litter, characteristics variations and need, litter decomposition process, decomposition rates, nutrient dynamics,

2. PARVATI TAMRAKAR
2ND SEM, MSC. FORESTRY,
GGU BILASPUR

3.  What is litter?
 Litter decomposition process
 Decomposition rates
 Nutrient dynamics

4.  Litter 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.

5.  Litter is characterized as fresh, un-decomposed, and
easily recognizable (by species and type) plant debris.
 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 litter is most directly affected By
ecosystem type.
 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-
• L – organic horizon characterized by relatively un-
decomposed plant material (described above).
• F – organic horizon found beneath L characterized by
accumulation of partly decomposed organic matter.
• H – organic horizon below F characterized by accumulation
of fully decomposed organic matter mostly indiscernible.

7.  Litter decomposition is defined as the process
through which dead organic material is broken down
into particles of progressively smaller size, until the
structure can no longer be recognized, and organic
molecules are mineralized to their prime
constituents: H2O, CO2 and mineral components.
 During the process, recalcitrant organic compounds
are formed and dissolved organic carbon may be
leached to the mineral soil. It is also universally
recognized that there are three main processes
through which decomposition occurs:
(1) leaching of soluble compounds into the soil,
(2) fragmentation of litter into smaller sizes and
(3) catabolism by decomposer organisms (i.e. micro-
organisms and fauna).

9. Rates of leaf litter decomposition provide another indicator of
ecosystem function widely used in rivers (Boyero et al.,
2011; Sponseller and Benfield, 2001). Typically, this involves
leaving preweighed leaf litter in mesh bags for several weeks at a
site and then determining how much biomass is lost over the
period. Bags are best secured close to the stream bed to reduce
the influence of hydraulic conditions; bags floating in the water
column can influence decay rates (Mutch et al., 1983). In many
cases, leaf litter decomposition will be size-dependent, so it can
be useful having multiple bags with different mesh apertures and
different detritus sizes (Boulton and Boon, 1991). A key difficulty
with leaf litter decomposition is that it can be difficult comparing
between sites if leaf litter composition is not the same, as some
leaves and twigs will decompose faster than others. An
alternative technique that may circumvent that issue is using
cotton strips and popsicle sticks instead of leaf litter (Tank and
Winterbourn, 1996; Hildrew et al., 1984; Egglishaw, 1972).
Cotton decomposition can be either measured as loss of biomass
or loss of tensile strength. Cotton strips and popsicle strips are
inexpensive and considerably reduce sample variability.

10.  The biological degradation of litter is mainly performed by
microbial decomposers, including bacteria, fungi,
and actinomycetes, which have lower C:N ratios than most litter
types. For instance, forest-leaf litter has a C:N ratio of 58:1–88:1
(McGroddy et al., 2004); microbial C:N ratio is approximately 9:1
(Cleveland and Liptzin, 2007). In general, for microbial activity,
an optimal litter C:N ratio is 20–30. If the litter C:N ratio is
< 20:1 during litter decomposition, then mineralization likely
occurs. If the ratio is > 30:1, then immobilization possibly
occurs. In this sense, forest litter has a higher C:N ratio to
support normal microbial activity.
 Experiments have shown that litter decomposition can be
enhanced when C:nutrient ratios are altered by adding nutrients.
For instance, adding P and micronutrients enhance leaf-
litter decomposition in a lowland Panamanian forest; Na shortage
slows the carbon cycle (Kaspari et al., 2009). These results have
suggested that tropical forests are a non-Liebig world of
multiple nutrient limitations, with at least four elements shaping
the rates of litterfall and decomposition (Kaspari et al., 2008).

11. Manzoni et al. (2008) showed that N loss occurs
slower than C loss for most litter decomposition
at a global scale. Thus, semi-decomposed litter
N likely accumulates, and the N:C ratio of the
litter increases throughout decomposition. This
result has suggested that decomposers prefer
the strategy of lowering their carbon-use
efficiency to exploit residues containing low-
initial nitrogen concentration.
Furthermore, microorganisms use their
own stoichiometry to a particular transformed
material during decomposition because these
organisms have a relatively fixed C:N ratio. Thus,
C-rich litter causes microorganisms to release
more C in the form of CO2 into the atmosphere
as microbes attempt to maintain a favorable
C:nutrient ratio (Manzoni et al., 2008).

12.  Litter decomposition supplies nutrients to the soil
solution, which renders them available for plant and
soil microbial uptake. In addition to litter quality,
other factors affect decomposition including
moisture, temperature, soil nutrient availability, and
particle size. Faster decay rates may result in more
efficient nutrient cycling; thus, more plant biomass
is produced per unit of nutrient. This is particularly
true when losses after decomposition are limited.
Litter decay rates vary, but typically 40%–60% of
warm-season grass litter decays per year [27].
Combining litter deposition, nutrient concentration,
and decay rates allow for the estimation of litter
nutrient release [28]. It is important to account for
both above- and below-ground litter when
estimating litter nutrient contribution, but
understanding processes involving below-ground
litter presents significant challenges.

13.  Nutrient release from decomposing litter is important, but
in some cases, the timing of nutrient release may not
match crop nutrient demand. In semiarid regions, litter
deposited during the dry season accumulates until the
beginning of the following rainy season because limited
moisture during the dry season prohibits decomposition.
Likewise, regions with cold temperatures during the winter
have reduced litter decomposition. As a result, a flush of
decomposition occurs at the beginning of the rainy, warm
season with a surplus of nutrients. Often, during this time
of the year the forages are in the early stages of regrowth
after the prolonged dry (or cold) season. Many times the
shortage of forage during this period forces land
managers to stock pastures to take advantage of this fresh
regrowth. This will result in nutrient losses via excreta and
reduced regrowth due to overgrazing. From a nutrient
management perspective, an efficient practice is to allow
the forages more time to regrow by utilizing efficiently the
nutrient surplus from litter that occurs at the beginning of
the season

14.  C. Liu, X. Sun, in Reference Module in Earth
Systems and Environmental Sciences, 2013.
 José C.B. Dubeux Jr., Lynn E. Sollenberger,
in Management Strategies for Sustainable Cattle
Production in Southern Pastures, 2020.
 C.M.N. Panitz, in Coastal Plant Communities of
Latin America, 1992.
 Adam D. Canning, Russell G. Death,
in Encyclopedia of Ecology (Second Edition), 2019
 www.hindawi.com
 www.researchgate.net
 www.sciencedirect.com