Flood and fire affect the soil seed bank of riparian forest in the Pantanal wetland

Thiago Da Costa Kohagura,Francielli Bao,Arnildo Pott,Evaldo Benedito De Souza,Fernando Alves Ferreira

doi:10.1590/2175-7860202071013

Thiago Da Costa Kohagura, Francielli Bao + Show 3 more

Open Access

https://doi.org/10.1590/2175-7860202071013

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Abstract

Abstract Flood and fire can harm plants but they can have survival strategies, such as the seed bank. We aimed to determine the influence of fire and flood on the richness, abundance and diversity of the seed bank. Sampling was carried out in October/2013, year of prolonged drought, and October/2014, year of a heavy flood, in ten areas along the Paraguay River. The areas were selected in satellite images, five with old burn (2010, three years before sampling) and five with recent burn (2013, three months before sampling). In each area, we marked a 20 m long transect with ten 20 × 20 cm quadrats where we collected 5 cm deep topsoil samples, five with and five without litter. Seed bank richness and abundance were determined by seedling emergence. Old burn areas presented greater abundance than recent burn. The drier year presented greater abundance, richness and diversity than flood year. Removal of litter reduced the richness only in the wetter year. There was no difference in richness in the drier year. The removal of the litter did not affect the abundance and diversity. Interaction between fire and flood did not affect richness, abundance and diversity of the seed bank.

Highlights

The soil seed bank is a strategy to ensure the vegetation regeneration after a disturbance, or seasonal events such as fire (Santana et al.2010) and flood (Hölzel & Otte 2004)
The most abundant genera were Cecropia, Cyperus, Ludwigia, Hymenachne, Borreria and Randia, expressing 68.5% of the total of species recorded in the seed bank, and the main species were Cyperus haspan L. (11%), Cecropia pachystachya (10%), Borreria quadrifaria E.L
We observed that interannual differences in flood and different intervals in fire history can influence abundance, diversity and species richness of the riparian forest seed bank

Summary

Introduction

The soil seed bank is a strategy to ensure the vegetation regeneration after a disturbance, or seasonal events such as fire (Santana et al.2010) and flood (Hölzel & Otte 2004). Water dispersed seeds come mixed with plant debris, in great part from aquatic plants that germinate during floods (Bao et al 2017). This accumulated organic debris, associated with aquatic macrophyte dieback, can capture and trap dispersing seeds (Ruprecht & Szabó 2012), potentially increasing local seed bank abundance and richness (Bao et al 2018). Flood acts as a trigger for the seedling emergence of annual species, rapidly withdrawing seeds from the bank and reducing its richness and abundance (Souza et al 2016). There are few pieces of evidence of differences of seed bank richness and abundance between dry and flooded years

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