Arthropods, flooding, and wood decay

Background/Question/Methods

This study sought to determine how termites and other wood-feeding arthropods contribute to wood decay and how these contributions are affected by seasonal flooding. Twenty transects were established, evenly divided between flooded and unflooded hardwood/pine forests in Mississippi, USA. Two hundred 0.5 m loblolly pine logs were cut from freshly felled trees. One caged log (i.e., to exclude all arthropods) and one uncaged log were placed at five locations in each transect. After 6, 12 and 18 months, wood specific gravity was compared between caged and uncaged logs and between flooded and unflooded forests. In addition, 12 wooden stakes were driven into the ground in each transect to monitor termite activity. The stakes were collected after 3, 6 or 12 months to compare termite presence or absence between flooded and unflooded forests.

Results/Conclusions

After 18 months of sampling, wood specific gravity was lower in unflooded forests than in flooded forests (P<0.001) and for uncaged logs compared to caged logs (P<0.1). As the rate at which termites attacked the monitoring stakes was about five times higher in unflooded forests than in flooded forests, flooding appeared to substantially reduce termite activity. There was no interaction between forest type and treatment (i.e., caged vs. uncaged), however, suggesting that differences in termite activity between forest types may have little influence on decay rates, at least within the time frame studied thus far.