Table 2 Key determinants of the sensitivity of the contrasting states of each ecosystem component to a hypothetical warming scenario assessed by expert knowledge

From: Expert elicitation of state shifts and divergent sensitivities to climate warming across northern ecosystems

Permafrost
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. Polar desert continuous permafrost	2. Polar tundra continuous permafrost	10–100	NA	Vegetation state shift*	See vegetation (polar desert to polar tundra)
2. Polar tundra continuous permafrost	3. Extensive discontinuous permafrost	10–100	- Permafrost thickness - Permafrost extent	NA	- Vegetation cover - Snowpack properties - Soil characteristics - Topography - Precipitation - Ground ice content
3. Extensive discontinuous permafrost	4. Sporadic discontinuous permafrost	10–100	- Permafrost thickness - Permafrost extent	NA	- Vegetation cover - Snowpack properties - Soil characteristics - Topography - Precipitation - Ground ice content
4. Sporadic discontinuous permafrost	5. Relict permafrost	10–100 to >100	- Permafrost thickness - Permafrost extent	NA	- Vegetation cover - Snowpack properties - Soil characteristics - Topography - Precipitation - Ground ice content - Permafrost depth - Fire regime

Peatlands
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. Polygonal peatlands	2. Complex of tundra peatlands	10–100	NA	Permafrost degradation	- Soil characteristics - Topography - Precipitation - Ground ice content - Plant species colonization rate
2. Complex of tundra peatlands	4. Non-permafrost peatlands	>100	NA	Permafrost degradation	- Soil characteristics - Topography - Precipitation - Ground ice content - Plant species colonization rate
3. Mosaic of palsa and peat plateau peatlands	4. Non-permafrost peatlands	10–100	NA	Permafrost state shift	- Plant species colonization rate - See permafrost (extensive discontinuous to sporadic discontinuous).

Lakes
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. Perennial ice cover lake	2. Intermittent ice cover lake	1–10	- Lake ice cover - Lake water temperature	NA	- Exposure to solar radiation and wind
2. Intermittent ice cover lake	3. Seasonal ice cover/clear lake	1–10	- Lake ice cover - Lake water temperature	NA	- Exposure to solar radiation and wind
3. Seasonal ice cover/clear lake	4. Seasonal ice cover/low colour lake	10–100	NA	- Vegetation densification - Changes in plant assemblages - Permafrost degradation	- Catchment soil characteristics and hydrology
4. Seasonal ice cover/low colour lake	5. Seasonal ice cover/high colour lake	10–100	NA	- Vegetation densification - Changes in plant assemblages - Permafrost degradation	- Catchment soil characteristics and hydrology

Snowpack
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. Polar desert snowpack	2. Polar tundra snowpack	10–100	NA	Vegetation state shift	See Vegetation (polar desert to polar tundra).
2. Polar tundra snowpack	3. Shrub tundra snowpack	10–100	NA	Vegetation state shift	See Vegetation (polar tundra to shrub tundra).
3. Shrub tundra snowpack	4. Boreal forest snowpack	>100	NA	Vegetation state shift	See Vegetation (shrub tundra to forest).

Vegetation
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. Polar desert vegetation	2. Polar tundra vegetation	10–100	Plant growth, survival and reproduction	NA	- Precipitation - Topography - Soil characteristics - Exposure to solar radiation and wind
2. Polar tundra vegetation	3. Shrub tundra vegetation	10–100	Plant growth, survival and reproduction	NA	- Precipitation - Topography - Soil characteristics - Exposure to solar radiation and wind - Plant species colonization rate - Herbivory
3. Shrub tundra vegetation	5. Closed-crown coniferous forest 6. Mixed wood boreal forest	>100	Plant growth, survival and reproduction	NA	- Precipitation - Topography - Soil characteristics - Exposure to solar radiation and wind - Plant species colonization rate - Herbivory - Frequency and intensity of disturbances (fire, insects)
4. Open-crown coniferous forest	5. Closed-crown coniferous forest 6. Mixed wood boreal forest	>100	Plant growth, survival and reproduction	NA	- Precipitation - Topography - Soil characteristics - Exposure to solar radiation and wind - Plant species colonization rate - Herbivory - Frequency and intensity of disturbances (fire, insects)
5. Closed-crown coniferous forest	6. Mixed wood forest	>100	Plant growth, survival and reproduction	NA	- Precipitation - Topography - Soil characteristics - Exposure to solar radiation and wind - Plant species colonization rate - Herbivory - Frequency and intensity of disturbances (fire, insects)

Vertebrates
State shift		Sensitivity (Response time, in years)	Key determinants of response time		Local conditions modulating response time
From	To	Sensitivity (Response time, in years)	Direct effects of air temperature on	Indirect effects of air temperature via	Local conditions modulating response time
1. High-Arctic vertebrates	2. Arctic vertebrates	1–10 to 10–100	NA	Lake state shift	- Vertebrate species colonization rate - Species interactions - See Lakes (perennial ice cover to intermittent ice cover).
2. Arctic vertebrates	3. Low Arctic vertebrates	10–100	NA	Vegetation state shift	- Vertebrate species colonization rate - Species interactions - See Vegetation (polar tundra to shrub tundra).
3. Low Arctic vertebrates	4. Boreal vertebrates	>100	NA	Vegetation state shift	- Vertebrate species colonization rate - Species interactions - See Vegetation (shrub tundra to forest).

The sensitivity is quantified by response time, which is the estimated time required for a component at critical threshold to shift from an initial state to a resulting state following an exposure to a step change of 5 °C increase in mean annual temperature. Temperature can have many effects on ecosystem components. Indirect effects are those involving another ecosystem component included in the study. Local conditions that can modulate response time (i.e., increase or decrease response time within the selected time interval) are also indicated.
^*Here, key determinants are the main direct or indirect effects of temperature on abiotic or biotic factors (with the latter highlighted in boldface) that determine the time required for a component to shift from an initial state to a resulting state (response time).

Back to article page

Table 2 Key determinants of the sensitivity of the contrasting states of each ecosystem component to a hypothetical warming scenario assessed by expert knowledge

Search

Quick links