Peat bog and alluvial deposits reveal land degradation during 16th and 17th century colonisation of the western Carpathians (Czech Republic)

Wallachian (shepherd) colonisation of the upper parts of Carpathians, the second largest mountain range in Europe, provides a unique opportunity to study human-induced ecological changes and subsequent sediment mobilisation within slope and fluvial systems. The Wallachians came to the nearly pristine landscape in the Czech part of the Western Carpathians during the 16–17th Century bringing large scale deforestation and grazing to the upper parts of its ridges. Despite the importance of this event, there is a lack of high-resolution multi-proxy reconstructions to help to decipher the relative influence of anthropogenic and climate factors on this landscape. Here we provide a ca. 2.1 kyr record obtained from a peat bog where, using chronological, sedimentological and pollen analyses, we were able to differentiate between environmental conditions before, during and after colonisation. Prior to colonisation, climate deterioration following the onset of Little Ice Age caused changes in forest composition and erosion events (causing a ~AD 0–1500 gap in the record). Abrupt human-induced deforestation detected in the pollen record, together with the abundant fine-grained minerogenic content of peat deposits between AD ~1640 and AD 1870, correspond to increased runoff and sheet erosion on slopes; enhanced by Little Ice Age climate deterioration. The sedimentary record in alluvial deposits downstream indicates that the colonisation of the mountain slopes in this region not only had a local effect on soil degradation, but it also increased the net aggradation of overbank deposits within valley floors. After reforestation, net aggradation was replaced by river incision into alluvia

Interpreting the effect of regional climate fluctuations on Quercus robur L. trees under a temperate continental climate (southern Romania)

To determine oak tree sensitivity to climate fluctuations as a precipitation predictor, we eliminated monthly climate data and computed the growth-precipitation correlation using mean daily values calculated in time intervals. Precipitation from March through May is the primary limiting factor in intra-annual tree-ring growth for Quercus robur L. in southern Romania. Bootstrap correlations between the residual series and monthly average precipitation showed a positive dependence (r = 0.4). Using CLIMTREG software and daily climate data, we obtained correlation values of (0.6) and a better understanding of on-going tree radial growth. We found that the oak growth process is active during two distinct periods in the study area, December 22th–February 10th (earlywood) and March 04th–June 13th (latewood). For the studied oak tree population, the correlation with climate was positive with respect to precipitation and negative with respect to temperature. This indicates that annual tree-ring formation was influenced by the precipitation regime and frequency and by the degree of drought. These results also indicate that different behaviours occur among the examined earlywood and latewood under the same climatic conditions, which were then analysed

L' évaluation du risque géomorphologique dans le bassin hidrographique Suha Mică (droit affluent de la riviere Moldova)

La cartographie des aires qui présentent un risque géomorphologique est devenue une nécessité sociale. Dans le domaine de la recherche des processus concernant le versant et le canal (le lit de la rivière) des éléments indicateurs ont été signalés, et qui peuvent conduire à faire l’inventaire des facteurs de risque locaux. Parmi les nombreuses ossibilités de combinaison des facteurs géomorphologiques qui déterminent la susceptibilité au risque d’un territoire, on a considéré comme étant édifiants pour la zone ’étude les suivants : géologie, pente, l’exposition des versants, l’utilisation des terrains. La carte à risque montre le niveau de l’exposition des certaines aires à un grand dangeret implique une évaluation quantitative stricte. Un niveau élevé de prédisposition au risque d’un territoire s’identifie en plan physique par une susceptibilité accrue aux processus géomorphologiques actuels spécifiques. Sur la base de plusieurs éléments cartographiques on a réalisé la carte de l’expansion des aires avec les processus géomorphologiques actuels dominants, et puis, sur la base des paramètres géographiques mentionnés antérieurement (ci-dessus), on a réalisé la carte du sque géomorphologique pour le bassin hydrographique Suha Mică. Notre étude est originale parce que, par la cartographie géomorphologique détailléeui a été réalisée avant la carte à risque, on a eu la possibilité de vérifier sur le terrain quel facteur est plus important pour l’exposition au risque des différentes unités des aires dansa zone étudiée. Par rapport aux autres réalisations de ce type, où la lithologie a un pourcentage maximum, dans notre cas, le facteur déterminant est la pente du versant. Cefait a mené à une réalisation cartographique plus véridique, fait qu’on a pu voir lors de la vérification de la carte à risque géomorphologique, sur la base de la carte de l’extensiondes aires affectés par les processus géomorphologiques actuels dominants.</p

Subfossil oaks from alluvial deposits and their role in past fluvial activities analysis: case study East Carpathian rivers, Romania

Dendrochronological research was conducted in Europe in several centers whereby oak trees, regardless of species, originating from various archaeological sites were studied. Thereby, several shronologies were assembled in Ireland, Germany and the UK, covering the past 7000 to 8000 years. The environment impacts on tree growth by generating higher / lower growth ratescompared to the multinannual average, thus indicating extreme years. The patterns of extreme years pertaining to individual sequences are subsequently synchronized by cross-dating.The study area consists of two rivers with different typologies but comparable in terms of size: river Moldova (braided to wandering channel in the lower reach) and river Siret (sinuosmeandering channel). Along the 100 km-long floodplain of the former and the 144 km-long floodplain of the latter we found and sampled 77 subfossil trunks from which 26 were subjectedto 14C dating</p

The Climatic Response of Tree Ring Width Components of Ash (Fraxinus excelsior L.) and Common Oak (Quercus robur L.) from Eastern Europe

This paper aims to develop the first differentiated (earlywood&mdash;EW, latewood&mdash;LW, and total ring width&mdash;RW) dendrochronological series for ash (Fraxinus excelsior L.) and oak (Quercus robur L.) trees from the Republic of Moldova, and to analyze their climatic response and their spatio-temporal stability. For this, 18 ash and 26 oak trees were cored from the Dobru�a protected area, Republic of Moldova, Eastern Europe, and new EW, LW, and RW chronologies were developed for ash and oak covering the last century. The obtained results showed that the RW and LW have a similar climatic response for both species, while EW is capturing interannual climate variations and has a different reaction. The analyses performed with monthly climatic data revealed a significant and negative correlation with the mean air temperature and a significant and positive correlation with precipitation and the Standardized Precipitation-Evapotranspiration Index (SPEI) for both ash and oak. The temperature during the vegetation period has a strong influence on all tree-ring components of ash, while for oak the strong correlation was found only for LW. The positive and significant correlation between LW and RW with precipitation for both species, suggests that ash and oak are sensitive to the hydrological component and the precipitation is the main tree growth-limiting factor. Despite the significant correlation with precipitation and temperature for the whole analyzed period, the 25-year moving correlation analyses show that they are not stable in time and can switch from positive to negative or vice versa, while the correlation with SPEI3 drought index, which is a integration of both climatic parameters, is stable in time. By employing the stability map analysis, we show that oak and ash tree ring components, from the eastern part of the Republic of Moldova, have a stable and significant correlation with SPEI3 and scPDSI drought indices from February (January) until September, over the eastern part of Europe