Despite the large body of theory concerning multiple disturbances, there have been relatively few attempts to test the theoretical assumptions of how and if disturbances interact. Of particular importance is whether disturbance events are linked, as this can influence the probability and intensity of ecological change. Disturbances are linked when one disturbance event increases or decreases the likelihood or extent of another. To this end, we used two long-term, multi-disturbance experiments in northern Wisconsin to determine whether earthworm invasion is linked to canopy gap creation and white-tailed deer browsing. These three disturbances are common and influential within North American temperate forests, making any interactions among them particularly important to understand. We expected both deer and canopy gaps to favor invasive earthworms, particularly species that live close to or on the soil surface. However, we found only partial support for our hypotheses, as both deer exclosures and canopy gaps decreased earthworms in each experiment. Further, earthworm density increased the most over time in areas far from the gap center and in areas with deer present. Deer exclosures primarily decreased Aporrectodea and Lumbricus species, while gaps decreased Dendrobaena and Lumbricus species. Our findings show that earthworm invasion is linked to deer presence and gap-creating disturbances, which provides new insight toward multiple disturbance theory, aboveground-belowground dynamics, and temperate forest management.

Managed Old Growth Silviculture Study (MOSS) - The MOSS experiment has several harvest-created canopy gap treatments across the three replicate sites that were established in the winter of 2007 and 2008. We used the “Large Gaps” treatment, which consists of 16, 24-m diameter canopy gaps within a 48-ha stand, and the "control" which is just an unharvested stand. One gap could not be found at ARGN, leading to a total count of 47 gaps. Each gap had a small deer exclosure beneath it. We collected invasive earthworms inside and outside of deer exclosures that were either under a canopy gap or under a closed canopy. 

Flambeau Experiment (The FE) - Similar to MOSS, the Flambeau experiment also manipulates canopy gaps and deer exclosures. We used ten 22-m canopy gaps, five of which were unfenced and five of which had deer exclosures around the entirety of the gap. Gaps were established in January 2007 and fencing was established in the fall of 2007. We sampled earthworms along a north-south transect through the fenced or unfenced gap. Earthworms were also sampled in 2006 within this experiment, prior to disturbance treatment, and then again in 2019, thirteen years after disturbance treatments. 

Data Processing - All earthworms were taken back to the lab, measured, and identified to species. Each worm's biomass was estimated using allometric equations from Hale et al. (2004). Earthworms were binned by the most common genera and scale to a m² basis for figure creation. More detail can be found in the corresponding manuscript.

Data - Data represents the earthworm biomass and density across both experiments. In addition, genera-specific earthworm data is provided.

Reedetal2023_AnalysisScript.R for all analyses done in the corresponding publication

Reedetal2023_FigureScript.R to recreate all figures and tables in the corresponding