PARENT SESSION
Contributed Oral Session 33: Grassland and Shrubland Communities
Monday, August 8, 1:30 PM - 5:00 PM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal
Effects of fertilization and haying on grassland productivity, community properties and relationships to spectral reflectance.
Murphy, Cheryl*,1, Foster, Bryan1, Ramspott, Matthew2, Price, Kevin2, Kindscher, Kelly3, 1 University of Kansas, Lawrence, KS, USA2 University of Kansas, Lawrence, KS, USA3 University of Kansas, Lawrence, KS, USA
ABSTRACT- Managed grasslands composed of introduced C3 grasses now dominate large areas of eastern Kansas that were once occupied by native tall-grass prairie. In 2000 we established a long-term field experiment to evaluate the interactive effects of cool-season grassland management (fertilization and haying) on plant productivity, soil processes and plant community structure. In addition, we sought to evaluate the utility of the Normalized Difference Vegetation Index (NDVI), derived from aerially-acquired spectral reflectance data, in discriminating these treatment effects. In 2003 we found that vegetative production was increased significantly by fertilization, but to the greatest extent in hayed plots. In unfertilized field plots, haying had no impact on productivity, an indication that vegetative re-growth compensated for biomass removal. However, in fertilized plots, haying led to a significant increase in productivity, suggesting overcompensation for the loss of biomass. Plant diversity was significantly reduced by fertilization, but only in the absence of haying. NDVI varied significantly over the 2003 growing season, reflecting the typical spring and fall growth peaks of the dominate C3 grasses. NDVI also differed significantly among the experimental treatments, the extent to which depended upon the time of year that NDVI was measured. When integrating across the entire growing season, NDVI explained more than 90% of the among-plot variation in plant productivity and more than 50% of the among-plot variation in plant diversity. These preliminary findings suggest that: 1) fertilization and haying interact strongly to impact community and ecosystem attributes in these managed grasslands; and 2) remotely-sensed NDVI may be useful for evaluating and predicting these responses in the context of the broader agricultural landscape.
Key words: grassland, productivity, biodiversity, NDVI