Data for linked disturbance in the temperate forest: earthworms, deer, and canopy gaps

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.