Leaf mold

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Leaf mold (spelled leaf mould outside of the United States) is the compost produced by decomposition of shaded [1] deciduous shrub and tree leaves, primarily by fungal breakdown in a slower, cooler manner as opposed to the bacterial degradation of leaves. [2] [3]

Contents

Description

Leaves shed in autumn tend to have a very low nitrogen content and are often dry. Their main constituents, cellulose and lignin, are two recalcitrant molecules resistant to degradation. [4] [5] Because of this, autumn leaves break down far more slowly than most other compost ingredients which may take a very long time on their own. Specialised biota, such as molds, [6] produce extracellular enzymes [7] which can easily break down those complex plant polymers(cellulose, lignin and hemicellulose) [8] into biologically accessible forms [9] enriching the soil environment.

The importance of this decomposition of the leaves and other shed plant litter is that their degradation and decomposition forms a critical step in the mineralization of organic nutrients and their recycling. [9]

Time and process

Fungal decomposition of a heap of leaves in damp temperate climates can take between one and three years to break down into a dark brown fine powdery humic matter. A succession of different fungal species may be involved. [10] A range of micro detritivores are also involved in converting the leaf material into a fine-grained humus, including many isopods, millipedes, earthworms, etc.

Uses

In the natural environment, the decomposition of leaves provides a moist growing medium for young plants and protects the ground from drying out during periods of low rainfall. It is a significant component of soil organic matter, particularly in temperate deciduous woodland. The slow rate of decomposition gradually releases plant nutrients bound up in the leaves back into the environment to be re-used by plants. Autumn leaves are often collected in gardens and farms into pits or containers for the resultant leaf mold to be used later.

Oxygen and moisture are essential for leaf decomposition. Leaf mold is not high in nutrient content but is an excellent humic soil conditioner because its structure and moisture retention provide a good growing medium for seedling roots.

Leaves collected from roads and pavements may be contaminated by pollutants which can become more concentrated as the leaves decompose into a smaller volume [11]

See also

Related Research Articles

<span class="mw-page-title-main">Humus</span> Organic matter in soils resulting from decay of plant and animal materials

In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin word for "earth" or "ground".

<span class="mw-page-title-main">Mycelium</span> Vegetative part of a fungus

Mycelium is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates into a monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form fruiting bodies such as mushrooms. A mycelium may be minute, forming a colony that is too small to see, or may grow to span thousands of acres as in Armillaria.

<span class="mw-page-title-main">Lignin</span> Structural phenolic polymer in plant cell walls

Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors.

<span class="mw-page-title-main">Detritivore</span> Animal that feeds on decomposing plant and animal parts as well as faeces

Detritivores are heterotrophs that obtain nutrients by consuming detritus. There are many kinds of invertebrates, vertebrates, and plants that carry out coprophagy. By doing so, all these detritivores contribute to decomposition and the nutrient cycles. Detritivores should be distinguished from other decomposers, such as many species of bacteria, fungi and protists, which are unable to ingest discrete lumps of matter. Instead, these other decomposers live by absorbing and metabolizing on a molecular scale. The terms detritivore and decomposer are often used interchangeably, but they describe different organisms. Detritivores are usually arthropods and help in the process of remineralization. Detritivores perform the first stage of remineralization, by fragmenting the dead plant matter, allowing decomposers to perform the second stage of remineralization.

Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come from the feces and remains of organisms such as plants and animals. Organic molecules can also be made by chemical reactions that do not involve life. Basic structures are created from cellulose, tannin, cutin, and lignin, along with other various proteins, lipids, and carbohydrates. Organic matter is very important in the movement of nutrients in the environment and plays a role in water retention on the surface of the planet.

<span class="mw-page-title-main">Ecosystem ecology</span> Study of living and non-living components of ecosystems and their interactions

Ecosystem ecology is the integrated study of living (biotic) and non-living (abiotic) components of ecosystems and their interactions within an ecosystem framework. This science examines how ecosystems work and relates this to their components such as chemicals, bedrock, soil, plants, and animals.

<span class="mw-page-title-main">Corn stover</span> Corn (maize) plant parts left in field after harvest

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<span class="mw-page-title-main">Abscission</span> Shedding of various parts of an organism

Abscission is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a tail to evade a predator. In mycology, it is the liberation of a fungal spore. In cell biology, abscission refers to the separation of two daughter cells at the completion of cytokinesis.

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<span class="mw-page-title-main">Soil biology</span> Study of living things in soil

Soil biology is the study of microbial and faunal activity and ecology in soil. Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their life cycle within a soil profile, or at the soil-litter interface. These organisms include earthworms, nematodes, protozoa, fungi, bacteria, different arthropods, as well as some reptiles, and species of burrowing mammals like gophers, moles and prairie dogs. Soil biology plays a vital role in determining many soil characteristics. The decomposition of organic matter by soil organisms has an immense influence on soil fertility, plant growth, soil structure, and carbon storage. As a relatively new science, much remains unknown about soil biology and its effect on soil ecosystems.

Lignin-modifying enzymes (LMEs) are various types of enzymes produced by fungi and bacteria that catalyze the breakdown of lignin, a biopolymer commonly found in the cell walls of plants. The terms ligninases and lignases are older names for the same class, but the name "lignin-modifying enzymes" is now preferred, given that these enzymes are not hydrolytic but rather oxidative by their enzymatic mechanisms. LMEs include peroxidases, such as lignin peroxidase, manganese peroxidase, versatile peroxidase, and many phenoloxidases of the laccase type.

<span class="mw-page-title-main">Wood-decay fungus</span> Any species of fungus that digests moist wood, causing it to rot

A wood-decay or xylophagous fungus is any species of fungus that digests moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria, are parasitic and colonize living trees. Excessive moisture above the fibre saturation point in wood is required for fungal colonization and proliferation. In nature, this process causes the breakdown of complex molecules and leads to the return of nutrients to the soil. Wood-decay fungi consume wood in various ways; for example, some attack the carbohydrates in wood, and some others decay lignin. The rate of decay of wooden materials in various climates can be estimated by empirical models.

<i>Mycena galopus</i> Species of fungus

Mycena galopus, commonly known as the milky mycena, milking bonnet or milk-drop mycena, is an inedible species of fungus in the family Mycenaceae of the order Agaricales. It produces small mushrooms that have grayish-brown, bell-shaped, radially-grooved caps up to 2.5 cm (1 in) wide. The gills are whitish to gray, widely spaced, and squarely attached to the stem. The slender stems are up to 8 cm (3 in) long, and pale gray at the top, becoming almost black at the hairy base. The stem will ooze a whitish latex if it is injured or broken. The variety nigra has a dark gray cap, while the variety candida is white. All varieties of the mushroom occur during summer and autumn on leaf litter in coniferous and deciduous woodland.

<i>Mycena polygramma</i> Species of fungus

Mycena polygramma, commonly known as the grooved bonnet, is a species of mushroom in the family Mycenaceae. The inedible fruit bodies are small, pale gray-brown mushrooms with broadly conical caps, pinkish gills. They are found in small troops on stumps and branches of deciduous and occasionally coniferous trees. The mushroom is found in Asia, Europe, and North America, where it is typically found on twigs or buried wood, carrying out its role in the forest ecosystem by decomposing organic matter, recycling nutrients, and forming humus in the soil. M. polygramma contains two uncommon hydroxy fatty acids and is also a bioluminescent fungus whose intensity of light emission follows a diurnal pattern.

<span class="mw-page-title-main">Plant litter</span> Dead plant material that has fallen to the ground

Plant litter is dead plant material that have fallen to the ground. This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon. Litter is an important factor in ecosystem dynamics, as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil fertility.

Myceliophthora thermophila is an ascomycete fungus that grows optimally at 45–50 °C (113–122 °F). It efficiently degrades cellulose and is of interest in the production of biofuels. The genome has recently been sequenced, revealing the full range of enzymes used by this organism for the degradation of plant cell wall material.

<span class="mw-page-title-main">Fungal extracellular enzyme activity</span> Enzymes produced by fungi and secreted outside their cells

Extracellular enzymes or exoenzymes are synthesized inside the cell and then secreted outside the cell, where their function is to break down complex macromolecules into smaller units to be taken up by the cell for growth and assimilation. These enzymes degrade complex organic matter such as cellulose and hemicellulose into simple sugars that enzyme-producing organisms use as a source of carbon, energy, and nutrients. Grouped as hydrolases, lyases, oxidoreductases and transferases, these extracellular enzymes control soil enzyme activity through efficient degradation of biopolymers.

Hypotermes makhamensis is a species of termite in the subfamily Macrotermitinae of the family Termitidae. It lives in dry evergreen forests in tropical south-eastern Asia and builds termite mounds in which it cultivates fungus for use as food.

Whendee Silver is an American ecosystem ecologist and biogeochemist.

Saprotrophic bacteria are bacteria that are typically soil-dwelling and utilize saprotrophic nutrition as their primary energy source. They are often associated with soil fungi that also use saprotrophic nutrition and both are classified as saprotrophs.

References

  1. Travis, Mike. "Leaf Mold compost" (PDF).
  2. Travis, Mike. "Leaf Mold Compost" (PDF).
  3. Trautmann, Nancy; Olynciw, Elaina (1996). "Compost Microorganisms". Cornell Waste Management Institute.
  4. Kai Yue; et al. (2016). "Degradation of lignin and cellulose during foliar litter decomposition in an alpine forest river". Ecosphere. 7 (10). Bibcode:2016Ecosp...7E1523Y. doi: 10.1002/ecs2.1523 .
  5. "Compost Chemistry". Cornell University. Retrieved 6 October 2016.
  6. Lakna (6 December 2017). "Difference Between Mold and Fungus". Pediaa. Retrieved 16 December 2021.
  7. Anna M Romaní; et al. (2016). "Interactions of bacteria and fungi on decomposing litter: differential extracellular enzyme activities". Ecology. 87 (10): 2559–2569. doi:10.1890/0012-9658(2006)87[2559:iobafo]2.0.co;2. hdl: 10256/7689 . PMID   17089664.
  8. Anna M Romaní; et al. (2006). "Interactions of bacteria and fungi on decomposing litter: differential extracellular enzyme activities". Ecology. 87 (10): 2559–2569. doi:10.1890/0012-9658(2006)87[2559:iobafo]2.0.co;2. hdl: 10256/7689 . PMID   17089664.
  9. 1 2 Kai Yue; et al. (31 October 2016). "Degradation of lignin and cellulose during foliar litter decomposition in an alpine forest river". Ecosphere. 7 (10). Bibcode:2016Ecosp...7E1523Y. doi: 10.1002/ecs2.1523 .
  10. Jana Voříšková1; Petr Baldrian (11 October 2012). "Fungal community on decomposing leaf litter undergoes rapid successional changes". The ISME Journal. 7 (3): 477–486. doi:10.1038/ismej.2012.116. PMC   3578564 . PMID   23051693.{{cite journal}}: CS1 maint: numeric names: authors list (link)
  11. "Leaf litter in street sweepings: investigation into collection and treatment" (PDF). The Environment Agency. Retrieved 6 October 2016.