Testate amoebae taxonomy and trait diversity are coupled along an openness and wetness gradient in pine-dominated Baltic bogs

Testate amoebae response and vegetation composition after plantation removal on a former raised bog

Extensive drainage of peatlands in north-west Europe for the purposes of afforestation for timber production and harvesting has altered the carbon balance and biodiversity value. Large-scale restoration projects aim to reinstate hydrological conditions to keep carbon locked up in the peat and to restart active peat growth. Testate amoebae are an informal grouping of well-studied protists in peatland environments and as microbial consumers play an important role in nutrient and carbon cycling. Using a space for time substitution approach, this study investigated the response of testate amoebae assemblages and vegetation composition after tree removal on a drained raised bog. There was a clear difference in microbial assemblages between open and a chronosequenceof restoration areas. Results suggest microbial recovery after rewetting is a slow process with plant composition showing a faster response than the microbial assemblage. Mixotrophic testate amoebae had not recovered seventeen years following plantation removal and the establishment of Sphagnum mosses in the wetter microforms. These results suggest that vegetation composition and Testate amoeba assemblages respond differently to environmental drivers at forest-to-bog restoration areas. Local physicochemical peat properties were a stronger driver of the testate assemblage compared with vegetation. Complete recovery of microbial assemblages may take place over decadal timescales.

Long-term microclimate study of a peatland in Central Europe to understand microrefugia

Peatlands perform many important ecosystem functions at both the local and global scale, including hydrologic and climatic regulation. Although peatlands often act as climatic microrefugia, they have rarely been the subject of long-term microclimatic studies. In this study, we aimed to compare the local climatic conditions of a mid-forest mire to that of an open area and examine the differences in microclimates within the mire based on plant community diversity, shading, and water table depths. The peatland studied in this work was significantly cooler than the reference site, mainly due to a higher decline in nighttime air temperatures. However, the daily maximum air temperature near the ground was often higher. We also noticed that microclimates significantly differed within the studied peatland. Wet and shaded microsites were cooler than the sites having a lower water level and receiving higher amounts of solar radiation. The results of the study suggest that peatlands have locally cooler climates, and thus can serve as climate change refugia. These findings can help us interpret reconstructed data from the peat archive, and, when combined with experiments, identify tipping points for peatland ecosystems.

Pine Forest Management and Disturbance in Northern Poland: Combining High-Resolution 100-Year-Old Paleoecological and Remote Sensing Data

Global warming has compelled to strengthen the resilience of European forests. Due to repeated droughts and heatwaves, weakened trees become vulnerable to insect outbreaks, pathogen invasions, and strong winds. This study combines high-resolution analysis of a 100-year-old high-resolution peat archive synthesized from the Martwe peatland in Poland with remote sensing data. We present the first REVEALS based vegetation reconstruction in a tornado-hit area from Poland on the background of previous forest management in monocultural even-aged stands – Tuchola Pinewoods. During the 20th century, the pine monocultures surrounding the peatland were affected by clear-cutting and insect outbreaks. In 2012, a tornado, destroyed ca. 550 ha of pine forest around the peatland. The palynological record reflects these major events of the past 100 years as well as changes in forest practices. Our study showed the strong relationships between the decrease of Pinus sylvestris (Scots pine) in palynological record as well as planting patterns after the tornado. Moreover, past forestry practices [such as domination of Pinus sylvestris, the collapse of Picea abies (Norway spruce), low share of Betula spec. (birch) due to Pinus sylvestris promotion and probable also to a lesser by removal of Betula as a “forest weed,” and low plant coverage of tree species due to clear-cutting and cutting after insect outbreaks] were well identified in the proxy record. In monocultures managed over decades, the reconstruction of vegetation may be challenging due to changes in the age composition of the Pinus sylvestris stands. We found that through historical, remote sensing, and paleoecological data, the dynamics of disturbances such as insect outbreaks and tornadoes, as well as the changing perceptions of local society about forests, can be determined.

Multiple convergences in the evolutionary history of the testate amoeba family Arcellidae (Amoebozoa: Arcellinida: Sphaerothecina): when the ecology rules the morphology

Protists are probably the most species-rich eukaryotes, yet their systematics are inaccurate, leading to an underestimation of their actual diversity. Arcellinida (= lobose testate amoebae) are amoebozoans that build a test (a hard shell) whose shape and composition are taxonomically informative. One of the most successful groups is Arcellidae, a family found worldwide in many freshwater and terrestrial environments where they are indicators of environmental quality. However, the systematics of the family is based on works published nearly a century ago. We re-evaluated the systematics based on single-cell barcoding, morphological and ecological data. Overall, test shape appears to be more related to environmental characteristics than to the species’ phylogenetic position. We show several convergences in organisms with similar ecology, some traditionally described species being paraphyletic. Based on conservative traits, we review the synapomorphies of the infraorder Sphaerothecina, compile a list of synonyms and describe a new genus Galeripora, with five new combinations. Seven new species: Arcella guadarramensis sp. nov., Galeripora balari sp. nov., Galeripora bufonipellita sp. nov., Galeripora galeriformis sp. nov., Galeripora naiadis sp. nov., Galeripora sitiens sp. nov. andGaleripora succelli sp. nov. are also described here.

Diversity of Testate Amoebae as an Indicator of the Conservation Status of Peatlands in Southwest Europe

Testate amoebae are one of the most studied groups of microorganisms in Sphagnum peatland ecosystems and, therefore, one of the most reliable bioindicators of their ecological status. Peatland ecosystems are supported by a delicate biogeochemical balance that leads to the formation of peat, one of the main sinks of C, as a result of soil–atmosphere interaction, but currently they are one of the most threatened wetland types at their southern distribution limit. In the European continent, where climatic conditions limit peat formation, they have endured significant anthropic pressure for centuries, and the risk of loss of biodiversity linked to these ecosystems is critical. In addition, peatlands are poorly known ecosystems in the Iberian Peninsula compared with other wetlands; therefore, we have studied the chemical parameters of water and the diversity patterns of testate amoebae in the western Iberian Peninsula to better understand the current status of these ecosystems. The analysis of testate amoeba communities showed an inverse relationship between the diversity and conservation status of these peatlands, both in relation to chemical parameters (i.e., pH, electrical conductivity, phosphates) and to the proportion of anthropized area, with a marked geographical pattern in the degree of anthropogenic disturbance.