Food Supply Early in the Plant Growing Season: Influences from Elk Abundance and Precipitation
Date
2020-05
Authors
Williamson, Lee H.
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Abstract
Large herbivores interact with plant communities via grazing and trampling, and
the response of plant communities to these disturbances is influenced by available
moisture. Whether herbivore disturbances and available moisture influence biomass of
plant communities additively or multiplicatively, however, can vary based on the
temporal and spatial scale at which these factors are observed. Examining these
relationships is needed to understand the dynamics of plant and herbivore populations.
Early in the plant growing season, many plants put most of their energy goes towards
above ground growth, and herbivore disturbances can accelerate this growth given
adequate soil moisture. The relationship between these factors can also vary spatially as
conditions for plant growth differ. I measured the entire food supply for a non-migratory
population of elk (Cervus elaphus) in a temperate rainforest over a 15-year period when
population abundance and total precipitation varied. The food supply was a 50-hectare
meadow complex that was divided into 7 sectors, 2-10 hectares in size. I compared linear
mixed effect models using Aikaike Information Criterion to determine whether elk
abundance and total precipitation had an additive or multiplicative influence on the
herbivore food supply. The selected model included elk abundance and precipitation as
additive, not multiplicative, predictors of food supply. Also, the relationship between
food supply and precipitation varied across sectors. Forage biomass in some sectors
showed a positive asymptotic relationship with precipitation but in other sectors showed little increase with precipitation. Even in this temperate rainforest, elk herbivory
influenced meadow plant communities independently of precipitation.
Description
Keywords
Elk, Precipitation, Forage, Biomass
Citation
Williamson, L. H. (2020). <i>Food supply early in the plant growing season: Influences from elk abundance and precipitation</i> (Unpublished thesis). Texas State University, San Marcos, Texas.