Debarya glyptosperma (De Bary) Wittrock 1872 (Zygnemataceae, Chlorophyta) as a possible airborne alga : a contribution to its palaeoeocological interpretation

This paper reports the fi nding of Debarya glyptosperma zygospores in xeric grasslands far from the natural habitat of algal species. This fact suggests that this species is an airborne alga and this has not been reported before. What is more the discoidal shape of the zygospores may dispose this taxon among the Zygnemataceae family towards air dispersion. This new information may assist in assessing it as an indicator of limnic conditions. However, the simple discovery of Debarya without any accompanying algal taxa and/or other water plants should not be conclusively interpreted as proof of the existence of water bodies because the zygospores might originate from distant transport

Kettle-hole peatlands as carbon hot spots : Unveiling controls of carbon accumulation rates during the last two millennia

Funding Information: We would like to thank the anonymous reviewers for their comments that helped us to improve the manuscript. The research was funded by the National Science Centre (Poland), grant 2015/17/B/ST10/01656.Peer reviewe

Neodymium isotopes in peat reveal past local environmental disturbances

Funding The Stawek profile radiocarbon dating and investigation and neodymium measurements were financed by the National Science Centre, Poland, grants no. 2019/03/X/ST10/00849 and 2020/39/D/ST10/00641. The Głęboczek profile radiocarbon dating and investigation were financed by the National Science Centre, Poland, grant no. 2015/17/B/ST10/01656.Peer reviewedPublisher PD

Znaczenie wspólnych badań historycznych i paleoekologicznych nad wpływem człowieka na środowisko. Przykład ze stanowiska Kazanie we wschodniej Wielkopolsce

The aim of the article is to present the potential of interdisciplinary research on the human impact on the environment in the past on the example of a site in Greater Poland (Wielkopolska). It uses high-resolution palaeoecological analyses of peat archives from the Kazanie peat bog as well as archaeological and historical materials reflecting the settlement and economic activity of the inhabitants of Pobiedziska and surrounding villages throughout last 1200 years.Celem artykułu jest przedstawienie potencjału interdyscyplinarnych badań nad wpływem człowieka na środowisko w przeszłości na przykładzie Wielkopolski. Zostaną w nim wykorzystane wysokorozdzielcze analizy paleoekologiczne źródeł przyrodniczych wydobytych z torfowiska Kazanie oraz materiały archeologiczne i historyczne obrazujące osadnictwo i aktywność gospodarczą mieszkańców Pobiedzisk i okolicznych wsi w ciągu ostatnich 1200 lat

Znaczenie wysokorozdzielczych wielowskaźnikowych (multi-proxy) badań paleoekologicznych dla geografii historycznej i historii gospodarczej

The article presents the importance of palaeoecology for the study of economic history, historical geography and environmental history. The text introduces the methodological possibilities of palaeoecology. We pay attention to the unused potential of high resolution palaeoecology. By using natural archives (sediments of lakes and peatlands), we are able to trace the history of changes in nature. We can reconstruct history and better understand the changes in Poland’s ecosystems and its economic development.Artykuł prezentuje znaczenie paleoekologii dla badań historii gospodarczej, geografii historycznej i historii środowiskowej. Praca przybliża możliwości metodyczne paleoekologii. Zwracamy uwagę na niewykorzystany dotąd potencjał wysokorozdzielczej paleoekologii. Wykorzystując naturalne archiwa (osady jezior i torfowisk), jesteśmy w stanie prześledzić historię przemian przyrody, możemy zrekonstruować historię i lepiej zrozumieć zmiany ekosystemów Polski oraz jej rozwój ekonomiczny

Impact of climate change on the ecology of the Kyambangunguru crater marsh in southwestern Tanzania during the Late Holocene

Instrumental records of temperature and hydrological regimes in East Africa evidence frequent droughts with dramatic effects on population and ecosystems. Sources of these climatic variations remain largely unconstrained, partly because of a paucity of Late Holocene records. Here, we present a multi-proxy analysis of a 4-m continuous sediment core collected in the Kyambangunguru crater marsh, in southwest Tanzania, covering the last 4000 yrs (cal. BP). We used microscopic (macro-remains, microfossils, palynofacies, pollen), elemental (carbon, nitrogen contents), molecular (br GDGTs, n-alkanes) and compound-specific isotopic (δ2H n-alkanes) investigations to reconstruct the environmental history of the marsh. The multi proxy record reveals that, 2500 years ago, the marsh underwent a major ecological transition from a lake to a peatland. Temperature and hydrological reconstructions evidence warmer and drier conditions between 2200 and 860 cal. BP, which probably triggered the establishment of a perennial peatland. This study is one of the first combined temperature and precipitation record of Late Holocene in the region and highlights changes in the spatial distribution of the East African climate regimes. Several cold periods are observed, between 3300 and 2000 cal. BP and since 630 cal. BP, the latter corresponding to the Little Ice Age. Moreover, wetter conditions are reported during the Medieval Climate Anomaly in contrast to other north-eastern African records suggesting that Tanzania is located at the transition between two hydro-climatic zones (north-eastern versus southern Africa) and has experienced variable contributions of these two zones over the last millennium

Holocene fire activity during low-natural flammability periods reveals scale-dependent cultural human-fire relationships in Europe

Fire is a natural component of global biogeochemical cycles and closely related to changes in human land use. Whereas climate-fuel relationships seem to drive both global and subcontinental fire regimes, human-induced fires are prominent mainly on a local scale. Furthermore, the basic assumption that relates humans and fire regimes in terms of population densities, suggesting that few human-induced fires should occur in periods and areas of low population density, is currently debated. Here, we analyze human-fire relationships throughout the Holocene and discuss how and to what extent human driven fires affected the landscape transformation in the Central European Lowlands (CEL). We present sedimentary charcoal composites on three spatial scales and compare them with climate model output and land cover reconstructions from pollen records. Our findings indicate that widespread natural fires only occurred during the early Holocene. Natural conditions (climate and vegetation) limited the extent of wildfires beginning 8500 cal. BP, and diverging subregional charcoal composites suggest that Mesolithic hunter-gatherers maintained a culturally diverse use of fire. Divergence in regional charcoal composites marks the spread of sedentary cultures in the western and eastern CEL The intensification of human land use during the last millennium drove an increase in fire activity to early-Holocene levels across the CEL Hence, humans have significantly affected natural fire regimes beyond the local scale - even in periods of low population densities - depending on diverse cultural land-use strategies. We find that humans have strongly affected land-cover- and biogeochemical cycles since Mesolithic times

Fire hazard modulation by long-term dynamics in land cover and dominant forest type in eastern and central Europe

Wildfire occurrence is influenced by climate, vegetation and human activities. A key challenge for understanding the risk of fires is quantifying the mediating effect of vegetation on fire regimes. Here, we explore the relative importance of Holocene land cover, land use, dominant functional forest type, and climate dynamics on biomass burning in temperate and boreo-nemoral regions of central and eastern Europe over the past 12 kyr. We used an extensive data set of Holocene pollen and sedimentary charcoal records, in combination with climate simulations and statistical modelling. Biomass burning was highest during the early Holocene and lowest during the mid-Holocene in all three ecoregions (Atlantic, continental and boreo-nemoral) but was more spatially variable over the past 3–4 kyr. Although climate explained a significant variance in biomass burning during the early Holocene, tree cover was consistently the highest predictor of past biomass burning over the past 8 kyr. In temperate forests, biomass burning was high at ~ 45% tree cover and decreased to a minimum at between 60% and 70% tree cover. In needleleaf-dominated forests, biomass burning was highest at ~60 %–65%tree cover and steeply declined at > 65% tree cover. Biomass burning also increased when arable lands and grasslands reached ~15 %–20 %, although this relationship was variable depending on land use practice via ignition sources, fuel type and quantities. Higher tree cover reduced the amount of solar radiation reaching the forest floor and could provide moister, more wind-protected microclimates underneath canopies, thereby decreasing fuel flammability. Tree cover at which biomass burning increased appears to be driven by warmer and drier summer conditions during the early Holocene and by increasing human influence on land cover during the late Holocene. We suggest that longterm fire hazard may be effectively reduced through land cover management, given that land cover has controlled fire regimes under the dynamic climates of the Holocene