Coarse woody debris stores 8% of the global carbon stocks and releases it to the atmosphere through decomposition. Climate change increases global temperatures, and thus might increase the activity of bacteria, fungi, and insects. Forest restoration can enhance the recovery of dead wood and associated insect communities, but its effects on dead wood decomposition in tropical regions are unknown.
Objectives and Hypotheses
Our objective was to evaluate the role of insect colonization and forest restoration on dead wood decomposition. We first hypothesized that dead logs colonized by insects would decompose faster than dead logs not colonized by insects. Second, we hypothesized that dead logs would decompose faster in natural regeneration, because natural regeneration sites had a more open canopy and likely had higher temperatures that should increase decomposer activity.
We introduced freshly cut logs of Inga edulis (N = 180 total, 30 per treatment combination), into three restoration treatments: natural regeneration, restoration plantations, and old-growth forests. Within each of these restoration treatments, we further assigned logs to one of three exclusion treatment: logs inside exclusions, logs inside exclusions with holes drilled in them to mimic physical damage by insects, and control logs without exclusions. We collected the logs after one year, extracted arthropods using modified Berlese funnels, and counted and identified all arthropods. We then estimated the proportion of log mass loss.
Decomposer arthropod abundance was higher in logs inside exclusions with holes in restoration plantations only and was significantly affected by log treatment (X2 = 18.2, p Implications and conclusions
Our results suggest that fungi and bacteria are responsible for the average 38% mass loss seen in this experiment for Inga edulis during the first year of decomposition. We also show that the conditions in natural regeneration do allow slightly faster decomposition than in restoration plantations and reference forest. Our study demonstrates that even though natural regeneration can contain less dead wood, it can fulfill the same functions as plantations in terms of dead wood decomposition and small arthropod communities.
dead wood, decomposition, arthropods, tropical forest restoration,