Environmental Changes and Human Impacts on Landscapes near Medieval Steklyanukha-2 Fortress in Russia from Early Iron Age to Modern Times

The development of landscapes in one of the most populated river basins of the southern Russian Far East was studied using pollen and diatom data. The study sites were a multi-layered mountain fortress, Steklyanukha-2, and an Upper Holocene high floodplain sequence of the Steklyanukha River. Buried soil from the fluvial section acts as an environmental archive of the time in which people from the Yankovskaya archeological cultures settled in the river basin. The soil was formed under conditions of decreasing water supply in the valley and prolonged droughts. Findings of pollen Fagopyrum and Urtica signal economic activity in the Early Iron Age.Floodplain lake sediments accumulated from 1.6 to 0.5 kyr, when the valley was actively developed during the Middle Ages. There are signals of the development of secondary birch and oak forests. In the cultural layer of the fortress and lake sediments formed in the Middle Ages, Ambrosia and Xanthium pollens were found and are reliable evidence of agricultural activity in the valley. The pollens of plants typically seen in human-disturbed areas were also found. Indirect evidence of human activity includes non-pollen palynomorphs.The study of diatoms in a depression near a rampart confirmed the archaeologists' assumption that it was used as a water reserve. Pollen spectra from surface soils reflect agricultural activity in the river basin since the second half of the 19th century. The largest amount of pollen of alien and synanthropic plants and weeds, as well as spores of pathogenic fungi and fire indicators, were found here.

Impact of Variegated Temperature, CO<SUB>2</SUB>and Relative Humidity on Survival and Development of Beet Armyworm <i>Spodoptera exigua</i>(Hubner) under Controlled Growth Chamber

Climate change will have a noteworthy bearing on survival, development, and population dynamics of insect pests. Therefore, we contemplated the survival and development of beet army worm, Spodoptera exigua under different temperatures, (15°C, 25°C, 35°C, and 45°C), CO2 (350, 550, 750 ppm) and relative humidity (55%, 65%, 75% and 85%) regimes. Maximum larval and pupal weights were recorded in insects reared at 25°C. The growth of S. exigua was faster at 35°C (larval period 7.4 days and pupal period 4.5 days) than at lower temperatures. At 15°C, the larval period was extended for 61.4 days and there was no adult emergence from the pupae till 90 days. The S. exigua hatchling was absent at 45°C. The larval survival ranged from 31.6% - 57.2%, maximum survival was recorded at 25°C, and minimum at 45°C. The maximum (84.27%) and minimum adult emergence were recorded in insects reared at 25°C and 35°C respectively. Maximum fecundity (384.3 eggs/female) and egg viability (51.97%) were recorded in insects reared at 25°C. Larval and pupal periods increased with an increase in CO2 concentration. The highest pupal weights (128.6 mg/larva) were recorded at 550 ppm. The highest larval survival (73.50%) was recorded at 550 ppm and minimum (37.00%) at 750 ppm CO2. Fecundity was the highest in insects reared at 550 ppm CO2 (657.4 eggs/female), and the lowest at 750 ppm. Maximum larval and pupal weights were recorded in insects reared at 75% relative humidity (RH). The growth rate of S. exigua was faster at 85% RH than at lower RH. The larval survival ranged between 40.0% - 58.5%. Maximum adult emergence (88.91%) was recorded in insects reared at 75% RH and minimum at 85% RH. Maximum fecundity (447.6 eggs/female) and the highest egg viability (72.95%) were recorded in insects reared at 75% and 65% RH respectively. Elevated temperatures and relative moistness will diminish the life cycle, while hoisted CO2 will drag the life expectancy. Therefore, there is a need for thorough assessment of the impact of climatic factors on the population dynamics of insect pests, crop losses, and sustainability of crop production.

Alternating influences of the Westerlies and Indian Summer Monsoon on the hydroclimate of the source region of the Yarlung Tsangpo over past 4000 yr

The Yarlung Tsangpo,the longest river in the southern Tibetan Plateau(TP),has attracted much research attention aimed at understanding the factors controlling its modern hydrology and possible future discharge in the context of ongoing climate change.However,partly due to the complex regional climatic background,no consistent conclusions have been reached,especially for its upper reaches.Paleohydrological reconstructions of the source region of the Yarlung Tsangpo can potentially improve our understanding of the history of humidity and its response to climatic variability.In this study,we used a 97 cm gravity core from Gongzhu Co to reconstruct the hydrology change during the late Holocene.The core was dated using AMS ^(14)C and Pb/Cs methods,and we used measurements of element contents(determined by high-resolution XRF scanning),grain size,IC/TOC,and magnetic susceptibility to reconstruct hydroclimatic changes in the source of the Yarlung Tsangpo watershed since~4000 yr ago.Combined with a modern meteorological data set,we found that PC1 of the XRF data,the Ca/(Fe+Ti)ratio,and EM1 of the grain size data were indicative of changes in humidity.Our records demonstrate a wet interval during~4-1.7 ka BP(ka=1000 yr,BP represents years before 1950 AD),followed by a dry period during since~1 ka BP.Comparison with independent regional paleoclimatic records revealed shifts in the dominant factors controlling humidity.The wet interval during~4-1.7 ka BP was coeval with a strengthened Westerlies,implying a dominant moisture supply from northern high latitudes.However,the extremely low values of Ca/(Fe+Ti)ratio during~4-2.5 ka BP indicate potential glacial freshwater source,which is corroborated by the concurrent high magnetic susceptibility values and increased grain size.The rapid drying trend during~1.7-1 ka BP suggests a switch in moisture supply from the Westerlies to the Indian Summer Monsoon(ISM).We attribute the drought conditions after~1 ka BP to a weakened ISM,although a Westerlies influence and the potential effect of high temperatures on evaporation cannot be excluded.We suggest that future hydroclimatic research in this region should attempt to distinguish the individual moisture contributions of the ISM and the Westerlies during the last millennium.