1 Influence of hydroclimatic forcing on stream temperatures – role of riparian management on ecosystem response “North-Watch” Workshop III: Hydroecological responses to climate change in northern catchments Iain Malcolm Outline • Why are we interested in stream temperature? • Evidence of changing stream temperatures in Scotland • Processes controlling stream temperature • Physical controls on stream temperature • Riparian woodland and stream temperature • Riparian woodland: Understanding implications for fish • Practical value, what are we asked, what can we say
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1
Influence of hydroclimatic forcing on stream
temperatures – role of riparian management on
ecosystem response
“North-Watch” Workshop III: Hydroecological responses to climate change in northern catchments
Iain Malcolm
Outline
• Why are we interested in stream temperature?
• Evidence of changing stream temperatures in Scotland
• Processes controlling stream temperature
• Physical controls on stream temperature
• Riparian woodland and stream temperature
• Riparian woodland: Understanding implications for fish
• Practical value, what are we asked, what can we say
2
Why are we interested?
• Influences physical, chemical and biological processes
• In fish influences growth and survival at various life stages, ova, juvenile, adult
• Also has potential to influence population demographics and production
• Potentially important for assessment (including tool development)
• Increasing interest under climate change
• Implications for fish populations and mitigation / adaptation?
Evidence for changing stream temperature
• Not allot of data
• Very few records > 2
decades
• Especially sites independent
of significant landuse
change
• Data from Girnock Burn -
First 30 years published by
Langan et al., 2001
• 1966-2006 Ca. 0.6 degree
increase in mean T20
/06/19
66
20/06/19
71
20/06/19
76
20/06/19
81
20/06/19
86
20/06/19
91
20/06/19
96
20/06/20
01
20/06/20
06
0
5
10
15
20
Tem
pera
ture
(D
egre
es C
)
Date
3
Seasonal variability in mean monthly temperature trends
(1966-2005)
JanApril
OctJuly
Gurney et al., 2009
-0.76 Deg. C1.04 Deg. C
1.46 Deg. C-0.57 Deg. C
Processes controlling stream temperature
• Stream temperature is the net outcome of range of energy exchange processes
• Boundaries at stream – streambed and stream-atmosphere