Analysis of Ciliate Community Diversity in Decaying Pinus nigra Logs

Ciliates are an important component of the detritus and energy flow in forest ecosystems. The present study aims to provide an early insight into the abundance and composition of the ciliate community inhabiting deadwood in relation to the different decay classes. We took advantage of a mesocosm experiment of black pine deadwood already underway to evaluate changes in chemical properties, microbial communities, and potential CO2 emissions over time. The abundance and the number of ciliate taxa increased as wood decay progressed. Greater diversity was observed in the early stages of decomposition, while similarity in community composition increased along the decomposition gradient with several taxa commonly found in the more decomposed classes 3-5. The identified species were related to soil-inhabiting ciliates and mainly belonged to Colpodea and Spirotrichea classes. Ciliate abundance correlated positively with bacterial abundance, total nitrogen (N), and CO2 potential production, while it correlated negatively with the C/N ratio. Through grazing activity, ciliates contribute to regulate the degrading activity of microbial communities inhabiting deadwood and CO2 emission, enhancing soil fertility. Looking ahead, specific ciliate taxa may be used as indicators of the stage of decomposition and their biodiversity may provide knowledge into deadwood decay activity.