Gabriela Florescu

Last Millennium hydro-climate variability in Central–Eastern Europe (Northern Carpathians, Romania)

Proxy-based reconstructions of climate variability over the last millennium provide important insights for understanding current climate change within a long-term context. Past hydrological changes are particularly difficult to reconstruct, yet rainfall patterns and variability are among the most critical environmental variables. Ombrotrophic bogs, entirely dependent on water from precipitation and sensitive to changes in the balance between precipitation and evapotranspiration, are highly suitable for such hydro-climate reconstructions. We present a multi-proxy analysis (testate amoebae, plant macrofossils, stable carbon isotopes in Sphagnum, pollen, spores and macroscopic charcoal) from an ombrotrophic peat profile from the Rodna Mountains (northern Romania) to establish a quantitative record of hydro-climatic changes. We identify five main stages: wet surface mire conditions between AD 800 and 1150 and AD 1800 and 1950, and drying of the mire surface between AD 1300 and 1450, AD 1550 and 1750 and AD 1950 and 2012. Our multi-proxy reconstructions suggest that conditions during the Medieval Climate Anomaly (MCA) period (AD 900–1150) were considerably wetter than today, while during most of the ‘Little Ice Age’ (LIA; AD 1500–1850), they were dry. Mire surface conditions in the Rodna Mountains have dried markedly over the last 40 years mainly as a result of anthropogenic climate change approaching the driest conditions seen over the last 1000 years. There is a marked difference between current hydro-climatic conditions (dry mire) and those of the MCA (wet mire). This implies that for the study region, the MCA cannot provide analogous climatic conditions to the contemporary situation. Our reconstructions are in partial agreement with water table estimates elsewhere in central and eastern Europe but generally contrast with those from NW Europe, especially during LIA. We suggest that these distinctive regional differences result from fluctuations in large-scale atmospheric circulation, which determine the relative influences of continental and oceanic air masses.

Lakes, Lacustrine Sediments, and Palaeoenvironmental Reconstructions

Acting as sensitive and accurate barometers, lake and peat sediment records enable us to acquire an increasingly broader perspective on the mechanisms behind climatic and environmental changes. Over the past two decades, the rising number and amount of data yielded by palaeolimnological studies for the Central–Eastern Europe, in general, and Romania, in particular, allowed for the construction of a wide network of well-dated records which enabled comparison with the hallmark palaeoclimatic event stratigraphy of the North–Atlantic area and Western Europe. More specifically, the combined use of biological indicators with physical and geochemical data resulted in a multi-proxy approach for a variety of sites extending from the Transylvanian lowlands to the uplands of the Romanian Carpathians and spanning throughout the Holocene to the Pleniglacial. This section introduces a brief synthesis of the most outstanding results delivered by various investigations on Romanian lake and peat archives. Among these, lakes and peat bogs which came into existence during deglaciation, including both glacial lakes located in higher elevation mountain areas and lakes formed at lower elevations due to landslides subsequent to permafrost thaw are prevalent, and were preferred for such studies due to their long lifespan and location in mountain areas which have exhibited increased sensitivity to centennial and millennial-scale climate changes. The potential of lacustrine sediments for inferring past dynamics of climate and environmental conditions prompts us to highlight the necessity for expanding the spatiotemporal coverage of such studies in Romania in an attempt to create a relatively unitary perspective on regional palaeoenvironmental evolution.

Palaeoecological assessment of prehistoric and historic human impact in the high elevation areas of the Northern Carpathians, Romania

This paper presents a high resolution, multi-proxy palaeoenvironmental reconstruction (pollen, dung fungal spores, micro and macro-charcoal, mineral magnetic properties and geochemistry) in three sedimentary sequences located at different elevations across the Northern Carpathians (Romania) over the Late Holocene (i.e. the last 4000 years). We aim to: i) determine what aspects of prehistoric and historic human activity (e.g. burning, clearing, grazing) have shaped the landscapes of today, and ii) use this information to facilitate their environmental management and conservation strategies to maintain the ecological and economic sustainability of extant habitats in the currently changing environment

Fire as a driver of ecosystem dynamics in Central and Eastern Europe throughout the Lateglacial and Holocene

Sedimentary microscopic charcoal (particles smaller than 150 microns) has been used to describe multi-decadal to millennial scale biomass burning at regional scales, whereas macroscopic charcoal (particles larger than 150 microns) analysis is increasingly used to investigate past biomass burning at a local scale

The effect of past fire activity on soil erosional processes in two subalpine sediment records from Rodna Mountains, Northern Romanian Carpathians

Fire is an important disturbance factor across a variety of vegetation zones and one of the major causes of geomorphological and ecological changes (Shakesby&Doerr, 2006). In the context of current and anticipated climate change, fire severity and frequency is expected to increase. The impact of fire in shaping the physical, chemical, biological characteristics of a soil surface is mediated by the interaction between climate factors, vegetation attributes and human activities. Depending on the size, duration and temperature reached, fire usually consumes the litter and vegetation cover. It consequently changes soil stability by enhancing rain-splash detachment, modifying infiltration and promoting soil erosion. Nonetheless, the long-term geomorphological effects of fire activity revealed by lake sediment records have been sparsely investigated in terms of both geographical coverage and range of environmental characteristics. Therefore, a better understanding of fire activity in a future warmer climate will be crucial in assessing and predicting landscape dynamics, feedback mechanisms and sensitivity to soil erosion with different fire behaviour.

1000 years of high resolution environmental change in the Eastern Carpathians, NE Romania: a multi-proxy approach

Climate changes and anthropogenic activities are projected to have a significant impact on mountain environments. This is because of their ecosystems’ sensitivity and increased response to the extreme weather events and natural catastrophes (Beniston, 2000). The modification of climatic conditions can therefore impact heavily on mountain ecosystems. Furthermore, human impact has been shown to modify environmental response to climatic stressors (Beniston, 2003; Jones & Mann, 2004). This holds particularly true because mountain regions are usually at the border of conflicting interests between economic development and environmental conservation (IPCC, 1996). Deciphering the relation between local mountain environment, climate variability and human components therefore becomes of great importance for both regional climate study and local socio-economies.