Responses of Ground-Dwelling Invertebrates to Gap Formation and Accumulation of Woody Debris from Invasive Species, Wind, and Salvage Logging

Abstract

Natural and anthropogenic disturbances alter canopy structure, understory vegetation, amount of woody debris, and the litter and soil layers in forest ecosystems. These environmental changes impact forest communities, including ground-dwelling invertebrates that are key regulators of ecosystem processes. Variation in frequency, intensity, duration, and spatial scale of disturbances affect the magnitude of these environmental changes and how forest communities and ecosystems are impacted over time. We propose conceptual models that describe the dynamic temporal effects of disturbance caused by invasive insects, wind, and salvage logging on canopy gap formation and accumulation of coarse woody debris (CWD), and their impacts on ground-dwelling invertebrate communities. In the context of this framework, predictions are generated and their implications for ground-dwelling invertebrate communities are discussed.

Dynamic Responses of Ground-Dwelling Invertebrate Communities to Disturbance in Forest Ecosystems

“…For invasive insects, such as EAB, an inverse temporal relationship is predicted for the effect sizes of canopy gaps and accumulation of CWD on ground-dwelling invertebrate communities (Figure 1). As the effects of gaps diminish with canopy closure, the effects of CWD increase over time as trees fall [50,98,99]. These patterns have the potential to impact populations of ground-dwelling invertebrates in dynamic ways.…”

Ecological Impacts of Emerald Ash Borer in Forests at the Epicenter of the Invasion in North America

“…Widespread tree mortality caused by alien insects may also have indirect effects on invertebrate populations and communities [3]. Perry and Herms [76] proposed a model of dynamic temporal effects of disturbance caused by tree-killing invasive insects, including gap formation and accumulation of coarse woody debris (CWD) ( Figure 5), on ground-dwelling invertebrate populations and communities. The model predicts the magnitude of effects of gap formation and accumulation of CWD will transition over time in opposing ways as ash mortality in the stand progresses from early to late stages.…”

“…The formation of canopy gaps is predicted to have the greatest impact on ground-dwelling invertebrate diversity and abundance during early stages of ash mortality when gaps are presumably at their maximum size after tree death, with impacts diminishing over time as gaps close. Impacts of CWD, in contrast, are predicted to increase over time [76] as ash trees die, standing snags fall, and CWD accumulates and decomposes on the forest floor. For example, Higham et al [74] observed rapid accumulation of CWD across a chronosequence of ash mortality in Ohio, and in the Upper Huron River watershed, the number of fallen ash trees increased by 76% from 2008-2012, and volume of ash CWD increased by 53% [77].…”

Observations of reduced ET and persistent elevated water table beneath a riparian forest gap following emerald ash borer invasion and tree mortality

“…Coarse woody debris accumulates at varying scales and patterns as dead trees break and fall (Engelken et al, 2020; Klooster et al, 2018; Larson et al, 2023; Robertson et al, 2018; Telander et al, 2015). These interactions generate ecohydrological cascades that are challenging to quantify or predict but have the potential to fundamentally alter ecosystem services and function in affected forests (e.g., Flower et al, 2013; Lovett et al, 2004, 2006; Morin & Liebhold, 2015; Perry & Herms, 2017).…”