[MCN] Big flood in Yellowstone-> surge of cottonwoods-> bison get it before elk

[Lance Olsen]

Ecohydrology   29 August 2016  Early View Online Version of Record 
published before inclusion in an issue

The influence of floods and herbivory on cottonwood establishment and 
growth in Yellowstone National Park
Joshua R. Rose,  J. Cooper


Abstract [Bold added]
http://onlinelibrary.wiley.com/doi/10.1002/eco.1768/full

Herbivory by ungulates can shape the structure and function of 
riparian forests. However, our understanding of the interactions 
between herbivores and cottonwoods (Populus spp.) is largely derived 
from studies of domestic livestock grazing and may not reflect free 
ranging herds of wild ungulates. In this study, we quantified the 
influence of stream hydrologic regime and herbivory by wild ungulates 
on cottonwood establishment and growth along three rivers in 
Yellowstone National Park's northern range.

Approximately 1.36 of the existing 1.37 million cottonwoods 
representing approximately 66% of the cottonwood stand area in 
Yellowstone's northern range was established between 1995 and 2008 by 
the largest flood sequence in recorded history. Coincidentally, the 
flood sequence began in the years immediately following wolf (Canis 
lupus) reintroduction to Yellowstone National Park. The flows caused 
large-scale channel changes and provided suitable habitat for 
cottonwood seedling establishment and survival. Over 92% of the 
cottonwoods occurred along the Lamar River, and recruitment along 
this river appears to follow infrequent large peak flows. Soda Butte 
Creek and the Gardner River cottonwoods exhibited nearly annual 
recruitment. The resulting cottonwood biomass from the flooding 
events has exceeded herbivore demand. Even at relatively low 
consumption rates, bison are able to remove a significant proportion 
of total cottonwood production in the study areas limiting plant 
height and forage available to wintering elk. We conclude that the 
large cottonwood recruitment event that began in the late 1990s was 
due to a rare series of large snowmelt-driven floods.

-- 
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"Mammals in the study region face an uncertain future. The negative 
impact of drought, the short-lived nature of post-drought recovery 
and, now, the possibility of a new drought beginning forewarn of 
further declines. The stark contrast between the optimal and current 
fire-age distributions means that reducing the incidence of further 
fires is critical to enhance the capacity of native mammal 
communities to weather an increasingly turbulent climate."

Susannah Hale et al. Fire and climatic extremes shape mammal 
distributions in a fire-prone landscape, Diversity and Distributions, 
Early View - Online Version of Record before inclusion in an issue. 
August 24, 2016  
http://onlinelibrary.wiley.com/doi/10.1111/ddi.12471/full




















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