Hydrology and Earth System Sciences
www.hydrol-earth-syst-sci.net
1027-5606
1607-7938
4
1
2000
10.5194/hess-4-95-2000
http://www.hydrol-earth-syst-sci.net/4/95/2000/
http://www.hydrol-earth-syst-sci.net/4/95/2000/hess-4-95-2000.html
http://www.hydrol-earth-syst-sci.net/4/95/2000/hess-4-95-2000.pdf
95
104
0000-00-00
Effects of plantation forest clearfelling on stream temperatures in the Plynlimon experimental catchments, mid-Wales
T. Stott
S. Marks
Liverpool John Moores University, I. M. Marsh Campus, Barkhill Road, Liverpool L17 6BD, U.K.
Institute of Hydrology, Staylittle, Llanbrynmair, Powys, U.K. Now at Environmental Agency, Sir John Moore House, Victoria Square, Bodmin, Cornwall PL31 1EB, U.K.
e-mail for corresponding author: T.A.STOTT@LIVJM.ac.uk
Hourly stream temperatures monitored over 28
months, which spanned a 3 month period of environmentally sensitive plot-scale
harvesting of 20 ha. (20%) of the Nant Tanllwyth catchment (0.89 km<sup>2</sup>)
on the south side of the main stream in early 1996, resulted in a 0.58°C
(p< 0.001) increase in monthly mean stream temperature. Over the same 28 month
experimental period, there was no significant increase in the monthly mean air
temperature recorded at a nearby automatic weather station. Monthly mean
temperatures are highest in July and August in the year before and the year
after the clearfelling, and one of the main effects of the clearfelling was to
decrease the difference between the monthly mean stream and air temperatures.
Despite the air temperatures being cooler in the post-clearfelling year, the
stream temperatures still showed an increase in the summer months.
<br>Monthly mean maximum stream temperatures, also highest in July and August in the
year before and the year after the clearfelling, showed a marked increase of
7.0°C: in July and 5.3°C in August from the pre- to the post-clearfelling
years, while monthly mean minimum air temperatures actually showed a slight
decrease for the same months. The likely effects on stream fauna are discussed,
as are suggestions for, and likely effects of, buffer strips alongside the
streams.</p>
<p style="line-height: 20px;"><b>Keywords:</b> stream temperature; air temperature; ground surface
temperature; clearfelling; Plynlimon</p>