『Abstract
Prairie grasslands are very species rich but have declined in
their extent considerably due to land-use change and exploitation.
Many remaining prairie fragments are situated within an agricultural
matrix and can be subjected to high levels of atmospheric ammonia
deposition from animal units. Three prairie fragments in Minnesota
that were located in close proximity to feedlots were selected,
and 500-m transects were studied at an increasing distance from
the feedlot. Changes in soil pH, soil nitrate concentration, and
soil ammonium concentration with increasing distance from the
source were variable between the sites, possibly due to differences
in the processing of nitrogen in the soil and the degree of nitrogen
limitation. Species richness showed significant negative relationships
with ammonia deposition and soil nitrate concentration, whereas
aboveground biomass showed a positive relationship with ammonia
deposition. Both the richness and biomass of non-graminoid species
declined with increasing soil nitrate concentration, whereas graminoid
biomass was positively related to ammonia deposition and was negatively
associated to richness. Bromus inermis, a non-native perennial
grass, was the main species that increased at high deposition.
The results of this study have important implications for the
conservation and restoration of prairie grasslands.
Keywords: Ammonia; Soil biogeochemistry; Bromus inermis;
Nitrogen deposition; Prairie; Species richness』
1. Introduction
2. Methods
3. Results
3.1. Deposition
3.1.1. Soil chemistry
3.1.2. Plant species composition
4. Discussion
4.1. Soil chemistry
4.2. Species composition
Acknowledgements
References