干旱区生态环境知识资源中心

We examined the dynamics of cryptogamic soil crusts in a derived (disclimax) grassland near Orange in south-eastern Australia. Changes in the cover of cryptogamic crusts and floristics and abundance of the constituent species were measured on four treatments with two levels each of grazing and cultivation. Twenty-two lichens, mosses and livenworts were found at the study site and, of these, 13 were collected in the quadrats. Three moss species (Barbula calycina, Eccremidium arcuatum and Bryum pachytheca) and one lichen species (Cladonia tessalata) accounted for 67% of total cover-abundance scores. Generally, cover-abundance was significantly higher in the unvegetated microsites than in the vegetated microsites. Species richness was not significantly different between the four grazing-cultivation treatments but, on average, there were significantly more species in the unvegetated microsites (mean = 3.2 species) than in the vegetated microsites (0.54 species). Grazing and cultivation resulted in significantly greater cover of bare ground and consequently significantly greater crust cover. Averaged across all treatments, approximately half of the area of unvegetated soil was occupied by cryptogams. Overall, the results indicate that lichens and bryophytes are important components of derived temperate grasslands, surviving in even densely vegetated swards. This study suggests that strategics which disturb the soil surface (e.g. grazing and cultivation) will stimulate the abundance and cover of soil crust organisms by increasing the availability of unvegetated microsites.