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Based on compilation of a large number of archaeological and palaeosol 14C-ages, the Summed Probability Method is used to reconstruct population history and climatic patterns on the Chinese Loess Plateau during the period 8.5–3.5 cal. ka BP. During this period, the population experienced two major expansion periods and several climatic fluctuations. The first population expansion began at around 7.8 cal. ka BP, and the second at around 5.8 cal. ka BP. During the first period, although already in combination with cultivation of broomcorn millet the population growth was supported mainly by hunting and gathering. With the switch from broomcorn millet to foxtail millet, plant cultivation became the major factor promoting a second population increase. In this paper, we demonstrate that, initially, suitable climate and agriculture both can facilitate population growth and climate events had a significant influence on demographic fluctuations. However, when reaching the threshold of land capacity, population became increasingly more sensitive towards climate fluctuations. [ABSTRACT FROM AUTHOR]

In the coastal lowlands of Mozambique, an expansion of savannas at the cost of forests has been attributed to anthropogenic influence. There are few investigations that have studied vegetation dynamics over the long term. Pollen analysis from two sedimentary cores in the Chibuene area, 7 km south of Vilanculos presented in this paper show that the coastal area 1600 years ago consisted of a mosaic of forests, Miombo woodlands and grasslands. The data also show that the area supported extensive forests in the past until AD 1400-1600 when the forests declined dramatically. Changing settlement patterns, as suggested from archaeological excavations, cannot be correlated with the forest decline and the charcoal abundance, in the sedimentary cores does not suggest an intensification of farming. Instead the decline of forests appears to be temporally correlated with a prolonged period of repeated dry spells associated with the 'Little Ice Age', which caused a shift in vegetation whereby typical forest species as Trema, Celtis and Moraceae were outcompeted on account of the droughts. This study challenges rooted assumptions about the cause of decline of forests in the coastal region. It also suggests that the forest fragments present on the Mozambique coast today are naturally subject to threat from climatic stress and as such are highly sensitive areas to future climate change. [ABSTRACT FROM AUTHOR]

Quantitative reconstruction of past vegetation is one of the primary goals in Quaternary palynology and palaeoecology but still remains difficult. This paper proposes a model, REVEALS, that estimates regional vegetation composition using pollen from ‘large lakes’ that have small site-to-site variations of pollen assemblages even if vegetation is highly heterogeneous. Once these data have been used to quantify regional vegetation composition within 104-105 km², background pollen, one of the parameters crucial for vegetation reconstruction, can be estimated for smaller-sized sites, and incorporated into the Landscape Reconstruction Algorithm (LRA), a multistep framework for quantitative reconstruction of vegetation in smaller areas (≤/104 ha). Simulations using the POLLSCAPE modelling show that REVEALS can provide accurate estimates of regional vegetation composition in various landscapes and under different atmospheric conditions. If pollen assemblages from lakes that are much smaller than ‘large lakes’ are used, estimates of regional vegetation at individual sites could be significantly different from the expected values, and their site-to-site variation could be large. However, when pollen data from multiple lakes ≥100-500 ha in size are available, REVEALS can provide accurate estimates of the regional vegetation with relatively small standard errors. Quantitative reconstruction of regional landscape and vegetation change will be critical for testing some of the controversial hypotheses and concepts in global change and conservation research, such as the impacts of agricultural activities on global climate over the last 8000 years and the open-woodland hypothesis in northern Europe in the early Holocene. [ABSTRACT FROM AUTHOR]