Nutrients and trace elements of semi-arid dwarf and fully developed mangrove soils, northwestern Venezuela

Abstract

Mangrove forests are characterized by a high carbon storage capacity. Anthropogenic activities and the climate change are threatening the stability of these ecosystems, specially those that are surviving on extreme environmental conditions, representing the most susceptible groups. This study aims to understand the geochemical differences of soils of mangrove forest with diverse degree of development of Rhizophora mangle and Avicennia germinans, located in two semi-arid regions from the Falcon state, Venezuela. The soil samples were collected in Punta Caimán region (dwarf mangroves of less than 2 meters height) and Boca de caño lagoon (fully developed mangroves of up to 8 meters height). The trace elements and macronutrients were determined in two sequential extraction, first with 1M HCl followed by an extraction with ultrapure grade $$HNO_{3}$$ H N O 3 . Results showed that, in general, dwarf mangroves have limited capability to accumulate organic matter in the soil (average TOC of $$0.6 \pm 0.2\%$$ 0.6 ± 0.2 % ) and that the sampled surface soils from the dwarf mangrove region had no differences with deeper material. On the other hand, the TOC of soils dominated by developed mangroves is $$6 \pm 2 \%$$ 6 ± 2 % , representative of semi-arid conditions. Moreover, the soils dominated by dwarf mangroves are characterized high concentrations of trace elements related to the chalcophile group. The difference in soil chemistry between Rhizophora mangle and Avicennia germinans becomes significant when mangroves are fully developed. Finally, soils of dwarf mangrove forests presented a greater concentration of trace elements than soils of fully developed mangroves, which might be due to a different sediment source, to an anthropogenic influence or to the difference in organic matter.

Tracking the long‐term vegetation and soil characteristics of restored mangroves: a case study from Guyana's coast

“…The natural mangroves at our sites were taller than the restored mangroves, except for the 11‐year‐old stand. Several factors may have contributed to this pattern, such as favorable environmental conditions and higher levels of essential nutrients such as Ca, Mg, N, P, K, and Na in this restored site than in the 11‐year‐old natural stand (Reef et al 2010; Lovelock et al 2014; Romero‐Mujalli & Melendez 2023). The 9‐year‐old natural mangrove stand was the tallest, potentially due to higher observed Ca and N levels promoting increased plant growth.…”