Impacts of emerald ash borer-induced tree mortality on leaf litter arthropods and exotic earthworms

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

“…Activity-abundance of ground beetles initially was lower in canopy gaps, but these effects were ephemeral, suggesting some degree of resilience to small-scale canopy gaps [53,89]. During late stages of ash mortality, higher densities of ground-dwelling invertebrates were observed near ash CWD, including earthworms, spiders, harvestmen, isopods, millipedes, beetles, and springtails [78]. Further investigation revealed increased activity-abundance, evenness, and diversity of invertebrates near recently fallen than more decayed ash CWD [90].…”

“…The speed, synchrony, and specificity of ash mortality differs from gap-phase dynamics caused by other forest insects. EAB-induced ash mortality increases both the frequency of canopy gaps as ash trees die ( Figure 1A) and the accumulation of ash CWD as trees fall ( Figure 1B) [78,89]. Our model predicts that this pattern of tree mortality has an inverse temporal relationship in the effect sizes of canopy gaps and accumulation of ash CWD on ground-dwelling invertebrate communities (Table 1), as the effects of canopy gaps diminish with canopy closure, while the effects of ash CWD are predicted to increase and change over time as trees fall and decompose [60].…”

“…Gaps are presumably at their maximum size soon after tree death, and gaps created by EAB-induced tree mortality averaged 18.8% (±1.8) to 26.5% (±2.0) canopy openness [53,89]. Growth from understory and canopy trees closed the gaps, decreasing their canopy openness to 1-10% during late stages of ash mortality [78,90].…”

“…Canopy gaps consistently influence the structure of invertebrate communities [53,60,74,75], as do the presence and amount of CWD [76][77][78][79], suggesting that both are key structural features in forests. Formation of canopy gaps and accumulation of CWD may have interacting effects on ground-dwelling invertebrate communities due to their differing impacts on the forest floor environment.…”

Effects of Small-Scale Dead Wood Additions on Beetles in Southeastern U.S. Pine Forests

“…Many non-saproxylic ground-dwelling arthropods benefit from dead wood as well. For instance, a number of studies have shown litter-dwelling arthropods and other invertebrates to be more numerous immediately next to dead wood than short distances away from it [5][6][7][8][9][10][11][12][13][14][15][16][17]. These results can be attributed variously to dead wood providing a relatively stable source of moisture [18][19][20], shelter from predators or adverse weather conditions, and an abundance of prey or other food items.…”