Myxomycete colonization on translocated and non-translocated dead leaves from temperate and tropical forests

Samples of dead leaves on the forest floor were collected from a locality in central Costa Rica and another locality in northwest Arkansas in the United States and then were placed in fine-mesh nylon bags,autoclaved and left out in the field for four months.Half of the bags prepared with sterile material from each country were placed out in the country where they were collected,and the other half were placed in the other country.A characterization of forest structure and ground leaf chemistry was carried out for both localities and both leaf types.When recollected,all samples were processed for myxomycetes with the use of the moist chamber culture technique.The cultures yielded a total of 156 records of myxomycetes representing 16 species,but only 13 records and six species were isolated from the samples left out in Costa Rica.One hundred percent of cultures placed out in Arkansas produced myxomycetes,whereas only 68%of those placed out in Costa Rica were positive for these organisms.Differences in species richness and number of records were observed across forests where the samples were placed out,and no differences were observed based on the origin of the leaves.Results suggested that myxomycete colonization in the studied areas is primarily affected by the dynamics of the forest type and secondarily by substrate attributes.Some myxomycete species recorded on leaves with poorer chemical values are also consistent with field data.In the present study,the more open character of the temperate forest in Arkansas without a film of water layer covering the leaves on the ground seemed to have played a role in the establishment of myxomycete propagules in the sterile material during the time of the investigation.

Effect of forest disturbance on myxomycete assemblages in the southwestern Peruvian Amazon

Although the effects of microenvironmental factors on distribution patterns in myxomycetes have been investigated,studies of the responses of this group of organisms to different regimes of forest disturbance are relatively few in number.In an effort to understand the implications of forest fragmentation and habitat loss on myxomycetes,the project described herein was carried out at the Los Amigos Biological Station in southeastern Peru.The structure and composition of assemblages of myxomycetes were investigated in relation to three different forest types and climatic periods in the area of study.An analysis of the most commonly recorded substrates was carried out as well.The results suggested that habitat loss,through differences in forest structure,was the factor determining most of the differences in fruiting body abundance of myxomycetes among forest types.In addition,a switch in the ecological strategy of dispersal seemed to be an important factor accounting for differences in the fruiting body abundance and structure of assemblages of myxomycetes between collecting periods.This study provides evidence indicating that for microbial assemblages to maintain the balance of functional interactions within a particular forest ecosystem,the conservation of the forests themselves should be considered.

Myxomycetes associated with grasslands of the western central United States

The assemblages of myxomycetes associated with the three types of temperate grasslands(tall grass,mixed grass and short grass)found across the western central United States were examined by collecting samples for isolation of these organisms from nine study sites.Samples consisted of two types of ground litter,two types of aerial litter(dead but still attached plant parts)and dung.These were brought back to the laboratory and used to prepare a series of moist chamber cultures.These cultures yielded 1,301 collections of myxomycetes representing 59 species in 18 genera.Some collections could be identified only to genus and one in particular(Lepidoderma sp.)appears to be an undescribed taxon.Physarum spectabile was recorded for the first time in North America.Overall,only eight species(Badhamia melanospora,Didymium anellus,D.difforme,D.squamulosum,Perichaena depressa,Physarum cinereum,P.pusillum,and Stemonitis fusca)were recovered from all nine study sites and thus are considered to represent a core component of the myxomycete biota of temperate grasslands.