Distribution of Herbaceous Species in the Soil Seed Bank of a Flood Seasonality Area, Northern Pantanal, Brazil

Abstract

To identify factors affecting the spatial distribution of soil seed banks of herbaceous species in the Pantanal floodplain, Brazil, the aims of this study were: to characterize the seed bank in terms of the abundance, richness and composition of germinated seeds; to relate these characteristics to flood duration, elevation, chemical and physical properties of the soil and to examine the seed bank's spatial pattern. Soil samples were collected at 14 points and were then placed in a greenhouse to allow germination to occur. Each sample point had the flood level monitored, the elevation measured and the soil properties identified. A total of 1710 seedlings from 26 species were recorded, of which Echinodorus tenelus was the most abundant (24.9%). Cyperaceae and Poaceae were the richest floristic families (5 species each), with Alismataceae the most represented in terms of number of individuals (36% of the total). Duration of flooding plays an important role in determining Pantanal soil seed banks. The flood pulse influences the abundance (r = 0.79; P = 0.006; partial), richness (r = 0.61; P = 0.02; partial) and composition of the soil seed bank (Pillai trace = 0.552; P = 0.027), carrying the seeds to areas where the duration of flood is longer. Except for aluminium, the soil characteristics expressed by the first principal component of PCA exert indirect positive effects on the seed bank. This is because this component was correlated with the duration of inundation (r = 0.76). Elevation and the toxic effect of aluminium do not vary sufficiently to be able to influence seed bank characteristics. The correlograms show that soil seed banks have no discernible spatial pattern, even though most species are dispersed hydrochorically. This suggests that, at the scale of the study, the tendency for flooding to cause homogeneous dispersion has no influence on seed-bank spatial structure, because of the complexity of flood-plain geomorphology.

Spatial distribution of fish assemblages along environmental gradients in the temporary ponds of Northern Pantanal, Brazil

“…Still, the temporary water bodies or seasonally flooded plains in this region, especially those near the floodplain of Cuiabá river, have been receiving attention only recently. Some notable examples of research on this subject are the pioneering studies on microcrustaceans (Fantin-Cruz et al, 2008), aquatic invertebrates (Santos and Callil, 2010), fish fauna (Fernandes et al, 2010a(Fernandes et al, , 2010b, and seed banks (Pagotto et al, 2011). Several fish species of temporary environments in this region have great importance since they are major food items for wading birds and so they contribute to maintain aquatic and terrestrial food webs.…”

Poaceae em uma planície de inundação no Brasil: listagem florística e novas ocorrências

“…Este sucesso das gramíneas de porte herbáceo e perenes em planícies de inundação pode estar relacionado com as condições de anoxia do sedimento (Worbes 1997). Outros fatores como diferentes posições topográficas e propriedades físico-químicas do sedimento também podem estar relacionados (Pagotto et al 2011). As semelhanças nas condições edáficas e aspectos geomorfológicos entre a PIAP e o Pantanal podem ser também apontados como prováveis fatores para a existência de um considerável número de espécies (63 spp.)…”

Factors structuring the spatial distribution of Chironomidae larvae community in the floodplain of the northern Pantanal, Brazil

“…In studies with other groups, in environments with this same dynamics, the flood duration (hydroperiod) is the determining factor for the spatial distribution of species (Fantin-Cruz et al, 2008;Fernandes et al, 2010;Pagotto et al, 2011;Tondato et al, 2013).…”

“…The Chironomidae community usually changes in response to physical and chemical variations of the water (Higuti and Takeda 2002). The geomorphological, hydraulic and limnological variations, as well as the size of particles comprising the sediment, are some of the factors that influence the temporal and spatial distribution of this community (Stevaux and Takeda 2002;Ali et al, 2002;Marchese et al, 2005).…”