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Occlusion of carbon (C) within phytoliths (PhytOC) is becoming one of the most promising terrestrial C sequestration mechanisms. This study explored the production of PhytOC within 35 bamboo species belonging to three ecotypes using methods of microwave digestion. The aim of this study is to explore the present and potential C sequestration rate within phytoliths of bamboo species from three ecotypes. PhytOC content in bamboos of three ecotypes ranges from 0.07 % to 0.42 %. The mean PhytOC production flux decreases as: clustered bamboo (0.050 ± 0.016 t CO2 ha−1 a−1) ≈ mixed bamboo (0.049 ± 0.016 t CO2 ha−1 a−1) > scattered bamboo (0.038 ± 0.020 t CO2 ha−1 a−1). The phytolith carbon sequestration in Chinese bamboo is estimated to be 0.293 ± 0.127 Tg (1 Tg = 1012 g) CO2 a−1; approximately 75 %, 3 %, and 22 % of which is contributed from scattered, mixed and clustered bamboo, respectively. Taking the PhytOC production flux of 0.18 ± 0.12 t CO2 ha−1 a−1 and current annual area increasing rate of 3 %, global bamboo phytoliths would sequester 11.9 ± 7.9 Tg CO2 a−1 by 2050. Consequently, bamboo forests have significant potential to mitigate the increasing concentration of atmospheric CO2 by maximizing PhytOC production flux and expanding bamboos.

Climatic variability during the Holocene and corresponding anthropogenic response have gained considerable attention in different parts of India, but surprisingly very little is known on climate-human interrelationship from eastern India especially from the Gangetic plains of West Bengal. As climate has played significant role behind the collapse of many of the ancient human civilizations hence, to explore the reason behind the abandonment of any archaeological site, understanding of the climate of the contemporaneous past is a prerequisite. Agricultural development, subsistence strategies and dynamic behavior of climate in the Lower Gangetic plains of West Bengal since ca. 3600 cal a BP (Chalcolithic period) and post-Chalcolithic period (ca. 2350-2120 cal a BP to recent) were explored using multiproxy approach including plant-animal macro remains, wood charcoals and pollen and non-pollen palynomorphs from an archaeological site at Pakhanna, district Bankura in West Bengal, India. Evidences from palynological and phytolith data suggest that a warm-moist tropical climate during ca. 3600 cal a BP supported the spread of a village farming community in this part of lower Gangetic plains of West Bengal who practiced double-cropping as evidenced by the recovery of cereals (rice) and pulses (black gram) from the cultural deposits of Chalcolithic and Early Historic periods. In addition, a plenty of animal remains (opercula of carp fishes, fragments of plastron of Indian Soft Shelled Turtle, Indian Flap Shelled Turtle, ramus of mandible with teeth of Indian Boar) from similar cultural deposits indicate their probable inclusion in dietary list. The climate started changing during the onset of Early Historic period ca. 2350 cal a BP as revealed by pollen and phytolith proxies and became warmer and drier than that in earlier phase which is continuing till recent. The observations of palynological and phytolith data were also corroborated by the results of correspondence analysis (CA) and canonical correspondence analysis (CCA) respectively. Recovery of rice and mustard from Early Historic deposits suggests their continued cultivation at a later phase. Rich assemblages of animal macro remains from the post-Chalcolithic deposits (ca. 2350-2120 cal a BP) indicate their use as food resources in later phase too. Considering the database obtained from all the proxies it can be concluded that a moist-tropical climatic condition was prevailing during Chalcolithic period (ca. 3600 cal a BP) and later gradually shifted to a slight drier condition in lower Gangetic West Bengal.

Phytoliths are noncrystalline minerals that form inside cells and cell walls of different parts of plants. Organic carbon in living cells can be occluded in phytoliths during plant growth. It has been documented that the occluded carbon within phytoliths is an important long-term terrestrial carbon reservoir that has a major role in the global carbon cycle. Common millet and foxtail millet have become typical dry-farming crops in China since the Neolithic Age. The study of carbon conservation within phytoliths in these crops could provide insights into anthropogenic influences on the carbon cycle. In this study, we analyzed the carbon content in phytoliths of common millet and foxtail millet. The results indicated that (1) common millet and foxtail millet contained 0.136% ± 0.070% and 0.129%± 0.085% phytolith-occluded carbon (PhytOC) on a dry mass basis, respectively; (2) based on the mean annual production of common millet and foxtail millet in the last 10 years, the phytolith occluded carbon accumulation rate of common millet and foxtail millet was approximately 0.023 ± 0.015 and 0.020± 0.010 t CO2 ha−1 a−1, respectively; (3) assuming a similar phytolith occluded carbon accumulation rate as for common millet (the highest accumulation rate was 0.038 t CO2 ha−1 a−1), this could result in the sequestration of 2.37 × 106 t CO2 per year for the 62.4 × 106 ha dry-farming crops in China. Although there was a decline in the annual production rate and planting area of foxtail millet during 1949 to 2008, the total phytolith carbon sequestration rate was 7×106 t CO2 within the 60-year period. However, phytolith occluded carbon has not yet been fully considered as a global carbon sink. Also, this carbon fraction is probably one of the best candidates for the missing carbon sink.

Measuring the response of terrestrial ecosystems to elevated CO2 concentrations is very important for understanding the effects of global change. In this study, OTC (open top chambers) were used to simulate elevated CO2 concentrations in the Songnen Grassland. As well, phytoliths in Leymus chinensis were extracted to study the relationships between phytoliths and CO2 concentration. The results show the rondel is abundant in Leymus chinensis, while the trapeziform polylobate is rare. When phytolith production is increased, the rondel phytoliths grow bigger and the proportions of the different phytolith types changes under high CO2 concentration. These types include elongate hollow, acicular hair cell, square and laminate and are only observed in samples grown under high CO2 concentrations. All this evidence demonstrates that phytoliths in Leymus chinensis are sensitive to CO2 concentration, and indicate that phytolith analysis may have potential use in the study of global change, identifying different ecotypes of Leymus chinensis and for the reconstruction of paleoatmospheric CO2 concentrations.

To identify and study the Neolithic rice paddy in Shandong, eastern China, is not only an important issue in the development of Chinese rice agriculture, but also a key part of the study on rice spread in East Asia. Due to the limitation of archaeological materials and the research methods, there have been no discoveries about the Neolithic rice paddy in Shandong Province for a long time. Based on the identification of possible rice paddy by archaeological excavation, phytolith analysis of soil samples from this “paddy” has been systematically carried out and the results have shown a 4600–4300 years old rice paddy preserved at the Zhaojiazhuang site. This is the first examination and study of the rice paddy in North China by systematic phytolith analysis, which is very important for the Neolithic archaeological research and the study of the eastward spread of rice agricultural techniques in East Asia.

A study on phytoliths and their climate indexes is carried out fromHomo erectus’ cave deposits in Hulu Cave, Nanjing. Evidence shows that phytolith assemblages of the cave deposits are dominated by the cold resistant types with a lower warm index, reflecting an overall cold inclined climate. This possibly connects the cave deposits with glacial climate to a great extent, which is in accordance with the northern fauna revealed by fossil mammals and temperate climate indicated by pollen assemblages. According to the distributional state of the phytoliths and their climate indexes on 4 profiles in the cave, it is revealed that profiles I and II display certain cold/warm, and dry/wet fluctuations; profile HI shows a humid and cold condition with the highest humility in the cave deposits; while profile IV indicates a possible quick accumulating process because of its stable climate indexes except for its bottom and top.

Shanghai Museum has got great achievements in re-excavating Guangfulin relics. It is the first time that the cultural remains of Wangyoufang type is found above the Liangzhu cultural remains which comes from East Henan Province, providing previous materials for researching culture evolution around Taihu Lake. Samples were taken from the immature soil layer and cultural layers of Guangfulin relics for phytolith analysis. According to the systemic research for the archaeological remains and phytolith fossil, the phytoliths in Guangfulin relics can be divided into four zones. The development of rice agriculture and living condition of Guangfulin ancestors was discussed based on the existing rice fan-shaped phytolith, rice shell phytolith, diatom fossil and archaeology evidence in the same layer. The Guangfulin relics has gradually developed since a high sea level 5000 years ago, and the broad rice agriculture has simultaneously developed. The newly re-excavated relics provides valuable materials for the research of ancestors and ancient culture in Shanghai.

The macro-environment of the region and the site agriculture interpreted from the phytolith assemblages at Yingyang site are as follows: i)In the mid-late period of Yangshao Culture five thousand years ago, the regional climate of Dengfeng County is warm and wet; ii)In the mid-late period of Yangshao Culture, rice farming may have been practised in the region.

As an important long-term terrestrial carbon sequestration mechanism, biogeochemical sequestration of carbon within phytoliths may play a significant role in the global carbon cycle and climate change. The aim of this study is to explore the potential of carbon bio-sequestration within phytoliths produced by wetland plants. The results show that the occluded carbon content of phytoliths in wetland plants ranges from 0.49% to 3.97%, with a CV (coefficient of variation) value of 810%. The data also indicate that the phytolith-occluded carbon (PhytOC) content of biomass for wetland plants depends not only on the phytolith content of biomass, but also the efficiency of carbon occlusion within phytoliths during plant growth in herb-dominated fens. The fluxes of carbon bio-sequestration within phytoliths of herb-dominated fen plants range from 0.003 to 0.077 t CO2 equivalents t-e-CO2 ha−1 a−1. In China, 0.04×106 to 1.05×106 t CO2 equivalents per year may be sequestrated in phytoliths of herbaceous-dominated fen plants. Globally, taking a fen area of 1.48×108 ha and the largest phytolith carbon biosequestration flux (0.077 t-e-CO2 ha−1 a−1) for herb-dominated fen plants, about 1.14×107 t CO2 equivalents per year would have been sequestrated in phytoliths of fen plants. If other wetland plants have similar PhytOC production flux with herb-dominated fen plants (0.077 t-e-CO2 ha−1 a−1), about 4.39×107 t-e-CO2 a−1 may be sequestrated in the phytoliths of world wetland plants. The data indicate that the management of wetland ecosystems (e.g. selection of plant species) to maximize the production of PhytOC have the potential to bio-sequestrate considerable quantities of atmospheric CO2.