Plant functional structure along salinity gradients in Iranian salt marshes

Zeinab Matinzadeh, University of Tehran, Tehran, Iran (Islamic Republic of), Jesús López-Angulo, Universidad Rey Juan Carlos, Madrid, Spain, Adrián Escudero, Biology & Geology Department, Rey Juan Carlos University, Móstoles-Madrid, Spain, Sara Palacio, Instituto Pirenaico de Zaragoza (CSIC), Spain, Mehdi Abedi, Department of Range Management, Tarbiat Modares University, Iran (Islamic Republic of) and Hossein Akhani, Botany, University of Tehran, Tehran, Iran

Background/Question/Methods
Salt marshes are unique natural habitat between sea/lake and land which need to be conserved and protected from the effects of global change drivers. Understanding plant community assembly processes based on the variation in plant functional structures along environmental gradients is critical to predict the response of plant communities to future environmental changes. However, we have almost no previous study considering the functional determinants of halophyte communities. In this regard, we evaluated the role of deterministic prevalent processes in community assembly and also the changes in the functional community structure along soil gradients including salinity, in four Iranian salt marshes; Lake Urmia, Lake Meyghan, Musa estuary and Nayband Bay.
We sampled ten leaves per species and plot from 16 sites in salt marshes to measure leaf traits. Five soil samples were sampled from each plot and 30 variables were analyzed in those samples. We considered community assembly processes across all plots using null model and one sample t-test. In addition we examined functional structure changes in soil variable gradient using linear mixed effect models.
Results/Conclusions

Our results showed that the structures of observed communities were not significantly different from randomly assembled communities. However, we found variations in trait functional structure along environmental gradients. Specially, we found that functional diversity and community weighted mean of leaf thickness tended to increase along salinity, while those in leaf shape increase towards soil potassium availability.
Our results suggest that the ecological filters that constrain the pool of species in these harsh ecosystems blur any signature of other local processes. However, the assessment of the variations in functional structure of the plant communities along environmental gradients revealed the effect of different ecological processes (e.g. habitat heterogeneity), which drives the assembly of halophyte communities in Iranian salt marshes.