Increased precipitation during the Little Ice Age in northern Taiwan inferred from diatoms and geochemistry in a sediment core from a subalpine lake

We studied diatoms in a 55.5-cm-long sediment core from a subalpine lake in northern Taiwan, Tsuifong Lake (TFL), to investigate environmental changes from AD 490 to present. Diatom assemblages of the last century were dominated by acidophilous species, whereas alkaliphilous taxa dominated the record between AD 1480 and 1910. Over the studied time frame, four decadal periods with high precipitation were inferred from evidence of elevated soil input from the watershed, supported by the stable isotope signatures (δ¹⁵N, δ¹³C) of organic matter and magnetic susceptibility of the sediments. We compared the inferred changes in pH of TFL to values obtained from three other Taiwanese subalpine lakes. The present study revealed that elevated precipitation was associated with increased solar irradiance over the last five centuries, with a stable dry period between AD 490 and 1450. Acidification of TFL in the last ~100 years was a consequence of deforestation and acid rain.     

Land subsidence pattern controlled by old alpine basement faults in the Kashmar Valley, northeast Iran: results from InSAR and levelling

Fluid storage systems, such as oil, gas, magma or water reservoirs, are often controlled by the host rock structure and faulted terrain. In sedimentary basins, where no direct information about underlying structure is available, the pattern of ground deformation may allow us to assess the buried fault arrangement. We provide an example in the semi-arid area of Iran, in the Kashmar Valley, a region subject to land subsidence due to water overexploitation. Geodetically determined subsidence rates in the Kashmar Valley exceed 15–30 cm yr⁻¹. The pattern of surface deformation is strongly non-uniform and displays NE–SW elongated bowls of subsidence. The trend resembles old Cretaceous-to-Tertiary faults that evolved during early alpine tectonic deformation. Although these early alpine structures are considered tectonically inactive in the present day, the observed land subsidence pattern indicates significant structural control on the geometry of the aquifer basin and its deformation during reservoir drainage.     

Soil and plant composition in the Noun river catchment basin,Western Cameroon: a contribution to the development of a biogeochemical baseline

Soils and selected edible plants of the Noun river catchment basin of western Cameroon were sampled to investigate the distribution of trace elements, based on the preliminary idea of unusual anomalies. Analytical techniques for trace elements included ICP-AES, GF-AAS, and ICP-MS. Further soil analyses comprised the mineralogy and contents of the biogenic elements carbon, nitrogen and sulphur (CNS). The trace element concentrations in the soils reflect those of the lithogeochemical background of the pluto-volcanic rocks of the region. This is consistent with the results from the mineralogical analyses and physicochemical parameters such as pH, taken in the field, which also do not suggest any geochemical anomaly. Most trace elements analyzed in the plants showed concentrations that reflect those of the soils (Al, Fe, Ti, and Rb). However, some trace elements were enriched in the plants as compared to the soils, such as Zn, Cu, Cd, Mo (excluding yam), Ni (peanut), Ba (peanut), Sr (peanut, bean), and B. Trace elements such as As, Cr, V, and Se were not bioavailable for all the analyzed plants. Besides, trace elements such as Cu, Zn, Mo, Fe, Al, Ni, B, Ti, Rb, Cs, and Ba were in the range of phytotoxicity and reached or exceeded human food tolerance level (Cu). The plants with seeds showed a higher absorption of trace elements compared to plants with tubercles.     

Holocene Amazon rainforest–savanna dynamics and climatic implications: high‐resolution pollen record from Laguna Loma Linda in eastern Colombia

We present a high‐resolution pollen record of a 695‐cm‐long sediment core from Laguna Loma Linda, located at an altitude of 310 m in the transitional zone between the savannas of the Llanos Orientales and the Amazonian rainforest, about 100 km from the Eastern Cordillera. Based on eight AMS ¹⁴C ages, the record represents the last 8700 ¹⁴C yr BP. During the period from 8700 to 6000 ¹⁴C yr BP the vegetation was dominated by grass savanna with only a few woody taxa, such as Curatella and Byrsonima, present in low abundance. Gallery forest along the drainage system apparently was poorly developed. Compared with today, precipitation must have been significantly lower and seasonality stronger. During the period from 6000 to 3600 ¹⁴C yr BP, rainforest taxa increased markedly, reflecting an increase in precipitation. Rainforest and gallery forest taxa such as Moraceae/Urticaceae, Melastomataceae, Alchornea, Cecropia and Acalypha, were abundant, whereas Poaceae were reduced in frequency. From 3600 to 2300 ¹⁴C yr BP rainforest taxa continued to increase; Moraceae/Urticaceae became very frequent, and Myrtaceae and Myrsine became common. Savanna vegetation decreased continuously. We infer that precipitation was still increasing, and that the length of the annual dry period possibly shortened. From 2300 ¹⁴C yr BP onwards, grass savanna (mainly represented by Poaceae) expanded and Mauritia palms became frequent. This reflects increased human impact on the vegetation. Copyright © 2000 John Wiley & Sons, Ltd.     

Late Quaternary vegetational and climatic change in the Popayán region,southern Colombian Andes

Late Pleistocene and Holocene vegetational and climatic change have been studied palynologically at a site at 1750 m elevation in the subandean vegetation belt near Popayán, in the southern Colombian Andes. Time control on the pollen record is based on six AMS ¹⁴C ages, ranging from possibly Middle Pleniglacial time (around 50000 yr BP) to 1092 ± 44 yr BP. Because of the presence of two hiatuses only the Middle Pleniglacial and Late Holocene periods (the last 2300 yr BP) are represented. Pollen data indicate the presence of closed subandean forest during glacial time. Changes in the contribution of pollen originating from the uppermost and lowermost subandean forest belts, changes in the contribution of a number of other subandean forest taxa, and changes in species composition between the three pollen zones, suggest that the climate during the Middle Pleniglacial was markedly colder, and perhaps also wetter, than during the Late Holocene. Pollen assemblages from the Late Holocene indicate that the landscape has been affected by deforestation and agriculture since at least 2300 yr BP, but that human impact decreased in the last 780 yr BP. © 1998 John Wiley & Sons, Ltd.     

Food consumption,diet shifts and associated non-CO2 greenhouse gases from agricultural production

Today, the agricultural sector accounts for approximately 15% of total global anthropogenic emissions, mainly methane and nitrous oxide. Projecting the future development of agricultural non-CO₂ greenhouse gas (GHG) emissions is important to assess their impacts on the climate system but poses many problems as future demand of agricultural products is highly uncertain. We developed a global land use model (MAgPIE) that is suited to assess future anthropogenic agricultural non-CO₂ GHG emissions from various agricultural activities by combining socio-economic information on population, income, food demand, and production costs with spatially explicit environmental data on potential crop yields. In this article we describe how agricultural non-CO₂ GHG emissions are implemented within MAgPIE and compare our simulation results with other studies. Furthermore, we apply the model up to 2055 to assess the impact of future changes in food consumption and diet shifts, but also of technological mitigation options on agricultural non-CO₂ GHG emissions. As a result, we found that global agricultural non-CO₂ emissions increase significantly until 2055 if food energy consumption and diet preferences remain constant at the level of 1995. Non-CO₂ GHG emissions will rise even more if increasing food energy consumption and changing dietary preferences towards higher value foods, like meat and milk, with increasing income are taken into account. In contrast, under a scenario of reduced meat consumption, non-CO₂ GHG emissions would decrease even compared to 1995. Technological mitigation options in the agricultural sector have also the capability of decreasing non-CO₂ GHG emissions significantly. However, these technological mitigation options are not as effective as changes in food consumption. Highest reduction potentials will be achieved by a combination of both approaches.