Plant litter

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Leaf litter, mainly White Beech, Gmelina leichhardtii, from Black Bulga State Conservation Area, NSW, Australia Gmelina leaves forest floor.JPG
Leaf litter, mainly White Beech, Gmelina leichhardtii , from Black Bulga State Conservation Area, NSW, Australia

Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) 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 ("O" for "organic"). 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. [1]

Contents

Characteristics and variability

Plant litter, mainly western hemlock, Tsuga heterophylla, in Mount Baker-Snoqualmie National Forest, Washington, United States Western Hemlock litter.JPG
Plant litter, mainly western hemlock, Tsuga heterophylla , in Mount Baker–Snoqualmie National Forest, Washington, United States

Litterfall is characterized as fresh, undecomposed, and easily recognizable (by species and type) plant debris. This can be anything from leaves, cones, needles, twigs, bark, seeds/nuts, logs, or reproductive organs (e.g. the stamen of flowering plants). Items larger than 2 cm diameter are referred to as coarse litter, while anything smaller is referred to as fine litter or litter. The type of litterfall is most directly affected by ecosystem type. For example, leaf tissues account for about 70 percent of litterfall in forests, but woody litter tends to increase with forest age. [2] In grasslands, there is very little aboveground perennial tissue so the annual litterfall is very low and quite nearly equal to the net primary production. [3]

In soil science, soil litter is classified in three layers, which form on the surface of the O Horizon. These are the L, F, and H layers: [4]

The litter layer is quite variable in its thickness, decomposition rate and nutrient content and is affected in part by seasonality, plant species, climate, soil fertility, elevation, and latitude. [1] The most extreme variability of litterfall is seen as a function of seasonality; each individual species of plant has seasonal losses of certain parts of its body, which can be determined by the collection and classification of plant litterfall throughout the year, and in turn affects the thickness of the litter layer. In tropical environments, the largest amount of debris falls in the latter part of dry seasons and early during wet season. [5] As a result of this variability due to seasons, the decomposition rate for any given area will also be variable.

Litter fall in the North American Baldcypress Swamp Network, Illinois to Louisiana, 2003 Litterfall-Latitude.gif
Litter fall in the North American Baldcypress Swamp Network, Illinois to Louisiana, 2003

Latitude also has a strong effect on litterfall rates and thickness. Specifically, litterfall declines with increasing latitude. In tropical rainforests, there is a thin litter layer due to the rapid decomposition, [7] while in boreal forests, the rate of decomposition is slower and leads to the accumulation of a thick litter layer, also known as a mor. [3] Net primary production works inversely to this trend, suggesting that the accumulation of organic matter is mainly a result of decomposition rate.

Surface detritus facilitates the capture and infiltration of rainwater into lower soil layers. The surface detritus also protects soil from excess drying and warming. [8] Soil litter protects soil aggregates from raindrop impact, preventing the release of clay and silt particles from plugging soil pores. [9] Releasing clay and silt particles reduces the capacity for soil to absorb water and increases cross surface flow, accelerating soil erosion. In addition soil litter reduces wind erosion by preventing soil from losing moisture and providing cover preventing soil transportation.

Organic matter accumulation also helps protect soils from wildfire damage. Soil litter can be completely removed depending on intensity and severity of wildfires and season. [10] Regions with high frequency wildfires have reduced vegetation density and reduced soil litter accumulation. Climate also influences the depth of plant litter. Typically humid tropical and sub-tropical climates have reduced organic matter layers and horizons due to year-round decomposition and high vegetation density and growth. In temperate and cold climates, litter tends to accumulate and decompose slower due to a shorter growing season.

Net primary productivity

Net primary production and litterfall are intimately connected. In every terrestrial ecosystem, the largest fraction of all net primary production is lost to herbivores and litter fall.[ citation needed ] Due to their interconnectedness, global patterns of litterfall are similar to global patterns of net primary productivity. [3] Plant litter, which can be made up of fallen leaves, twigs, seeds, flowers, and other woody debris, makes up a large portion of above ground net primary production of all terrestrial ecosystems. Fungus plays a large role in cycling the nutrients from the plant litter back into the ecosystem. [11]

Habitat and food

Litter provides habitat for a variety of organisms.

Plants

Common wood sorrel (Oxalis acetosella) in Ivanovo Oblast, Russia Oxalis acetosella 5724.jpg
Common wood sorrel ( Oxalis acetosella ) in Ivanovo Oblast, Russia

Certain plants are specially adapted for germinating and thriving in the litter layers. [12] For example, bluebell ( Hyacinthoides non-scripta ) shoots puncture the layer to emerge in spring. Some plants with rhizomes, such as common wood sorrel ( Oxalis acetosella ) do well in this habitat. [7]

Detritivores and other decomposers

Fungi in the forest floor (Marselisborg Forests in Denmark) Svampe i Marselisborgskoven.jpg
Fungi in the forest floor (Marselisborg Forests in Denmark)
A skink, Eutropis multifasciata, in leaf litter in Sabah, Malaysia Eutropis multifasciata in leaf litter.JPG
A skink, Eutropis multifasciata , in leaf litter in Sabah, Malaysia

Many organisms that live on the forest floor are decomposers, such as fungi. Organisms whose diet consists of plant detritus, such as earthworms, are termed detritivores. The community of decomposers in the litter layer also includes bacteria, amoeba, nematodes, rotifer, tardigrades, springtails, cryptostigmata, potworms, insect larvae, mollusks, oribatid mites, woodlice, and millipedes. [7] Even some species of microcrustaceans, especially copepods (for instance Bryocyclops spp., Graeteriella spp.,Olmeccyclops hondo, Moraria spp.,Bryocamptus spp., Atheyella spp.) [13] live in moist leaf litter habitats and play an important role as predators and decomposers. [14]

The consumption of the litterfall by decomposers results in the breakdown of simple carbon compounds into carbon dioxide (CO2) and water (H2O), and releases inorganic ions (like nitrogen and phosphorus) into the soil where the surrounding plants can then reabsorb the nutrients that were shed as litterfall. In this way, litterfall becomes an important part of the nutrient cycle that sustains forest environments.

As litter decomposes, nutrients are released into the environment. The portion of the litter that is not readily decomposable is known as humus. Litter aids in soil moisture retention by cooling the ground surface and holding moisture in decaying organic matter. The flora and fauna working to decompose soil litter also aid in soil respiration. A litter layer of decomposing biomass provides a continuous energy source for macro- and micro-organisms. [15] [8]

Larger animals

Numerous reptiles, amphibians, birds, and even some mammals rely on litter for shelter and forage. Amphibians such as salamanders and caecilians inhabit the damp microclimate underneath fallen leaves for part or all of their life cycle. This makes them difficult to observe. A BBC film crew captured footage of a female caecilian with young for the first time in a documentary that aired in 2008. [16] Some species of birds, such as the ovenbird of eastern North America for example, require leaf litter for both foraging and material for nests. [17] Sometimes litterfall even provides energy to much larger mammals, such as in boreal forests where lichen litterfall is one of the main constituents of wintering deer and elk diets. [18]

Nutrient cycle

During leaf senescence, a portion of the plant's nutrients are reabsorbed from the leaves. The nutrient concentrations in litterfall differ from the nutrient concentrations in the mature foliage by the reabsorption of constituents during leaf senescence. [3] Plants that grow in areas with low nutrient availability tend to produce litter with low nutrient concentrations, as a larger proportion of the available nutrients is reabsorbed. After senescence, the nutrient-enriched leaves become litterfall and settle on the soil below.

A budget for organic matter in a mature (120-year-old) Scots pine monoculture (SWECON site). Based on data from Andersson et al.(1980). Units are in kg of organic matter per ha. Att. -attached; Surf. -surface; min. -mineral; and veg. -vegetation Litter-nutrient cycle2.gif
A budget for organic matter in a mature (120-year-old) Scots pine monoculture (SWECON site). Based on data from Andersson et al.(1980). Units are in kg of organic matter per ha. Att. -attached; Surf. -surface; min. -mineral; and veg. -vegetation

Litterfall is the dominant pathway for nutrient return to the soil, especially for nitrogen (N) and phosphorus (P). The accumulation of these nutrients in the top layer of soil is known as soil immobilization. Once the litterfall has settled, decomposition of the litter layer, accomplished through the leaching of nutrients by rainfall and throughfall and by the efforts of detritivores, releases the breakdown products into the soil below and therefore contributes to the cation exchange capacity of the soil. This holds especially true for highly weathered tropical soils. [20] Decomposition rate is tied to the type of litterfall present. [12]

Leaching is the process by which cations such as iron (Fe) and aluminum (Al), as well as organic matter are removed from the litterfall and transported downward into the soil below. This process is known as podzolization and is particularly intense in boreal and cool temperate forests that are mainly constituted by coniferous pines whose litterfall is rich in phenolic compounds and fulvic acid. [3]

By the process of biological decomposition by microfauna, bacteria, and fungi, CO2 and H2O, nutrient elements, and a decomposition-resistant organic substance called humus are released. Humus composes the bulk of organic matter in the lower soil profile. [3]

The decline of nutrient ratios is also a function of decomposition of litterfall (i.e. as litterfall decomposes, more nutrients enter the soil below and the litter will have a lower nutrient ratio). Litterfall containing high nutrient concentrations will decompose more rapidly and asymptote as those nutrients decrease. [21] Knowing this, ecologists have been able to use nutrient concentrations as measured by remote sensing as an index of a potential rate of decomposition for any given area. [22] Globally, data from various forest ecosystems shows an inverse relationship in the decline in nutrient ratios to the apparent nutrition availability of the forest. [3]

Once nutrients have re-entered the soil, the plants can then reabsorb them through their roots. Therefore, nutrient reabsorption during senescence presents an opportunity for a plant's future net primary production use. A relationship between nutrient stores can also be defined as:

annual storage of nutrients in plant tissues + replacement of losses from litterfall and leaching = the amount of uptake in an ecosystem

Non-terrestrial Litterfall

Non-terrestrial litterfall follows a very different path. Litter is produced both inland by terrestrial plants and moved to the coast by fluvial processes, and by mangrove ecosystems. [23] From the coast Robertson & Daniel 1989 found it is then removed by the tide, crabs and microbes. They also noticed that which of those three is most significant depends on the tidal regime. Nordhaus et al. 2011 find crabs forage for leaves at low tide and if their detritivory is the predominant disposal route, they can take 80% of leaf material. Bakkar et al 2017 studied the chemical contribution of the resulting crab defecation. They find crabs pass a noticeable amount of undegraded lignins to both the sediments and water composition. They also find that the exact carbonaceous contribution of each plant species can be traced from the plant, through the crab, to its sediment or water disposition in this way. Crabs are usually the only significant macrofauna in this process, however Raw et al 2017 find Terebralia palustris competes with crabs unusually vigorously in southeast Asia. [24]

Collection and analysis

The main objectives of litterfall sampling and analysis are to quantify litterfall production and chemical composition over time in order to assess the variation in litterfall quantities, and hence its role in nutrient cycling across an environmental gradient of climate (moisture and temperature) and soil conditions. [25]

Ecologists employ a simple approach to the collection of litterfall, most of which centers around one piece of equipment, known as a litterbag. A litterbag is simply any type of container that can be set out in any given area for a specified amount of time to collect the plant litter that falls from the canopy above.

Litterfall and throughfall collectors at beech stand in Thetford, East Anglia Litterbags.jpg
Litterfall and throughfall collectors at beech stand in Thetford, East Anglia

Litterbags are generally set in random locations within a given area and marked with GPS or local coordinates, and then monitored on a specific time interval. Once the samples have been collected, they are usually classified on type, size and species (if possible) and recorded on a spreadsheet. [27] When measuring bulk litterfall for an area, ecologists will weigh the dry contents of the litterbag. By this method litterfall flux can be defined as:

litterfall (kg m−2 yr−1) = total litter mass (kg) / litterbag area (m2) [28]

The litterbag may also be used to study decomposition of the litter layer. By confining fresh litter in the mesh bags and placing them on the ground, an ecologist can monitor and collect the decay measurements of that litter. [7] An exponential decay pattern has been produced by this type of experiment: , where is the initial leaf litter and is a constant fraction of detrital mass. [3]

The mass-balance approach is also utilized in these experiments and suggests that the decomposition for a given amount of time should equal the input of litterfall for that same amount of time.

litterfall = k(detrital mass) [3]

For study various groups from edaphic fauna you need a different mesh sizes in the litterbags [29]

Issues

Change due to invasive earthworms

In some regions of glaciated North America, earthworms have been introduced where they are not native. Non-native earthworms have led to environmental changes by accelerating the rate of decomposition of litter. These changes are being studied, but may have negative impacts on some inhabitants such as salamanders. [30]

Forest litter raking

Leaf litter accumulation depends on factors like wind, decomposition rate and species composition of the forest. The quantity, depth and humidity of leaf litter varies in different habitats. The leaf litter found in primary forests is more abundant, deeper and holds more humidity than in secondary forests. This condition also allows for a more stable leaf litter quantity throughout the year. [31] This thin, delicate layer of organic material can be easily affected by humans. For instance, forest litter raking as a replacement for straw in husbandry is an old non-timber practice in forest management that has been widespread in Europe since the seventeenth century. [32] [33] In 1853, an estimated 50 Tg of dry litter per year was raked in European forests, when the practice reached its peak. [34] This human disturbance, if not combined with other degradation factors, could promote podzolisation; if managed properly (for example, by burying litter removed after its use in animal husbandry), even the repeated removal of forest biomass may not have negative effects on pedogenesis. [35]

See also

Related Research Articles

<span class="mw-page-title-main">Ecosystem</span> Community of living organisms together with the nonliving components of their environment

An ecosystem consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and microbes.

<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">Soil</span> Mixture of organic matter, minerals, gases, liquids, and organisms that together support life

Soil, commonly referred to as dirt or earth, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life of plants and soil organisms. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.

<span class="mw-page-title-main">Energy flow (ecology)</span> Flow of energy through food chains in ecological energetics

Energy flow is the flow of energy through living things within an ecosystem. All living organisms can be organized into producers and consumers, and those producers and consumers can further be organized into a food chain. Each of the levels within the food chain is a trophic level. In order to more efficiently show the quantity of organisms at each trophic level, these food chains are then organized into trophic pyramids. The arrows in the food chain show that the energy flow is unidirectional, with the head of an arrow indicating the direction of energy flow; energy is lost as heat at each step along the way.

<span class="mw-page-title-main">Decomposer</span> Organism that breaks down dead or decaying organisms

Decomposers are organisms that break down dead or decaying organisms; they carry out decomposition, a process possible by only certain kingdoms, such as fungi. Like herbivores and predators, decomposers are heterotrophic, meaning that they use organic substrates to get their energy, carbon and nutrients for growth and development. While the terms decomposer and detritivore are often interchangeably used, detritivores ingest and digest dead matter internally, while decomposers directly absorb nutrients through external chemical and biological processes. Thus, invertebrates such as earthworms, woodlice, and sea cucumbers are technically detritivores, not decomposers, since they are unable to absorb nutrients without ingesting them.

<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. They should be distinguished from other decomposers, such as many species of bacteria, fungi and protists, which are unable to ingest discrete lumps of matter, but instead 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.

<span class="mw-page-title-main">Tropical rainforest</span> Forest in areas with heavy rainfall in the tropics

Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as lowland equatorial evergreen rainforest. True rainforests are typically found between 10 degrees north and south of the equator ; they are a sub-set of the tropical forest biome that occurs roughly within the 28-degree latitudes. Within the World Wildlife Fund's biome classification, tropical rainforests are a type of tropical moist broadleaf forest that also includes the more extensive seasonal tropical forests.

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">Detritus</span> Dead particulate organic material

In biology, detritus is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts communities of microorganisms that colonize and decompose it. In terrestrial ecosystems it is present as leaf litter and other organic matter that is intermixed with soil, which is denominated "soil organic matter". The detritus of aquatic ecosystems is organic material that is suspended in the water and accumulates in depositions on the floor of the body of water; when this floor is a seabed, such a deposition is denominated "marine snow".

<span class="mw-page-title-main">Microbial loop</span>

The microbial loop describes a trophic pathway where, in aquatic systems, dissolved organic carbon (DOC) is returned to higher trophic levels via its incorporation into bacterial biomass, and then coupled with the classic food chain formed by phytoplankton-zooplankton-nekton. In soil systems, the microbial loop refers to soil carbon. The term microbial loop was coined by Farooq Azam, Tom Fenchel et al. in 1983 to include the role played by bacteria in the carbon and nutrient cycles of the marine environment.

Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous benefits to the physical and chemical properties of soil and its capacity to provide regulatory ecosystem services. SOM is especially critical for soil functions and quality.

<span class="mw-page-title-main">Forest floor</span> Layer of the forest ecosystem above the soil composed of primarily non-living organic material

The forest floor, also called detritus or duff, is the part of a forest ecosystem that mediates between the living, aboveground portion of the forest and the mineral soil, principally composed of dead and decaying plant matter such as rotting wood and shed leaves. In some countries, like Canada, forest floor refers to L, F and H organic horizons. It hosts a wide variety of decomposers and predators, including invertebrates, fungi, algae, bacteria, and archaea.

<span class="mw-page-title-main">Invasive earthworms of North America</span>

Invasive species of earthworms from the suborder Lumbricina have been expanding their range in North America. Their introduction can have marked effects on the nutrient cycles in temperate forests. These earthworms increase the cycling and leaching of nutrients by breaking up decaying organic matter and spreading it into the soil. Since plants native to these northern forests are evolutionarily adapted to the presence of thick layers of decaying organic matter, the introduction of worms can lead to loss of biodiversity as young plants face less nutrient-rich conditions. Some species of trees and other plants may be incapable of surviving such changes in available nutrients. This change in the plant diversity in turn affects other organisms and often leads to increased invasions of other exotic species as well as overall forest decline. They do not require a mate to reproduce, allowing them to spread faster.

<span class="mw-page-title-main">Nutrient cycle</span> Set of processes exchanging nutrients between parts of a system

A nutrient cycle is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include the carbon cycle, sulfur cycle, nitrogen cycle, water cycle, phosphorus cycle, oxygen cycle, among others that continually recycle along with other mineral nutrients into productive ecological nutrition.

<span class="mw-page-title-main">Mycorrhizal fungi and soil carbon storage</span>

Soil carbon storage is an important function of terrestrial ecosystems. Soil contains more carbon than plants and the atmosphere combined. Understanding what maintains the soil carbon pool is important to understand the current distribution of carbon on Earth, and how it will respond to environmental change. While much research has been done on how plants, free-living microbial decomposers, and soil minerals affect this pool of carbon, it is recently coming to light that mycorrhizal fungi—symbiotic fungi that associate with roots of almost all living plants—may play an important role in maintaining this pool as well. Measurements of plant carbon allocation to mycorrhizal fungi have been estimated to be 5 to 20% of total plant carbon uptake, and in some ecosystems the biomass of mycorrhizal fungi can be comparable to the biomass of fine roots. Recent research has shown that mycorrhizal fungi hold 50 to 70 percent of the total carbon stored in leaf litter and soil on forested islands in Sweden. Turnover of mycorrhizal biomass into the soil carbon pool is thought to be rapid and has been shown in some ecosystems to be the dominant pathway by which living carbon enters the soil carbon pool.

Whendee Silver is an American ecosystem ecologist and biogeochemist.

<span class="mw-page-title-main">Mor humus</span> Humus formed in coniferous forests

Mor humus is a form of forest floor humus occurring mostly in coniferous forests. Mor humus consists of evergreen needles and woody debris that litter the forest floor. This litter is slow to decompose, in part due to their chemical composition, but also because of the generally cool and wet conditions where mor humus is found. This results in low bacterial activity and an absence of earthworms and other soil fauna. Because of this, most of the organic matter decomposition in mor humus is carried out by fungi.

Moder is a forest floor type formed under mixed-wood and pure deciduous forests. Moder is a kind of humus whose properties are the transition between mor humus and mull humus types. Moders are similar to mors as they are made up of partially to fully humified organic components accumulated on the mineral soil. Compared to mulls, moders are zoologically active. In addition, moders present as in the middle of mors and mulls with a higher decomposition capacity than mull but lower than mor. Moders are characterized by a slow rate of litter decomposition by litter-dwelling organisms and fungi, leading to the accumulation of organic residues. Moder humus forms share the features of the mull and mor humus forms.

The term humus form is not the same as the term humus. Forest humus form describes the various arrangement of organic and mineral horizons at the top of soil profiles. It can be composed entirely of organic horizons, meaning an absence of the mineral horizon. Experts worldwide have developed different types of classifications over time, and humus forms are mainly categorized into mull, mor, and moder orders in the ecosystems of British Columbia. Mull humus form is distinguishable from the other two forms in formation, nutrient cycling, productivity, etc.

References

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  21. ↑ Scott D. Bridgham; John Pastor; Charles A. McClaugherty & Curtis J. Richardson (1995). "Nutrient-use efficiency: a litterfall index, a model, and a test along a nutrient-availability gradient in North Carolina peatlands" (PDF). The American Naturalist . 145 (1): 1–21. doi:10.1086/285725. S2CID   84467103. Archived from the original (PDF) on 2011-08-13.
  22. ↑ Melillo, J.M., & J.R. Gosz. “Interactions of Biogeochemical Cycles in Forest Ecosystems” Scientific Committee on Problems of the Environment (SCOPE). Vol. 21: The Major Biogeochemical Cycles and Their Interactions, Ch. 6. (1983).
  23. ↑ Stoler, Aaron B.; Relyea, Rick A. (May 2020). "Reviewing the role of plant litter inputs to forested wetland ecosystems: leafing through the literature". Ecological Monographs. 90 (2). doi:10.1002/ecm.1400. ISSN   0012-9615. S2CID   214580288.
  24. ↑ Cragg, Simon M.; Friess, Daniel A.; Gillis, Lucy G.; Trevathan-Tackett, Stacey M.; Terrett, Oliver M.; Watts, Joy E.M.; Distel, Daniel L.; Dupree, Paul (2020-01-03). "Vascular Plants Are Globally Significant Contributors to Marine Carbon Fluxes and Sinks". Annual Review of Marine Science . Annual Reviews. 12 (1): 469–497. Bibcode:2020ARMS...12..469C. doi:10.1146/annurev-marine-010318-095333. ISSN   1941-1405. PMID   31505131. S2CID   202555776.
  25. ↑ Simmons, Jeffrey A. “Measuring Litterfall Flux.” West Virginia Wesleyan College (2003).
  26. ↑ "Spatial variations of nitrogen deposition and its effect on forest biochemical processes". Forest Research. Retrieved March 27, 2011.
  27. ↑ Estrella, Stephanie. “Standard Operating Procedures for Litterfall Collection, Processing, and Analysis: Version 2.0.” Washington State Department of Ecology. (2008).
  28. ↑ Bastrup-Birk, A., & Nathalie Bréda. “Report on Sampling and Analysis of Litterfall” United Nations Economic Commission for Europe Convention on Long-Range Transboundary Air Pollution: International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests. (2004).
  29. ↑ Castro-Huerta, R., Falco, L., Sandler, R., Coviella, C. (2015). "Differential contribution of soil biota groups to plant litter decomposition as mediated by soil use". PeerJ . 3: e826. doi:10.7717/peerj.826. PMC   4359044 . PMID   25780777.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  30. ↑ Maerz, John C.; Nuzzo, Victoria A.; Blossey, Bernd (2009). "Declines in Woodland Salamander Abundance Associated with Non-Native Earthworm and Plant Invasions" (PDF). Conservation Biology. 23 (4): 975–981. doi:10.1111/j.1523-1739.2009.01167.x. PMID   19236449. S2CID   24139505 . Retrieved 28 April 2012.
  31. ↑ Barrientos, Zaidett (2012). "Dynamics of leaf litter humidity, depth and quantity: two restoration strategies failed to mimic ground microhabitat conditions of a low montane and premontane forest in Costa Rica" (PDF). Revista de Biología Tropical. 60 (3): 1041–1053. doi:10.15517/rbt.v60i3.1756. PMID   23025078.
  32. ↑ Bürgi, M., Gimmi, U. (2007). "Three objectives of historical ecology: the case of litter collecting in Central European forests". Landscape Ecology. 22: 77–87. doi:10.1007/s10980-007-9128-0. hdl: 20.500.11850/58945 . S2CID   21130814.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  33. ↑ Gimmi, U., Poulter, B., Wolf, A., Portner, H., Weber, P., Bürgi, M. (2013). "Soil carbon pools in Swiss forests show legacy effects from historic forest litter raking" (PDF). Landscape Ecology. 28 (5): 385–846. doi:10.1007/s10980-012-9778-4. hdl:20.500.11850/66782. S2CID   16930894.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  34. ↑ McGrath, M.J.; et al. (2015). "Reconstructing European forest management from 1600 to 2010". Biogeosciences. 12 (14): 4291–4316. Bibcode:2015BGeo...12.4291M. doi: 10.5194/bg-12-4291-2015 .
  35. ↑ Scalenghe, R, Minoja, A.P., Zimmermann, S., Bertini, S. (2016). "Consequence of litter removal on pedogenesis: A case study in Bachs and Irchel (Switzerland)". Geoderma. 271: 191–201. Bibcode:2016Geode.271..191S. doi:10.1016/j.geoderma.2016.02.024.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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