Aho (1998) hypothesized that pikas worked as ecosystem engineers by building relatively rich soils (via decomposing haypiles and fecal accumulations) in otherwise barren scree. Soils from twenty one paired on-haypile and off-haypile sites were gathered from Rendezvous Peak Grand Teton National Park to determine if the habitats differed in total soil nitrogen.
data(pika)A data frame with 22 observations on the following 2 variables.
Haypilea numeric vector
On.Off..Na numeric vector
Aho, K., Huntly N., Moen J., and T. Oksanen (1998) Pikas (Ochotona princeps: Lagomorpha) as allogenic engineers in an alpine ecosystem. Oecologia. 114 (3): 405-409.