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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]

The delta region of the Amu-dar'ya has a complex history of shifting river channels that has impacted extensively on the Aral Sea and on the areas of the delta that saw human settlement from prehistoric times onwards. This paper explores evidence drawn from archeological, historical and environmental data relating to lakes that formed in the south of the delta on the east bank of the river and their impact on settlement patterns in this area, in particular the potential impact of variable flooding on the major fortified site of Akchakhan-kala. Testing of the area around the sites showed that the site had not been flooded but was founded on riverine or lacustrine clays. Shortly after the initial abandonment of the site, the immediate environment was covered by dune fields. [ABSTRACT FROM AUTHOR]

In this paper, we describe a 5500-year long core obtained from a lake in the Prealps of northern Italy to investigate the impact of human communities on the lacustrine environment. Specifically, we report micro-botanical proxies (upland and aquatic pollen, algae, cyanobacteria, dung spores, microcharcoal particles), sedimentary parameters (LOI steps, calcimetry, FTIR spectra) and nutrients (P forms, C/N and K) on paired samples in a high-resolution stratigraphy, dated by 14C AMS dating and tie point correlation. Independent archaeological evidence indicates the existence of lakeside settlements and farming in Bronze Age times from c. 4000 to 3300 cal yrs. BP. The impact of this Bronze Age village is recorded by an accumulation of plant detritus, pollen, charcoal and abundant wood and bone-derived ash. Intensive P mineralization by ash production was accompanied by the rapid burial of P inorg , K, and microcharcoal. Correlated peaks of P org and pasture plant pollen mark the contribution of animal husbandry to P org lake sink. The nutrient flux produced by external catchment cropping contrasts with the internal flux discharged by prehistoric dwelling and in turn distinguishes domestic hearth production from a contribution by animal husbandry. Forest conditions and lake sedimentation returned to semi-natural baseline at the end of this 700-year long phase of Early to Middle Bronze Age settlement, but pollen proxies indicate that lake-side forests did not fully recover. Lake Lucone represents a key site, since it documents interactions between bronze Age settlements and related ecological impacts on both terrestrial environment and lacustrine sedimentation, as recorded in a continuous sequence, as well as the end of Bronze Age pile dwelling culture. • A multi proxy study reveals a 5500-year long history of intermittent human impact. • A Bronze Age lake-side settlement strongly effected aquatic and terrestrial ecosystems. • Semi-natural forest and lake sedimentation was restored following decline of the settlement. • Internal or external sourcing and sink of P forms reflect lake-side settlement and farming. • Sediment composition relate to changes in the flux of organic and ash particles. [ABSTRACT FROM AUTHOR]

Abstract: High-resolution macroscopic charcoal and pollen analyses were used to reconstruct the fire and vegetation history of the Willamette Valley for the last 1200years. Presented in this paper are three new paleoecological reconstructions from Lake Oswego, Porter Lake, and Warner Lake, Oregon, and portions of previous reconstructions from Battle Ground Lake, Washington, and Beaver Lake, Oregon. The reconstructions show that prior to Euro-American settlement vegetation and fire regimes were influenced by a combination of natural and anthropogenic factors. Battle Ground Lake shows a stronger influence from climate, while Lake Oswego, Beaver Lake, Porter Lake, and Warner Lake were more controlled by human activity. However, human-set fires were also modulated by regional climate variability during the Medieval Climate Anomaly and the Little Ice Age. Fire reconstructions from Battle Ground Lake, Lake Oswego, Beaver Lake, and Porter Lake imply that fires were infrequent in the Willamette Valley 200–300years prior to Euro-American settlement. The decline of Native American populations due to introduced disease may have led to this reduction in fire activity. The prehistoric record from Warner Lake, however, indicates that fires in the foothills of the Cascade Range were more frequent than on the valley floor, at least until ca. AD 1800. The historic portions of the reconstructions indicate that Euro-American land clearance for agriculture and logging produced the most dramatic shifts in vegetation and fire regimes. All five records indicate that few fires in the Willamette Valley have occurred since ca. AD 1930, and fires today are predominantly grass fires. [ABSTRACT FROM AUTHOR]

Abstract: Major ecological changes related to anthropogenic activities begin on islands with initial human settlement. Key factors to understanding insular Holocene ecological changes are the arrival dates of both humans and alien species to the islands. In this context, finely stratified fossil sites are powerful tools to study the chronology and causes of these changes. Previous work, based on conventional 14C ages of land snails coming from the finely stratified site Cueva del Llano at Fuerteventura (Canary Islands, eastern Atlantic Ocean), indicates that one of the major ecological changes that took place in this archipelago–the arrival of house mouse Mus musculus–occurred around 7000 yrs ago, thus before the first arrival of humans to the islands. To extend these studies, we obtained 14C ages by accelerator mass spectrometer (AMS) directly on bone collagen from selected bones of rodents: lava mouse Malpaisomys insularis and house mouse, from seven sites: Cueva del Llano, Cueva de Villaverde and Malpaís de La Arena I & II (Fuerteventura), El Bebedero and Jameo de la Puerta Falsa (Lanzarote), and Barranco de la Baranda (La Palma). The new ages derived from the upper levels of Cueva del Llano (CLL 9.1–9.2) indicate a very young age for these materials, between 1667–1949 and 1261–1391 cal AD. These results support a more recent and very different chronology for the Holocene ecological changes that occurred on these islands compared to previous studies. Explanations for the stratigraphically anomalous age shown in previous papers are put forward. On the other hand, the available 14C ages indicate that the house mouse arrived on the eastern Canary Islands some time between 756 cal BC–313 cal AD and, probably from there, spread to the other islands before European contact. [Copyright &y& Elsevier]