Invertebrate community response to coarse woody debris removal for bioenergy production from intensively managed forests

Abstract

Abstract. Increased market viability of harvest residues as forest bioenergy feedstock may escalate removal of coarse woody debris in managed forests. Meanwhile, many forest invertebrates use coarse woody debris for cover, food, and reproduction. Few studies have explicitly addressed effects of operational-scale woody biomass harvesting on invertebrates following clearcutting. Therefore, we measured invertebrate community response to large-scale harvest residue removal and micro-site manipulations of harvest residue availability in recently clearcut, intensively managed loblolly pine (Pinus taeda) forests in North Carolina (NC; n = 4) and Georgia (GA; n = 4), USA. We captured 39,794 surface-active invertebrates representing 171 taxonomic groups using pitfall traps situated among micro-site locations (i.e., purposefully retained piles of hardwood stems and piles of conifer stems and areas without coarse woody debris in NC; windrows and no windrows in GA). Micro-site locations were located within six, large-scale treatments (7.16-14.3 ha) in clearcuts. Large-scale treatments represented intensive harvest residue removal, 15% and 30% harvest residue retention, and no harvest residue removal. In NC, ground beetles (Coleoptera: Carabidae) and crickets (Orthoptera: Gryllidae) were three times more abundant in treatments with no harvest residue removal than those with the most intensive harvest residue removal and were reduced in treatments that retained 15% or 30% of harvest residues, although not significantly. Invertebrate taxa richness was greater at micro-site locations with retained hardwood and pine (Pinus spp.) harvest residues than those with minimal amounts of coarse woody debris. In both states, relative abundances of several invertebrate taxa, including cave crickets (Orthoptera: Rhaphidophoridae), fungus gnats (Diptera: Mycetophilidae and Sciaridae), millipedes (Diplopoda), and wood roaches (Blattodea: Ectobiidae), were greater at micro-site locations with retained harvest residues than those with minimal coarse woody debris. Intensified woody biomass harvesting without retention of ≥15% of harvest residue volume may reduce invertebrate taxa richness and abundances of some key invertebrate taxa in regenerating stands. Further, harvest residue management during and after woody biomass harvesting may be an important consideration for maintaining invertebrate diversity and conserving invertebrates that are influential in the maintenance of ecosystem function and integrity in young forests.

Effects of Post-Fire Deadwood Management on Soil Macroarthropod Communities

“…Overall, the abundance of individuals and the number of orders were lowest in the salvage logging treatment, and communities differed between treatments. Similar results have been obtained in previous studies [39,[73][74][75], showing a reduction in the abundance of several invertebrate groups following the large-scale implementation of wood and litter removal treatments (though note that our study did not include an unmanaged control treatment). In fact, the common practice of salvage logging can affect many different groups of organisms, particularly those dependent on dead wood, in a consistent way, as shown by a recent global meta-analysis [25].…”

Ground Beetle (Coleoptera: Carabidae) Response to Harvest Residue Retention: Implications for Sustainable Forest Bioenergy Production

“…Coarse woody debris is a critical component of forest ecosystems that acts as a carbon sink, retains nutrients, and influences water dynamics [6,7]. Coarse woody debris also may be used by a variety of wildlife for food and cover, including birds [8,9], small mammals [10,11], amphibians [12,13], and especially invertebrates [14][15][16][17]. For example, invertebrates use coarse woody debris for refugia, foraging, oviposition sites, and, in the case of saproxylic insects, food [18,19].…”

“…Management of coarse woody debris may play a pivotal role in conservation of invertebrates in forested ecosystems [16,17,20,21]. While relationships between saproxylic insects and coarse woody debris have been extensively studied (e.g., [22,23]), research on facultative interactions between epigaeic invertebrates and coarse woody debris historically has been lacking and has yielded mixed results [18].…”

Wildflower plantings harbor increased arthropod richness and abundance within agricultural areas in Florida (USA)

“…Indeed, analyzing traps separately can result in conflicting results (Blaauw and Isaacs 2015). We set the cutoff for inclusion of individual invertebrate taxon in analyses at the break between abundant and rare invertebrate groups, thereby excluding all rare bees and other invertebrates with relatively low relative abundances from analyses (Grodsky et al 2018a, b). For example, the cutoff between abundant and rare invertebrates in treatments was n = 107 because counts of invertebrate captures dropped from n = 107 to n ≤ 71 at that point on the plot.…”

“…We plotted number of captures of all captured invertebrate taxa from all sampling techniques (sweep netting, pitfalls, and pan traps) and visually binned them into one of the following three abundance levels: (1) superabundant; (2) abundant; and (3) rare (Grodsky et al. , b). We pooled invertebrates among sampling techniques because we were interested in the overall invertebrate community response to wildflower plantings and not individual sampling technique efficacy.…”