Global Change and Response of Coastal Dune Plants to the Combined Effects of Increased Sand Accretion (Burial) and Nutrient Availability

Abstract

Coastal dune plants are subjected to natural multiple stresses and vulnerable to global change. Some changes associated with global change could interact in their effects on vegetation. As vegetation plays a fundamental role in building and stabilizing dune systems, effective coastal habitat management requires a better understanding of the combined effects of such changes on plant populations. A manipulative experiment was conducted along a Mediterranean dune system to examine the individual and combined effects of increased sediment accretion (burial) and nitrogen enrichment associated with predicted global change on the performance of young clones of Sporobolus virginicus, a widespread dune stabilizing species. Increased burial severity resulted in the production of taller but thinner shoots, while nutrient enrichment stimulated rhizome production. Nutrient enrichment increased total plant biomass up to moderate burial levels (50% of plant height), but it had not effect at the highest burial level (100% of plant height). The effects of such factors on total biomass, shoot biomass and branching were influenced by spatial variation in natural factors at the scale of hundreds of metres. These results indicate that the effects of burial and nutrient enrichment on plant performance were not independent. Their combined effects may not be predicted by knowing the individual effects, at least under the study conditions. Under global change scenarios, increased nutrient input could alleviate nutrient stress in S. virginicus, enhancing clonal expansion and productivity, but this benefit could be offset by increased sand accretion levels equal or exceeding 100% of plant height. Depletion of stored reserves for emerging from sand could increase plant vulnerability to other stresses in the long-term. The results emphasize the need to incorporate statistical designs for detecting non-independent effects of multiple changes and adequate spatial replication in future works to anticipate the impact of global change on dune ecosystem functioning.

The combined effects of sediment accretion (burial) and nutrient enrichment on the growth and propagation of Phalaris arundinacea

“…For sand dune species, nutrient enrichment generally increased plant performance up to moderate burial, but it had no or even a negative effect at a deep burial level114. However, for P. arundinacea , nutrient enrichment increased root mass ratio and ramet production under partially buried conditions, and no consistent increase in root mass ratio and ramet production was found with surface plantings.…”

“…Moreover, the effects of sediment accretion and nutrient enrichment on plant performance might not be independent1415. For example, increased nutrient supply may facilitate the acclimation of coastal dune species to sand accretion1416.…”

“…For example, increased nutrient supply may facilitate the acclimation of coastal dune species to sand accretion1416. However, the concurrent effects of sediment accretion and nutrient enrichment on growth and propagation of clonal macrophytes have rarely been examined in lacustrine wetlands.…”

The Impact of Physical Disturbance and Increased Sand Burial on Clonal Growth and Spatial Colonization of Sporobolus virginicus in a Coastal Dune System

“…It can reproduce sexually but seedlings have been rarely observed on mobile dunes [36–38], and thus clonal growth seems to play a major role in maintaining populations and colonizing dune habitats. Available data on the growth pattern of the species are scarce [39–41], and virtually nothing is known on the degree of physiological integration and apical dominance.…”

Effects of sand burial and overstory tree age on seedling establishment in coastal Pinus thunbergii forests in the northern Shandong Peninsula, China

“…High investment in stem biomass could increase stem elongation of seedlings, making them less vulnerable to burial (Brown 1997, Xu et al 2013a. Frosini et al (2012) did not find the root/shoot ratio of Sporobolus virginicus (L.) Kunth was affected significantly by sand burial. Sykes and Wilson (1990) reported six of 29 New Zealand sand dune species decreased root/shoot ratios with depth, four species did not change significantly, while 19 species increased root/shoot ratios.…”