We assessed total mercury (THg) concentrations and greenhouse gas (GHG) emissions in pristine and managed hemiboreal peatlands in Latvia, aiming to identify environmental factors that potentially affect their variation. The THg concentrations in soil ranged from <1 µg kg−1 to 194.4 µg kg−1. No significant differences between THg concentrations in disturbed and undisturbed peatlands were found, however, the upper soil layer in the disturbed sites had significantly higher THg concentration. During May–August, the mean CO2 emissions (autotrophic and heterotrophic respiration) from the soil ranged from 20.1 ± 5.0 to 104.6 ± 22.7 mg CO2-C m−2 h−1, N2O emissions ranged from −0.97 to 13.4 ± 11.6 µg N2O-N m−2 h−1, but the highest spatial variation was found for mean CH4 emissions—ranging from 30.8 ± 0.7 to 3448.9 ± 1087.8 µg CH4-C m−2 h−1. No significant differences in CO2 and N2O emissions between disturbed and undisturbed peatlands were observed, but CH4 emissions from undisturbed peatlands were significantly higher. Complex impacts of environmental factors on the variation of THg concentrations and GHG emissions were identified, important for peatland management to minimize the adverse effects of changes in the biogeochemical cycle of the biophilic elements of soil organic matter and contaminants, such as Hg.

Today, when anthropogenic pressure on natural ecosystems promotes degradation of natural habitats and facilitates distribution of alien species, local disturbances such as forest management become more significant in relation to alien plant species expansion. The aim of this study was to investigate the impact of forest road and drainage network reconstruction on the vegetation composition focusing on the expansion of invasive alien plant species. The occurrence and coverage of vascular plant and bryophyte species were recorded within 160 sample plots along four forest roads and four drainage ditches. This paper summarises the first results of this study. The main results indicate that small-scale linear corridors like forest roads and drainage networks can promote the expansion of invasive alien plant species.

Retention of trees from the previous generation is one of the most widespread conservation practices in forests used for timber production. Despite the comparatively long history of this approach in Europe, there is a lack of long-term studies on the effectiveness of retention trees in preserving epiphyte communities. We compared the diversity of bryophyte and lichen species on retention trees in 20 young forest stands in Latvia in two assessments, 11 years and 18 years after clearfelling. Linear mixed-effects models showed that richness of both lichens and bryophytes remained stable during the assessment years, while bryophyte cover and diversity on retention trees increased over time. The main indicator of higher species richness, cover and diversity on retention trees in managed forests in hemi-boreal vegetation zone was the tree species, with deciduous trees playing the key role. They also provided essential habitat for rare species. Regarding bryophytes, ash, elm, and aspen can be suggested as more efficient retention trees, thus aiding the continuity of bryophyte succession in young forest stands. For lichens, lime could also be prioritised.

Broad-leaved trees play an important role in supporting epiphyte richness in deciduous forests. In this study we tested which broad-leaved forest stands in terms of tree composition best predicted biodiversity in regard to bryophyte species number and their functional traits. The bryoflora was surveyed in 70 stands differing in dominant broad-leaved tree species. One circular plot with diameter 30 meters was established in each stand situated in different parts of Latvia. Fifty-three of the plots were located in stands identified as protected habitats of the European Union. In total, 82 bryophyte species were recorded. At plot level the total number of species ranged between 6 and 38 species. Using principal component analysis (PCA), the ordination axes explained 41% of the variation in composition of bryophytes. The PCA axes were related to tree species composition. The presence of broad-leaved trees, especially ash, lime, and oak, was connected with higher species richness. Generalised linear models confirmed that epiphyte richness, both at the total and indicator species levels, was higher in ash stands. From the functional traits, all expected life-strategy and life-form categories were recorded. The most represented life-forms were smooth mats, tall turfs, and rough mats, while the dominant life-strategy was perennial stayers, followed by competitive perennials and long-lived shuttles. Functional trait richness was highest in Fraxinus excelsior, Tilia cordata, and Quercus robur forest stands.