Vegetation changes associated with a population irruption by Roosevelt elk

Ecology and Evolution
NPS
By: , and 

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Abstract

Interactions between large herbivores and their food supply are central to the study of population dynamics. We assessed temporal and spatial patterns in meadow plant biomass over a 23-year period for meadow complexes that were spatially linked to three distinct populations of Roosevelt elk (Cervus elaphus roosevelti) in northwestern California. Our objectives were to determine whether the plant community exhibited a tolerant or resistant response when elk population growth became irruptive. Plant biomass for the three meadow complexes inhabited by the elk populations was measured using Normalized Difference Vegetation Index (NDVI), which was derived from Landsat 5 Thematic Mapper imagery. Elk populations exhibited different patterns of growth through the time series, whereby one population underwent a complete four-stage irruptive growth pattern while the other two did not. Temporal changes in NDVI for the meadow complex used by the irruptive population suggested a decline in forage biomass during the end of the dry season and a temporal decline in spatial variation of NDVI at the peak of plant biomass in May. Conversely, no such patterns were detected in the meadow complexes inhabited by the nonirruptive populations. Our findings suggest that the meadow complex used by the irruptive elk population may have undergone changes in plant community composition favoring plants that were resistant to elk grazing.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Vegetation changes associated with a population irruption by Roosevelt elk
Series title Ecology and Evolution
DOI 10.1002/ece3.1327
Volume 5
Issue 1
Year Published 2015
Language English
Publisher Blackwell Pub. Ltd.
Publisher location Oxford
Contributing office(s) Western Ecological Research Center
Description 12 p.
First page 109
Last page 120
Online Only (Y/N) N
Additional Online Files (Y/N) N