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The objective of this paper is to examine the representativeness of charcoal taxa at archeological sites in northern China. We carried out standardized laboratory compression tests on 168 samples representing 21 taxa charred at four different temperatures to characterize the mechanical properties of common taxa in temperate China. The results indicate that significant fragmentation differences occur between taxa. Ring-porous/semi-ring-porous taxa with a moderate density (>0.55 g/cm3) are overrepresented, while those with a very low to low density (<0.55 g/cm3) are moderately represented. Diffuse-porous taxa with slightly dense uniseriate rays, rare multiseriate rays and distinct helical thickenings are underrepresented, and those with slightly dense multiseriate rays are overrepresented, while those with rare to moderate multiseriate rays and helical thickening absence are moderately represented. Gymnosperm trees are generally well represented. Among the ubiquitous taxa at the archeological sites across northern China, Quercus and Ulmus may be overrepresented, and Pinus, Salix, Populus, and Acer may be underrepresented, while Betula may be moderately represented. [ABSTRACT FROM AUTHOR]

Aim The aims of this paper are to reconstruct the vegetation and fire history over the past 2000 years in a well-preserved rain-forest area, to understand interactions between climate, fire, and vegetation, and to predict how rain forest responds to global warming and increased intensity of human activity. Location Xishuangbanna, south-west China, 21–22° N, 101–102° E. Methods Phytolith (plant opal silica bodies) morphotypes, assemblages, and indices were used to reconstruct palaeovegetation and palaeoclimate changes in detail. Micro-charcoal particles found in phytolith slides, together with burnt phytoliths and highly weathered bulliform cells, were employed to reconstruct a record of past fire occurrence. A survey of field sediments, lithology, and 14C dating were also employed. Results Phytoliths were divided into 11 groups and classified into 33 well-described morphotypes according to their shape under light microscopy and their presumed anatomical origins and ecological significance. The phytolith assemblages were divided into six significant zones that reveal a complete history of vegetation changes corresponding to climate variation and fire occurrence. Phytolith assemblages and indices show that the palaeoclimate in the study area is characterized by the alternation of warm–wet and cool–dry conditions. Phytolith and charcoal records reveal that 12 fire episodes occurred. Comparison of burnt phytoliths with an aridity index (Iph) shows that fire episodes have a strong relationship with drought events. Main conclusions Our results indicate that fire occurrence in the tropical rain forest of Xishuangbanna is predominantly under the control of natural climate variability (drought events). Nearly every fire episode is coupled with a climatic event and has triggered vegetation composition changes marked by a pronounced expansion of grasses. This indicates that drought interacts with fire to exert a strong influence on the ecological dynamics of the rain forest. However, the impact of human activity in recent centuries is also significant. Our results are important for understanding the interactions between climate, fire, and vegetation, and for predicting how rain forest responds to global warming and increased human activity. [ABSTRACT FROM AUTHOR]

Iron and steel sector is the largest industrial energy consumer and emission source of greenhouse gas and air pollutants in China. Therefore, it is imperative to conduct a quantitative assessment for energy conservation potential and environmental benefits of China's iron and steel industry. Energy efficiency improvement, EAF promotion and charcoal substitution are efficient measures to achieve cleaner and sustainable development. In this paper, five scenarios are designed for comprehensively analyzing the multiple factors influencing the potential for energy conservation and emission reduction. Furthermore, emissions reduction benefits of air pollutants are combined with Conservation Supply Curves to accurately evaluate the cost of the technology. A comprehensive emission inventory of air pollutants is established. The results show that under the synergistic effects of charcoal substitution, EAF improvement and energy efficiency improvement, significant environmental benefits have been achieved. Energy intensity was reduced obviously from 16.59 GJ/t-steel in 2017 to 14.46 GJ/t-steel in 2030 in integrated scenario, while the emission intensity of GHG, SO 2 , NO x , PM 2.5 , PM 10 , CO and VOCs in 2030 is decreased by 21.53%, 14.59%, 17.07%, 0.16%, 0.22%, 16.5% and 20.67% compared with business-as-usual scenario. In addition, combining Conservation Supply Curves with emissions reduction benefits can significantly reduce the cost of the technology, which has a great significance to the popularization and application of technologies. Sensitivity analysis in terms of discount rate and energy price is conducted. This study could help policy makers to cast light on the status quo and prompt more effective policies for China's iron and steel industry. Image 1 • Energy conservation and emission reduction supply curve model was established. • Mitigation potential of three greenhouse gases and six air pollutants were studied. • The effect of charcoal substitution in the iron-making process was evaluated. • Five scenarios were set to assess the energy saving and mitigation potential. [ABSTRACT FROM AUTHOR]