Coarse woody debris
Encyclopedia
Coarse woody debris is a term used in English-speaking countries for fallen dead tree
s and the remains of large branch
es on the ground in forest
s. Some prefer the term coarse woody habitat (CWH). A dead standing tree is known as a snag
and provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from 2.5–20 cm (0.984251968503937–7.9 in) in diameter.
Since the 1970s, forest manager
s worldwide have been encouraged to allow dead trees and woody debris to remain in woodlands, recycling nutrients
trapped in the wood and providing food
and habitat
for a wide range of organisms, thereby improving biodiversity
. This natural process of woody growth, decomposition
, and recycling may aid in the renewal of ancient forests.
s, as well as catastrophic events such as fires
and storms
, are all sources of CWD. The ancient
, or old growth, forest, with its dead trees and woody remains lying where they fell to feed new vegetation, constitutes the ideal woodland in terms of recycling and regeneration. In healthy temperate forest
s, dead wood comprises up to thirty per cent of all woody biomass
.
In recent British studies, woods managed for timber had between a third and a seventh less fallen debris than unmanaged woods that had been left undisturbed for many years, while in recently coppiced
woods the amount of CWD was almost zero.
In old growth Douglas-fir forests of the Pacific Northwest
of North America, CWD concentrations were found to be from 72 metric tons/hectare (64,000 pounds/acre) in drier sites to 174 t/ha (155,000 lb/acre) in moister sites. Australian native forests
have mean CWD concentrations ranging from 19 t/ha (17,000 lb/acre) to 134 t/ha (120,000 lb/acre), depending on forest type.
recycles nutrients
that are essential for living organisms, such as carbon
, nitrogen
, potassium
, and phosphorus
. Saprotrophic
fungi and detritivore
s such as bacteria
and insects directly consume dead wood, releasing nutrients by converting them into other forms of organic matter
which may then be consumed by other organisms. CWD, while itself not particularly rich in nitrogen, contributes nitrogen to the ecosystem by acting as a host for nonsymbiotic
free-living nitrogen-fixing
bacteria
.
Scientific studies show that coarse woody debris can be a significant contributor to biological
carbon sequestration. Trees store atmospheric carbon in their wood using photosynthesis
. Once the trees die, fungi and other saprotrophs transfer some of that carbon from CWD into the soil
. This sequestration can continue in old-growth forests for hundreds of years.
, coarse woody debris helps to maintain the biodiversity
of forest ecosystems. Up to forty percent of all forest fauna is dependent on CWD. Studies in western North America showed that only five per cent of living trees consisted of living cells by volume, whereas in dead wood it was as high as forty percent by volume, mainly fungi and bacteria. Colonizing organisms that live on the remains of cambium
and sapwood
of dead trees aid decomposition and attract predator
s that prey on them and so continue the chain of metabolizing the biomass.
The list of organisms dependent on CWD for habitat or as a food source includes bacteria
, fungi
, lichen
s, moss
es and other plant
s, and in the animal kingdom, invertebrate
s such as termite
s, ant
s, beetle
s, and snail
s, amphibian
s such as salamander
s, reptile
s such as the slow-worm
, as well as bird
s and small mammal
s. One third of all woodland birds live in the cavities of dead tree trunks. Woodpecker
s, tits, chickadee
s, and owl
s all live in dead trees, and grouse
shelter behind woody debris.
Plants use coarse woody debris as habitat, often covering them with moss
es and lichen
s. In some forests with dense ground cover or waterlogged soils, germination
on top of CWD is a competitive advantage. Large fragments of CWD that provide such habitat for herb
s, shrub
s, and tree
s are called nurse log
s. CWD can also protect young plants from herbivory damage by acting as barriers to browsing animals.
The persistence of coarse woody debris can shelter organisms during a large disturbance to the ecosystem such as wildfire
or logging
.
Fallen debris and trees in streams provide shelter for fish
and mammals by modifying the flow of water and sediment through the channel. This stream debris may be referred to as large woody debris
.
of precipitation is improved as well. During dry weather, CWD slows evaporation
of soil moisture and provides damp microhabitats for moisture-sensitive organisms.
, Scotland
, the Trees for Life group found the black tinder fungus beetle (Bolitothorus reticulatus) is dependent on a particular fungus (Fomes fomentarius
), which itself grows only on dead birch
. Another insect, the pine hoverfly (Blera fallax
), requires rotting Scots Pine
in order to reproduce.
In certain subtropical areas such as Australia
where bushfire
constitutes a major hazard, the amount of CWD left standing or lying is determined by what may be considered safe in the course of reasonable fire prevention. However, when fires do occur, invertebrates find shelter either within or beneath dead tree logs.
In Canada, bear
s seek out dead tree logs to tear open and look for and feed on ant
s and beetle
s, a fact that has encouraged the authorities to reserve a sufficient amount of coarse woody debris for these purposes. In North America, too, CWD is often used as barriers to prevent browsing
deer
and elk
from damaging young trees.
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s and the remains of large branch
Branch
A branch or tree branch is a woody structural member connected to but not part of the central trunk of a tree...
es on the ground in forest
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s. Some prefer the term coarse woody habitat (CWH). A dead standing tree is known as a snag
Snag
In forest ecology, a snag refers to a standing, partly or completely dead tree, often missing a top or most of the smaller branches. In freshwater ecology it refers to trees, branches, and other pieces of naturally occurring wood found sunken in rivers and streams; it is also known as coarse woody...
and provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from 2.5–20 cm (0.984251968503937–7.9 in) in diameter.
Since the 1970s, forest manager
Forest management
200px|thumb|right|[[Sustainable development|Sustainable]] forest management carried out by [[Complejo Forestal y Maderero Panguipulli|Complejo Panguipulli]] has contributed to the preservation of the forested landscape around [[Neltume]], a sawmill town in Chile...
s worldwide have been encouraged to allow dead trees and woody debris to remain in woodlands, recycling nutrients
Biogeochemical cycle
In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth. A cycle is a series of change which comes back to the starting point and which can...
trapped in the wood and providing food
Heterotrophic nutrition
Heterotrophic nutrition is nutrition obtained by digesting organic compounds.Animals, fungi, many prokaryotes and protoctists are unable to synthesize organic compounds to use as food...
and habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
for a wide range of organisms, thereby improving biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. This natural process of woody growth, decomposition
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
, and recycling may aid in the renewal of ancient forests.
Sources
Natural tree mortality, disease, and insectInsect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, as well as catastrophic events such as fires
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
and storms
Windthrow
In forestry, windthrow refers to trees uprooted or broken by wind. Breakage of the tree bole instead of uprooting is sometimes called windsnap.- Causes :...
, are all sources of CWD. The ancient
Ancient woodland
Ancient woodland is a term used in the United Kingdom to refer specifically to woodland that has existed continuously since 1600 or before in England and Wales . Before those dates, planting of new woodland was uncommon, so a wood present in 1600 was likely to have developed naturally...
, or old growth, forest, with its dead trees and woody remains lying where they fell to feed new vegetation, constitutes the ideal woodland in terms of recycling and regeneration. In healthy temperate forest
Temperate forest
Temperate forests correspond to forest concentrations formed in the northern hemisphere. Main characteristics include: wide leaves, big and tall trees and non seasonal vegetation...
s, dead wood comprises up to thirty per cent of all woody biomass
Biomass (ecology)
Biomass, in ecology, is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms,...
.
In recent British studies, woods managed for timber had between a third and a seventh less fallen debris than unmanaged woods that had been left undisturbed for many years, while in recently coppiced
Coppicing
Coppicing is a traditional method of woodland management which takes advantage of the fact that many trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level...
woods the amount of CWD was almost zero.
In old growth Douglas-fir forests of the Pacific Northwest
Pacific Northwest
The Pacific Northwest is a region in northwestern North America, bounded by the Pacific Ocean to the west and, loosely, by the Rocky Mountains on the east. Definitions of the region vary and there is no commonly agreed upon boundary, even among Pacific Northwesterners. A common concept of the...
of North America, CWD concentrations were found to be from 72 metric tons/hectare (64,000 pounds/acre) in drier sites to 174 t/ha (155,000 lb/acre) in moister sites. Australian native forests
Forests of Australia
Australia has many forests of importance due to significant features, despite being one of the driest continents. Australia has approximately 147 million hectares of native forest which represents some 19% of land use....
have mean CWD concentrations ranging from 19 t/ha (17,000 lb/acre) to 134 t/ha (120,000 lb/acre), depending on forest type.
Benefits
Nutrient cycling
Coarse woody debris and its subsequent decompositionDecomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...
recycles nutrients
Biogeochemical cycle
In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth. A cycle is a series of change which comes back to the starting point and which can...
that are essential for living organisms, such as carbon
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
, nitrogen
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...
, potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
, and phosphorus
Phosphorus cycle
The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and...
. Saprotrophic
Saprotrophic nutrition
Saprotrophic nutrition is a process of chemoheterotrophic extra-cellular digestion involved in the processing of dead or decayed organic matter that occurs in saprotrophs or heterotrophs, and is most often associated with fungi, for example Mucor and Rhizopus...
fungi and detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
s such as bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
and insects directly consume dead wood, releasing nutrients by converting them into other forms of organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
which may then be consumed by other organisms. CWD, while itself not particularly rich in nitrogen, contributes nitrogen to the ecosystem by acting as a host for nonsymbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...
free-living nitrogen-fixing
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
bacteria
Diazotroph
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia.A diazotroph is an organism that is able to grow without external sources of fixed nitrogen. Examples of organisms that do this are rhizobia and Frankia and Azospirillum. All diazotrophs...
.
Scientific studies show that coarse woody debris can be a significant contributor to biological
Biosequestration
Biosequestration is the capture and storage of the atmospheric greenhouse gas carbon dioxide by biological processes.This may be by increased photosynthesis ; by enhanced soil carbon trapping in agriculture; or by the use of algal bio sequestration to absorb the carbon...
carbon sequestration. Trees store atmospheric carbon in their wood using photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
. Once the trees die, fungi and other saprotrophs transfer some of that carbon from CWD into the soil
Soil carbon
Soil carbon is the generic name for carbon held within the soil, primarily in association with its organic content. Soil carbon is the largest terrestrial pool of carbon. Humans have, and will likely continue to have, significant impacts on the size of this pool...
. This sequestration can continue in old-growth forests for hundreds of years.
Habitat
By providing both food and microhabitats for many speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, coarse woody debris helps to maintain the biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
of forest ecosystems. Up to forty percent of all forest fauna is dependent on CWD. Studies in western North America showed that only five per cent of living trees consisted of living cells by volume, whereas in dead wood it was as high as forty percent by volume, mainly fungi and bacteria. Colonizing organisms that live on the remains of cambium
Cambium (botany)
A cambium , in botany, is a tissue layer that provide undifferentiated cells for plant growth. It forms parallel rows of cells, which result in secondary tissues....
and sapwood
Sapwood
Sapwood may refer to:* Sapwood, the part of living wood where sap flows, as distinct from the heartwood, where it doesn't* SS-6 Sapwood, the NATO reporting name for the R-7 Semyorka intercontinental ballistic missile...
of dead trees aid decomposition and attract predator
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
s that prey on them and so continue the chain of metabolizing the biomass.
The list of organisms dependent on CWD for habitat or as a food source includes bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, fungi
Wood-decay fungus
A wood-decay fungus is a variety of fungus that digests moist wood, causing it to rot. Some wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria , are parasitic and colonize living trees. Fungi that not only grow on wood but actually cause it to decay, are called...
, lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
s, moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es and other plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s, and in the animal kingdom, invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s such as termite
Termite
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera , but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea...
s, ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, and snail
Snail
Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...
s, amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
s such as salamander
Salamander
Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant...
s, reptile
Reptile
Reptiles are members of a class of air-breathing, ectothermic vertebrates which are characterized by laying shelled eggs , and having skin covered in scales and/or scutes. They are tetrapods, either having four limbs or being descended from four-limbed ancestors...
s such as the slow-worm
Anguis fragilis
Anguis fragilis, or slow worm, slow-worm or slowworm, is a limbless reptile native to Eurasia. It is also sometimes referred to as the blindworm or blind worm, though the Royal Society for the Protection of Birds considers this to be incorrect.Slow worms are semi-fossorial lizards spending much...
, as well as bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s and small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s. One third of all woodland birds live in the cavities of dead tree trunks. Woodpecker
Woodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
s, tits, chickadee
Chickadee
Chickadee is a group of birds in the Paridae familyChickadee may also refer to:* USS Chickadee , a minesweeper in the United States Navy* Chickadee , a Canadian children's magazine-See also:* Black-capped Chickadee...
s, and owl
Owl
Owls are a group of birds that belong to the order Strigiformes, constituting 200 bird of prey species. Most are solitary and nocturnal, with some exceptions . Owls hunt mostly small mammals, insects, and other birds, although a few species specialize in hunting fish...
s all live in dead trees, and grouse
Grouse
Grouse are a group of birds from the order Galliformes. They are sometimes considered a family Tetraonidae, though the American Ornithologists' Union and many others include grouse as a subfamily Tetraoninae in the family Phasianidae...
shelter behind woody debris.
Plants use coarse woody debris as habitat, often covering them with moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es and lichen
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
s. In some forests with dense ground cover or waterlogged soils, germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
on top of CWD is a competitive advantage. Large fragments of CWD that provide such habitat for herb
Herb
Except in botanical usage, an herb is "any plant with leaves, seeds, or flowers used for flavoring, food, medicine, or perfume" or "a part of such a plant as used in cooking"...
s, shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s, and tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s are called nurse log
Nurse log
A nurse log is a fallen tree which, as it decays, provides ecological facilitation to seedlings. Broader definitions include providing shade or support to other plants. Some of the advantages a nurse log offers to a seedling are: water, moss thickness, leaf litter, mycorrhizae, disease protection,...
s. CWD can also protect young plants from herbivory damage by acting as barriers to browsing animals.
The persistence of coarse woody debris can shelter organisms during a large disturbance to the ecosystem such as wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
or logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
.
Fallen debris and trees in streams provide shelter for fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and mammals by modifying the flow of water and sediment through the channel. This stream debris may be referred to as large woody debris
Large Woody Debris
Large woody debris are the logs, sticks, branches, and other wood that falls into streams and rivers. This debris can influence the flow and the shape of the stream channel...
.
Soil
Coarse woody debris, particularly on slopes, stabilizes soils by slowing downslope movement of organic matter and mineral soil. Leaves and other debris collect behind CWD, allowing for decomposition to occur. InfiltrationInfiltration (hydrology)
Infiltration is the process by which water on the ground surface enters the soil. Infiltration rate in soil science is a measure of the rate at which soil is able to absorb rainfall or irrigation. It is measured in inches per hour or millimeters per hour. The rate decreases as the soil becomes...
of precipitation is improved as well. During dry weather, CWD slows evaporation
Evapotranspiration
Evapotranspiration is a term used to describe the sum of evaporation and plant transpiration from the Earth's land surface to atmosphere. Evaporation accounts for the movement of water to the air from sources such as the soil, canopy interception, and waterbodies...
of soil moisture and provides damp microhabitats for moisture-sensitive organisms.
Regional examples
In Glen AffricGlen Affric
right|300px|thumb|Glen AffricGlen Affric is a glen south-west of the village of Cannich in the Highland region of Scotland, some to the west of Loch Ness. The River Affric runs along its length, passing through Loch Affric and Loch Beinn a' Mheadhoin .It used to be part of the lands of the Clan...
, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, the Trees for Life group found the black tinder fungus beetle (Bolitothorus reticulatus) is dependent on a particular fungus (Fomes fomentarius
Fomes fomentarius
Fomes fomentarius is a species of fungal plant pathogen found in Europe, Asia, Africa and North America...
), which itself grows only on dead birch
Birch
Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...
. Another insect, the pine hoverfly (Blera fallax
Blera fallax
Blera fallax or the pine hoverfly is a rare species of hoverfly normally associated with mature pine tree in Northern and Central Europe.-Biology:...
), requires rotting Scots Pine
Scots Pine
Pinus sylvestris, commonly known as the Scots Pine, is a species of pine native to Europe and Asia, ranging from Scotland, Ireland and Portugal in the west, east to eastern Siberia, south to the Caucasus Mountains, and as far north as well inside the Arctic Circle in Scandinavia...
in order to reproduce.
In certain subtropical areas such as Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
where bushfire
Bushfires in Australia
Bushfires in Australia are frequently occurring events during the hotter months of the year due to Australia's mostly hot, dry climate. Large areas of land are ravaged every year by bushfires, which also cause property damage and loss of life....
constitutes a major hazard, the amount of CWD left standing or lying is determined by what may be considered safe in the course of reasonable fire prevention. However, when fires do occur, invertebrates find shelter either within or beneath dead tree logs.
In Canada, bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
s seek out dead tree logs to tear open and look for and feed on ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s and beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, a fact that has encouraged the authorities to reserve a sufficient amount of coarse woody debris for these purposes. In North America, too, CWD is often used as barriers to prevent browsing
Browsing (predation)
Browsing is a type of herbivory in which an herbivore feeds on leaves, soft shoots, or fruits of high growing, generally woody, plants such as shrubs. This is contrasted with grazing, usually associated with animals feeding on grass or other low vegetation...
deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
and elk
Elk
The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:...
from damaging young trees.
See also
- Large Woody DebrisLarge Woody DebrisLarge woody debris are the logs, sticks, branches, and other wood that falls into streams and rivers. This debris can influence the flow and the shape of the stream channel...
- SnagSnagIn forest ecology, a snag refers to a standing, partly or completely dead tree, often missing a top or most of the smaller branches. In freshwater ecology it refers to trees, branches, and other pieces of naturally occurring wood found sunken in rivers and streams; it is also known as coarse woody...
- Tree hollowTree hollowA tree hollow or tree hole is a semi-enclosed cavity which has naturally formed in the trunk or branch of a tree. These are predominantly found in old trees, whether living or not...
- Nurse logNurse logA nurse log is a fallen tree which, as it decays, provides ecological facilitation to seedlings. Broader definitions include providing shade or support to other plants. Some of the advantages a nurse log offers to a seedling are: water, moss thickness, leaf litter, mycorrhizae, disease protection,...
- Soil lifeSoil lifeSoil life or soil biota is a collective term for all the organisms living within the soil.-Overview:In balanced soil, plants grow in an active and steady environment. The mineral content of the soil and its heartiful structure are important for their well-being, but it is the life in the earth that...
- LitterfallLitterfallLitterfall is the transport of leaves, bark, twigs and other forms of dead organic material and its constituent nutrients from the aerial parts of the biosphere to the top layer of soil, commonly known as the litter layer or O horizon.Litterfall has occupied the attention of ecologists at length...
Further reading
- Franklin J. F., Lindenmayer D., MacMahon J. A., McKee A., Magnuson J., Perry D. A., Waide R. & Foster D. (2000). "Threads of Continuity". Conservation Biology in Practice. [Malden, MA] Blackwell Science, Inc. 1(1) pp9–16.
- Proceedings of the Symposium on the Ecology and Management of Dead Wood in Western Forests. PSW-GTR-181. William F. Laudenslayer, Jr., Patrick J. Shea, Bradley E. Valentine, C. Phillip Weatherspoon, and Thomas E. Lisle Technical Coordinators.