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Blog - ecosystem services

Wild life and deadwood.

Wild life and deadwood.

by The blog at woodlands.co.uk, 28 April, 2023, 0 comments

For biodiversity to flourish, a wide variety of microhabitats is needed.  With many micro-habitats, more species are able to thrive. It may seem counter-intuitive but deadwood offers opportunities for a diverse range of species. Within a woodland, there are various types of deadwood, providing shelter and food for many organisms.  Perhaps one of the most obvious examples of deadwood is standing but dead trees.  If the dead tree was a veteran, then it will provide a variety of micro-habitats.  Holes and crevices may be used by bats and birds, the decaying wood will be colonised by bacteria and fungi, bracket fungi may erupt - whilst the bark will continue to offer a substrate for mosses and lichens.  As the wood decays, the material becomes a home for saproxylic beetles. Stag beetle larvae feed on decaying wood underground,  whilst the adults rely on fat reserves built up during their larval stage. Adults can ‘drink' oozing sap  and the juice of soft, rotting fruit. In the UK, some 650 beetle species are associated with deadwood [visit Dr Ross Piper’s website for full details of these insects].  As with many insects, many saproxylic beetles are threatened with extinction - due to the decline in the number of veteran / ancient trees.  Saproxylic beetles, apart from being important in the recycling of materials, are also food for birds and mammals. A previous blog has extolled the virtue of dead hedges.  Dead hedges are simply piles of branches and twigs arranged to create a barrier / hedge. They represent  a way of disposing of material that arises from thinning or clearing operations in woodlands. This ‘waste material’ of saplings and side branches are sometimes referred to as “arisings" by tree surgeons, or "lop and top” by foresters. Using this material in this way is good for wildlife, particularly for small mammals and birds - as it gives them somewhere to shelter from the wind and rain, and protection from predators. It's also good for insects.  As the material rots and decomposes, it adds humus / nutrients to the underlying soil. Larger pieces of wood from the felling of trees can be arranged to form a stack or pile, by simply laying branches and logs on top of one another  Such a stack wil rot and decay over time, but will provide a home to a variety of wildlife. So, deadwood in its various forms, is an important part of woodland ecosystems. It has a role in delivering biodiversity, but it also provides ‘ecosystem services’, such as soil formation and nutrient cycling. Deadwood contributes to the detrital food chain, which is driven by fungi, bacteria and detritivores.   Below : All that remains of a historic tree - the Wilberforce Oak. It was here at Holwood House (Keston , near Hayes, Bromley) in 1788 that William Wilberforce resolved to address the task of abolishing the slave trade. It took some twenty years for his vision to be realised. [Thanks to Ruth for images of the Wilberforce Oak] https://en.wikipedia.org/wiki/Holwood_House
The wood wide web, an underground network.

The wood wide web, an underground network.

by The blog at woodlands.co.uk, 29 November, 2022, 0 comments

Most months, Jasper has introduced us to a new fungus or group of fungi that have made their appearance in woodlands,  some on trees or branches or leaves, others simply emerging from the soil.  Some fungi are parasitic or biotrophic requiring a living host organism on which they feed.  Then there are those that live in and feed on dead and decaying matter in the soil; these are termed saprobic or saprophytic.  The structures that we normally see (particularly at this time of the year) are the fruiting or reproductive bodies of the fungus / fungi.  The majority of a fungus exists as a network of microscopic ‘tubes’ that permeate either the host organism, or the soil / decaying matter in which the fungus has made its ‘home’.  An individual tube is known as a hypha and collectively they form a complex network - the mycelium. The fungal mycelia present in the soil form a vast underground network.   Some of these fungi enter into beneficial associations with plants - mycorrhizal associations.  The fungal hyphae wrap themselves around (and sometimes into) the roots of plants and trees, with whom they share minerals and nutrients. Generally speaking, the fungus helps to supply the plant with mineral nutrients (like nitrates / phosphates) and in return receives carbohydrate material from the plant’s photosynthetic capacity.  These mycorrhizal systems form part of what has been termed the ‘wood wide web’.  Dr. Suzanne Simard, a forest ecologist from the University of British Columbia, coined the term to describe the complex relationships between fungi and plants in woodland and forest ecosystems. It has been suggested that (millions of years ago) fungi helped plants transition from their aquatic home to life on land, with the fungal network serving as a ‘root system’.  Fungi (and bacteria) release enzymes (biological catalysts) and these help break down the complex compounds (like lignin, cellulose and starch) present in dead plants and animals.  As a result of this decomposition, humus is formed. Humus is a colloid.  A complex mixture of materials, some in solution, some in suspension. Humus binds the inorganic mineral particles of the soil together, is a store of nutrients and helps water retention.  The fungal network in the soil sequesters enormous amounts of carbon.  The soil is one of the Earth’s main carbon ‘sinks’.   If soil is over-worked or damaged by the intensive and extensive use of chemicals in farming, then it degrades and with it the rich microbial network. Damage to the soil and its complex microbial population can impact on the growth of plants - from the simplest green plants to the largest trees. Not only are soil fungi and bacteria involved in the cycling of carbon and nitrogen, but they help maintain the fertility and structure of the soil.  Soil is the ultimate recycling system, we need to cherish the soil and its fungal and bacterial populations - it helps maintain the ecosystem services on which we all depend.  Without healthy soils, we face a very bleak future.  
The lost trees of Dartmoor

The lost trees of Dartmoor

by The blog at woodlands.co.uk, 25 February, 2022, 4 comments

Certain upland areas of the UK , such as Dartmoor, have experienced long term grazing.  This has lead to soil compaction, which in turn means that water run-off is greater. Instead of percolating into the soil, rain water runs over the surface and into rivers. This can lead to flooding during extreme weather events.   Dartmoor (National Park) is a large upland area, which historically was dominated by oak woodland.  Oak woodland now covers a very small area.   The region is now dominated by blanket bog, heathland and acid grassland.  The number of grazing animals (sheep, cattle and ponies - deer) increased significantly between the 1950s and 2000, resulting in soil compaction. Researchers at the University of Plymouth have investigated areas of upland pasture on Dartmoor, and the potential for the establishment of native oak saplings. Working with test sites, they were able to show that significant improvements in soil properties could be observed with 15 years of sapling establishment.   The most effective location (in terms of flood prevention) for sapling / tree planting was on steep hillside on the edge of upland areas.   Their initial work on the planting of woodland has since been expanded to determine the factors that affect the establishment of the tree (oak) saplings.  Their most recent paper notes that the presence of livestock meant that fewer oak saplings survived and those that did were smaller.  However, the effects of cattle and ponies was not always negative in that their trampling could reduce the growth of bracken - allowing more light to reach young tree saplings. [caption id="attachment_34391" align="aligncenter" width="650"] A southern upload moorland - Exmoor[/caption] The research team formulated a number of recommendations relating to the creation / establishment of woodlands in such upland pastures. Livestock should be excluded in areas where there are seedlings and young saplings (1 - 3 years). This exclusion should last for some 12 years. Larger oak (4 - 7 yrs) saplings can be planted into areas of dense vegetation, as this protects the saplings from livestock. Livestock could be allowed to graze in the vicinity of mature oak trees as this would reduce dense, competitive vegetation, allowing seedlings to grow / develop.  Strategic planting and management should be considered  / encouraged for upland slopes where drainage is poor - to allow for soil recovery and development of ecosystem services (flood mitigation). Whilst natural tree colonisation is a low-cost and environmentally sensitive mechanism to promote woodland expansion (working towards government targets on climate mitigation, carbon sequestration etc.), it is likely that the expansion of oak woodland into upland pasture systems will require strategic planting and informed livestock management. [caption id="attachment_37920" align="aligncenter" width="650"] Exmoor Ponies.[/caption] Full details of their paper can be found here : https://besjournals.onlinelibrary.wiley.com/doi/10.1002/2688-8319.12126  (Thanks to Art for images of exmoor and ponies).
pollution over city

The loss of animal species, and the effects on fruit and seed dispersal.

by The blog at woodlands.co.uk, 23 February, 2022, 0 comments

Sadly, the world is losing species, both plant and animal, at a significant rate.  Indeed, some claim that we are now experiencing the sixth mass extinction.  In contrast to previous extinctions (the Permian extinction is thought to be due to an asteroid impact), the present loss of species is largely associated with a mix of direct and indirect human activities. These include :- destruction and fragmentation of habitats,  Exploitation fishing stocks and hunting (think dodo),  chemical pollution,  invasive / introduced species, and  human-caused global warming The loss of animal species has knock-on effects in terms of food chains and biodiversity. Plants are also affected as many rely on animals for the dispersal of their fruits and seeds.  In times of global warming, it is essential that plants can reach new areas that are suitable for their growth.  If not, they are stuck in areas where they may not be able to survive in the changed / changing conditions.  This could mean that plant species are lost, together with the ‘ecosystem services’ that they provide (be it food, timber, carbon storage, flood mitigation etc).  Seed dispersal is also important in terms of recovery from ecological disasters, like wildfires.  Natural forest regrowth usually happens through seed dispersal. If an ecosystem is rich in species, it is generally more resilient to environmental change.  The relationship between fruit / seed dispersal and animals has been significantly affected by the creation of roads, motorways, farms, and the development of cities - essentially habitat fragmentation.  Animal dispersal is often associated with fleshy fruits.  Whilst this is particularly true / obvious for many tropical fruits, it is also the case for many plants in temperate regions.  Berries, hips and haws are dispersed by animal means, with birds being particularly important agents. Several pines produce large seeds and attract corvids such as nutcrackers and jays. The birds, sometimes called scatter hoarders, collect seeds and bury them in areas away from the parent trees but in habitats suitable for the next generation of trees  Mammals also play significant roles.  In Africa, elephants are important  seed  dispersers  for  numerous  species; they  have an extra-ordinary sense of smell and will search out ripe, fleshy fruits. Some seeds have been shown to be distributed 60+ kilometres from a parent plant. Not only this, but the journey through the gut of the elephant seemingly increases the chance of germination, and being deposited in the dung reduces the chance of the seed being eaten by beetles.  Some monkeys in South and Central America eat as many as fifty different types of fruit in a day. carrying some off in their stomachs and dropping others to the ground. In Britain, as part of their diet, foxes will eat various wild fruits, like blackberries; squirrels eat nuts; and mice / voles eat grass and other seeds.  Even invertebrates, like ants, disperse seeds. This may be through the activity of harvester ants, which, like squirrels and other ‘gatherers’,  forage the ground of the wood or forest (collectively) gathering large quantities of seeds and  then transport them back to their nests / colonies.  As they transport the seeds, some get dropped or lost on the way.  Others may be ‘cached’ in or near the nest for later consumption but then are ‘forgotten’ or ignored. Some fruits contain seeds covered with a sticky substance as is the case of Mistletoe. When birds feed on the fruits, the seeds often stick to the beaks of birds.  Then, they may wipe the sticky seed off on a branch;  or it may be eaten and pass out in the bird’s droppings. The ‘glue’ (viscin) around the seed helps fasten the seed in place. Even humans carry seeds far away for plants, for example, by taking an apple on a picnic and throwing the core with its seeds into the bushes. Or seeds may transported in the mud sticking to boots and shoes, or indeed on tractors, cars or other machinery. The loss / extinction of animal species from any given habitat will sooner or later effect the plants.  We are only beginning to fully appreciate the interdependence of life.    The loss of any species - plant or animal - will undoubtedly have unintended and unforeseen consequences which can only be to the detriment of all life on earth.  

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