干旱区生态环境知识资源中心

We describe the ecology of a highly specialized community of ravine myxomycetes from sandstone gorges of the Saxonian Switzerland region (near Dresden, Germany). Five taxa, Colladerma robustum, Diderma ochraceum, Lamproderma columbinum, L. puncticulatum agg. and Lepidoderma tigrinum, account for 87% of all records. Colloderma robustum and Diderma lucidum are new records for Germany; Diderma ochraceum was known from a few collections only. A total of 127 small-scale vegetation releves showed that the community occurs only in deep and narrow ravines (mean horizon openness 4.9%) on nearly vertical rocks (mean inclination 79 degrees), and preferentially in northern exposition (42% of all releves). Substrate pH is very acidic (mean 3.35). At the fructification time of the myxomycetes (beginning of October) the microclimate is very constant with temperatures around 10 C and nearly 100% relative humidity around the day. Beside green algae (associated with 100% of all myxomycete records, most common was Coccomyxa confluens (Kutz.) Fott s.l.) the bryophytes Mylia taylorii (64%), Dicranodontium denudatum (59%), Tetraphis pellucida (50%) and Diplophyllum albicans (40%) were of high indicator value for this community. Low values for niche width of the five more common myxomycete species reflect the high degree of specialization for the community as a whole, whereas niche overlap between species is high. Low values for the Cole index of association can be interpreted as competition between species or, more likely, reflect the relative rarity of fruiting colonies.