ISO/TS 18718:2026

Technical
Specification
ISO/TS 18718
First edition
Soil functions and related
2026-01
ecosystem services — Definitions,
descriptions and conceptual
framework
Fonctions des sols et services écosystémiques rendus —
Définitions, descriptions et cadre conceptuel
Reference number
© ISO 2026
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General consideration . 4
5 Description of ecological soil functions . 4
5.1 General .4
5.2 Water regulation, retention and release.4
5.3 Organic matter storage, transformation and recycling .4
5.4 Nutrient cycling .5
5.5 Contaminant retention, transformation and degradation .5
5.6 Gas exchanges with atmosphere .5
5.7 Habitat provision .6
5.8 Physical stability .6
6 Description of soil ecosystem services . 8
6.1 General .8
6.2 Biomass production .8
6.3 Hydrological control (purification, supply, regulation) .8
6.4 Erosion control .8
6.5 Nutrient and element cycling . .8
6.6 Climate regulation .8
6.7 Biodiversity maintenance and resilience .9
6.8 Pest, disease control, plant health promotion .9
6.9 Contaminant-related ecosystem services .9
6.10 Air quality regulation .9
7 Conceptual framework of ecosystems services provided by soils . 9
Bibliography .11

iii
Foreword
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iv
Introduction
Ecosystem services can be seen as the various ways nature provides a service to people. Since they are
quite easily understandable and communicable, policy makers and citizens have asked for valuations of
ecosystem services provided by land (not just soil). Several international, EU, national or local assessments
have been conducted leading to a great number of publications, the most famous one being the Millennium
[6]
Ecosystem Assessment. These valuations have proposed their own frameworks (linking soil functions
with ecosystem services) and definitions, leading to a wide diversity of results. Moreover, frameworks for
soil health and soil quality assessment are increasingly integrating ecosystem services and soil function
[7]
concepts. However, terminology and definitions are different between natural sciences dealing with soil
functions, and socio-economics and environmental economics sciences pushing the ‘ecosystem services’
concepts. Within these disciplines there are also different definitions across countries or policy areas, and
even within countries, the understanding of definitions used in science can be different from policy. Having
an international common way to describe and to assess soil functions and related ecosystem services is
crucial to further compare valuations made in different countries, soil types and land uses for management
or remediation purposes. For communication purposes, transparency and consistency, common and shared
definitions and conceptual frameworks are needed. The effectiveness of policies and management depends
on selecting methods that are functionally aligned with the defined objectives.
This document presents the conceptual links between ecological soil functions and ecosystem services
provided by soils. It includes the description of main biotic and abiotic processes underlying soil functioning
and connections with several ecosystem services. The document also defines all terms and concepts needed
to support the developed framework for the assessment of soil functions and related ecosystem services.
1)
This document should be read in conjunction with ISO/TS 18721 that presents the soil characteristics and
indicators needed to assess ecological soil functions (see Figure 1).
Figure 1 — Links between this document (ISO/TS 18718) and ISO/TS 18721 on the soil functions
and related ecosystem services
1) Under preparation. Stage at the time of publication: ISO/DTS 18721.

v
Technical Specification ISO/TS 18718:2026(en)
Soil functions and related ecosystem services — Definitions,
descriptions and conceptual framework
1 Scope
This document provides definitions, descriptions and a framework for the assessment of ecological soil
functions and of related ecosystem services, based on a review of existing documents. It describes the main
characteristics of key ecological soil functions and how they relate to soil characteristics and to ecosystem
services.
This document does not cover non-ecological soil functions, e.g. the support of infrastructures and archives,
the provision of raw material.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
soil
upper layer of the Earth’s crust transformed by weathering and physical-chemical and biological processes
and composed of mineral particles, organic matter, water, air, and living organisms organized in soil horizons
Note 1 to entry: In a broader horizon civil engineering sense, soil includes topsoil (3.2) and subsoil (3.3); deposits such
as clays, silts, sands, gravels, cobbles, boulders, and organic matter and deposits such as peat; materials of human
origin such as wastes; ground gas and moisture; and living organisms.
[SOURCE: ISO 11074:2025, 3.448]
3.2
topsoil
upper layers of a natural soil (3.1) that is generally dark coloured and has a higher content of organic matter
and nutrients when compared to the (mineral) horizons below, excluding the humus layer
Note 1 to entry: For arable land, topsoil refers to the ploughed soil depth, while for grassland, it is the soil layer with
high root content.
[SOURCE: ISO 11074:2025, 3.536]
3.3
subsoil
natural soil material below the topsoil (3.2) and overlying the parent material
Note 1 to entry: Much of the original rock structure has usually been obliterated by pedogenic processes.
[SOURCE: ISO 11074:2025, 3.506]

3.4
ecosystem service
benefit people obtain from one or several ecosystems
Note 1 to entry: These are generally distinguished into provisioning, regulating, supporting and cultural services.
Note 2 to entry: Ecosystem services are sometimes called “environmental services” or “ecological services”.
[SOURCE: ISO 14050:2020, 3.2.4 modified — Notes 1 and 2 to entry have been added.]
3.5
soil ecosystem service
soil-related subset of ecosystem services (3.4) directly and indirectly controlled or provided by soils (3.1) and
their chemical, physical and biological characteristics (3.12), processes and functions
3.6
soil function
role performed by soil (3.1) that supports ecosystems, the biosphere, the water environment and human
activities
Note 1 to entry: Soil functions are the result of one or a combination of soil processes (3.8) that drive the dynamics of
the ecosystem structure or composition.
[SOURCE: ISO 11074:2025, 3.453 modified — Note 1 to entry has been added.]
3.7
retention function
ability of soils (3.1) or soil materials to adsorb contaminants (3.15) in such a way that they cannot be
mobilised through the water pathway and translocated into the terrestrial food chain
[SOURCE: ISO 11074:2025,3.390]
3.8
soil process
physical, chemical or biological interactions among soil components underlying soil formation, soil functions
(3.6) and ecosystem services (3.4) and which can be used for their quantification
3.9
soil health
performance of a soil (3.1), at a given time, compared to its maximum potential
Note 1 to entry: The maximum potential of a soil is its soil quality (3.10).
Note 2 to entry: Adapted from Reference [8].
3.10
soil quality
long-term maximum potential of a soil (3.1) to function and provide ecosystem services (3.4),
taking into account its intrinsic properties and local biophysical conditions
Note 1 to entry: This definition differs from the one given in ISO 11074:2025, 3.466. It has been adapted to the context
of soil health assessment.
Note 2 to entry: Adapted from Reference [8].
3.11
indicator
quantitative, qualitative or binary variable that can be measured, estimated, calculated or described,
representing the status of conditions and the impact of operations and management
Note 1 to entry: An indicator is generally backed up by an interpretation framework.

[SOURCE: ISO 14050:2020, 3.2.24 modified — “estimated” has been added; “the status of operations,
management, conditions or impacts” has been replaced by “the status of conditions and the impact of
operations and management”; Note 1 to entry has been added.]
3.12
characteristic
property or attribute of a material that is measured, compared, or observed
[SOURCE: ISO 11074:2025, 3.70]
3.13
soil structure
arrangement of mineral particles and organic matter to form aggregates which produce macrostructures
and microstructures in the soil
[SOURCE: ISO 11074:2025, 3.475]
3.14
macropore
large pore created by both physical processes and biological agents
Note 1 to entry: Large pores are pores between 50 µm and 75 µm in diameter
Note 2 to entry: Physical processes include for example swell-shrink and freeze-thaw.
Note 3 to entry: Biological agents include plant roots and soil fauna.
3.15
contaminant
substance or agent present in an environmental medium as a result of human activity or a result of natural
event, or both
Note 1 to entry: There is no assumption in this definition that harm results from the presence of the contaminant.
[SOURCE: ISO 11074:2025, 3.91 modified — “or a result of natural event, or both” has been added.]
3.16
pollutant
substance or agent present in an environmental medium which, due to its properties, amount or
concentration, causes adverse impacts on the environmental medium
Note 1 to entry: A pollutant can cause adverse effects on the ecosystems and human health.
[SOURCE: ISO 11074:2025, 3.328 modified — Note 1 to entry has been added.]
3.17
decomposition
breakdown of complex organic substances into simpler molecules or ions by physical, chemical or biological
processes, or a combination of these
[SOURCE: ISO 11074:2025, 3.113]
3.18
degradation
physical and chemical breakdown of the substances
[SOURCE: ISO 11074:2025, 3.116]
3.19
soil erosion
removal of soil by the physical forces of water, wind and other agents
Note 1 to entry: Other agents include ice, snow, plants, animals, humans.

[SOURCE: ISO 14055-1:2017, 3.2.15 modified — “and other agents” has been added to the definition; the
original notes to entry have been removed and a new Note 1 to entry has been added.]
3.20
percolation
transport of infiltration water through a layer of soil
[SOURCE: ISO 18772:2008, 3.11]
4 General consideration
This document describes the various biotic and abiotic processes that contribute to the ecological soil
functions, which in turn support ecosystem services. Clauses 5 and 6 describe the main ecological soil
functions and their links with ecosystem services supported by soils. Clause 7 proposes a conceptual
framework linking processes to functions and services, and it integrates natural drivers, soil management
and the demands of society. Such information is needed to assess soil health and soil quality.
5 Description of ecological soil functions
5.1 General
[9]
Each soil function can be divided into different sub-functions.
Table 1 details soil functions and illustrates how these functions and sub-functions are influenced and
connected to either biological or physico-chemical processes, or both.
5.2 Water regulation, retention and release
Water regulation, retention and release refer to the capacity of the soil to receive, store and conduct water
for subsequent use (e.g. by plants) and to prevent drought, flooding and soil erosion. It is supported by the
following sub-functions:
— Water retention: the capacity of soil to store water mainly depending on its thickness, texture, amount of
gravel/stones, organic matter content and structure, the latter being influenced by e.g. climate, biological
activities, and soil management practices;
— Infiltration and percolation depend on soil texture and are maintained through a continuum of bio-
physical processes, supported by the soil biota. These are considered ecosystem engineers (such as
earthworms, enchytraeids, ants, fungal hyphae, plant roots) that develop e.g. macropores, which provide
a conduit for water within the solid phase. Physical and chemical impact, such as compaction, crust
formation, soil frost, hydrophobicity, are also of importance for infiltration and percolation.
5.3 Organic matter storage, transformation and recycling
This function includes soil processes that contribute to the incorporation of organic matter in the soil and its
decomposition. The function can be defined by three main groups of processes which take place in the soil:
— Decomposition includes the biological processes controlling the breakdown of organic matter which
results in the production of CO and CH . Almost all soil organisms play a role in the decomposition of
2 4
organic matter.
— Resource reallocation includes processes that make resources available, unavailable or that replace
them. This includes mixing and moving soil through leaching, bioturbation, occlusion of organic matter
by aggregation, allocation of assimilated C and N from plants and microbes into the soil by exudation,
and the uptake of C and N by the food web.
— Biochemical transformation includes processes involved in the conversions of molecules. This
includes transformations of inorganic molecules that lead to the production of N O (nitrification and
denitrification), as well as the consumption of CH (methanotrophy). Biochemical transformations are
mainly performed by soil microorganisms.
5.4 Nutrient cycling
This function refers to the capacity of a soil to release, take up and recycle nutrients from different inputs
(
...