Assessing the vulnerability of blanket peat to climate change using an ensemble of statistical bioclimatic envelope models

Abstract

ABSTRACT:We assessed the vulnerability of blanket peat to climate change in Great Britain using an ensemble of 8 bioclimatic envelope models. We used 4 published models that ranged from simple threshold models, based on total annual precipitation, to Generalised Linear Models (GLMs, based on mean annual temperature). In addition, 4 new models were developed which included measures of water deficit as threshold, classification tree, GLM and generalised additive models (GAM). Models that included measures of both hydrological conditions and maximum temperature provided a better fit to the mapped peat area than models based on hydrological variables alone. Under UKCIP02 projections for high (A1F1) and low (B1) greenhouse gas emission scenarios, 7 out of the 8 models showed a decline in the bioclimatic space associated with blanket peat. Eastern regions (Northumbria, North York Moors, Orkney) were shown to be more vulnerable than higher-altitude, western areas (Highlands, Western Isles and Argyle, Bute and The Trossachs). These results suggest a long-term decline in the distribution of actively growing blanket peat, especially under the high emissions scenario, although it is emphasised that existing peatlands may well persist for decades under a changing climate. Observational data from long-term monitoring and manipulation experiments in combination with process-based models are required to explore the nature and magnitude of climate change impacts on these vulnerable areas more fully.

Transient simulations of the carbon and nitrogen dynamics in northern peatlands: from the Last Glacial Maximum to the 21st century

“…A previous study on peatland model intercomparisons suggests that the bioclimatic space associated with peat could decline considerably under a changing climate (Clark et al, 2010). The importance of high-latitude processes is further underlined by Stocker et al (2013), who show that annual CH 4 emissions from peatlands increase considerably (+120-200 %) until 2100 AD in the case of RCP 8.5.…”

“…On the other hand, warmer temperatures enhance water loss through evaporation and transpiration, which in turn affects water table position and eventually NPP. This process seems to be an important factor for peatland modeling (Clark et al, 2010). In addition, warmer temperatures increase soil C decomposition and emissions of the greenhouse gases (GHG), including carbon dioxide (CO 2 ) and methane (CH 4 ).…”

Bioclimatic envelope model of climate change impacts on blanket peatland distribution in Great Britain

“…A blanket peatland map was produced by combining the mapped area of blanket peatlands from the soil survey map for England and Wales (NATMAPvector, 1:250 000) and Scotland (National Soils Map, NSM, 1:250 000) (as described fully in Clark et al 2010). In England and Wales, peat soils meet both of the following criteria: (1) either > 40 cm of organic material is found within the upper 80 cm of the soil profile, or > 30 cm of organic material rests directly on bedrock or skeletal material; and (2) no superficial non-humose mineral horizons with a colour value of 4 or more that extends below 30 cm depth (Clayden & Hollis 1984).…”

Prediction of blanket peat erosion across Great Britain under environmental change

“…4) are consistent with results from previous bioclimatic envelope modelling for blanket peatlands. Both Gallego-Sala et al (2010) and Clark et al (2010) demonstrated that the geographical distribution of bioclimatic space suitable for blanket peatlands may gradually retreat towards the north and west of Great Britain. The low rate of the relative change and the absolute value of mean annual erosion at site 7 do not follow the general spatial pattern across Great Britain.…”

“…PET was calculated with a temperature-based model originally proposed by Oudin et al (2005). The model was modified to include wind speed and vegetation height, as used in the blanket peatland PET estimation by Clark (2005) for our study site 7 (see Fig. 1).…”