Development of modern analogues for natural, mowed and grazed grasslands using pollen assemblages and coprophilous fungi

Abstract

Tens of thousands of hectares of salt marsh have formed along eastern Canada's macro-tidal Bay of Fundy. Most of these marshes have been diked and converted to agricultural land since the arrival of Acadian settlers in the 17th century. Although there are currently no controlled salt marsh restoration efforts underway in the Bay of Fundy, there are isolated examples of salt marshes that were restored as a result of unplanned dike breaches. In an effort to develop pollen modern analogues of local dikeland and salt marsh land uses, surface soil samples were collected from John Lusby Marsh, a dikeland to which tidal flooding was restored in the late 1940s, and two nearby diked marshes, one left fallow and one under active agricultural management. Using discriminant analysis (DA) and principal components analysis (PCA) we successfully separated pollen assemblages representing three grassland land use types: salt marsh, farmed dikeland and fallow dikeland. The farmed dikeland land use was further divided into grazed or manured land use and hayed or unmanured land use based on the presence and relative proportions of coprophilous fungal spores such as Sordaria-type, Tripterospora-type, Cercophora-type, Chaetomium-type, Podospora-type and Sporormiella-type. This work marks the first attempt at incorporating dung fungal spores into a palynological analysis using controlled conditions and demonstrates how the inclusion of dung fungal spore abundances can relay information on past land uses. This brings a new interpretive dimension to palynological analyses without requiring any additional sample collection or preparation.