### Changes in vegetation

#### Indicators:

Potential vegetation Potential vegetation gained (relative to 1970) Potential vegetation lost (relative to 1970) | Threat to natural vegetation (graph) Threat to bioreserves (map) Threat to natural vegetation (map)

The change in vegetation illustrates the impacts of climate change on unmanaged vegetation or ecosystems. We assess possible shifts in vegetation zones as a major impact indicator. These shifts are modelled with the BIOME model, which is part of the terrestrial vegetation model. BIOME calculates the global potential vegetation patterns for each climate. The potential vegetation is the equilibrium vegetation that should eventually develop under a given climate. It is generally agreed that current vegetation patterns are in equilibrium with current climate but not with a changed climate. The shifts in vegetation zones however does not occur instanteneously. Especially for slow-growing species, such as trees, there are long lag times.

The impact on vegetation does not consider the impacts of changes in land cover due to changing land use as calculated by the land-cover model. These changes are shown in the state land use indicators.

| #### Potential vegetation
| unit: none dimension: land-cover type

The potential vegetation is the equilibrium vegetation that develops under given climate conditions. Potential vegetation is modelled with the BIOME model, which is part of the terrestrial vegetation model. The model uses a series of plant functional types (e.g. needle-leafed and broad-leafed trees, shrubs and grasses) together with their phenology (e.g. deciduousness vs. evergreen; warm vs. cold) to assemble large-scale vegetation patterns. Each plant functional type is delimited by several climatic variables (temperature of the coldest and warmest month, temperature sums; moisture index) that are strongly correlated with frost and drought resistance, growth form and productivity. In IMAGE 2.4 potential vegetation is used in the background. It functions as an attractor towards the actual vegetation develops after changes in climate occur or after abandonment of agricultural land.

| #### Potential vegetation gained (relative to 1970)
| unit: none dimension:land-cover type

The potential vegetation gained relative to 1970 depicts the changes in potential vegetation, as simulated by BIOME model. The coloured areas change from the original potential vegetation type in 1970 into the new potential vegetation type. The new potential vegetation type is displayed on the map. This indicates the response of current potential vegetation

| #### Potential vegetation lost (relative to 1970)
| unit: none dimension: land-cover type

The potential vegetation lost relative to 1970 depicts the changes in potential vegetation, as simulated by BIOME model. The colored areas change from the original potential vegetation type in 1970 into another potential vegetation type. The old potential vegetation type is displayed on the map. This indicates the sensitivity of current potential vegetation.

| #### Threat to natural vegetation (graph)
| unit: 1000 km2 (thousand square km) dimension: region, threat, area type

The threat to natural vegetation depicts the changes in potential vegetation since 1970, as simulated by BIOME model, combined with a model for calculating the possible adaptation of vegetation. This model assumes that plants can migrate by propagules over the landscape. The maximum distance of dispersal and lag times caused by the successful establishment of propagules are considered. For example, the change from a needle-leafed forest into a broad-leafed forest is slow and strongly depends on the distance of available propagules. The change of forests into grasslands is rapid because the dispersal rate of grasses is large. The threat of vegetation is presented in the classes 'adaptation' or 'no adaptation'. Adapted vegetation is the vegetation that resembles the potential vegetation, while non-adapted vegetation is still the original vegetation type, because the new vegetation type has not been established. It is reasonable to assume that the non-adapted vegetation is a degraded form of the original vegetation. Here the impacts are most severe.
The area class provides the additional possibility to check the status of bioreserves. Be aware that the total area of bioreserves is small compared to the total area. Differences are displayed best when the scale of the y-axis is adjusted.

| #### Threat to bioreserves (map)
| unit: dimension:

The World Conservation Monitoring Centre in Cambridge has provided a database with the location, size and status of reserves larger than 2500 ha. In the 'threat to bioreserves' map we list those bioreserves in which the original vegetation changes into another vegetation. If this occurs then the original objectives for protection are most likely not being met any more and the intended protection of the species in this bioreserve failed. We have separated the bioreserves into the most valuable ones and others. The impacts on both classes are displayed.

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| #### Threat to natural vegetation (map)
| unit: dimension: threat, area type

The threat to natural vegetation map displays the changes in potential vegetation since 1970, as simulated by BIOME model, combined with a model for calculating the possible adaptation of vegetation. This model assumes that plants can migrate by propagules over the landscape. The maximum distance of dispersal and lag times caused by the successful establishment of propagules are considered. For example, the change from a needle-leafed forest into a broad-leafed forest is slow and strongly depends on the distance of available propagules. The change of forests into grasslands is rapid because the dispersal rate of grasses is large. The threat of vegetation is presented in the classes 'adaptation' or 'no adaptation'. Adapted vegetation is the vegetation that resembles the potential vegetation, while non-adapted vegetation is still the original vegetation type because the new vegetation type has not been established. It is reasonable to assume that the non-adapted vegetation is a degraded form of the original vegetation. Here the impacts are most severe.