How Do Plants and Climatic Conditions Control Soil Properties in Hypersaline Tidal Flats?

Abstract

Hypersaline tidal flats (HTF) are ecotones associated with mangrove ecosystems in arid and semiarid coasts. They are predominantly vegetated by halophytes which are related to environmental stabilization and fauna protection. Some plants thrive in HTF by modifying soil biogeochemical conditions at their rhizospheres, expanding across barren soils. Thus, we aimed to study rhizospheric and the adjacent bulk soils of the three most abundant plant species in HTF under a seasonal semiarid climate of northeastern Brazil. We analyzed both rhizospheric and bulk soils of vegetation patches in wet and dry seasons. We found that HTF soils are a heterogeneous system highly influenced by water availability and plant activity. The soils were mostly sandy textured, containing low C and N contents, and hypersaline conditions. Comparing bulk and rhizospheric soils, we concluded that plants changed their own rhizosphere by creating nutrient pools to improve survival under saline conditions. Seasonal changes also affected soil biogeochemical processes in HTF, mainly the bulk soils by changing water availability. Understanding rhizospheric changes by halophytes, their expansion over barren soils, and the amelioration of soil physicochemical conditions, are fundamental to provide support for preservation and management of coastal ecosystems, including HTF.