Lateral expansion of floating vegetation mats over the surface of aquatic ecosystems (terrestrialization) is one of the ways of peatland development. This process was commonly studied in kettle-hole ...lakes, whereas karst ponds have received less attention. We used a suite of palaeoecological analyses at Karstovoe mire (Mordovia, Russia) to reconstruct the formation of a floating Sphagnum-dominated peat mat over the karst pond. The results show that the floating peat mat had covered the central part of the pond by ca. AD 1600. Remains of Scirpus sp. and Calamagrostis sp. in the basal layers indicate that these plants might form a framework on which Sphagnum mosses and sedges were established. The terrestrialization could be triggered by the ‘Medieval Warm Period’ (AD 950–1250) as droughts reduce water levels and allow the pioneering plants to colonize exposed bottom sediments on the margins of lakes. Later, the development of the mire was mainly driven by autogenic factors that could be explained by the relatively stable hydrological regime in freely floating or poorly attached vegetation mats. In the mid 19th century, the surface wetness of the mire started to decline that can be related to both increased human activity associated with fires and to a greater thickness of the mat so that autogenic and allogenic effects were difficult to disentangle. In less than a century after that, the fen transformed to a pioneer raised mire. Our results show complex and context-dependent effect of autogenic and allogenic factors on the development of floating peat mats.
Global urbanization has resulted in local habitat fragmentation, influencing ecological processes and biodiversity conservation. However, little is known about the diversity and distribution of ...microbial communities across urban biotopes. Here, we compared testate amoeba communities in Moscow (63 samples from five urban parks) and Xiamen (69 samples from six urban parks) across four biotopes (tree hole, moss, soil, and sediment) to better understand microbial diversity and ecological processes shaping microbial communities. A total of 116 morphospecies (31 genera), corresponding to 90 in Moscow and 84 in Xiamen, were identified using light microscopy. The species richness per sample (mean ± standard error) was higher in Moscow parks (14 ± 1 species,
n
= 63) than Xiamen parks. The mean species richness per biotope was highest in the mosses (13 ± 1 species,
n
= 33). 13–26% of the total species richness was shared by all biotopes, indicating the ubiquitous distribution of testate amoeba morphospecies. The community composition in different biotopes markedly differed in both Moscow and Xiamen regions. Community connectivity varied among biotopes, and community complexity and dynamics were substantially stronger in soil and sediment. The stochastic processes explained a significantly high percentage of community composition in all biotopes (57–81%) in 11 parks. The standardized effect size for C-score in all biotopes changed from 1.48 to 6.92, indicating the enhanced significance of deterministic processes for the testate amoeba communities. The different relative importance of stochastic or deterministic processes in four studied biotopes suggests that factors influencing the testate amoeba communities greatly vary across heterogeneous urban environments.
Palaeoecological analyses of Falkland Island peat profiles have largely been confined to pollen analyses. In order to improve understanding of long-term Falkland Island peat development processes, ...the plant macrofossil and stable isotope stratigraphy of an 11,550 year Falkland Island Cortaderia pilosa (‘whitegrass’) peat profile was investigated. The peatland developed into an acid, whitegrass peatland via a poor fen stage. Macrofossil charcoal indicate that local fires have frequently occurred throughout the development of the peatland. Raman spectroscopy analyses indicate changes in the intensity of burning which are likely to be related to changes in fuel types, abundance of fine fuels due to reduced evapotranspiration/higher rainfall (under weaker Southern Westerly Winds), peat moisture and human disturbance. Stable isotope and thermogravimetric analyses were used to identify a period of enhanced decomposition of the peat matrices dating from ∼7020 cal yr BP, which possibly reflects increasing strength of the Southern Westerly winds. The application of Raman spectroscopy and thermogravimetric analyses to the Falkland Island peat profile identified changes in fire intensity and decomposition which were not detectable using the techniques of macrofossil charcoal and plant macrofossil analyses.
•An 11,550 year Falkland Island peat profile records a constant presence of burning.•Raman spectroscopy identifies changes in burning intensity.•TGA analyses indicate changes in the preservation of the peat matrices.•Increased strength of the Southern Westerly winds identified at ∼7020 cal. BP.
Using the territory of the Orlovskoye Polesye National Park as a case study within the catchment basin of the Oka River (Mid-Russian Uplands, Oryol Region, Russia), we obtained palaeoecological data ...for studying response of forest landscapes within the forest-steppe ecotone to climate change and human impact through the Late Holocene. The paper presents reconstruction of environmental change on a local to regional scales based on plant macrofossil, spore-pollen and testate amoeba records from a peat core along with reconstruction of woodland coverage inferred from pollen data. Over the past 4000 years, the total woodland coverage has fluctuated insignificantly, ranging from 38 to 52%, while the structure of the forest has changed radically. Prior to 1500 cal. yr BP, both birch-pine and mixed temperate deciduous forests of oak, elm, ash and lime with Scots pine and well-developed shrub understory of hazel and alder grew in the region. The subsequent agricultural colonization of the territory led to a reduction of a broadleaved trees in forest stands since 1500 cal. yr BP. During the last few centuries, human activity largely associated with cutting/burning trees and farming favored the expansion of secondary forests dominated by birch.
Peatlands are remarkable for their specific biodiversity, crucial role in carbon cycling and climate change. Their deposits preserve organism remains that can be used to reconstruct long-term ...ecosystem and environmental changes as well as human impact in the prehistorical and historical past. This study presents a new multi-proxy reconstruction of the peatland and vegetation development investigating climate dynamics and human impact at the border between mixed and boreal forests in the Valdai Uplands (the East European Plain, Russia) during most of the Holocene. We performed plant macrofossil, pollen, testate amoeba, Cladocera, diatom, peat humification, loss on ignition, carbon and nitrogen content, δ13C and δ15N analyses supported by radiocarbon dating of the peat deposits from the Krivetskiy Mokh mire. The results of the study indicate that the wetland ecosystem underwent a classic hydroserial succession from a lake (8300 BC–900 BC) terrestrialized through a fen (900 BC–630 AD) to an ombrotrophic bog (630 AD–until present) and responded to climate changes documented over the Holocene. Each stage was associated with clear changes in local diversity of organisms responding mostly to autogenic successional changes during the lake stage and to allogenic factors at the fen-bog stage. The latter can be related to increased human impact and greater sensitivity of peatland ecosystems to external, especially climatic, drivers as compared to lakes.
Testate amoebae are unicellular eukaryotic organisms covered with an external skeleton called a shell. They are an important component of many terrestrial ecosystems, especially peatlands, where they ...can be preserved in peat deposits and used as a proxy of surface wetness in paleoecological reconstructions. Here, we represent a database from a vast but poorly studied region of the Western Siberia Lowland containing information on TA occurrences in relation to substrate moisture and WTD. The dataset includes 88 species from 32 genera, with 2181 incidences and 21,562 counted individuals. All samples were collected in oligotrophic peatlands and prepared using the method of wet sieving with a subsequent sedimentation of aqueous suspensions. This database contributes to the understanding of the distribution of testate amoebae and can be further used in large-scale investigations.
Despite their huge extent, the peatlands of Russia are an under-exploited source of data on palaeoenvironmental change. We investigated the Holocene history of Staroselsky Moch, an ombrotrophic ...peatland in the Tver Region of European Russia by analysis of testate amoebae, peat physical properties, plant macrofossils and pollen. The peatland developed through a classic hydroseral succession in the early Holocene with a sharp decline in mineral input to 6200 cal. BC followed by an abrupt transition from fen to bog vegetation around 5500 cal. BC. Through the Holocene, the peatland has accumulated carbon at a mean apparent rate of 21.5 g C m−2 yr−1 suggesting that carbon accumulation rates in peatlands of European Russia lie close to the global average, and contrasting with a short sequence of eddy-covariance data which implies a net loss of carbon. The testate amoeba record shows considerable variability which may be driven by climate, but changes are not well replicated in the macrofossil or pollen data. We tentatively infer (1) a phase of early Holocene warming commencing around 7200 cal. BC, (2) dry peatland surface conditions c. 3700–3900 cal. BC, (3) a shift to wetter conditions from c. 3900 cal. BC, and (4) drier conditions from c. 400 cal. BC onwards. More robust and precise hydroclimatic reconstructions for this region will require the development of a regional transfer function and the replication of results between cores and sites.
In the Caucasus, the total area taken up by glaciers is known to have reduced by 23% over the last 20 years. This natural experiment allows for additive and replacement models of autogenic succession ...of biocoenoses within paraglacial landscapes to be tested. A certain risk of the extinction of cryophilic species also exists. However, montane paraglacial successions of invertebrate assemblages have hitherto been studied neither in the Caucasus nor in Russia as a whole. Structural changes of taxocoenoses were traced in a spatial and temporal sequence of ten properly dated paraglacial sites in the Tsey Gorge, North Ossetia − Alania (1–170-years old) among the testate amoebae, earthworms, molluscs, myriapods, mites, spiders, harvestmen, pseudoscorpions, collembolans, and beetles. As the glacier retreats, in place of bare paraglacial wastelands, grassland communities are formed that, after 10–14 years, are replaced by shrub vegetation and, on 30–35-year old surfaces, by forest communities. Most of the invertebrate groups, once “appearing” along a postglacial transect, were recorded from most older plots as well. Yet, their taxocoenoses underwent considerable transformations through increasing (or an increase turning into some decline in beetles) the species diversity and a strong, often complete change in the taxonomic composition and dominance structure. The most considerable transformations were observed at all major vegetation changes. The “appearance” of some groups in the transect was determined not only by dispersion capacities but mainly by the environmental conditions of particular habitats. When comparing the composition of the pioneer postglacial species complex of the study region with that in the mountains of Europe’s south and north, its high-degree regional specificity was noted, sometimes shown at the family level (in spiders). Spatial β-diversity of all larger taxa studied was mainly attributed to turnover (due to “the replacement model” of succession). The general level of change diminished towards the later succession stages. Endemic arthropod species were revealed both in pioneer grassland and developed forest communities.
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