Bryophyte Mats Inhibit Germination of Non-native Species in Burnt Temperate Native Grassland Remnants

Abstract

Species-rich native grasslands in western Victoria, Australia, are often small, have a high perimeter to area ratio and are surrounded by non-native species. Few non-native species, however, have invaded them. A feature of species-rich grasslands is the presence of a bryophyte mat (composed of mosses and liverworts) that carpets the intertussock spaces. I assessed the role of these mats in plant invasions by sowing three non-native species (Briza maxima, Hypochoeris radicata, Plantago lanceolata) in replicated disturbed (mats removed) and undisturbed (mats intact) microsites at three grassland remnants (two recently burnt, one unburnt for 3 years) and followed seedling emergence, survival and growth for 5 months. Three native species were also sown for comparison. The rate of germination and total percent germination of non-native species were significantly enhanced at both burnt sites when the mat was disturbed. The large-seeded Briza maxima failed to germinate at both burnt sites in the absence of soil disturbance. The native species generally did not show a strong germination or growth response to soil disturbance in burnt areas. At the unburnt site, where monthly percent soil moisture was highest, final percent germination of the non-native and native species was greatest of any site in both microsites, and germination was not significantly affected by soil disturbance. Differences in the seed morphology of native and non-native species may play an important role in their ability to establish on bryophyte mats in moisture-limiting environments. Any activity that disrupts the mats in the frequently burnt, speciesrich grassland remnants is likely to significantly enhance the germination and subsequent growth by non-natives. However, where burning is infrequent, germination of some non-native species may be expected, regardless of disturbance, although growth will likely be favoured in disturbed areas.

Moss and Soil Substrates Interact with Moisture Level to Influence Germination by Three Wetland Tree Species

“…In this study the major effect appears to be physical with the presence of the moss lifting the germinating seed away from the soil surface decreasing the effective moisture level. These results are similar to those found in other studies where mosses affect moisture levels and thereby influence germination (e.g., [14,[17][18][19]22]. Competition for water may also have decreased available water levels.…”

“…In general the presence of a bryophyte mat may positively [7][8][9] or negatively [10][11][12][13][14][15][16] affect seed germination and seedling survival. Seeds that get caught in a moss mat often remain too dry to germinate or are too far from the ground for the radicle to reach the soil surface and fail to establish [17][18][19][20][21][22]. Competition for water between the moss and the seedling is an important factor, especially in dry habitats [14,23].…”

Species removal and experimental warming in a subarctic tundra plant community

“…Mosses were probably able to compete against the minor species. In fact, dense mats of mosses may prevent other species from establishing (ZamWr 2000;Morgan 2006). On the other hand, mosses are poor competitors for light due to their small size and may not be able to Wll gaps as fast as some dominant vascular plants.…”

Frequent fire promotes diversity and cover of biological soil crusts in a derived temperate grassland

“…Non-vascular plants, commonly known as cryptogams, are diverse and abundant in many ecosystems, and fulWl many important ecosystem functions including nitrogen Wxation, carbon sequestration, enhancing soil surface stability, providing habitat for soil micro-fauna, and inXuencing germination of vascular plants (Greene and Tongway 1989;Eldridge 2001;Belnap 2003;Morgan 2006). While information is available on successional changes in cryptogam composition following large disturbances such as Wre (Timoney et al 1997;Sim-Sim et al 2004), few studies address the eVects of Wre frequency on cryptogam richness and composition (e.g.…”