Holocene anthropogenic landscapes in the Balkans: the palaeobotanical evidence from southwestern Bulgaria

Palaeoecological reconstructions from the region of southwestern Bulgaria were used for inferring the human impact on the vegetation and landscape during the last 8 millennia. They are based on data from pollen analyses of lakes and peat-bogs, plant macrofossils, archaeobotanical finds and radiocarbon dating. During the early Holocene, after 7900?cal. b.p. (5950?cal. b.c.) the climate changed to cooler summers, milder winters and higher precipitation resulting in the formation of a coniferous belt dominated by Pinus sp. and Abies alba. These favorable environmental pre-conditions had a positive influence on the Neolithisation of the Balkans after the 8200?cal. b.p. (6250?cal. b.c.) cold event, which caused drought in the Eastern Mediterranean. Direct evidence from wood charcoal records from the Neolithic settlement layers in the study area shows a slight modification of the surrounding woodlands and an increase of the light-demanding components, probably expressed through larger forest border zones and thinning out of the wood stands. The increase in the number of settlements in the valleys of southwestern Bulgaria intensified the human activity visible in the palaeobotanical record from 6950?cal. b.p. (5000?cal. b.c.) onwards. Between ca. 5700–5100?cal. b.p. (3800–3200?cal. b.c.) signs of anthropogenic influence on the vegetation are virtually absent. The intensity of human impact increased notably after 3200?cal. b.p. (1400–1250?cal. b.c., approx. Late Bronze Age), documented by a rise of pollen anthropogenic indicators. The final transformations in the natural forest cover after 2750?cal. b.p. (800?cal. b.c. onset of the Iron Age) marked the reduction of the coniferous forests dominated by Abies alba and Pinus sp. and the expansion of Fagus sylvatica and Picea abies. These vegetation changes are contemporaneous with increase of the palaeofire activities and the next peak of anthropogenic indicators. The changes in the landscape during the Roman period and the medieval period reflect regional environmental features and were forced by the diversification of anthropogenic activity.     

7. Mire Straldza (Southeastern Bulgaria): Late Holocene vegetation history

Aeroallergens of the southeastern Missouri region were determined by skin test frequencies of 817 consecutive individuals and compared and contrasted with five years of air sampling using the Rotorod sampler. Household inhalants were found to induce the most frequently positive skin tests, especially house dust, feathers, house dust mite, wool, cat epithelium, tobacco, dog epithelium, and horse epithelium. Among the trees, pollen extracts of Acer saccharum (maple), Acer negundo (box-elder), Carya ovata/C. illinoensis (hickory/pecan), Juglans nigra (walnut), and Ulmus americana (elm) were the most commonly positive. A slightly higher level of skin reactivity was found to grass pollen extracts with Anlhoxanthum odoralum (sweet vernal), Phleum pratense (timothy), Cynodon dactylon (Bermuda), Agrostis alba (red top) and Festuca elatior (meadow fescue), all being quite similar in incidence, but Sorghum halepense (Johnson grass) was clearly less important. Ambrosia spp. (ragweed) and Xanthium commune (cocklebur) were the most frequent weed reactions with ragweed the most prominent allergen of outside environmental origin. Of the genera of fungi, skin tests to Epicoccum were most frequently positive. When reactivity level is considered, the other important fungi are Alternaria, Candida, Cladosporium, Curvularia, and Fusarium. Air sampling data generally correlates well with the positive skin tests frequencies i.e., the most numerous pollen, ragweed, has the highest skin test frequency and reactivity level. Similarly among the fungi the most numerous spores, Cladosporium, Alternaria, Fusarium, and Epicoccum have the highest frequencies and reactivity levels. Certain species appear to be able to sensitize patients in lower concentrations, such as box-elder and the grasses. Oak pollen and Cladosporium spores appear in large numbers, but seem less sensitizing.     

Palaeoecological studies at the Kaliakra area, northeastern Bulgarian Black Sea coast: 6000?years of natural and anthropogenic change

A 7.5 m sediment core from Lake Bolata, a small former coastal liman lake in northeastern Bulgaria, was analyzed for pollen and plant macrofossil content in attempt to trace the changes in the vegetation, human impact and the influence of the Black Sea during the last ca. 6,000 years. Lake Bolata started its existence when the rising Black Sea level reached the elevation of the bottom of the depression. By that time nearly all tree species were already present in this area with the exception of Carpinus orientalis. The comparison of the arrival time of oriental hornbeam at different sites along the Bulgarian Black Sea confirmed the reliability of the local radiocarbon chronology. For the period under study the vegetation of the region around the site can be described as a forest-steppe due to NAP values higher than 40% of the pollen sum. Forests on the slopes of the river canyon consisted of Quercus spp., Acer, Carpinus orientalis, Fraxinus ornus, Fagus and possibly Tilia. Riverine forests formed stands composed of Salix, Alnus, Ulmus, Fraxinus, Carpinus betulus and Vitis as a liana. The vegetation on the Cape Kaliakra plateau, bordering the canyon, was dominated by diverse herbs and most of these could be considered xerophytes. The oldest occupation period belongs to the Eneolithic, documented by the occurrences of Triticum-type pollen at 5570–5170 cal b.p. (3620–3220 b.c.). The next period of higher continuous Cerealia-type values corresponds to 3450–1830 cal b.p. (1500 b.c.–a.d. 120). The macrofossil record chiefly provides evidence about plant communities of aquatics and helophytes.     

Towards the vegetation and settlement history of the southern Dobrudza coastal region, north-eastern Bulgaria: A pollen diagram from Lake Durankulak

Palynological investigation and radiocarbon dating of a 6-m core from lake Durankulak, north-eastern Bulgaria, enables vegetation development and human occupation from ca. 5500–5300 cal. B.C. onwards to be traced. Steppe vegetation that included with groves of deciduous trees asQuercus, Ulmus, Carpinus belulus andCorylus changed to a forest-steppe after 4000 cal. B.C. The archaeopalynological record indicates three distinct phases of human activity as follows: (1) 5300–4200 cal. B.C. (late Neolithic and Eneolithic) during which farming, that included a substantial arable component, was pursued, (2) 3500–3000 cal. B.C. (transition to early Bronze Age) when stock rearing appears to have dominated, and (3) after 1300 cal. B.C. (late Bronze Age) when arable farming again assumed importance. The palynological data correlate well with the rich archaeological record for human settlement that is available for the region from late Neolithic times onwards.     

Comparing pollen spectra from modified Tauber traps and moss samples: examples from a selection of woodlands across Europe

This paper compares pollen spectra derived from modified Tauber traps and moss samples from a selection of woodland types from Bulgaria, the Czech Republic, Georgia, Greece, Poland, Switzerland and Wales. The study examines the representation of individual taxa in the two sampling media and aims to ascertain the duration of pollen deposition captured by a moss. The latter aim was pursued through the calculation of dissimilarity indexes to assess how many years of pollen deposited in a pollen trap yield percentage values that are most similar to those obtained from the moss. The results are broadly scattered; the majority of moss samples being most similar to several years of pollen deposition in the adjacent trap. For a selection of samples, a comparison of the pollen accumulation rate in pollen traps with the pollen concentration in the moss per unit surface indicates that the entrapment and/or preservation of individual pollen types in the moss differ from that in the pollen trap. A comparison of the proportion of different taxa in the moss with the pollen spectrum of 2 years of pollen deposition in the trap also revealed large differences. There is a tendency for bisaccate grains such as Pinus and Picea to have a higher representation in moss than in traps but there is considerable regional variation. The results indicate that pollen proportions from moss samples often represent the pollen deposition of one area over several years. However, bisaccate pollen grains tend to be over-represented in moss samples compared to both pollen traps and, potentially, lake sediments.