Streamside forests reduce nutrient pollution of aquatic
ecosystems
Donald E. Weller, Thomas E. Jordan, and Matthew E. Baker
Smithsonian EnvironmentalResearch Center
Ecosystem services• Terrestrial
– Wildlife habitat– Carbon sequestration– Forest products
• Aquatic– Aquatic food chain– Control temperature– Pollutant regulation– Nutrient removal
Field studies of nitrogen removal
Distance from field toward stream (m)
Nitr
ate
conc
entr
atio
n (m
g N
/l)
Mid-Atlantic removal results
National stream and river restoration
Riparian restorations1990-2003
> 20,000projects
> $5 billion
Buffer prevalence varies widely
Problems “scaling up” . . .Watershed results mixed
Transect results striking
?
(Mal)adaptive management
Knowledge
Evaluation
Measurement
Implementation
Overlay sources and streams on elevation
Identify downhill transport pathways
transportpathwayfor 1 pixel
Quantify width & aggregate paths
Well-buffered pathway
Not so well-buffered
New geographic analysis
sources flowpaths sinks
Prioritizing management efforts
>375 m250 m120 m20 m
<20 m
Buffer Width
Chesapeake Bay example
321 watersheds3 physiographic
provinces focus on cropland
and buffersempirical models for
stream nitrate
Benefits differ among regions
Physiographic provinceCP PD AM
Nitr
ate
conc
entra
tion
(mg
N/l)
0
1
2
3
4
buffer leakage
restored bufferremoval
current bufferremoval
non-crop
Stream Nutrient Levels
<no buffers
<current buffers
<complete buffer
<no cropland
Overall reductions
Physiographic provinceAll
Nitr
ate
conc
entra
tion
(mg
N/l)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
buffer leakage
restored bufferremoval
current bufferremoval
non-crop
16%
32%
68%
Policy implications• Protect riparian areas
– Conserve existing forest buffers– Restore missing forest buffers
• Outreach and education• Focus incentive funding
– Regional targeting– Site level targeting
• Implement adaptive management– Improve models for estimating benefits– Measure outcomes
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