2.7 - Changes in Biomes
Latitudinal and altitudinal shifts in biomes due to climate change
Climate change has historically influenced the distribution of biomes, and current models predict significant shifts in their locations as global temperatures continue to rise. These changes occur both latitudinally, relative to the Equator, and altitudinally, as biomes move to higher elevations.
Predicted movements of biomes
- Latitudinal shifts - Biomes are expected to move polewards as temperatures increase, altering the distribution of ecosystems away from equatorial regions.
- Altitudinal shifts - Vegetation zones on mountains are shifting upwards, with species moving to higher elevations to escape rising temperatures.
- Loss of specific biomes - Low-lying biomes, such as mangroves, risk being submerged due to rising sea levels, while high-altitude biomes may disappear as they have no further space to migrate upwards.
Impact on mountain vegetation zones
| Climate scenario | Vegetation zones (highest to lowest elevation) | Notable changes |
|---|---|---|
| Under current conditions (pre-climate change) | Alpine zone (e.g., permanent snow/ice, sparse vegetation) | Highest elevation, very cold, limited plant life. |
| Sub-alpine zone (e.g., coniferous forest, hardy shrubs) | Below alpine, cold-tolerant trees, harsh winters. | |
| Montane zone (e.g., mixed deciduous and coniferous forest) | Moderate elevation, diverse forest, distinct seasons. | |
| Foothill/Lowland zone (e.g., grassland, agricultural land) | Lowest elevation, warmer, more fertile soil. | |
| With climate change (warming climate) | Alpine zone (shrinks, or disappears entirely) | As temperatures rise, the permanent snow/ice recedes, reducing the area of this zone. Species adapted to extreme cold face habitat loss. |
| Sub-alpine zone (shifts upwards, potentially replacing alpine) | coniferous forests expand into areas previously occupied by alpine vegetation. Species from lower zones migrate upwards. | |
| Montane zone (shifts upwards, replacing sub-alpine) | Mixed forests move to higher elevations, encroaching on former sub-alpine areas. | |
| Foothill/Lowland zone (expands upwards, potentially replacing montane) | Warmer-adapted species and agricultural land extend further up the mountain slopes. |
Impacts on species composition and biodiversity
The rapid pace of current climate change means that many species may not be able to adapt or migrate quickly enough to follow their preferred climatic conditions.
This can lead to:
- Biodiversity loss - Species unable to adapt or migrate face extinction.
- Changes in community structure - New species may colonise areas, outcompeting native species or altering food webs.
- Increased vulnerability - Stressed ecosystems are more susceptible to disease outbreaks and invasive species.
Effects on animal migrations and habitat corridors
As biomes shift, animals that undertake seasonal migrations or require specific habitats for different life stages face significant challenges.
Key impacts include:
- Disrupted migration routes - Traditional routes may become unsuitable, or key stopover points may disappear.
- Loss of habitat corridors - Natural pathways connecting fragmented habitats are crucial for species movement. Climate change can degrade these corridors or make them impassable.
- Increased human-wildlife conflict - Animals may move into human-dominated areas in search of new habitats or food sources.
Conservation efforts increasingly focus on establishing and maintaining ecological corridors to allow species to move in response to climate change.
Changes to agricultural patterns and crop yields
Climate change directly impacts agriculture, leading to shifts in where crops can be grown and how productive they will be.
Key changes include:
- Shifts in suitable growing regions - Traditional agricultural zones may become too hot or dry, requiring farmers to move to new areas, often at higher latitudes or altitudes.
- Altered crop yields - Some regions may see initial increases in yields due to longer growing seasons or increased CO2, while others will experience significant declines due to heat stress, water scarcity, or increased pest outbreaks.
- Water resource availability - Changes in precipitation patterns, including more frequent droughts or intense rainfall, will affect irrigation needs and water supply for crops. This disproportionately impacts areas already facing water stress.
- Food security implications - Global food production patterns will be disrupted, potentially leading to food shortages and price volatility, particularly in vulnerable regions.
Soil erosion and degradation linked to global warming
Global warming contributes to soil erosion and degradation through several mechanisms:
- Increased temperatures - Higher temperatures can accelerate the decomposition of organic matter in soil, reducing its fertility and water retention capacity.
- Altered precipitation patterns - More intense rainfall events can lead to increased surface runoff and erosion, washing away topsoil. Conversely, prolonged droughts can dry out soil, making it more susceptible to wind erosion once vegetation cover is lost.
- Vegetation change - Shifts in biomes and plant communities can alter ground cover, leaving soil exposed to erosive forces.
- Permafrost thaw - In polar and high-altitude regions, thawing permafrost releases trapped carbon and can lead to ground subsidence, destabilising landscapes and increasing erosion.
- Desertification - In already arid and semi-arid regions, rising temperatures and reduced rainfall can accelerate desertification, turning productive land into barren desert.
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