Definitions:

The indicator is composed of two sub-indicators to monitor progress towards the conservation of mountain ecosystems:

Sub-indicator 15.4.2a, Mountain Green Cover Index (MGCI), is designed to measure the extent and changes of green cover - i.e. forest, shrubs, trees, pasture land, cropland, etc. – in mountain areas. MGCI is defined as the percentage of green cover over the total surface of the mountain area of a given country and for given reporting year. The aim of the index is to monitor the evolution of green cover and thus assess the status of conservation of mountain ecosystems.

Sub-indicator 15.4.2b, Proportion of degraded mountain land, is designed to monitor the extent of degraded mountain land as a result of land cover change in a given country and for given reporting year. Similarly to sub-indicator ‘’trends in land cover” under SDG Indicator 15.3.1 (Sims et al. 2021), mountain ecosystem degradation and recovery is assessed based on the definition of land cover type transitions that indicate improving, stable or degrading conservation status. The definition of degradation adopted for the computation of this indicator is the one established Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)^[1].

Concepts:

Mountain area is defined according to the UNEP-WCMC (2002) method. It defines total global mountain area as the sum of seven classes (commonly known as ‘Kapos mountain classes’), based on elevation, slope and local elevation ranges (Table 1).

Table 1. Global mountain classes as defined by UNEP-WCMC (2002)

Kapos Mountain Class	Description
Class 1	Elevation >= 4500 meters
Class 2	Elevation >= 3500 & < 4500 meters
Class 3	Elevation >= 2500 & < 3500 meters
Class 4	Elevation >= 1500 & < 2500 meters & slope >= 2 degrees
Class 5	Elevation>= 1000 & < 1500 meters & slope >= 5 degrees OR local (7 km radius) elevation range > 300 meters
Class 6	Elevation >= 300 & < 1000 meters & local (7 km radius) elevation range > 300 meters
Class 7	Inner isolated areas (<=25 Km² in size) that do not meet criteria but surrounded by mountains

Prior to the methodological refinement of this indicator approved by the Inter-agency and Expert Group on SDG Indicators (IAEG-SDG) in June 2022, the UNEP-WCMC classification was used to disaggregate the indicator by Kapos mountain classes. This is no longer the case, with Kapos mountain classes having been replaced by bioclimatic belts (see section 2.c below).

Land cover refers to the observed physical cover of the Earth’s surface. It includes vegetation and man-made features as well as bare rock, bare soil and inland water surfaces (FAO-GTOS, 2009). The primary units for characterizing land cover are categories (e.g. Forest or Open Water). These categories must be defined following a standardized land cover classification in order to identify land cover changes consistently over time. Several global standards of land cover classifications have been developed by international initiatives for this purpose.

For the purposes of standardization and harmonization when reporting on SDG Indicator 15.4.2, this indicator has adapted the land cover classification established by the United Nations Statistical Commission’s System of Environmental and Economic Accounting (UN-SEEA) (UN Statistical Division, 2014) by selecting the most relevant SEEA classes for mountain ecosystems and aggregating all croplands classes (Table 2).

Table 2. Left: Land cover classification established by the UN-SEEA (Source: UN Statistical Division, 2014). Right: Adapted land cover classification for the computation and aggregate reporting on SDG Indicator 15.4.2.

Original UN – SEEA land cover classification (n=14)	SDG Indicator 15.4.2 land cover classification (n=10)
1 Artificial surfaces	1 Artificial surfaces
2 Herbaceous crops	2 Croplands
3 Woody crops
4 Multiple or layered crops
5 Grassland	3 Grasslands
6 Tree-covered areas	4 Tree-covered areas
7 Mangroves	Discarded. Not relevant for mountains
8 Shrub-covered areas	5 Shrub-covered areas
9 Shrubs and/or herbaceous vegetation, aquatic or regularly flooded	6 Shrubs and/or herbaceous vegetation, aquatic or regularly flooded
10 Sparsely natural vegetated areas	7 Sparsely natural vegetated areas
11 Terrestrial barren land	8 Terrestrial barren land
12 Permanent snow and glaciers	9 Permanent snow and glaciers
13 Inland water bodies	10 Inland water bodies
14 Coastal water bodies and intertidal areas	Discarded. Not relevant for mountains

Land cover serves different functions for SDG Indicator 15.4.2:

In sub-indicator 15.4.2a, land cover is used to categorize land into green and non-green cover areas. As showed in Table 3, green cover includes areas covered by both natural vegetation and vegetation resulting from anthropic activity. Non-green areas include non-vegetated areas such as bare land, water, permanent ice/snow, urban areas and sparsely vegetated areas. In addition, land cover is used to disaggregate the indicator into the 10 land cover classes included in Table 2, thus increasing the indicator’s policy relevance.

Table 3. Classification of SEEA land cover classes into green and non-green cover.

SEEA land cover classes	Green/Non-green
Croplands	Green
Grasslands	Green
Tree-covered areas	Green
Shrub-covered areas	Green
Shrubs and/or herbaceous vegetation, aquatic or regularly flooded	Green
Artificial surfaces	Non-green
Sparsely natural vegetated areas	Non-green
Terrestrial barren land	Non-green
Permanent snow and glaciers	Non-green
Inland water bodies	Non-green

In sub-indicator 15.4.2b, land cover is used to identify areas where changes in the type of land cover (land cover transitions) may indicate a decline or loss of biodiversity, mountain ecosystem functions or services that are considered desirable in a local or national context. A transition that indicates a decline or loss of biodiversity and mountain ecosystem services of the land is considered degradation. The definition of land cover transitions is documented in a transition matrix that specifies the land cover changes occurring in a given land unit (pixel) as being either degradation, improvement or neutral transitions.

¹

IPBES defines land degradation as “the many human-caused processes that drive the decline or loss in biodiversity, ecosystem functions or ecosystem services in any terrestrial and associated aquatic ecosystems” (IPBES, 2018) ↑

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Rætta metadátur: 15.4.2