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Structural change impacts on arthropod activity and heterotrophic respiration

Project Abstract: 
Soil heterotrophic respiration has largely been ignored as a source of carbon flux despite more carbon released per organism than soil-dwelling micro-organisms. Similarly, biotic responses to aboveground disturbance on below ground communities is poorly understood, despite its significance to ecosystem function. Soil properties such as soil chemistry, respiration, and decomposition are heavily influenced by bioturbating arthropods and microbe communities which maintain soil functionality in an ecosystem. Thus, understanding heterotrophic respiration and biotic responses of below-ground communities to large-scale forest disturbance can shape our understanding of ecosystem function. In this study, a large-scale forest disturbance experiment (FoRTE) alters canopy structure along a gradient, thus changing energy availability on the forest floor. The goal of this study is to characterize soil arthropod community’s response to a gradient of structural change in varying landscapes through arthropod biomass, activity, and community structure. In order to do this, pitfall traps will be placed in the center and 4 cardinal corners of each disturbance-severity plot for each landscape. Pitfall traps will be left out for 72 hours, collected, and identified for (at least) 3 sampling periods. Heterotrophic respiration associated with each plot and pitfall trap will be estimated from biomass and analyzed for implications within carbon cycling regimes.
Years Active: 
2024
Research sites: 
Methods: 
To build on the data collected from pitfall traps in 2023, the same approach to collect epigeal ground-dwelling arthropods will be used (Woodcock, 2005). Each FoRTE subplot will have 5 pitfall traps positioned at the North, South, East, West, and Center points of all 32 subplots. Individual 120mL polypropylene cups will be placed 10m apart, flush with the soil, and left to sit for 7 days to avoid digging in effects (Greenslade, 1973). Roughly 30mL of propylene glycol (recreational vehicle anti-freeze, Prestone ® LowTox Automotive Antifreeze/coolant) will be poured into the pitfall traps after the 12 day waiting period. Pitfall traps will be deployed 3 times, beginning in early June, once in mid July, and ending in late August (Lynch et al., 1988; Herbers 1985). Pitfall traps set will be left for 72 hours during a period of no rain. With ants being the targeted group for Rs analysis, I will sample soil respiration using a LiCor-6800 in 4 randomized locations with a 0.5m radius of each of three pitfall traps per subplot. The 0.5m radius establishes a 1m range wherein the majority of ants home range lies (Devigne and Detrain, 2006). The locations for the soil collar within the pitfall radius will be systematically randomized. All invertebrates collected from pitfall traps will be processed in the lab, where community composition and biomass will be measured.