Peatland Management: Climate change and UK

The largest uncertainty in the future trajectory of peatlands in the UK and the policy surrounding their management has to be that of Climate change and its potential impact on their form and processes. Although management currently stems around encouraging rehabilitation of natural surfaces to increase biodiversity and carbon sequestration as seen in the EU habitat directive 7110, the implications of climate change may force changes in peatlands and therefore the management priorities surrounding them.

Dried peat surface  in the Peak District froma nice photography collection:  http://bleaklow.com/2003/09/15/close_up_to_the_dark_peak.html 

The work conducted by Harriet Orr and colleagues at the Environment Agency Climate change research group has aimed to answer the questions below:

·         What are the climate and hydrogeographic conditions which determine where peat exists now and where it will be found in the future?

·         Will peat still form in the uplands in 2100?

(Holden 2009)

The group have gone about answering these by employing “Bioclimatic envelope models” which relate the distribution of Upland blanket peat to environmental variables such as temperature and precipitation. This allows them to assess the vulnerability of peatland surfaces within the UK to future climate predictions. The UKCIP (a great online resource by the way: http://www.ukcip.org.uk/ ) have produced predictions of future climate based for low, medium and high emission scenarios for 2020, 2050 and 2080. Employing these data within the model, a listing of the “most” down to the “least” vulnerable peatlands was produced for the regions of the UK.

Figure 1: A vulnerability assessment of UK peatland ranked from “most” to “least”.

(Sourced from: Environment Agency Climate Change Science Programme and the NERC QUEST joint working group meeting on: Climate change and uplands: science to inform adaptation November 2007, Bristol

http://quest.bris.ac.uk/workshops/upland/EA-QUEST_Uplands_wkshp_rept.pdf )

As we can see the vulnerability varies across all the Nations of the UK however, the Highlands which constitute the largest single resource are predicted to be the least vulnerable, with other large agglomerations in Scotland such as the Grampians, Western Isles, Argyle, Bute and Trossachs also facing relatively lower vulnerability.

Large resource areas such as Northumbria, Peak District and the Central Belt are however, vulnerable. This is particularly poignant as these regions are bordered by densely populated regions and therefore influence relatively important drainage catchments as previously discussed. They also provide key regions of biodiversity and thus a drying will most probably translate to a shift in ecosystem composition from individual species and loss of essential habitat in for the regions biodiversity (Weltzein et al. 2003).

This is noted by the conservation agencies responsible for these sites. The Peak District National Park Authority (2012) identify the issue of increased fire risk on the upland peatland in relation to climate change as well as a potential increase in the erosion of peat.

Blanket bog already exists within its climatic limit within the Peak District and thus a change could prove fatal to the species assemblages present as re introduction and conservation schemes could not sustainably maintain the vegetation assemblages. This may serve to; along with a reduction or even halt to peat production, to change the management policies

The findings of this study and other models that suggest that the role of blanket peatlands in carbon sequestration will decrease, suggest perhaps a change in policies that are currently shaping the management of UK peatlands. The current focus on managing bodies on regeneration efforts within regions of greatest vulnerability may prove to be a misuse of resources as changes to climate may exceed the environmental limits of the current species composition (Holden 2009).

In conclusion, climate is changing and will alter peatlands within the next century. The net result of the change in climate inputs is still uncertain however, modelling can provide a means to focus management schemes as different peatlands across the UK are vulnerable to climate by differing factors. The focus of management schemes may have to alter within the next century as the impacts of climate change become apparent.

Yours

Matt

References:

Peak District National Park Authority., 2012. Blanket Bog.[pdf] Derbyshire: Peak District National Park Authority Available at:

http://www.peakdistrict.gov.uk/__data/assets/pdf_file/0016/134053/Blanket-Bog.pdf

[Accessed 19 November 2012].

Holden, J., 2009. A grip-blocking overview.[pdf] Edale:Moors for the Future Partnership.

Available at: http://www.moorsforthefuture.org.uk/sites/default/files/Holden%20(2009)%20grip%20block%20review.pdf  [Accessed 19 November 2012].

Weltzin, J.F., Bridgham, S.D, Pastor, J., Chen, J. and Harth, C. 2003. Potential effects of warming and drying on peatland plant community composition. Global Change Biology 9, 141-151

Peatland Management: Blanket peats and the upland hydrology of the UK

Hey guys, I thought in we'd take a look at the topic area of peatlands and their place in the landscapes of the UK into the future. I've had to limit the content, but even doing that its still been necessary to split the topic into two posts. In the first we’ll take a look at specifically Upland Blanket Bogs which constitute 87% of the UK peat resource (Holden 2009). I'll discuss their impact on the hydrology of drainage catchments and the potential impact of direct human alteration to them. In the second post we will then take a gander at the MASSIVE issue of climate change and the future of peatlands in the UK.

As can be seen from the distribution of relief, precipitation and peat soil in the UK (Figures 1, 2, 3), Peatlands (primarily upland blanket bogs) cover large areas of high relief which constitute significant sources of water to catchments due to their high amounts of precipitation. It is important to understand how peatlands impact the hydrology of upland regions and the rivers sourced from them, in order to assess the impact of anthropigenic activity on the hydrology of the bog and whole catchments.

Figure 1: UK relief map

Figure 3: Peat and Peaty soil area coverage

Figure 2: Rainfall amount annual average 1981-2010

 

                                            

Rivers whose sources are located in upland blanket peat have been shown to express “quickflow”, meaning that discharge rises and falls sharply with precipitation events. An interesting study conducted by Bullock and Acreman (2003) claims to have disproved the often used metaphor that blanket peat acts as a large “sponge” depressing the flashiness of discharge events, (at least that’s what my Geography teacher told me). Although peat does retain large volumes of water the storage capability for single precipitation events is low as the peat complex is already saturated. On average the water table is no more than 40cm from the surface and even throughout periods of drought water retention is high. Thus the storage capacity including surface pooling is low, leading to fast reaction times in the discharge of peatlands

Undisturbed blanket peat soils express primarily saturation overland flow and through-flow in response to rainfall events, which in turn are processes that cause rapid movement of water from the slope to the channel. A key cause of this is the characteristics of the peat that result in almost no lateral flow of water between pores below a few centimetres of the surface. In addition to these processes are soil pipes which form large networks under the peat surface and provide relatively high discharge rates of up to 14 l/s, with studies suggesting they can contribute 10-50% of streamflow (Holden 2009). So although Blanket Upland Bogs do provide some base flow component to catchment streams/rivers, as they are large stores within the catchment throughout the year, they do not provide significant flood relief.

An example of this that is close to my heart (as it flooded my local) was the 8^th-9^th June 2012 flooding of the Aberystwyth area. The region is typified by shallow peats with soil piping that have a low storage capacity for rainfall events. Within the River Leri Catchment; which is small and steep spanning from the Pumlumon massif within the Cambrian mountains to the sea, the short lag and peak lag times associated with the heavy rainfall event resulted in rapid flooding that caught people unawares in the Dol-y-Bont Caravan site and flooded The White Lion (Y Llew Gwyn) in Tal-Y-Bont!!!!!!!!

 An Aerial view of the flood extent within the River Leri catchment over Dol y Bont and Borth.

An important consideration with peatlands within the UK is that, almost all altered in some way by human activity generally through cutting, burning or drainage. In the case of drainage, observations of drained upland blanket peats have displayed both increases and decreases in peak flood discharge within different locations (Holden 2009). By lowering the water table through the installation of drainage ditches, there is an increase in the soil storage capacity for rainfall however, this can be counteracted by ditches ability to speed up the transfer of water from the peat to the stream/river channel.

Gilman (2002) in a study of Cors Llyn in Mid Wales identified ditch network design, slope and local vegetative cover as important variables in the rate and volume of discharge produced by a drained region. This topic is of particular importance in that rehabilitation of active peat surfaces as it is noted under the EU habitat Directive as a priority and thus across the UK drainage ditches are being blocked in order to re-establish the water table in disturbed sites. This policy, which has driven protection designations of SSSI’s and SAC’s to upland blanket bogs means that the emphasis remains on the ecology and not perhaps runoff and flood risk. However, will that remain so? It seems to me that it depends on the future of active peat surfaces as carbon sinks into the future.

So there we have stay tuned for the next blog where we'll get to grips with climate change and it's impications of Peatlands and the plocies that shape these landscapes.

Catch you later
Matt

References:

Bullock, A. and Acreman, M., 2003. The role of wetlands in the hydrological cycle. Hydrology and Earth System Sciences, 7, 358-389.

Gilman, K., 2002. A review of evapotranspiration rates from wetland and wetland catchment plant communities, with particular reference to Cors y Llyn NNR, Powys, Wales, CCW Science Report; 504, Countryside Council for Wales, Bangor

Holden, J., 2009. A grip-blocking overview.[pdf] Edale:Moors for the Future Partnership.

Available at: http://www.moorsforthefuture.org.uk/sites/default/files/Holden%20(2009)%20grip%20block%20review.pdf [Accessed 19 November 2012].

Hot under the collar?

Hello, I hope you’re well and life’s dealing you a good hand at the moment. My apologies for being so lax in providing you with your weekly update of peatland factoids, but a combination of hurricane and Arctic swells, kept me in the water a bit too much last week.

The topic for this post, as you can see from the title is; CLIMATE CHANGE!!!!!!! Alterations to the climate and their causes are well documented and presented far more concisely than I can hope to achieve in a few sentences, so here’s a good link on the general context for this post:

http://news.bbc.co.uk/1/shared/spl/hi/sci_nat/04/climate_change/html/climate.stm

Evidently this whole business is of huge importance for the future of global biomes and ecosystems within them. The alteration to climate will vary across the globe and so within an assessment of potential impacts on ecosystems, key environmental variables must be identified along with their value ranges which support certain vegetation assemblages.

Moore (2002) identifies that climate change threatens to change Peatlands primarily through alterations to temperature and precipitation (directly for bogs or indirectly through groundwater recharge for fens).

As discussed previously a key dynamic of peatland formation and development is the unbalanced relationship between biomass deposition and decomposition. The product of any biological process is produced though the energy available to a system. Thus with an increase in temperature there is an increase in the biomass grown, but also decomposed. Davidson and Janssesns (2006) state that the understanding of feedbacks within soil substrates to discern the role of intrinsic temperature sensitivity on decomposition from those obscured by environmental constraints which themselves can be subject to climate, is a tad difficult... to say the least.

Something that be assured is that with increased atmospheric Carbon dioxide and nitrate deposition the biomass productivity will increase globally and thus the fundamental control on the opposing factors of peat formation is the future distribution of precipitation as this restricts oxygen concentrations and thus decomposition.

The role of this relationship will dictate the future view of peatlands within the climate system as either sinks or sources of greenhouse gases. In Moore (2002) the danger of increases in decomposition are made plain in that peatlands may become sources of Carbon dioxide as well as methane and nitrous oxide. These gases would contribute to a positive feedback system in which climate change would intensify thereby threatening the release of more of the 455Gt store of carbon which constitutes 25% of the global soil carbon store.

Below is a good summary video of the feedback systems:

http://www.youtube.com/watch?v=PLfhWVZ7k10

 

 So climate change will impact, but it largely depends on precipitation. In the next instalment we’ll take a look at climate projections for the UK and see how peatland cover will be looking up to the 2080’s.  

Cheers

Matt

References:

Davidson, E.A., & I.A., Janssens., 2006. Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature, vol. 440, p165-173

Moore, P.D.,2002. The future of cool temperate bogs. Environmental Conservation, vol.29, p3-20.