Hedgerow agroforestry in England and Wales: increasing width to sequester additional carbon

Axe, IMS, Grange, I and Conway, J (2018) Hedgerow agroforestry in England and Wales: increasing width to sequester additional carbon. In: 4th European Agroforestry Conference, 24-30 May 2018, Njimegen, The Netherlands. (Submitted)

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Abstract

Hedgerow systems are one of the more prominent agroforestry systems in temperate European agriculture, and the UK has the second largest extent of these in the European Union (Herzog 2000; den Herder et al. 2016). An estimated 456 000 km of hedge in England and Wales has been actively managed (Carey et al. 2008); which limits hedge outward growth, and maintains an effective barrier to livestock (Pollard et al. 1974). This management consists of a short period trimming cycle every 1 - 3 years, and a long period structural restoration cycle, after approximately 40 years growth (Staley et al. 2015). A mechanical flail is used for the short period trimming cycle by 92% of farmers in England and Wales (Britt et al. 2011). Typical ‘Enclosure’ hedges in England and Wales were planted with only hawthorn (Crataegus monogyna), in single, or double rows, from the 16th Century onwards (Maclean 2006). Hawthorn is still the dominant woody species, found within 90% of hedges in England and Wales, but a mix of woody species is common, and blackthorn (Prunus spinosa) is the second most frequent species, found within 50% of these hedges (Barr et al. 2000). The potential for temperate agroforestry to sequester carbon (C), and mitigate rising levels of Green-House Gasses (GHG), is beginning to receive more attention (Udawatta and Jose 2012). Axe et al. (2017) showed the potential to sequester C where wider managed hedges had greater C stocks (t C km-1 ). Allowing such hedges to grow wider from lateral branch growth only, without increasing planting density, may not be the most effective way to accumulate Above Ground Biomass (AGB) C. It also introduces uncertainty in using area C stock values (t C ha-1 ) to estimate AGB C (t C), as this parameter assumes a linear relationship with hedge width. Here new data on the contribution made by blackthorn to AGB C stock, and the correlation between hedge width and t C km-1 , from the pilot study of triennially flailed hedge biomass (Axe et al. 2017), along with supporting evidence on shrub growth in unmanaged hedges (Küppers 1985), is examined to advance how atmospheric C could be sequestered by increasing hedge width.

Item Type: Conference or Workshop Item (Paper)
Keywords: Crataegus monogyna, Prunus spinosa, agroforestry, basal area, biomass, carbon, carbon sequestration, growth, width,
Divisions: Agriculture, Food and Environment
Depositing User: Marieke Guy
Date Deposited: 14 Jan 2019 15:56
Last Modified: 22 May 2019 15:02
URI: http://rau.repository.guildhe.ac.uk/id/eprint/16089

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