Humusica 1, article 7: Terrestrial humus systems and forms – Field practice and sampling problems

doi:10.1016/j.apsoil.2017.05.028

Applied Soil Ecology

Volume 122, Part 1, January 2018, Pages 92-102

https://doi.org/10.1016/j.apsoil.2017.05.028 Get rights and content

Abstract

The present paper should be read after the six preceding articles dealing with fundamental concepts, vocabulary, principles and keys of our morpho-functional classification of humus systems and forms, the whole book being conceived as a guide for field studies. It now concerns seven questions which may arise when passing from knowledge to practice or, in other terms, from concepts to real things. In the field, humipedons can differ from reported photographs. Trees, bushes and/or herbs interfere with soil functioning and may generate different humipedons even over a relatively small surface. More generally a researcher must select a few unit plots representative of a given natural floor for defining the frame of his investigation. In this article, authors present some practical and theoretical landmarks and illustrate some solutions for studying humipedons in common natural sites, and replacing them within ecosystem dynamics.

Section snippets

What are humus systems and humus forms?

Let’s put a glance to the superficial soil, in a forest, a meadow or a garden. With a spade, cut a pit to see the soil with the naked eye, without any instrument other than your glasses, if any. What do you see?

Colours are not distributed at random. More generally, the colour of the soil becomes clearer from the top to the bottom of the soil profile thus revealed. These colour changes indicate how organic matter is distributed throughout the soil. Original molecules with a high content in

Where and how to find humus forms?

Humus forms can be found everywhere life is present, and where organic matter and mineral matter are interfering. For water body sediments, other concepts are in use and very little is still known about life under water. Humus forms can be found everywhere, from seashores to mountain summits, from desert to polar biomes. The concept of humus form embraces not only well-aerated deposits (called Terrestrial humus forms) but also those saturated with water (called Histic humus forms), including

How carefully to observe humus forms?

The naked eye, eventually aided with a portable magnifying glass, allows easily discerning details to a tenth mm, the size of fine sand grains (see more details in Humusica 1, article 4). This is enough to discern faecal pellets deposited by most soil-building animals (Fig. 5a, b), to the exception of those of small enchytraeid worms, the size of which is often ≤ 50 μm (Ponge, 1999). Enchytraeid faeces are roughly isodiametric and poorly compact and form a fine dark powder which, when moistened,

Prelude

“Why am I growing up, dad?”

“I don’t know, we grow up, become old, and die. Nobody knows why.”

Interrogative eyes: “……?”

“A general attraction sticks together particles and forms larger bodies. A guy like you, eats and grows.

‘Then?’

“Then, you’ll stop growing and become old”.

“Why do we die, in the end?”

“We are like card towers; there is a moment they crash down.”

“ ….dad, with plastic blocks, I can build higher towers”.

Door opens. Mam: “Time for lunch!”

Strategies

A recycling process occurs at many scales of

Where and when humus forms are changing?

As suggested above, humus forms result from the interplay between parent rock, climate, vegetation and soil life (Ponge, 2003, Labaz et al., 2014) and they mediate most well-known plant-soil feedbacks (Targulian and Krasilnikov, 2007, Ponge, 2013). Geology and climate have been identified as main drivers of humus form changes at large scale (Ponge et al., 2011) while at small scale vegetation seems to play a decisive role in humus form heterogeneity (Kounda-Kiki et al., 2008). Any change in one

At which scales humus forms can be investigated?

A general terrestrial ecosystem is made of humus systems and forms which occupy the landscape as tri-dimensional covers (Klinka et al., 1981). Enclosing ecosystems in imaginary boxes (arbitrarily represented as cubes) gives a physical space to the system, helping better understanding the phenomena taking place at its inside. Dimensions and orientation of each imaginary box depend on scale of the study. If the reader is interested at describing fine-scale processes, for example how particular

Do we need classifying all humus forms observable on the field?

Jean-Marie Géhu, an unforgettable professor of phytosociology (Braun-Blanquet, 1964) at the University of Paris, was able to detect imperceptible variations in the composition and functioning of plant communities (Géhu, 1980, 1991, 1992; Géhu and Rivas-Martinez, 1981). Even a very weak depression in the soil (few centimetres) was at the origin of a change of vegetation on the forest floor, accompanied by slight variations in soil characteristics (pH, texture, structure, water content, etc.).

References (69)

N. Bernier et al.
Humus form dynamics during the sylvogenetic cycle in a mountain spruce forest
Soil Biol. Biochem.
(1994)
J. Bierkens et al.
Comparative sensitivity of 20 bioassays for soil quality
Chemosphere
(1998)
K.G. Eilers et al.
Digging deeper to find unique microbial communities: the strong effect of depth on the structure of bacterial and archaeal communities in soil
Soil Biol. Biochem.
(2012)
C. Kounda-Kiki et al.
Humus profiles and successional development in a rock savanna (Nouragues inselberg, French Guiana): a micro-morphological approach infers fire as a disturbance event
Pedobiologia
(2008)
J.F. Ponge et al.
Humus Index as an indicator of forest stand and soil properties
For. Ecol. Manag.
(2006)
J.F. Ponge et al.
Geology and climate conditions affect more humus forms than forest canopies at large scale in temperate forests
Geoderma
(2011)
J.F. Ponge
Food resources and diets of soil animals in a small area of Scots pine litter
Geoderma
(1991)
J.F. Ponge
Humus forms in terrestrial ecosystems: a framework to biodiversity
Soil Biol. Biochem.
(2003)
J.F. Ponge
Plant-soil feedbacks mediated by humus forms
Soil Biol. Biochem.
(2013)
V.O. Targulian et al.
Soil system and pedogenic processes: Self-organization, time scales, and environmental significance
Catena
(2007)

A. Zanella et al.

A European morpho-functional classification of humus forms

Geoderma

(2011)

A. Andreetta et al.

Forest humus forms as potential indicators of soil carbon storage in Mediterranean environments

Biol. Fertil. Soils

(2011)

F. Bednorz et al.

Humus forms in the forest-alpine tundra ecotone at Stillberg (Dischmatal, Switzerland): spatial heterogeneity and classification

Arctic Antarctic Alpine Res.

(2000)

N. Bernier

Earthworm feeding activity and development of the humus profile

Biol. Fertil. Soils

(1998)

J. Braun-Blanquet

Pflanzensoziologie. Grundzüge der vegetationskunde

(1964)

S.W. Buol et al.

Soil genesis and classification

Classification

(2011)

C.A. Cambardella et al.

Field-scale variability of soil properties in Central Iowa soils

Soil Sci. Soc. Am. J.

(1994)

I.C. Chen et al.

Rapid range shifts of species associated with high levels of climate warming

Science

(2011)

A. Chesson

Plant degradation by ruminants: parallels with litter decomposition in soils

D.C. Coleman et al.

Soil biology, soil ecology, and global change

Biol. Fertil. Soils

(1992)

J.H. Cornelissen et al.

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes

Ecol. Lett.

(2007)

P.M. Cox et al.

Acceleration of global warming due to carbon-cycle fedbacks in a coupled climate model

Nature

(2000)

De Nicola, C., Zanella, A., Testi, A., Fanelli, G., Pignatti, S., 2014. Humus forms in a Mediterranean area...

G.W. Dimbleby

The development of British heathlands and their soils

Oxford For. Mem.

(1962)

E.T. Elliott et al.

Let the soil work for us

Ecol. Bull.

(1988)

I.M. Emmer

Humus form characteristics in relation to undergrowth vegetation in a Pinus sylvestris forest

Acta Oecol.

(1994)

I.M. Emmer

Humus form development and succession of dwarf shrub vegetation in grass dominated primary Pinus sylvestris forests

Ann. Sci. For.

(1995)

N. Fierer et al.

Toward an ecological classification of soil bacteria

Ecology

(2007)

Géhu, J.M., Rivas-Martinez, S., 1981. Notions fondamentales de Phytosociologie. In: Dierschke, H. (ed.), Ber. der...

Géhu J.M., 1980. La phytosociologie d'aujourd'hui. Méthodes et orientations. Not. Fitosoc., 16, 1–16, Pavia. In:...

Géhu, J.M., 1991. L’analyse symphytosociologique et géosymphytosociologique de l’espace. Théorie et méthodologie. Coll....

J.M. Géhu

Réflexions sur les fondements syntaxonomiques nécessaires à une synthèse des végétations à l’échelle du continent européen et esquisse d’un synsystème dans l’optique de la phytosociologie Braun-Blanqueto-Tüxenienne

Ebauche de synsystème pour la France. Annali di Botanica

(1992)

J.M. Géhu

Epistémologie de la territorialité en phytosociologie

Giorn. Bot. Ital.

(1996)

P. Galvan et al.

Humus components and soil biogenic structures in Norway spruce ecosystems

Sci. Soc. Am. J.

(2008)

Cited by (11)

A bizarre layer cake: Why soil animals recolonizing polluted areas shape atypical humus forms
2023, Science of the Total Environment
During soil recolonization by macrofauna in areas previously defaunated by industrial pollution, non-typical humus forms are produced. Given that the evidence of zoogenic activity cessation with increased forest litter depth in these humus forms, we tested the hypothesis that the lower organic layers are more toxic than the upper ones. The studies were conducted in the southern taiga, near the Middle Ural Copper Smelter (Revda city, Russia), in spruce-fir and birch forests. We investigated the series of degraded humus forms at different recovery stages, including those without signs of regradation, as well as at the initial and advanced recovery stages. In the organic layers, each of which were 1–2 cm thick and 6–8 cm in total, we measured the following parameters: pH(water), total acidity, the content of exchangeable Ca²⁺ and Mg²⁺, acid-soluble and exchangeable metals (Cu, Pb, Fe, Cd, and Zn), organic carbon, and total nitrogen. Simultaneously, we diagnosed the degree of zoogenicity of the organic layers following the European morpho-functional classification of humus forms. Concentrations of the metals increased with forest litter depth, reaching a maximum at the boundary between the organic and organic-mineral horizons (the difference exceeded an order of magnitude). In the same direction, the acidity increased, but the saturation of the exchange complex with Ca²⁺ and Mg²⁺ decreased. Within a particular forest litter profile, metal concentrations and acidity were lower in the layer with the highest zoogenicity compared to the layer with the lowest zoogenicity. Based on the metals, pH(water), and exchange complex, the accuracy of the predictions of the degree of layer zoogenicity within the OF horizon in the discriminant analysis reached 100 %. These findings suggest that the vertical gradient of toxic burden persisting in the forest litter after pollution cessation can explain the recovery pattern of humus forms in the contaminated areas.
Non-typical degraded and regraded humus forms in metal-contaminated areas, or there and back again
2021, Geoderma
Citation Excerpt :
In total, we performed humus assays on 1,155 mini-plots in 2019. We identified horizons, morphologically described, and diagnosed humus form following the Classification (Zanella et al., 2018g; Zanella et al., 2018h; Zanella et al., 2018j). The thickness of organic (OL, OF, OH) and organic-mineral (A (g)) horizons was measured with an accuracy of 3–5 mm.
Chemically contaminated soils are not included in the European morpho-functional classification of humus systems and forms. However, they differ from the uncontaminated analogs in biological, chemical, and physical features. We investigated the topsoils contaminated by long-term sulfur dioxide and metal emissions from a copper smelter (southern taiga; conifer and deciduous forests; the Middle Urals, Russia). The smelter has been in operation for more than 80 years, but ten years ago, emissions almost ceased which initiated the recovery of adjacent ecosystems. We performed 1,155 humus profile descriptions on 231 sampling plots in highly contaminated, moderately contaminated, and background sites. In the contaminated sites, we found 21 non-typical humus forms that do not fit the European classification. Earthworms’ extinction caused by soil toxicity resulted in a Mull-to-Mor transformation of humus profiles. Recent recolonization of poorly decomposed litter by earthworms and other soil macrodetritivores after emission cessation triggered a Mor-to-Mull shift. Because different topsoil layers react to environmental changes with unequal rates, signs of several stages of humus evolution can be imprinted in one profile. More rapid degradation of organic horizons than organic-mineral ones results in non-typical Mor forms when the thick non-zoogenic OF combines with zoogenic A horizon. Zoogenic O horizons’ heterogeneity due to non-zoogenic inclusions, or inversion of the litter layers sequence, or lagging of A horizon recovery behind the O horizons, represents the discrepancies between non-typical regraded and typical humus forms. Mor-to-Mull recovery can occur with and without passing the Moder forms. In the first path, all intermediate stages at least fitted to one of the known humus systems. In the second path, intermediate humus forms are represented by non-zoogenic OF conjoining highly zoogenic OF and lacking OH horizon (we named such forms Mormull). In both paths, the recovery starts from the upper litter layer and spreads downward, i.e., the signs of the zoogenic activity change in the opposite direction than within the natural Mor profile. We consider the non-typical humus forms as non-equilibrium topsoil states that are ephemeral on the forest succession scale. We described non-typical humus forms in detail, proposed their evolutionary diagram, nomenclature, and preliminary typology, and extended the Humus Index with non-typical forms.
A Standardized Morpho-Functional Classification of the Planet’s Humipedons
2022, Soil Systems
Characterization of Sedimentary Humic Acids from Tropical Mangrove Ecosystems using UV-Visible Spectroscopy and Elemental Analysis - A Statistical Approach
2022, Research Journal of Chemistry and Environment
Litter removal effects on dynamics of soil humic substances in subalpine forests of western Sichuan, China
2022, Chinese Journal of Plant Ecology
Humic Substances: Hypotheses and Reality (a Review)
2021, Eurasian Soil Science

View all citing articles on Scopus

^☆: Background music while reading: Rock'n Roll Dance Show Medley # RD35: https://www.youtube.com/watch?v=sq--8HXYjnc or by Guido Fichtner, Paganini – The 37 guitar sonatas: https://www.youtube.com/watch?v=JVbA70FCpgA.

View full text

ReviewHumusica 1, article 7: Terrestrial humus systems and forms – Field practice and sampling problems☆

Abstract

Section snippets

What are humus systems and humus forms?

Where and how to find humus forms?

How carefully to observe humus forms?

Prelude

Strategies

Where and when humus forms are changing?

At which scales humus forms can be investigated?

Do we need classifying all humus forms observable on the field?

Soil Biol. Biochem.

Chemosphere

Soil Biol. Biochem.

Pedobiologia

For. Ecol. Manag.

Geoderma

Geoderma

Soil Biol. Biochem.

Soil Biol. Biochem.

Catena

Geoderma

Forest humus forms as potential indicators of soil carbon storage in Mediterranean environments

Biol. Fertil. Soils

Humus forms in the forest-alpine tundra ecotone at Stillberg (Dischmatal, Switzerland): spatial heterogeneity and classification

Arctic Antarctic Alpine Res.

Earthworm feeding activity and development of the humus profile

Biol. Fertil. Soils

Pflanzensoziologie. Grundzüge der vegetationskunde

Soil genesis and classification

Classification

Field-scale variability of soil properties in Central Iowa soils

Soil Sci. Soc. Am. J.

Rapid range shifts of species associated with high levels of climate warming

Science

Plant degradation by ruminants: parallels with litter decomposition in soils

Soil biology, soil ecology, and global change

Biol. Fertil. Soils

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes

Ecol. Lett.

Acceleration of global warming due to carbon-cycle fedbacks in a coupled climate model

Nature

The development of British heathlands and their soils

Oxford For. Mem.

Let the soil work for us

Ecol. Bull.

Humus form characteristics in relation to undergrowth vegetation in a Pinus sylvestris forest

Acta Oecol.

Humus form development and succession of dwarf shrub vegetation in grass dominated primary Pinus sylvestris forests

Ann. Sci. For.

Toward an ecological classification of soil bacteria

Ecology

Réflexions sur les fondements syntaxonomiques nécessaires à une synthèse des végétations à l’échelle du continent européen et esquisse d’un synsystème dans l’optique de la phytosociologie Braun-Blanqueto-Tüxenienne

Ebauche de synsystème pour la France. Annali di Botanica

Epistémologie de la territorialité en phytosociologie

Giorn. Bot. Ital.

Humus components and soil biogenic structures in Norway spruce ecosystems

Sci. Soc. Am. J.

Review
Humusica 1, article 7: Terrestrial humus systems and forms – Field practice and sampling problems☆