Document Type

Article

Publication Date

2011

Abstract

Heavily grazed riparian areas are commonly subject to channel incision, a lower water table, and reduced vegetation. Riparian vegetation dissipates flow energy which is critical to maintaining stable channel geometry. Occurrences of prairie cord grass (Spartina pectinata) stands were used as evidence of improved riparian health during post best management practice (BMP) assessment within a watershed frequented by ephemeral gullies. Presence/absence of S. pectinata was recorded during 2010 assessments of ephemeral channels with drainage areas ranging from .54 to 692 hectares. Reach locations (n = 115) were delineated using 2010 National Agriculture Imagery Program (NAIP) imagery resulting in 8-39 sample points per reach subsequently used to extract Normalized Difference Vegetation Index (NDVI) values from a series of Satellite Pour l'Observation de la Terre (SPOT) satellite imagery. Normalized NDVI values from 1,981 sample points were determined from pre (1987, 1994, and 1997) and post-BMP (2010) imagery. Mean normalized NDVI values calculated for each reach ranged from -1.33 to 3.16. ANOVA revealed no mean difference in normalized NDVI among S. pectinata classes for pre-BMP years (P = 0.85, 0.74, 0.82), respectively. However, in 2010 (post-BMP), S. pectinata sites had significantly higher normalized NDVI (1.23) compared to non-S. pectinata sites (0.89) (P = 0.01). Reappearance of S. pectinata due to changes in grazing regimes along with construction of off-stream watering sources was successfully detected remotely. Establishment of S. pectinata provides habitat heterogeneity and functions in reducing flow energy which is responsible for the current state of severely incised channels.

Publication Title

Proceedings of the South Dakota Academy of Science

Volume

90

First Page

202

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