Germination and seed water status of four grasses on moss-dominated biological soil crusts from arid lands

Abstract

Biological soil crusts dominated by drought-tolerant mosses are commonly found through arid and semiarid steppe communities of the northern Great Basin of North America. We conducted growth chamber experiments to investigate the effects of these crusts on the germination of four grasses: Festuca idahoensis, Festuca ovina, Elymus wawawaiensis and Bromus tectorum. For each of these species, we recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the tall moss Tortula ruralis and the other dominated by the short moss Bryum argenteum. On the short-moss crust, the final germination percentage was about half of that on bare soil. Also, the mean germination time was 4 days longer on short-mosses than on bare soil. In contrast to the shortmoss crust, the tall-moss crust did not reduce the final germination percentage but increased the mean germination time. Similar results were observed in the four grasses studied. To investigate the mechanism by which moss crusts affected germination, we analyzed the water status of seeds on bare soil and moss crusts. Six days after seeding, the water content of seeds on bare soil was approximately twice that of seeds on tall-or short-moss crust. Analysis of the time course of changes in seed weight and water potential in Bromus tectorum revealed that overtime seeds on tall mosses reached higher water content than those on short mosses. The increase in the water content of seeds on tall mosses occurred as the seeds gradually fell through the moss canopy. Taken together, our results indicate that biological soil crusts with distinct structural characteristics can have different effects on seed germination. Furthermore, this study revealed that a biological soil crust dominated by short mosses had a negative effect on seed water status and significantly reduced seed germination.

Alterations to biological soil crusts with alpine meadow retrogressive succession affect seeds germination of three plant species

“…This variation may be related to moss height, because if the moss grows high, surface seeds will not make contact with the soil, and moisture levels will be insufficient for germination. However in another study, Serpe et al (2006) observed that a biological soil crust dominated by short moss significantly inhibited germination of cheatgrass and three perennial grasses, while tall moss crust had little effect on germination, which is not in accordance with our results.…”

Biological Soil Crust effects and responses in arid ecosystems: recent advances at the species level

“…De esta manera, la presencia de la CBS facilita o limita la germinación de semillas, según la especie de CBS y de planta (Serpe et al 2006;Escudero et al 2007;Langhans et al 2009). Finalmente, la CBS interacciona con otros microorganismos y microfauna del suelo, ya que les proporciona recursos y un hábitat potencial (Neher et al 2003;Bamforth 2004;Castillo-Monroy et al 2011b).…”

Importance of soil and plant community disturbance for establishment of Bromus tectorum in the Intermountain West, USA

“…We did not examine BSC coverage in this study but lichen, moss, and cyanobacterial crusts were present and our soil surface disturbance removed these BSC. Lichen crusts can reduce the abundance of B. tectorum by 85% possibly through reducing germination percentage or inhibiting root penetration of soil (Serpe et al 2006, Deines et al 2007). Disruption of BSC was likely more important than litter presence in hindering B. tectorum establishment in this study although the interaction of BSC removal and litter presence is largely unexplored.…”