Effects of biological soil crusts and drought on emergence and survival of a Patagonian perennial grass in the Monte of Argentina

Abstract

Biological soil crusts are widely distributed in arid and semiarid regions. They have an important ecological role, especially by modifying physical and chemical properties of soils. Biological crusts may also modify seed germination and seedling establishment. The effects vary widely according to the type of crust and the vascular plant species. The objective of this study was to determine the effect of moss-dominated biological soil crusts on the emergence, biomass and survival of Poa ligularis Nees ex Steud. under different irrigation regimes. We collected seeds of P. ligularis and biological soil crusts composed of two species of mosses: Syntrichia princeps (De Not.) Mitt and Ceratodon purpureus (Hedw.) Brid. from an area in the Monte of Argentina. The result showed that seedling emergence of P. ligularis was higher in treatments with bare soil than in soil covered by crusts, and also in those with watering to field capacity. Mean emergence time was higher in treatments with bare soil and watering to field capacity. Seedling biomass also showed significant differences between treatments. These results suggest that biological soil crusts dominated by mosses do not promote P. ligularis emergence, although they would not affect its survival.

Seed rain alteration related to fire and grazing history in a semiarid shrubland

“…seed rain dramatically decreased under grazing, this could be because this disturbance has negative effects on the previously mentioned population attributes. This negative effect was notable in species with a low number of very dense panicles and seeds with a low dispersal capacity (O'Connor and Pickett, 1992;Pazos and Bertiller, 2007), as might be the case for these taxa (Funk et al, 2014). Our results showed that lower abundance of this taxon in the soil seed bank under grazing, as described by Morici et al (2006), might be due to its scarcity in the seed rain, in addition to the negative effects of cattle on the seed bank formation.…”

Biocrusts in the Context of Global Change

“…19 by Zhang et al). For example, it has been found that moss-dominated biocrusts lengthened the emergence time of the grass Poa ligularis under drought conditions, a response that was not observed when water availability did not limit seed germination (Funk et al 2014). Predicted changes to aridity (Feng and Fu 2013) could also significantly affect coupled C and nutrient cycling in drylands.…”

Divergence in physiological responses between cyanobacterial and lichen crusts to a gradient of simulated nitrogen deposition

“…The area of biocrusts can reach 70 % in some ecosystems (Evans and Johansen 1999). Development of biocrusts can stabilize sand surfaces (Hu et al 2002), change soil hydrological processes (Belnap 2006;Liu et al 2006), mediate plant growth and diversity (Funk et al 2014;Mendoza-Aguilar et al 2014;Pendleton et al 2003;Thiet et al 2014), and also fix N 2 (Abed et al 2010;Belnap 2002;Evans and Johansen 1999;Zhao et al 2014). Thus, biocrusts are dominant contributors to the stability of the structure and function of dry ecosystems.…”