标题：Changes in the decomposition process associated with the invasion of Gleditsia triacanthos (honey locust) in pampean streams (Buenos Aires, Argentina)
摘要：Pampean streams are characterized by herbaceous riparian vegetation and a great abundance of primary producers. In the past decades, the banks of many water courses in the Pampa Ondulada (Buenos Aires, Argentina) have been invaded by Gleditsia triacanthos. Therefore, the original herbaceous vegetation has been replaced by trees, leading to possible consequences in the functioning of the system. We compared the rate of litter breakdown and the structure of the communities of zoosporic true fungi and heterotrophic straminipiles associated with the litter in sites invaded and not invaded by G. triacanthos. Litter bags with two different mesh sizes were placed at three invaded and three non-invaded sites in three streams. In the invaded sites, leaves in the bags with larger mesh size decomposed at a faster rate than those in non-invaded sites, but the community structure and species composition of zoosporic true fungi and heterotrophic straminipiles did not differ. In addition, some variables related to the particulate material were significantly different between invaded and non-invaded sites. In non-invaded sites, where fine sediments were abundant, leaf burial may have played an important role by diminishing the fragmentation of the leaves or changing the environmental conditions for detritivorous invertebrates, thus determining the slow breakdown rates observed in the non-invaded sites.
关键词：decomposition; streams; invasion of honey locust; zoosporic fungi; heterotrophic straminipiles
