The grass is always greener (than the forest): is it the N?

Hannah TremblayCarleton 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•Craig See•Adam Wild•Clarissa Lyons•Austin McDonald•Shinjini Goswami•Russell Auwae

•Ruth Yanai

•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.