Search

Past plant diversity dynamics can provide a historical perspective on biodiversity change and ecosystem dynamics as a guide to conservation management in the future. Pollen analysis is one of the most widely used approaches to reconstruct plant diversity change through time, but the representativeness of pollen diversity to plant diversity is not yet fully understood and especially in open landscapes. In this paper, we compare pollen assemblages from topsoil in the open landscapes of the Tibetan Plateau with the surrounding vegetation to investigate their compositional similarity and the correlations between their diversity (richness and evenness), and to evaluate the influence of climate variables, landscape characteristics, and human disturbance on the pollen diversity. The results show that pollen assemblages vary obviously in different vegetation types and they can represent their surrounding plant communities at low taxonomic levels. Pollen richness boarders a better match with plant richness than pollen evenness with plant evenness across the whole study area, but the correlation is weak (r adj 2 < 0.2, p < 0.001). Transforming plants into their pollen equivalents has little improvement for the correlations between pollen and plant richness/evenness. Pollen richness and evenness can capture well the trend in plant richness and evenness along the vegetation gradient, suggesting that they can be used as gamma (landscape scale) rather than alpha (local scale) diversity metrics in the study area. Mean annual precipitation (MAP), mean annual temperature (MAT), and patch richness (PatchS) are positively associated with pollen richness. MAP, PatchS, and human disturbance (HD) are significantly predictors for pollen evenness. These confirm that pollen richness and evenness can provide insights into past plant diversity dynamics and help evaluating the effects of climate and habitat changes and human disturbance on long timescales. • Pollen assemblages represent surrounding plant communities at low taxonomic levels. • Pollen diversity is reliable proxy for plant diversity at the landscape scale. • Vegetation shift is an important prerequisite in studying past plant diversity. • Pollen-equivalent transformation cannot improve pollen-plant diversity correlations. • Pollen diversity can indicate changes in past climate and habitat conditions. [ABSTRACT FROM AUTHOR]

Recent discoveries of several Mesolithic sites within the Dagsmosse Basin, south-central Sweden, offer an opportunity to study the lifestyle and skillsets of Mesolithic hunter-gatherer-fishers operating in wetland environments. In this paper, we present a combined archaeological and palaeoecological analysis of a Mesolithic fenland environment using Repetitive-Proxy Pollen Analysis (RPPA) of early Holocene sequences. Based on comparison of stratigraphic profiles from two cores within the basin, we infer that the variance in pollen composition and anthropogenic signals reflect variability in human/vegetation interactions in the fenland, at different distances to the main human dwelling at Jussberg (9.0–8.2 ka cal BP). Our study describes the socio-environmental relations within the wetland and adjacent terrestrial areas, providing a basis for tracking changes in forager interactions with their surroundings during the Mesolithic. Pollen analysis is consistent with the previously established sequence of settlement phases and extent as well as providing new data concerning the anthropogenic impacts on plant communities within the wetland including the use, reuse, and management of vegetation taxa. Correlations between palaeoecological and archaeological data demonstrate that forager communities (i) prevailed in the open fenland landscape between 9.3 and 8.2 ka cal BP, (ii) actively altered taxa composition through small-scale clearings of pine (Pinus), birch (Betula) and sedges (Cyperaceae) and (iii) reduced canopy cover, possibly to intentionally encourage the growth of taxa such as hazel (Corylus), but that also promoted the establishment of pioneer plants such as mugwort (Artemisia) and bracken (Pteridium). • Mesolithic foragers impacted forest and grassland vegetation around the Dagsmosse basin as well as the wetland formation. • HGF clearance and plant-use was perceivable at multiple spatial scales through comparative pollen analysis. • Human activity and movement within the middle Scandinavian inland changed throughout the Mesolithic and the 8.2 ka stadial. [ABSTRACT FROM AUTHOR]

Human impact on the coastal plain of Southeast China has been well studied over late Holocene timescales; however, an understanding of anthropogenic impact in mountainous regions is still lacking. In this paper, we present records of vegetation, fire, and human impact, spanning the past 4000 years, with a resolution of ∼40 years, obtained from an upland peatland in Southeast China. The results reveal that climate change (dominated by the evolution of the East Asia Monsoon) was the most critical factor controlling vegetation before 1.0 cal kyr BP, while human impact gradually emerged as the primary driver after 1.0 cal kyr BP in the mountains of Southeast China. As such, the record of anthropic impact in mountainous regions lagged behind the signal from the coastal plains by some 2000–4000 years. As the population migrating from northern China dispersed into the mountainous regions of Southeast China, demand for agricultural land promoted slash-and-burn cultivation and the destruction of broad-leaf forest. • Three climatic stages identified spanning 4.0 cal kyr BP based on pollen and charcoal analysis. • Significant anthropogenic impact on mountain vegetation of Southeast China occurred in 1.0 kyr BP, lagged coastal plains by 2000–4000 years. • The population migrating from northern China dispersed into the mountainous regions of southeastern China in 1.0 kyr BP, urgent demand for cultivated land. [ABSTRACT FROM AUTHOR]