Hedgerows originated and coexist with
agriculture. They tell the story of the countryside and farming traditions over
many centuries. Some hedgerow systems in the UK date back to prehistoric times,
and most were well established by the Anglo-Saxon period. They were originally
planted to contain livestock, mark boundaries or to fulfil Parliamentary
Enclosure Acts. Hedgerows are a defining feature of the British landscape,
forming part of our cultural and landscape heritage. They are really something
to be proud of!
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| Britain's hedgerow landscape |
The importance of hedgerows for
biodiversity
The length of UK hedgerows is estimated to be
506 thousand miles. This makes them by far the largest nature reserve in the
UK! In present day agricultural landscapes, hedgerows are considered to have many
important ecological functions. They serve as refuges for species that were once widespread but
are now restricted to uncultivated field margins. Hedgerows also provide a
range of regulatory services, buffering against soil erosion and preventing the movement of
surface water flow and particulate movement.
They're in decline!
Agricultural modernisation was responsible for considerable changes in
both agricultural practices and landscape structure in the UK. We have seen a
huge decline in the traditional hedgerow network landscape during the last
century. This degradation of the rural landscape that has elapsed as a result
of agricultural intensification represents the decline of hedgerow habitats and
in my opinion this is a really serious impoverishment of the British landscape.
The condition of the UK's hedgerows is under
threat. Local hedgerow surveys show that only 41% of hedgerows are in favourable
condition. What is it that is threatening our hedgerows? Well, studies show
that nutrient enrichment
is the single most important reason for poor condition, with 38% of surveyed
hedgerows failing on this criterion.
Contemporary agriculture is highly dependent on
external outputs and high fertiliser rates are required to give high yields.
Herbicides and pesticides are applied to suppress weeds and to control pests.
However, unfortunately the devices that are used to apply these fertilisers and
agrochemicals are not very good at getting it only on the crop and so
non-target areas such as hedgerows are regularly hit! The nutrient enrichment
that occurs as a result of this drift has been shown to modify plant community organisation in
hedgerows.
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| Agrochemical drift poses a huge threat to hedgerow biodiversity |
What can be done?
Well the answer
is relatively simple... Many scientists are now advocating the incorporation of conservation headland at the edge of intensively farmed fields. A conservation headland is an area at
the edge of a field that receives reduced agrochemical and fertiliser inputs.
Scientists have shown that this is sufficient to reduce non-target deposition
significantly and thus prevent loss of biodiversity in our hedgerows.
Hi Rachel,
ReplyDeleteI agree with your points that hedgerows are vitally important to sustaining the health of our countryside and the state of biodiversity. You mention the use of a conservation headland as a solution to the damaging effects of nutrient enrichment from artificial fertilisers and pesticides, but I wondered what your opinions are on recent technological advancements that could reduce nutrient enrichment?
New spraying equipment now has GPS tracking that shows where chemicals have been applied on a monitor inside the cab, and will automatically turn off individual nozzles in order to prevent applications outside of the stated crop boundary. Do you think the use of such tools could be an equally significant solution?
Hi Hugo,
ReplyDeleteThank you for your comment! It's interesting that you say this because I recently read a paper by Byass and Lake (1977) in which they reported that drift was strongly influenced by the spraying equipment that was being used. They found that drift of pesticides was affected by factors such as boom height and nozzle type. They reported that under normal conditions, drift measurements varied from 1-15% of the amount applied to the crop at 1m from the last nozzle.
Misplacement of fertiliser is known to be less predictable. For example, Rew et al. (1992) found huge differences between different spreader types with a minimum amount of misplacement of 0% of the mean field rate and a maximum of 195%!
These reports show that clearly the type of spraying equipment is a significant control on the amount of drift that goes on. And so to answer your question, I would say that yes, adaptations to spraying equipment are certainly a viable solution to reducing levels of pesticide drift and fertiliser misplacement however I believe that for other conservation reasons - such as to increase the amount of uncultivated habitat for biodiversity - these solutions should by employed in conjunction with a conservation headland.