VARIABILITY IN MICROCLIMATE AND CARBON DYNAMICS IN HARDWOOD FORESTS MANAGED WITH THE IRREGULAR SHELTERWOOD REPRODUCTION METHOD

How do forest edges compare to intact interior forests in terms of carbon dynamics, and how is the microclimate altered through the creation of forest edges? Woody plants and trees can act as a carbon sink by using live and dead tissue to store varying amounts of carbon. However, factors such as age, species, respiration rates, and death alter the amount of carbon sequestered by the forest (Gorte, 2009). Additionally, widespread forest fragmentation has resulted in 20% of forests worldwide being located within 100 meters (m) of a forest edge (Haddad et al., 2015). Despite this fragmentation, current carbon models consider forests to be intact and therefore neglect edge effects (Reinmann & Hutyra, 2016), potentially increasing the amount of error in models of current carbon sequestration in our forests (Chaplin-Kramer et al., 2015). However, there are few studies to date on the effects of forest edges on carbon sequestration, and those that exist have produced conflicting results, which may indicate that results are sensitive to particular ecosystems or regions (Meeussen et al., 2021).

In this research, we investigated differences in carbon sequestration and depth of edge effects by studying microclimate variables, growth, and decomposition along a transect implemented within subtropical study sites receiving the irregular shelterwood reproduction method. Across transects, photosynthetically active radiation (PAR) was found to be altered for up to 15 m in either direction from a physical edge. Air and soil temperature appeared to be altered for approximately 20 m into uncut forests. However, determining depth of edge effects for additional microclimate variables, growth, and decomposition was more difficult. This may have occurred due to the small size of implemented gaps or natural canopy gaps within the uncut forests. Furthermore, nominal differences in carbon storage (C) on north and south facing edges indicate that edge aspect may have impacted amounts of C stored. Differences in microclimate variables and C observed across small distances suggest that small scale changes in silvicultural practices could have a greater than expected impact on net carbon sequestration and storage when implemented at larger scales.