Impacts of soil moisture level and organic matter content on growth of two Juncus species and Poa pratensis grown under acid soil conditions

The abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) has increased in coastal grasslands in Norway over recent decades, and their spread has coincided with increased precipitation in the region. Especially in water‐saturated, peaty soils, it appears from field observations that productive grasses cannot compete effectively with such rapidly growing rush plants. In autumn–winters of 2012–2013 and 2013–2014, a four‐factor, randomised block greenhouse experiment was performed to investigate the effect of different soil moisture regimes and organic matter contents on competition between these rush species and smooth meadow‐grass (Poa pratensis). The rush species were grown in monoculture and in competition with the meadow‐grass, using the equivalent of full and half the recommended seed rate for the latter. After about three months, above‐ and below‐ground dry matter was measured. J. effusus had more vigorous growth, producing on average 23–40% greater biomass in both fractions than J. conglomeratus. The competitive ability of both rush species declined with decreasing soil moisture; at the lowest levels of soil moisture, growth reductions were up to 93% in J. conglomeratus and 74% in J. effusus. Increasing water level in peat–sand mixture decreased competivitiveness of meadow‐grass, while pure peat, when moist, completely impeded its below‐ground development. These results show that control of rush plants through management may only be achieved if basic soil limitations have been resolved.publishedVersio

Field-Based near Infrared Spectroscopy for Analysis of Scandinavian Stone Age Rock Paintings

During the early autumn of 2014 a field-based near infrared (NIR) spectroscopy study was carried out at Swedish and Norwegian Stone Age rock painting sites. This article presents results from one of them, namely Flatruet, Härjedalen, Sweden. Here, field-based NIR measurements were conducted using the 908–1676 nm wavelength range to gather 479 spectra: 427 of rock paintings and 52 of local lithology background. The whole dataset was analysed using principal component analysis (PCA) and four principal components were extracted explaining 98.5% (PC1), 1.4% (PC2), 0.06% (PC3) and 0.04% (PC4). The PCA results showed that there was a large spread in the spectra of both background and red paint objects, but also some evidence of clustering could be seen where background and paintings could be separated. An improvement in separation was achieved with partial least squares discriminant analysis (PLS-DA) using the background and paint as categorical variables. The most important components of the PLS-DA model showed a better separation in the score plot. A small test set of 10 paint and 10 background samples showed that one of the paint samples and two of the background samples were misclassified. One conclusion is that there is a large spread in background due to varying precipitation of secondary iron oxides. It was also decided to look deeper into local models of painted elks and their pigments alone. This was done using local PCA models and soft independent modelling of class analogies showing that some painted elks could be separated from each other while others were quite similar, which is important for answering questions about origin, age and weathering

Plants as persons: perceptions of the natural world in the North European Mesolithic

From Crossref journal articles via Jisc Publications RouterHistory: ppub 2020-07-02, issued 2020-07-02, epub 2020-09-08Publication status: Publishe