Modern pollen–vegetation relationships in traditionally mown and unmanaged boreal rich-fen communities in central Norway

Abstract

Knowledge of the relationship between vegetation and modern pollen deposition is necessary to improve the interpretation of fossil pollen samples. We compared the cover of plant species and the modern pollen deposition in surface moss samples in 49 plots in rich-fen vegetation from the boreal vegetation zone in Norway in two areas (one oceanic and one more continental). These rich fens were used for traditional hay cutting until ca. 1950. Three management regimes are used: 1) biennial mowing 2) quadrennial mowing and 3) unmown. The unmown areas were traditional hay fens, with no management since the 1950s. Of the 89 plant taxa and corresponding 65 taxa of pollen and spores, 29 and 22, respectively, were sufficiently represented in both vegetation and as pollen, to allow direct comparisons of the two data sets. Most of the plant and pollen taxa were found in the plots from both study areas and in plots with different mowing frequency. Therefore, quantitative differences in vegetation cover and pollen percentages were the main focus in this investigation of plantpollen relationships in mown and unmown vegetation. The relative difference in plant cover was largest between biennially and unmown plots. 12 species showed a significant positive correlation with difference in plant cover between mown and unmown areas (p<0.05; Wilcoxon signed rank test), most pronounced for Molinia caerulea (most common in unmown plots), and Carex dioica and Thalictrum alpinum (most common in mown plots). A significant positive plant-pollen correlation (Spearman rank-correlation) was found for 10 pollen taxa. Thalictrum alpinum is a very good pollen indicator, and Cyperaceae, Eriophorum-type and Pedicularis-type are good pollen indicators of mowing. Poaceae/Molinia caerulea and Succisa pratensis are negatively correlated with mowing. The impact of mowing on species composition was similar in both study areas. Mown and unmown areas were differentiated in the vegetation data and could be identified by modern pollen data. These results will improve the interpretation of past land-use practices using pollen analysis of rich-fen vegetation.

Mire plant diversity change over the last 10,000 years: Importance of isostatic land uplift, climate and local conditions

“…In forested sites, Cyperaceae produce less pollen and the pollen signal is overwhelmed by tree pollen (Waller et al., 2005). Succisa ( Succisa pratensis ), which was an indicator of forested fens in our study, has been shown to be associated with unmanaged (not mown) fens in Norway (Fjordheim et al., 2018). Polypodiaceae and Prunus have also been shown to be associated with forested fen vegetation in English fens (Waller et al., 2017) and Polypodiaceae has been associated with increasing abundance of Pinus pollen in Latvian mire reconstructions (Ozola, 2013).…”

“…Succisa (Succisa pratensis), which was an indicator of forested fens in our study, has been shown to be associated with unmanaged (not mown) fens in Norway (Fjordheim et al, 2018). Polypodiaceae and…”

“…Pollen‐based classification is widely used in palaeoecological studies to help to interpret historical changes in plant communities (e.g. Felde et al., 2016; Fjordheim et al., 2018; Waller et al., 2017). The results of the current study, which compares modern pollen samples from different mire types with palaeo samples from mires, add to the findings that have demonstrated the usefulness of pollen‐based community classification for long‐term ecological studies in wetland systems (e.g.…”

Influence of taxonomic resolution on the value of anthropogenic pollen indicators

“…However, some promising technical innovation such as confocal microscopy might help in the future (Seppä and Bennett 2003). Interestingly, Eriophorum and Carex pollen (both apophytic Cyperaceae) could be amalgamated into Dulichium-type (Faegri and Iversen 1975), which might allow tentative reconstructions of landuse regimes (Fjordheim et al 2018) in the absence of other more specific human indicators. Dissimilarities derived from taxonomic precision were very high (up to 10%) during the Modern Period (after ad 1600; Fig.…”

Lluvia polínica en la selva baja caducifolia del cerro El Picante, San José Tilapa, Puebla, valle de Tehuacán-Cuicatlán

“…donde B 0 es el número de transectos donde están presentes tanto el tipo polínico como el grupo vegetal asociado; P 0 representa el número de transectos donde se registra el polen, pero la planta que lo produce no está presente en la vegetación, y P 1 es el número de transectos donde el tipo de polen está ausente, pero el taxón vegetal está presente en la vegetación. Según Fjordheim et al (2018), los valores de los índices de cada taxón se agruparon en las siguientes categorias: 1) tipo fuertemente asociado "TFA" cuando A > 0.65; 2) tipo asociado "TA", cuando A varía entre 0.65 y 0.5; 3) tipo débilmente asociado "TDA", donde A < 0.5 y además O y U son positivos; 4) tipo sobrerrepresentado "TOR", cuando A < 0.5 y U = 0; 5) tipo subrepresentado "TUR", con A < 0.5 y O = 0, y 6) tipo no asociado "TNA", en donde A = 0, además O y U son positivos. https://doi.org/10.…”