CLM20-2 full issue-1 - Flipbook - Page 29
A guide to conservation land management and greenhouse gas emissions
still release GHGs – albeit at
lower levels – but without the
benefit of providing food for
human consumption.
If considering replacing
grazing with cutting, it is
similarly important to bear in
mind that these different forms
of management also have quite
different effects on the vegetation
and its inhabitants. In particular,
mowing, by removing all of
the vegetation in an area in one
go, is catastrophic for many
invertebrates; tends to produce a
more uniform vegetation structure
than medium levels of livestock
grazing; is typically unselective in
the plant species that it removes;
Ponies release lower levels of methane per quantity of vegetation
and does not create gaps in the
removed compared to cattle or sheep. Natural England/Peter
sward that are necessary for
Roworth (CC BY-NC-ND 2.0)
plants to regenerate. Patchy and
rotational cutting can, though, be used to create
but, as shown in Table 1, sheep actually cause
more warming per livestock unit (i.e. per quantity structural mosaics and might be a realistic alternative
to livestock grazing at small sites, especially those
of vegetation removed).
where grazing is in any case difficult.
A common suggestion is to replace cattle with
The GHG flux from managing vegetation
ponies. If you are considering this, it is important to
by cutting will vary according to the fate of the
recognise that cattle and ponies have quite different
cut material. Using arisings from conservation
effects on vegetation structure and composition,
management to provide biomass (i.e. to burn to
and consequently on the vegetation’s inhabitants. In
release energy) or for composting can be valuable
addition, there is evidence that ponies trample more
ways of disposing of otherwise unwanted material,
birds’ nests per quantity of vegetation removed than
as well as sometimes generating an income to
cattle (Mandema et al. 2013). There do not appear
help fund conservation work. The use of biomass
to be significant differences in levels of methane
might, to a very limited extent, displace the burning
emissions between different breeds of livestock, with
of fossil fuels. Meanwhile, composting will not
any differences in overall GHG emissions being
significantly affect the GHG flux from a habitat,
due to their feed intake and the type of production
compared to leaving the arisings to decompose in
system (Dewhurst & Miller 2019). While replacing
situ. By contrast, using timber for construction will
commercial cattle with ponies will reduce GHG
benefit the climate by locking up the carbon in it.
emissions at a given site, the latter will nevertheless
Table 1. The estimated greenhouse gas (GHG) emissions, expressed as GWP100, from different types of
livestock. Data for GHG emissions are from IPCC (2019). Data on livestock units per animal are from Rural
Payments Agency (2021).
Type of livestock
Livestock units per animal
GHG emissions (t CO2e per year)
Per animal
Per livestock unit
Mature beef cow
1.0
1.404
1.4
A sheep and its lamb
0.1*
0.243
2.4
Pony
0.8
0.486
0.6
* Mean of value for upland and lowland sheep
Conservation Land Management Summer 2022 | Vol. 20 No. 2 27
