Intraspecific root trait variability along environmental gradients affects salt marsh resistance to lateral erosion
De Battisti, D.; Fowler, M.S.; Jenkins, S.R.; Skov, M.W.; Rossi, M.; Bouma, T.J.; Neyland, P.J.; Griffin, J.N. (2019). Intraspecific root trait variability along environmental gradients affects salt marsh resistance to lateral erosion. Front. Ecol. Evol. 7: 11. https://dx.doi.org/10.3389/fevo.2019.00150 In: Frontiers in Ecology and Evolution. Frontiers Media: Lausanne. ISSN 2296-701X; e-ISSN 2296-701X, more |   |
| Author keywords | resilience; sediment stability; response-effect framework; functional root traits; environmental gradients; root density |
| Authors | | Top | - De Battisti, D.
- Fowler, M.S.
- Jenkins, S.R., more
- Skov, M.W.
| - Rossi, M.
- Bouma, T.J., more
- Neyland, P.J.
- Griffin, J.N.
| |
| Abstract | Recent studies in salt marshes have demonstrated the role of plant roots in sedimentstabilisation, and hence the importance of marshes in providing coastal protection.However, the relative role of root traits and environmental factors in controlling sedimentstability, and how intraspecific variability of root traits vary within and among marshes,remain poorly understood. In this study, we investigated which root trait(s) drive sedimentstability (resistance to lateral erosion) in two marsh species with an important role incoastal protection (Spartina anglica and Atriplex portulacoides) and how the environmentaffects the expression of these traits. We sampled three marshes along salinity gradientsin each of two estuaries in Wales (UK), establishing replicate plots in the respectivedominant zones of each species. In all plots we sampled abiotic variables (sand, redoxpotential, pH, salinity) and root traits (root density, specific root density, root volume, rootlength density); in a subset of these plots (three per species in each marsh) we extractedsoil-plant cores and assessed their erosion resistance in a flume. Sediment stability wasenhanced by increases in root density and reductions in sand content. Abiotic variablesaffected root density in different ways depending on species: in S. anglica, redox was theonly significant factor, with a positive, linear effect on root density; in A. portulacoides,redox had a non-linear (U-shaped) effect on root density, while sand had a negativeeffect. Collectively, these results show that (i) intraspecific variability in root density caninfluence sediment stability in salt marshes, and (ii) sediment properties not only influencesediment stability directly, but also indirectly via root density. These results shed lighton spatial variability in the stability of salt marshes to lateral erosion and suggest thatroot density should be incorporated into coastal vegetation monitoring programs as aneasy-to-measure root trait that links the environment to sediment stability and hence tothe function and services provided by marshes. |
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