Responses of Uniola paniculata L. (Poaceae), an Essential Dune-Building Grass, to Complex Changing Environmental Gradients on the Coastal Dunes

Abstract

Coastal dunes are well known for plant species zonation but less is known about species-specific responses to underlying environmental gradients. We investigated variation in morphological traits and tissue nutrient concentration in Uniola paniculata, along a shoreline-tolandward gradient (transects spanning from the dunes directly behind the high tide mark to 40-100 m inland) in the southeast USA. Several environmental factors decreased with distance from the shoreline (soil B, K, Mg, Na; salinity, pH, and sand accretion), and differences were most pronounced between the 10 m closest to the shoreline and the remainder of the transect. In the 10 m closest to the shoreline, 94% more sand accumulated, which was 31% more saline. Additionally, plants here were taller, contained higher aboveground tissue N and K, and a higher percentage tended to flower. This contrasts with patterns found in salt marshes and saline desert dunes, where plant size is often negatively correlated with salinity. During the 2 years following the planned study, storms washed out ≤25 m of the transects. Resampling of the remaining sites demonstrated that even after erosion of the dune profile, a higher percentage of the plants in the 10 m closest to the shoreline plants tended to flower, relative to populations located further from the shore. Our findings suggested that the environment and plant response in the shoreward 10 m can re-establish relatively quickly.

Community Structure and Abiotic Determinants of Salt Marsh Plant Zonation Vary Across Topographic Gradients

“…It has been suggested that soil moisture content could affect seed germination of salt marsh plants (Noe and Zedler 2000) and that soil pH can affect performances of marsh plants by altering the form of inorganic ions available to the plants and the plantmycorrhizal associations (Montemayor et al 2008;Gormally and Donovan 2010). However, in our study, whether the statistically significant but limited variations in these abiotic factors do matter to the plants has to be further experimentally examined.…”

Positive Species Interactions as Drivers of Vegetation Change on a Barrier Island

“…Intense sand movement could obscure the effects of short-term shading by increasing evaporation or by burying growing seedlings (Zhang and Maun, 1990). This suggests that future studies of positive interactions in the foredune habitat should consider sediment stabilization by species as a mechanism of positive interactions such as facilitation (Gormally and Donovan, 2010;Oosting and Billings, 1942). In the interdune habitat, shading had the strongest positive effect on vegetation; however, shading appeared to play a role in encouraging vegetative growth only, while actually restricting species richness.…”

The role of arbuscular mycorrhizae in primary succession: differences and similarities across habitats

“…However, sand dunes were mostly approached to study cyclical succession and less as primary succession (Read 1989, Mueller 1999, Alarcón and Cuenca 2005, Camprubi et al 2010, Gormally and Donovan 2010. The question of AM-mediated plant-plant interactions in sand dunes also attracted some interest from researchers so that some preliminary information concerning the presence and role of AM already exists (Koske and Polson 1984, Sigüenza et al 1996, Kowalchuk et al 2002, Rilling et al 2003, Rodrígu-ez-Echeverría and Freitas 2006, Rodríguez Echeverría et al 2008, Blaszkowski et al 2009, Martínez-García 2010.…”

“…Receding glaciers provide another case of primary succession, although these are climatically biased because they are restricted to alpine-arctic regions (Garbarino et al 2010, Marteinsdóttir et al 2010, Robbins and Matthews 2010. Areas with intensive erosion and landslides (Walker et al 2009) including arid ecosystems (Pezzani et al 2006), as well as sand dunes (Gormally and Donovan 2010) can also provide chronosequences of land exposed to succession, although there is not much data on primary successions in these systems.…”