maintaining high species diversity, since the last ice age some 12,000 years ago. The cultivation of land for crops is also considered to have improved the landscape, with regards to creating conditions suitable for many wild flowers and insects. This is, of course, in spite of the glaring problem in that modern agricultural systems are generally monocultures; even on a genetic level. Curiously, prior to man’s working of the land, the outlook had not been that wild grazing ungulates (auroch, bison, deer, tarpan, wild boar, and so on) could have achieved the same sort of landscape, with the same sort of outcomes for biodiversity. Vera remarks that this is odd, because of the fact that both species of oak (Quercus robur and Quercus petraea), as well as hazel (Corylus avellana), feature rather readily within historical pollen records. These species do not successfully regenerate under closed canopies, as the seedlings are readily out-competed by more shade-tolerant species such as that of – but not exclusively – ash (Fraxinus excelsior), beech (Fagus sylvatica), field maple (Acer campestre), hornbeam (Carpinus betulus), and lime (Tilia cordata and Tilia platyphyllos).

Attempting to deconstruct this outlook, Vera lays out a very well-formed and well-presented argument, that is easily understood. Vera’s arguments stem from many origins, and there are chapters focussing on palynology (pollen studies), the use of the wilderness in the middle ages and how such a wilderness was defined by those around at the time who wrote literature and laws, case studies from across Europe exploring the regeneration of trees within old wood pastures and closed canopy stands (now forest reserves), and also a chapter on many species of tree found in Europe, and what conditions they require to be able to successfully regenerate from seed (or, in the case of species such as blackthorn, also from sucker). Vera rounds up with a short conclusion, and an even shorter still thought-provoking epilogue.

Throughout, I remained captivated by the book, and readily digested the information within. I constantly found myself able to relate what Vera was saying to my own personal experiences from exploring the landscape in the South East of England, and the use of case studies by Vera within the fifth chapter helped to paint this picture beyond my own realm of exploration. It is certainly clear, from what is presented in this chapter, that both oak and hazel are unable to regenerate successfully within the closed canopy situation, and their featuring within the landscapes is as a relic of the times of old, from when grazing (natural and human-induced) still occurred within the area. The loss in abundance of other tree species, namely both species of lime aforementioned, though also other species, is explained as well, and I found myself adding significantly to my understanding of woodland dynamics and history.

The fourth chapter, which focussed on the use of the wilderness from the middle ages through to 1900, improved my understanding further. Vera delves into old texts, sometimes via sources that cite much earlier texts (so second-hand referencing), and gives a convicing arguement as to why, in spite of what is generally considered today, the medieval landscape was not entirely high forest, but instead a mosaic of habitats including small grasslands and expansive steppes, park-like landscapes complete with mantle and fringe vegetation, groves, and forests (usually at higher altitudes, beyond wheere wild ungulates could access; generally due to less than ideal terrain). Vera remarks that old texts, in essence, had different interpretations of words that we now use to describe a forest, and this was because of how land was managed at the time, and the culture, amongst other reasons. For instance, the term ‘wald’, which is now generally considered to mean ‘forest’, once meant ‘wilderness’ (which may have been grassland, a park-like landscape, groves, or an actual forest). It was only more recently – around the 18th-19th century – that the meaning of such a word changed, to reflect the divorcing of pasture and woodland. At this time, foresters were pushing to remove grazing animals from where trees resided, in order to increase timber production.

Vera also makes, within this fourth chapter, the distinction between vegetative regeneration and regenerative regeneration. The former is via the re-sprouting of, for example, a coppice stool, whereas the latter is regeneration from seed. Old texts that refer to oak regenerating well within woodlands, Vera comments, actually refer to the vegetative regenerative capacity of oak, subsequent to harvesting oak stems and leaving a stool, from which new sprouts can rapidly form from. From seed, oaks will not be able to compete with other seedlings, and are out-competed (with lime being the most shade tolerant of all European trees). This also transfers into later life, where Vera states that oak is not out-competed because of its own age and decline, but because of the long-term ability for shade tolerant species of tree to catch up and overtake the oak. For instance, the beech, if growing alongside oak, and in light conditions, will initially lose out in the competition to oak, though after a period of around 100 years, it will catch up with the oak (in terms of height), grow above it, shade the oak out, and cause the oak to die from a lack of light. In this sense, we can see that the out-competing of oak is not isolated to the species’ infancy.

Of course, one cannot expect to take Vera’s word as gospel. As always, there are differing views, of which Vera presents one side of a multi-angled argument (a spectrum, if you will). The book has not been without its critics, just like how Vera criticised those who suggested the European landscape has always been covered, largely, with high forest. Nonetheless, I hugely enjoyed this book, and massively welcomed what Vera had to say. Having a broad horizon, and drawing in knowledge from an array of sources adopting various approaches to an argument, is important for any self-respecting indivual pursuing a better understanding of something – even if it doesn’t align with personal ideals. Else, there’d just be a world of ignorant bigots.

Without wanting to spoil the book any more, and without going into a bit of a tirade as to why absolute free speech must be safeguarded and also embraced (which would be a huge tangent to go off into during a book review on grazing ecology!), I heartedly recommend that you give serious consideration into buying this book. It’s not cheap, being nearly £100, though is genuinely worth it. It’s wonderfully enriching, and certainly ignites passion for wanting to explore the history of the landscape, and how we can approach modern day conservation, in an attempt to recreate the landscapes of the past for the benefit of biodiversity. If our baseline is wrong, and the landscapes weren’t historically mainly a closed canopy forest across Europe (and the east of the USA), then why is grazing prohibited from forest reserves? We know where Vera sits on the arguemnt, and it’s time for more people to get involved and form their own opinions as well. Buy (and then read!) this book.

Grazing Ecology and Forest History Vera
The book, upon my window sill.
Book review: Grazing Ecology and Forest History

Vacant urban plots are anything but a waste

Within many urban environments, one can come across vacant parcels of land. Such land parcels may be in residential, commercial, or industrial areas, and oftentimes they will be home to, because of the lack of disturbance and management of the land, plants. Some of these plants will, of course, be trees (of varying ages – depends on how long the land has been vacant for). In certain cities, the amount of vacant land may be particularly high, with declining fortunes of landowners, a worsening economy, and a change in demographics, being three drivers of the abandonment of land. In Detroit, USA, for example, around 32% of all urban land is currently vacant.Of course, in many aspects, this is not good, though is there a silver lining to such vacant plots? The study investigated in this post (referenced at the bottom) seeks to establish just that, in terms of ascertaining how valuable vacant land plots are as green infrastructure.

The study area for the investigation was the city of Roanoke, Virginia, USA. This city was chosen as it has a wide variety of different vacant land parcels, of which many are old industrial (manufacturing / factory) plots that were abandoned as the economy declined and technologies changed. In total, the vacant areas of land were split into five different categories, as shown in the below table. Overall, 114 vacant plots, both under public and private ownership, were sampled.

vacant land types city tree
The five types of vacant land, as defined by the authors.

Of these land types, an area amounting to nearly 30% of the entire city was considered to be classed as vacant. Granted, some areas are intentionally vacant, as they are floodplains, wetland areas, and so on. The table shown below gives more of an indication of what land types there are in the city, and how much of the total city area they comprise.

vacant land area tree
Total land area of the different vacant land types.

Within these vacant plots, there was a total of 210,000 trees (an average of 30.6% canopy cover, in these vacant areas); of which nearly 41% of the trees were quite small (below 15.2cm in diameter). The total number of trees are split as follows: (1) derelict: 25,725; (2) natural: 26,514; (3) post-industrial: 7,488; (4) transportation-related: 28.923, and; (5) unattended with vegetation: 121,613. Because of the species of trees found on the vacant sites (see below), it can be recognised that this data means many trees are young. This, in turn, means that the ecosystem services (filtering air pollutants, sequestering carbon, catching rainwater, cooling the urban environment, and so on) provided by the trees are rather limited, though as the authors note there is scope for the services to increase in time, as the trees mature. Of course, there are older trees within these vacant plots, and nearly 6% of all of the trees had a DBH of over, though the population is heavily skewed in favour of young trees. It is also worth noting that the invasive tree of heaven (Ailanthus altissima) features rather readily, and this may be undesirable on an ecological level. In fact, invasive non-native plants are perhaps more likely to be able to colonise vacant land plots than native ones, in many instances – particularly on brownfield sites.

tree species vacant land urban
A breakdown of the tree species found within the vacant plots. The three main species are American elm (16.5%), tree of heaven (12.3%), and box elder (6.7%).

Combined, the trees within the vacant plots do however have many benefits. First and foremost, they have a very positive impact upon air quality, by filtering out harmful pollutants that, as a result, has a monetary value attributed to it (as shown below). For example, nearly 30 metric tons of moderately-sized particulate matter is removed by the vegetation every year, and this equates to financial benefits of $450,000 (nearly $16,000 per metric ton).

trees pollution removal urban
The removal of pollutants by trees growing within vacant land parcels. The bars represent total pollution removal per year, whilst the triangles relate to the financial benefits.

Beyond the removal of air pollutants, the trees growing within vacant land also have a marked benefit when it comes to the sequestration of carbon. As carbon dioxide is considered by some (but not all) scientists as being a marked cause of climate change, some will promote the utilisation of trees for their assimilative capacity when it comes to storing carbon. In the study area, the 210,000 trees were found to sequester a gross total of 2,090 tons of carbon each year, which has a monetary value of $164,000. Granted, not all species are equal in this regard, and it is the American elm and the tree of heaven that top the charts for carbon sequestration (see the below graph), with the elm being far above anything else in this regard. Curiously, whilst the box elder is the third most common tree species within vacant plots, it does not rank third for carbon sequestration. When the authors looked at total carbon storage, which is what carbon has been stored over the trees’ lifetimes, a total of nearly 100,000 tons had been stored, which is valued at $7.6m. This value does however vary across vacant land types, with much of the carbon being stored in areas unattended that possess vegetation, though this may very likely be down to the fact that this land type has over half of the total 210,000 trees.

carbon sequestration trees vacant land
The total amount of caron sequestered, each year, by some of tree species found within vacant plots. Each metric ton of carbon sequestered is valued at $78.5.

These vacant land-borne trees also reduce the expenditure incurred by residents of the city, and particularly when it comes to heating or cooling of property. Each year, the trees reduced, by over $210,000, the expenses paid to heat and cool property. Such savings translate into indirect benefits for limiting air pollution, as this reduces cost is associated with reduced energy bills. This obviously means less energy was used, which implies that individuals emit (via consumption) fewer total pollutants, each year.

There also exists a structural value to the vegetation within these vacant plots, and for the city’s trees this amounts to $169m. Again, it is the unattended land that possesses vegetation that bears most of this value ($111m), as such land has by far the most trees, though other land types also have important financial values. The below table details exactly this.

structural value vacant land tree
The structural value of the trees within each land type, compared with the number of trees and the total cover of trees within each land type.

What I find particularly interesting about this study is that it suggests that we need to adopt a broader approach to how we view vacant areas of alnd within the city. Often, people will refer to areas of abandoned land within industrial and residential areas as wastelands, though according to this research they are anything but. Even though post-industrial and derelict land types themselves feature only to a small degree within the urban environment, they can certainly support tree populations, and the longer these areas remain void the better, from an environmental standpoint. Granted, there is a pursuit to re-build the economy after the banks managed to royally muck it all up and run off with billions in bailouts from the taxpayer, so such sites may be ear-marked for development if there is the justification, though at the same time there is huge opportunity to almost re-wild inner-city areas. Can there be a balance between the economy and the environment, therefore? If these sites are developed, perhaps there exists scope to retain some areas of trees. It’s also important to recognise the value these trees have by merely existing, and whilst it’s not a value that can be ‘cashed in’, it is nonetheless a value that should be properly recognised.

Source: Kim, G., Miller, P., & Nowak, D. (2015) Assessing urban vacant land ecosystem services: Urban vacant land as green infrastructure in the City of Roanoke, Virginia. Urban Forestry & Urban Greening. 14 (3). p519-526.

Vacant urban plots are anything but a waste

Bottle butt, Ganoderma sp., and Platanus x hispanica

I was in London today for a seminar, hosted the Arboricultual Association and presented by Barrell Tree Consultancy, regarding British Standard 5837:2012 and how to manage trees effectively on construction sites, in the lovely area of Bloomsbury Square. Characteristically, I was there very early, so had a chance to look around the trees in the garden square. Many of the trees were London plane, of which most were very mature. One drew my attention in particular, as it had very pronounced ‘bottle butt’. Lo-and-behold, there were old sporophores of what is probably Ganoderma australe, on two sides of the butt. Without question, this has at least partially facilitated in the creation of the bottle butt, as the fungus induces a white rot that de-lignifies the wood, making it soft. As a result, reaction growth is laid down, creating the bottle butt formation.

Platanus x hispanica Ganoderma sp 1
Here is the large London plane, which we can see has been crown reduced recently.
Platanus x hispanica Ganoderma sp 2
And the very distinct bottle butt, at the base.
Platanus x hispanica Ganoderma sp 3
Because of Ganoderma sp. colonisation!
Platanus x hispanica Ganoderma sp 4
Zooming in on the above sporophore.
Platanus x hispanica Ganoderma sp 5
On another side, we have two more sets of sporophores.
Platanus x hispanica Ganoderma sp 6
On the right…
Platanus x hispanica Ganoderma sp 7
…and on the left.
Bottle butt, Ganoderma sp., and Platanus x hispanica

The Eurasian jay and acorns – a symbiosis

Currently, I am on chapter 6 of Vera’s book Grazing Ecology and Forest History, and there’s a great sub-chapter (6.2.2) that explores the relationship between the Eurasian jay (Garrulus glandarius) and the oak. I learned a lot from reading this specific segment of the book, and thus hope that others also find the following information useful.

Firstly, one can certainly recognise that oak trees in Europe (Quercus petraea and Quercus robur) do not generally regenerate in woodland. Whilst acorns do germinate, after a period of usually less than a decade, they cease to be, as they are out-competed by shade-tolerant species, such as hornbeam (Carpinus betulus) and beech (Fagus sylvatica). Instead, oaks oft regenerate amongst thorny scrub (in grasslands, grazed areas, and within mantle and fringe vegetation bordering woodland), be the scrub comprised of hawthorn (Crataegus spp.), blackthorn (Prunus spinosa), holly (Ilex aquifolium), gorse (Ulex europaeus), or otherwise. In many an instance, one can perhaps wonder how the young oaks reached and regenerated within such scrub, and most notably so if there are no sizeable oaks within the immediate area. One explanation for this is, as explained by Vera, and courtesy of an array of sources, the Eurasian jay.

As an oak releases its fruit crop (acorns) into the harsh environment during September to November, the jay will collect many of the acorns (the healthy, ripe, good-sized ones, generally-speaking), and bury them at a distance from the tree that may vary from tens of metres to a few miles. When a jay collects only one or two acorns, it may bury them only a short distance from the point at which it gathered them from, but if the jay carries five or six acorns (in its gullet, throat, and beak – the largest being in its beak), then the acorns may be buried thousands of metres away. All of the acorns collected in one ‘trip’ will be buried in close proximity to one another, at a maximum spacing distance of around 15m (usually 0.5-2m spacings). At the level of a single jay, this dispersal of acorns may be relatively small, but when amplified to a group of jays 65 strong, research has indicated that (over the course of four weeks) up to 500,000 acorns may be dispersed. This dispersal is also very significant at distances from nearby oaks, with approximately 5,000 acorns per hectare when the nearest fruit-producing oak is around 200m away.

Eurasian jay acorn Quercus
A Eurasian jay with an acorn within its beak. Source: Phil Winter.

Jays also have a strong preference of burying their acorns in open areas with loose soil. Usually, this will be open areas outside of forests within grasslands and amongst thorny scrub (this explains why oaks may pop up amongst thick scrub), though if substantial forest clearings manifest (due to tree mortality – normally courtesy of windthrow and the forest edge effect), then they too may be alluring sites in which the jay may cache its treasure. Interestingly, open areas complete with loose soil and areas of thick scrub are akin to medieval wood pastures, where grazing would have occurred.

oak regeneration mantle and fringe
This young oak is growing amongst bramble and gorse, within a heathland area, and beyond the direct reach of a parent oak (meaning the acorn didn’t just fall into this spot). Thus, it is likely that it was buried by a jay.

Once the acorn has been buried by the jay, it will cover the site with soil and leaves, in order to hide it from sight. In order to re-find it, the jay will remember the vertical structures of vegetation in the immediate area – their memory of where they have planted acorns is, in fact, very good. Interestingly, a jay will only be able to find acorns it has buried – it will not be able to locate acorns buried by other jays, unless that other jay is also present at the time of digging up the acorn. Typically, the acorns they bury will be eaten throughout the year, though the months of April through to August mark the period when fewest acorns are dug up and eaten. This drop in predation by the jay fits in well with the period of acorn germination, with the stem emerging during May and the first few leaves unfolding in June.

This development of the small leaf crown co-incides with when jays will begin to search for acorns with a little more intent, as it is during this time that they will be feeding and training their young to fend for themselves. When a seedling (that is still green in the stem, and thus not lignified) is found from an acorn that the parent jay had buried, it will pull it up and eat the acorn, before depositing the little seedlng back into the ground rather crudely. Its young will, actually rather hilariously, mirror this behaviour, though with far less finesse, and pull up not only oak seedlings but anything else they find as well. This removal of the acorn does however not have a huge impact upon the oak seedling, as the strong and extensive tap root developed rapidly after germination means that the little oak seedling is securely anchored into the ground and can fend for itself, even if the acorn (provides energy for seedling growth) is lacking. Essentially, the uprooting is a trade-off that the oak tolerates well, so to be able to grow in the full sunlight conditions the jay opts to bury its acorns in (and where they will grow best, as the oak is not shade tolerant). Research has even shown that many oaks bear the scar of early uprooting by a jay, though since that time they have developed into healthy young trees. Importantly, this disturbance event only happens once (usually), as jays will only uproot small seedling that they buried. Jays are very ‘untrusting’ of ‘foreign’ or ‘alien’ acorns and oak seedlings, and thus will avoid them, by-and-large.

The symbiotic nature of the relationship between the oak and the jay is cemented when one recognises that both benefit very well from the association. As remarked above, the oak is able to regenerate in ideal conditions, though as the jay selects only the healthiest and larger acorns there’s also a direct filter placed upon acorn populations, that ensures only the strongest acorns ever have a good chance of germinating. Furthermore, the wide dispersal of acorns by the jay ensures that oak populations can spread quite markedly, with small satellite groves emerging at sometimes great distances from the parent tree. On the side of the jay, the provisioning of an important food source is critical, as without acorns the jay, in Europe, may have to find other significant sources of food with good nutritional value. Of course, it is also important that the right conditions are available for the jay – this means open areas of grassland, or mantle and fringe vegetation. Closed forests are not suitable for the jay, and it will thus not bury its acorns there. In fact, even though forest stands of oak produce 10-times more acorns than sparsely-populated open-grown oak pasture landscapes, the density of acorns within the soil buried by jays is 50-times greater within the open landscapes. Such landscapes are generated by grazing, according to Vera, and whilst modern grazing has been created by man (up until the decline on grazing, in recent times), historically the wild boar (Sus scrofa) would have provided good conditions (due to its disturbance of the soil in grasslands, which were created by large roaming herbivores – the auroch, deer, and wild horse, for example) for where the jay could bury its acorn collection.

Source: Vera, F. (2000) Grazing Ecology and Forest History. UK: CABI Publishing.

The Eurasian jay and acorns – a symbiosis

UK case law and overhanging tree branches

Whilst overhanging branches of a tree are not deemed trespass but instead nuisance, the case of Earl of Lonsdale v Nelson [1823], which dealt with trespass and not nuisance is perhaps a peculiar beginning. However, during the case’s hearing, the judge remarked that nuisances could be abated by the individual suffering from the nuisance without notice to the person causing the nuisance, though notably not when overhang was onto a public roadway or the overhang was from a tree whose owner would routinely tend to their trees themselves. The judge also remarked that permitting branches to overhang into a neighbouring property was a “most unequivocal act of negligence”, though caution must be exercised here as labelling overhang as negligent is lurking at the threshold of what could be considered appropriate for the situation. Instead, such overhang is referred to as nuisance, as outlined in the judge’s preceding comments. Building upon this ruling, the case of Rylands v Fletcher [1868], even though not to do with trees, set the precedent for foreseeability, and therefore because boundary trees will foreseeably encroach, via their branching crown (and roots), onto neighbouring land, the tree owner must, in readily recognising this, ensure the nuisance associated with their encroachment is abated. If not, if anything “mischievous” were to arise (including solely from the overhang detracting from the neighbour’s enjoyment of his or her land), the tree owner would be held liable.

The case of Earl of Lonsdale v Nelson [1823] was, at the Court of Appeal, considered in some detail during the case of Lemmon v Webb [1894], where the claimant, who owned a few large trees, consisting of oaks and elms, growing amongst a hedgerow on his property, filed a claim against Webb for damages when Webb cut off some of the branches to his boundary line without prior warning. In this instance, there was absolutely no question that Webb did indeed have the power to cut back the overhang, though discussions did take place of whether Lemmon had to be informed of such an action. Initially, Lemmon won the case with regards to this matter, though at appeal that was overturned. However, the judge at appeal did recognise that, particularly if trespass must occur for overhang to be removed, then the owner of the trees be informed prior to the works being carried out – though the judge did not mandate such a course of action, and thus there is no actual need to inform the owner of the trees if a neighbour seeks to remove overhang. All that is required is they prune the tree with “reasonable care”, and the removed wood (and leaves, flowers, etc – depends upon the time of year) is offered back to the tree’s owner as it was removed from the tree (who has the right to refuse them back, if they so desire). Such a precedent was established in the Mills v Brooker [1919] case.

ustulina deusta aesculus carnea 1
Overhanging branches from a red horse chestnut (Aesculus x carnea). Some lower ones have been pruned back.

Later, in Smith v Giddy [1904], a slightly different angle of approach could be seen. The claimant was contesting how Giddy’s trees were overhanging onto his property and impacting adversely upon the growth of his fruit trees. The judge ruled, in the case prior to it going to appeal (of which the outcome is not known), that if the trees are not doing any damage, then it may be up to the claimant (plaintiff) to abate the nuisance by cutting back to the boundary line. Only when overhang is actually causing damage is there a need for action on behalf of the grower of the trees, as in such a case one cannot expect the neighbour to fund such remedial works to ensure his or her property is once again free to a damaging agent.

More recently, courts seem only to rule that a tree is a nuisance if harm is being caused (stemming back from the case of Lemmon v Webb). Elliott v Islington LBC [1991] did come close to ruling a tree can be a nuisance merely for overhanging a property, though ultimately did not accept such a precedent. Instead, where overhang is not causing harm, it can be removed by the neighbour. Such a stance was also adopted by the judge in Perrin & Anor v Northampton Borough Council & Ors [2006], where it was ruled that “the owner of the land who has suffered the encroachment has a right to remove the overhanging boughs“, and also ruled in Delaware Mansions Limited & Others v Lord Mayor & Citizens of The City of Westminster [2001], where the judge remarked that overhang can be abated by the neighbouring land owner.

In terms of who can remove overhang, Read v J Lyons & Co [1947] stated that, and as subsequently re-affirmed by Hunter v Canary Wharf Ltd [1997], action of nuisance abatement can be undertaken by any person or persons who are the owner(s) of occupier(s) of the land affected by overhang. Overhang cannot however be removed by guests, lodgers, employees, or family members who do not have exclusive possession of the land affected. In the latter case of Hunter v Canary Wharf Ltd [1997], it was also ruled that nuisance can be divided into three categories: (1) nuisance by encroachment on a neighbour’s land, (2) nuisance by direct physical injury to a neighbour’s land, and (3) nuisance by interference with a neighbour’s quiet enjoyment of land. The encroachment of branches is typically, though not always, cited under the first reason.

UK case law and overhanging tree branches