Pocket gopher (Thomomys talpoides) soil disturbance peaks at mid-elevation and is associated with air temperature, forb cover, and plant diversity

Abstract

Burrowing mammals can be ecosystem engineers by increasing soil aeration and erosion and altering the structure of plant communities. Studies that characterize the constraints on the distributions of fossorial mammal disturbances to soil can help predict changes in ecosystem engineering under future climates. We quantified the density of soil disturbances caused by Thomomys talpoides (northern pocket gopher) over replicate elevation gradients spanning 2,700-4,000 m a.s.l. in the Upper Gunnison Basin, Colorado, USA. As a conceptual framework for predicting biogeographic variation in soil disturbance, we used the abundant center hypothesis (ACH), which proposes that species abundance declines monotonically away from the most abundant location in its distribution, with the assumption that ecosystem engineering scales with gopher abundance. We also evaluated the relative importance of abiotic and biotic variables as correlates of soil disturbance. Gopher disturbance peaked at mid elevations (~3,150 m), supporting the ACH. The best model for predicting gopher-caused soil disturbance contained both abiotic and biotic variables, with increased soil disturbance where mean annual temperature, forb cover, and plant diversity were greatest. Results suggest that mountain ecosystems may experience increases in gopher-caused soil disturbance as climate warms, possibly accompanied by increases in plant diversity and forb cover.

Altitudinal gradients fail to predict fungal symbiont responses to warming

“…Using model selection procedures as defined by Burnham and Anderson (), we built equations to predict climate variables from elevation, slope, and aspect, and then interpolated climate for each collection site (Lynn et al. ).…”

“…To examine whether climate variables predicted fungal distributions, we aggregated climate data from regional weather stations (Appendix S3: Table S4), including mean cumulative growing degree days (GDD, a measure of temperature combined with growing season length; Frank and Hofmann 1989), mean annual precipitation (MAP), which included both rain and snow, and mean snow depth (MSD). Using model selection procedures as defined by Burnham and Anderson (2002), we built equations to predict climate variables from elevation, slope, and aspect, and then interpolated climate for each collection site (Lynn et al 2018).…”

Context‐dependent biotic interactions control plant abundance across altitudinal environmental gradients

“…We also collected and pooled soil from the four transect ends to measure soil pH (Hanna Instruments HI 9813-6 Portable; Woonsocket, RI, USA). We used regional meteorological stations to interpolate climate data for each study site based on its elevation, slope and aspect (methods in Lynn et al 2018). Only mean annual temperature (MAT) was used in analyses due to high collinearity among climate variables.…”

“…Similar community weighted means were applied to arbuscular mycorrhizal fungi (AMF) colonization of roots, following Ranelli et al (2015). Gopher disturbance was assessed using methods of Lynn et al (2018).…”

“…Surprisingly, F. brachyphylla increased more with gopher disturbance in warmer sites than in cooler sites. Given that competition tends to increase in warm relative to cool sites in mountain ecosystems (Alexander et al 2015), greater gopher disturbance towards the warm end of F. brachyphylla's range, where gopher disturbance is highest (Lynn et al 2018), may suppress competitors and allow F. brachyphylla to persist in communities where it would otherwise be excluded (Grime 1973a, b, Huston 2014.…”