Mapping and Assessment of Ecosystems and Their Services (MAES)

The concept of Mapping and Assessment of Ecosystems and their Services (MAES) was introduced by the European Commission as a framework to provide governments, scientists, and stakeholders with consistent, comparable information on the state of ecosystems and the benefits they deliver to society. MAES integrates ecological, socioeconomic, and spatial data to support decisionmaking, policy development, and sustainable landuse planning.

Why MAES Matters

Ecosystems underpin many of the basic functions that enable human wellbeing: they regulate climate, purify water, pollinate crops, store carbon, and provide cultural and recreational values. Yet, rapid urbanisation, climate change, and intensive agriculture have altered ecosystem structure and function, often unnoticed until damage becomes irreversible. MAES offers a systematic way to:

• Identify where ecosystem services are generated and where they are used.
• Detect gaps in knowledge and data.
• Assess trends and pressures affecting ecosystem health.
• Inform policies such as the EU Biodiversity Strategy, the Green Deal and climate adaptation plans.

Core Components of MAES

1. Ecosystem Mapping

Ecosystem mapping produces spatially explicit representations of ecosystem types (forests, wetlands, grasslands, marine habitats, etc.) at a suitable resolution. It relies on remote sensing, national landcover inventories, and field surveys. Key steps include:

• Defining a consistent ecosystem classification (e.g., CORINE, EUNIS).
• Collecting satellite imagery (Sentinel2, Landsat) and LiDAR where available.
• Applying classification algorithms (random forests, deep learning) and validating with ground truth.

2. Ecosystem Condition Assessment

Condition assessment quantifies the health of each ecosystem type using indicators that reflect structure, composition, and functioning. Examples of indicators are:

• Forest canopy density, dead wood volume, and species richness.
• Water quality parameters (dissolved oxygen, nutrient load) for rivers and lakes.
• Soil organic carbon and erosion risk for agricultural lands.

3. Ecosystem Services Quantification

MAES distinguishes between four main categories of ecosystem services (ES):

• Provisioning food, timber, freshwater, genetic resources.
• Regulating climate regulation, flood mitigation, pollination.
• Cultural recreation, spiritual inspiration, tourism.
• Supporting soil formation, nutrient cycling, primary production.

Quantification can be performed with biophysical models (e.g., InVEST, ARIES) and linked to monetary valuation where appropriate.

4. Integration and Reporting

The final MAES product is a set of maps and data tables that illustrate the spatial distribution of ecosystem types, their condition, and the services they provide. Reports are structured to answer three fundamental questions:

• What ecosystems exist and where?
• What is their current condition?
• Which services do they deliver and to whom?

Figure 1: Simplified MAES workflow (source: European Commission)

Data Sources and Tools

Successful MAES implementation depends on open, highquality data and interoperable tools:

• Remote sensing platforms: ESA Sentinel, NASA Landsat, Copernicus Global Land Service.
• Geospatial databases: European Environment Agency (EEA) datasets, Global Biodiversity Information Facility (GBIF), CORINE Land Cover.
• Modeling suites: InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs), ARIES (Artificial Intelligence for Ecosystem Services), GLOBIOM.
• GIS software: QGIS (free), ArcGIS, Google Earth Engine for largescale processing.

Policy Context

MAES aligns with several European and global policy frameworks:

• EU Biodiversity Strategy for 2030 sets targets for restoring ecosystems and halting biodiversity loss.
• EU Climate Law & European Green Deal emphasizes naturebased solutions that rely on accurate ecosystem service assessments.
• UN Sustainable Development Goals (SDGs) especially Goal 15 (Life on Land) and Goal 13 (Climate Action).

By providing spatially explicit evidence, MAES supports the design of protectedarea networks, naturebased climate mitigation projects, and sustainable agriculture incentives.

Case Study: MAES in the Danube River Basin

The Danube basin, covering 19 countries, illustrates how MAES can be used at a transboundary scale:

1. Mapping: Highresolution landcover maps identified wetlands, floodplains, and forest patches along the river corridor.
2. Condition: Water quality monitoring indicated downstream eutrophication hotspots linked to agricultural runoff.
3. Services: Modeling showed that restored floodplain wetlands could reduce peak flood levels by up to 30% and sequester 1.2Mt of COyr.
4. Policy impact: The findings underpinned the EUs NatureBased Solutions for Flood Risk Management programme, leading to the designation of new Natura2000 sites.

Challenges and Opportunities

Data Gaps

Many regions lack finescale field data, especially for belowground processes and cultural services. Citizenscience platforms (e.g., iNaturalist) and emerging technologies such as UAVbased hyperspectral imaging are helping to close these gaps.

Scale Mismatch

Policy decisions are often made at national or regional scales, while ecosystem processes operate at finer spatial resolutions. Multiscale approachescombining local monitoring with panEU datasetsare essential to avoid scale blind spots.

Valuation Debate

Assigning monetary values to ecosystem services can facilitate costbenefit analyses but may oversimplify nonmaterial values. A mixedmethods approach that pairs economic valuation with qualitative assessments (e.g., narrative mapping) provides a more balanced view.

Future Directions

• Dynamic MAES integrating realtime satellite data and climate projections to produce forwardlooking service forecasts.
• Linkages with SDG Indicators aligning MAES outputs with the United Nations ecosystemrelated SDG metrics.
• Machinelearningenhanced classification using deep neural networks to improve ecosystem type discrimination, especially in heterogeneous landscapes.
• Crosssectoral cobenefits explicitly mapping how actions for climate mitigation (e.g., afforestation) also support biodiversity and water regulation.

Getting Started with a MAES Project

If you are planning a MAES assessment, follow these practical steps:

1. Define objectives and spatial extent. Clarify whether the focus is national policy, a river basin, or a specific protected area.
2. Choose a classification system. Adopt EUNIS or CORINE for consistency with EU datasets.
3. Gather baseline data. Collect remotesensing imagery, existing landcover maps, and any available socioeconomic statistics.
4. Design indicator set. Select condition and service indicators that are relevant, measurable, and dataavailable.
5. Model services. Use tools such as InVEST; calibrate with local measurements where possible.
6. Validate and iterate. Conduct field checks, engage local experts, and refine maps.
7. Produce deliverables. Create clear maps, data tables, and an executive summary that highlights key findings and policy recommendations.
8. Communicate. Share results with stakeholders through workshops, interactive web maps, and policy briefs.

Further Reading

• European Commission (2021). MAES Mapping and Assessment of Ecosystems and their Services Guidance. ec.europa.eu
• UNEP (2020). Nature-based Solutions and Ecosystem Services for Climate Change Adaptation and Mitigation. unep.org
• Plieninger, T. & Reisch, C. (2020). Ecosystem Services and Biodiversity in European Cities. Science of the Total Environment, 745, 141212.
• AlvarezNetto, A., & Bockstael, G. (2019). The role of MAES in the EU Biodiversity Strategy. Ecological Indicators, 100, 2231.

Mapping and Assessment of Ecosystems and their Services provides a robust, sciencebased foundation for preserving nature while supporting human prosperity. By translating complex ecological data into clear, spatially explicit information, MAES empowers policy makers, planners, and communities to make informed decisions that safeguard the planet for generations to come.