Acrostichum, a Pioneering Fern of Floodplain Areas from the Late Oligocene Sariñena Formation of the Iberian Peninsula

Abstract

Acrostichum is considered today an opportunistic fern in disturbed areas, which indicates the first stages of colonisation of such zones. However, in the fossil record, Acrostichum appears related to fluvio-lacustrine environments, freshwater marshes and mangrove deposits. We report here for first time fossil evidence of Acrostichum that reveals a pioneering behaviour of this fern in the colonisation of perturbed communities in Europe, which corroborates previous assumptions about the paleobiology of Acrostichum. Plant remains were collected from the Chattian (late Oligocene) La Val fossil site (Estadilla, Huesca, northeastern Spain) belonging to the Sariñena Formation, which mainly embraces crevasse splays, levees and floodplain deposits. Evidence shows that Acrostichum grew within the levee’s vegetal community or close to/on the river banks as well as on floodplain areas and closer to/on the shores of ephemeral ponds. But most importantly, the observed co-existence of Equisetum and Acrostichum remains in the same beds indicates that such strata represent short-lived inundated terrains, e.g., floodplains where the water table was temporarily stagnant. Evidence shows wetland environments dominated by pioneering taxa, implying a pioneering role for Acrostichum during the late Oligocene in the Iberian Peninsula.

Distribution pattern and ethnomedicinal uses of plants in Kanchanpur district, Far-Western Nepal

“…The maximum density was contributed by Imperata cylindrica (69.35 individuals m -2 ) and minimum by Equisetum hyemale (0.02 individuals m -2 ) and Saraca indica (0.02 individuals m -2 ). Both Imperata and Equisetum prefer disturbed site (Moreno-Dominguez et al 2016). Dominance of Imperata was already reported in crop fields of Chitwan (Dangol 2002) and natural vegetation in Arun valley (Chaudhary and Kunwar 2002).…”

Mapping the Late Miocene Pyrenean Forests of the La Cerdanya Basin, Spain

“…The site of La Val also revealed a high proportion of autochthonous and para-autochthonous impressions of Alnus and Pinus, similar to the abundance of these taxa in the La Cerdanya macroflora. As in the La Val site, Alnus in the La Cerdanya basin formed azonal deciduous riparian forests in stream and river margins [66,67]. These azonal forests could also have been present in the wetland and lacustrine environments of the La Cerdanya.…”

Does mangrove vegetation structure reflect human utilization of ecosystem goods and services?

“…For example, both T. populnea (L.) and Sol. ex Correa, a semi-mangrove 89 , 90 and A. aureum L. 91 , 92 are reported to colonize and increase on low saline soils in degraded mangrove forests. Qiu et al.…”

“… 87 The dominance of Acrostichum in the western bank forests could be associated with high degradation, as Acrostichum is considered an opportunistic species that pioneers degraded and low saline sections of mangrove forests. 92 In Sri Lanka, increasing freshwater conditions resulted in a >59% net increase in A. aureum . 39 The Ankobra estuary is a riverine type with low salinity range, therefore, in addition to mangrove tree felling, Acrostichum alone in this study contributed to about 56% of the dissimilarity in species composition among sites.…”