Land-use change effects on protozoic silicon pools in the Dajiuhu National Wetland Park, China

Many peatlands have been damaged by human activities like Sphagnum harvesting and draining reflected in reduced peatland areas and ecosystem functioning. Peatlands generally play an important role in global silicon (Si) cycling and maintain huge numbers of testate amoebae (TA). However, there is a lack of knowledge on (i) the quantity of protozoic Si pools (represented by siliceous shells of TA) in peatlands and (ii) how these pools respond to land use changes caused by human influence. In our study, we quantified protozoic Si pools in the Dajiuhu National Wetland Park, China, with a focus on the comparison between peatland and cropland areas (i.e., former peatland drained for agriculture). We found protozoic Si pools to (i) represent an important biogenic silica fraction in peatlands and (ii) significantly differ between peatlands and croplands with soil moisture as a key factor for protozoic Si pool quantity showing a significant decrease of these pools in drained areas (i.e., in croplands). From our results we concluded the decrease of protozoic Si pools due to land-use change to represent another example (apart from the loss of phytogenic Si) for anthropogenic desilication in agricultural biogeosystems in general.