Transcript The grass is always greener (than the forest)

The grass is always greener
(than the forest):
is it the N?
Hannah Tremblay
Carleton College, 2014
Background
• Fertilization and fossil fuels have more than
doubled amount of available N in biosphere
• Expansion of suburbs is one of the fastest
growing land uses
• Recent evidence suggests that urban soils may
be a sink for atmospheric N (Raciti et al. 2008)
The experiment
• To quantify the differences in total soil nitrogen,
available nitrate, and nitrification rates between
residential lawns and forested areas in northern
New Hampshire.
• How does the land use shift from forests to
lawns affect nitrification and mineralization
rates?
Methods: site selection
• 12 clusters
• 58 sites
• Personal
interview and
questionnaire
Methods:
In the field
• 5 volumetric, 5.8cm
diameter, 15cm deep
cores from lawns and
adjacent forests
• Vegetative cover and
tree inventory
recorded
• Measured area of
property
Methods: In the lab
• Soil sieved and homogenized
• Two 20 gram subsamples
▫ “Time 0” extraction: placed in a 250 ml Nalgene
bottle with 100ml of 2M KCl. Settled for 24 hours.
▫ “Time final” extraction: incubated for 21 days in a
1 pint mason jar and fanned every 3 days.
• Soil samples filtered and analyzed
Methods: In the lab
Results
P-value < .05
Moving forward
• Nitrification and mineralization rates
• Investigation of historical land use
• Relationship with vegetation
• Demographic information
Thank you
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Craig See
Adam Wild
Clarissa Lyons
Austin McDonald
Shinjini Goswami
Russell Auwae
• Ruth Yanai
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Melany Fisk
Tim Fahey
Paul Lilly
Peter Groffman
Paige Warren
Matt Vadeboncoeur
References
• Raciti SM, Groffman PM, Fahey TJ. 2008.
Nitrogen retention in urban lawns and forests.
Ecol Appl 18(7):1615–26.