Presentation Title

Large Variations in Throughfall Nitrogen Deposition Over Small Spatial Scales in Southern California Chaparral

Faculty Mentor

Dr. George Vourlitis

Start Date

17-11-2018 12:30 PM

End Date

17-11-2018 2:30 PM

Location

HARBESON 22

Session

POSTER 2

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Nitrogen (N) deposition describes the input of reactive nitrogen from the atmosphere to the biosphere due in part to fossil fuel emissions. This experiment analyzed and compared the dry deposition of ammonium (NH4) and nitrate (NO3) captured in through-fall over a period of 2 years. Measurements were conducted at three different sites comparing two different vegetation types: shrubs and forests. The deposition data were collected using ion exchange resin (IER) collectors and chemical extraction methods were used to measure the (N) collected in through- fall. Through-fall is the process of rain penetrating through the canopy of the plant to the soil surface. Every 3 months IER collectors were swapped out and replaced and leaf area index was measured. Meteorological data was collected and used from San Pasqual Valley, which is located approximately 25 km east of the study area. The seasonal variation in (NH4) and (NO3) through-fall as a function of site, vegetation type, and time were analyzed using repeated- measures ANOVA. Our null hypothesis was that (N) deposition would not be positively correlated with elevation and leaf area index. Our results indicated that through-fall (N) was significantly higher for trees than shrubs, and TIN (TIN= NH4+NO3) and (NH4) was positively correlated with elevation for trees but not shrubs. throughfall was approximately 2 times higher than (NO3) through-fall in tree canopies and almost 5 times higher than (NO3) through-fall in shrub canopies. Our data results indicated that large variations in the amount and type of (NH4 or NO3) of (N) through-fall over very small spatial scales were dependent on vegetation growth. These large variations increase the uncertainty of (N) deposition estimates from experimental measurements of (N) through-fall. These large differences were unexpected and suggest that spatial variations in N deposition are large in Southern California. Monitoring and understanding these patterns is crucial for ongoing research monitoring of N deposition as well as understanding potential environmental effects of increased N deposition locally and globally.

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Nov 17th, 12:30 PM Nov 17th, 2:30 PM

Large Variations in Throughfall Nitrogen Deposition Over Small Spatial Scales in Southern California Chaparral

HARBESON 22

Nitrogen (N) deposition describes the input of reactive nitrogen from the atmosphere to the biosphere due in part to fossil fuel emissions. This experiment analyzed and compared the dry deposition of ammonium (NH4) and nitrate (NO3) captured in through-fall over a period of 2 years. Measurements were conducted at three different sites comparing two different vegetation types: shrubs and forests. The deposition data were collected using ion exchange resin (IER) collectors and chemical extraction methods were used to measure the (N) collected in through- fall. Through-fall is the process of rain penetrating through the canopy of the plant to the soil surface. Every 3 months IER collectors were swapped out and replaced and leaf area index was measured. Meteorological data was collected and used from San Pasqual Valley, which is located approximately 25 km east of the study area. The seasonal variation in (NH4) and (NO3) through-fall as a function of site, vegetation type, and time were analyzed using repeated- measures ANOVA. Our null hypothesis was that (N) deposition would not be positively correlated with elevation and leaf area index. Our results indicated that through-fall (N) was significantly higher for trees than shrubs, and TIN (TIN= NH4+NO3) and (NH4) was positively correlated with elevation for trees but not shrubs. throughfall was approximately 2 times higher than (NO3) through-fall in tree canopies and almost 5 times higher than (NO3) through-fall in shrub canopies. Our data results indicated that large variations in the amount and type of (NH4 or NO3) of (N) through-fall over very small spatial scales were dependent on vegetation growth. These large variations increase the uncertainty of (N) deposition estimates from experimental measurements of (N) through-fall. These large differences were unexpected and suggest that spatial variations in N deposition are large in Southern California. Monitoring and understanding these patterns is crucial for ongoing research monitoring of N deposition as well as understanding potential environmental effects of increased N deposition locally and globally.