Germination and seedling establishment of two annual grasses on lichen-dominated biological soil crusts

Abstract

Biological soil crusts dominated by lichens are common components of shrub-steppe ecosystems in northwestern US. We conducted growth chamber experiments to investigate the effects of these crusts on seed germination and initial seedling establishment of two annual grasses; the highly invasive exotic Bromus tectorum L. and the native Vulpia microstachys Nutt. We recorded germination time courses on bare soil and two types of biological soil crusts; one composed predominantly of the lichen Diploschistes muscorum (Scop.) R. Sant. (lichen crust) and the other comprised of an assortment of lichens and mosses (mixed crust). Final germination on the lichen crust for both grass species was about a third of that on the bare soil surface. Mean germination time (MGT) was 3-4 days longer on the lichen crust compared with the bare soil. In contrast, there was no difference in germination percentage or MGT between the mixed crust and bare soil, and results were similar for both grass species. For both species, root penetration of germinating seeds on the lichen crust was lower than on the bare soil or mixed crust surfaces. The combined effects of the lichen crust on germination and root penetration resulted in an overall reduction in seedling establishment of 78% for V. microstachys and 85% for B. tectorum relative to the bare soil treatment. Our results clearly demonstrate that lichen-dominated biological soil crust can inhibit germination and root penetration, but the extent of these effects depends on the composition of the crust.

Impacts of warming and changes in precipitation frequency on the regeneration of two Acer species

“…To clarify the relevance and role of all these aspects and to unravel the effect of temperature and watering frequency, more experiments using different methods can be performed employing, for example, growth chambers (e.g. Deines et al, 2007;De Frenne et al, 2012). In addition, A. pseudoplatanus also showed provenance-specific responses to increases in temperature.…”

“…We analyze the impacts of warming and changes in precipitation frequency (as simulated by various watering intervals) on germination and early establishment of these two Acer species from different European provenances. A variety of techniques are available to study the effects of climate change on plant species including soil heating cables, open top chambers, growth chambers, and natural climatic gradients such as those across latitudes or elevations (Carón et al, 2015;De Frenne et al, 2013;Deines et al, 2007;Dunnett and Grime, 1999). The technique selected in each case depends on several factors including the life cycle phase that is being investigated.…”

Effect of biological soil crusts on the germination of three plant species under laboratory conditions

“…Due to the effects of microtopography, and water and nutrients fl uxes, BSC affect the distribution of resources in the soil, contributing to vegetation cluster patterns MARISELA PANDO-MORENO ET AL. (Deines et al, 2007) and probably improve water infi ltration and retention in the soil (Casenave and Valentin, 1989;Montaña et al, 1995;Rosentreter and Belnap, 2001;ReyesGómez et al, 2007;Yair, 2008;Chamizo et al, 2010).…”

“…Studies have shown BSC having either facilitative, inhibitory or no effect on vascular plant establishment and cover (During and Van Tooren, 1990;Belnap et al, 2001). Existing evidence suggests that the effects of crusts on seed germination vary depending on the soil crust composition and plant characteristics (Lesica and Shelly, 1992;Zaady et al, 1997;Prasse and Bornkamm, 2000;Rivera-Aguilar et al, 2005;Serpe et al, 2006;Deines et al, 2007), as seeds vary in their germination requirements and consequently may respond differently to the conditions created by the crust (Baskin and Baskin, 1998). Positive effects of the crust on vascular plants may be the result of improved soil moisture conditions and nutrient availability, as well as a decrease in predation (During and Van Tooren, 1990;Belnap and Harper, 1995).…”

“…germinated on a cyanobacteria crust and on bare soil. Deines et al (2007) compared germination of two grass species (Bromus tectorum L. and Vulpia microstachys (Nutt.) Benth.)…”