Fen Management Handbook - Scottish Natural Heritage

4.6 Identifying nutrient enrichment – initial (stage 1) assessment
1. Is there a nutrient
problem on your fen?
2. Where does the nutrient
source come from?
Can the entry point of the
nutrients be identified?
Measure general chemical
properties of water and soil
water (EC/pH)
Target measuring of air
/ water / soil nutrient
concentrations
(see 10.8, 10.9 and 10.10
in Section 10: Monitoring
to Inform Fen Management)
4.6.1 Deciding if your fen is at risk of nutrient enrichment
Although the varied character of fens complicates and in some cases precludes
definition of generic nutrient regimes, good habitat quality is usually associated with
low fertility substrata and key water inputs. This means that many fens within the UK
are at some risk of enrichment due to eutrophication – including from atmospheric
nitrogen deposition. In many cases this risk is significant, particularly for fens in
intensively farmed landscapes, such as basin fens, or sites close to sources of
enrichment such as busy roads, airports or power stations. The exceptions (i.e.
fens at lesser risk of nutrient enrichment) are upland springs and flushes that are
dependent on rainfall and/or fed by less enriched groundwater sources. However,
even these remote fens are likely to be affected by nitrogen inputs via rainfall which
may carry nutrients taken up some distance from where the rain actually falls.
Deciding if your fen is at risk of nutrient enrichment
– Identify in broad terms the target nutrient regime for the fen.
Does the vegetation show enrichment?
Is there a significant increase in nutrient
supply to the fen?
Where does the vegetation show enrichment?
1. How does this tie in with water supply?
– is the enrichment along a periodically
flooding drain?
– is the enrichment near a spring?
2. Is there a new intensive poultry farm
close by?
Take appropriate action (see Section 8:
Managing Fen Nutrient Enrichment)
– Identify if the fen is moving toward a more nutrient enriched status
(i.e. it is being degraded by nutrient enrichment and needs additional
restoration and/or protection measures) or if the habitat is satisfactory
and is being maintained by the existing management regime. Such
an assessment has to be done at the individual site level but, for the
purposes of an initial assessment, can be undertaken at a fairly broad
scale across the site.
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