Reconstructing the colonization and demographic dynamics that gave rise to extant forests is essential to forecasts of forest responses to environmental changes. Classical approaches to map how population of trees changed through space and time largely rely on pollen distribution patterns, with only a limited number of studies exploiting DNA molecules preserved in wooden tree archaeological and subfossil remains. Here, we advance such analyses by applying high-throughput (HTS) DNA sequencing to wood archaeological and subfossil material for the first time, using a comprehensive sample of 167 European white oak waterlogged remains spanning a large temporal (from 550 to 9,800 years) and geographical range across Europe. The successful characterization of the endogenous DNA and exogenous microbial DNA of 140 (~83%) samples helped the identification of environmental conditions favouring long-term DNA preservation in wood remains, and started to unveil the first trends in the DNA decay process in wood material. Additionally, the maternally inherited chloroplast haplotypes of 21 samples from three periods of forest human-induced use (Neolithic, Bronze Age and Middle Ages) were found to be consistent with those of modern populations growing in the same geographic areas. Our work paves the way for further studies aiming at using ancient DNA preserved in wood to reconstruct the micro-evolutionary response of trees to climate change and human forest management.

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The wild horse Equus ferus was one of the most frequent species of the Late Pleistocene large ungulate fauna in Eurasia and played an important role in the subsistence of human groups, especially at the end the Late Glacial. It is frequently assumed that E. ferus became extinct in Europe at the beginning of the Holocene because of the development of woodlands and loss of open habitats. Because of its preference for open habitats and in spite of its adaptability, the appearance or disappearance of the wild horse could therefore be a suitable palaeoecological indicator for the opening of the Holocene primeval woodlands. We revised the dating and reliability of the subfossil record and dated several bones by atomic mass spectrometry 14 C dating. From the beginning of the Holocene (9600 cal a BC) to the end of the Atlantic Period (3750 cal a BC) there are 207 archaeological sites with wild horse records available in Europe. E. ferus survived the Pleistocene Holocene transition in Europe, but the spatiotemporal dynamics of populations fluctuated remarkably in the early and middle Holocene. Small and sparse populations increasingly became extinct during the early Holocene, until between 7100 and 5500 cal a BC the wild horse was almost absent in central parts of the European Lowlands. Particular conditions in natural open patches in the canopy forests, chalklands and floodplains may have maintained the local survival of the horse in some regions of the Lowlands, however. In the Late Atlantic, between 5500 and 3750 cal a BC the range of the wild horse was again extended. It re-immigrated into central and western Europe, probably as a consequence of increasing landscape opening by Neolithic peoples. The data presented here may be a valuable part of the debate on the degree of openness of the early and middle Holocene landscape.

Biochar composting experiments were performed to determine whether composting is a suitable method to accelerate biochar surface oxidation for increasing its reactivity. To assess the results, surface properties of Terra Preta (Brazil) and ancient charcoal pit (Northern Italy) biochars were additionally investigated. Calculation of O/C ratios by energy-dispersive X-ray spectroscopy demonstrated the anticipated increasing values from fresh biochars (0.13) to composted biochars (0.40), and finally charcoal pit biochars (0.54) and ancient Terra Preta biochars (0.64). By means of Fourier transformation infrared microscopy, formation of carboxylic and phenolic groups on biochars surface could be detected. Carboxylic acids of three composted biochars increased up to 14%, whereas one composted biochar showed a 21% lower proportion of carboxylic acids compared to the corresponding fresh biochar. Phenolic groups increased by 23% for the last mentioned biochar, and on all other biochars phenolic groups decreased up to 22%. Results showed that biochar surface oxidation can be accelerated through composting but still far away from ancient biochars.