First high-resolution micropaleontologic investigation was carried out for bottom sediments of the Cheshskaya Bay (SE Barents Sea) and marine beds exposed in abrasive terrace along the eastern coast of the Kanin Peninsula. Sediments from 2 gravity cores and a 7.5-m thick terrace section were analyzed for pollen and non-pollen palynomorphs (NPP), including spores, freshwater green algae and cysts of marine dinoflagellates. The age of the sediments was constrained by the reference to the regional sea-level history from the earliest Holocene to present, thus the pollen records reveal the environmental history for the last ca. 10.0 ka. Sparse treeless vegetation with dwarf Betula and halophytic inhabitants of seaside watts (cereals, wormwood and sedges) indicating arctic desert environment with colder and drier than present climate dominated the Cheshskaya Bay coast during the early Preboreal period. Gradual advance of shrubby-birch and piny forest-tundra with alder communities along river valleys resulted from significant climate amelioration which concurred with the Pholas inundation since the Boreal period. Postdated expansion of tree-birch inland the Kanin Peninsula and firry-birch light-forests along the Cheshskaya Bay coast marked the Holocene regional climate optimum. Re-establishment of the dwarf-birch and piny forest tundra signalized vegetation feedback to the cooling since the end of Atlantic period.
The paper discusses the new results of vegetation and climate reconstructions based on pollen data from the area of the forest-steppe ecotone area in the central part of European Russia (the Upper Don River basin). The obtained evidence shows he occurrence of open forest-steppe and steppe landscape in the studied area during the Middle and Late Holocene. Climatic reconstructions using the best-modern-analogue (BMA) technique show that landscape dynamics in the region were driven by changes in effective moisture: an excess of precipitation over evaporation. The reductions in annual precipitation in 50–100 mm were sufficient to increase the share of steppe communities in the complex landscape (in time periods 7000–6000, 2500–1700 cal yr BP) and, probably, higher frequencies of wildfires. Signals of anthropogenic disturbance of vegetation are clearly pronounced in the pollen and plant macrofossil records since the middle Atlantic. However, human-induced changes in the vegetation remained subtle until the medieval period.
The Chinese Loess Plateau experiences the most severe soil erosion in the world, induced by the destruction of natural vegetation for cultivation. To stop soil erosion, in 1999 the Chinese government began an intensive afforestation program named Grain-for-Green-Policy in order to convert steep cultivated land to forest and grassland. Balancing afforestation with grain production and water use is crucial for obtaining sustainable effects of soil conservation. This study assessed the current balance among afforestation, grain production, and water use in river basins on the Chinese Loess Plateau. Annual afforested area, planted area of grain fields, precipitation, and irrigated area in these river basins were compared based on the data collected from the statistical yearbooks of the Yan’an City. River discharge and sediment yield in the areas were compared based on data collected from the Annual Report on Chinese Soil Conservation. The evapotranspiration rates of the main crops cultivated in each river basin were also compared. Collectively, the data suggest that the balance between afforestation, grain production, and water use has been improved by the Grain-for-Green-Policy in the river basins on the Chinese Loess Plateau.
This study examines geomorphological controls on the distribution and development of wetlands in the Hachimantai Volcanic Group, northeastern Japan. The study area is dissected by various sizes of landslides and has many wetlands of varied origin. Among 526 wetlands in the study area, 195 are on landslides and account for 63.9% of the total area of wetlands. Wetlands outside of landslides tend to be found in clusters on undissected volcanic surfaces. Many of these are small wetlands in nivation hollows that are supplied by meteoric water from snow, and some of them are ponds in the craters of Hachimantai volcano and large peat bogs on lava flows. Wetlands inside landslides are widely scattered in large or deep depressions along landslide scarps and in small depressions among pressure ridges. Many of these are ponds supplied mainly by groundwater. Large landslides tend to have ponds. On the larger landslides, depressions created by landslide processes provide favorable conditions for the development of wetlands, and their size is constrained by the microtopography of the landslide surface. When drainage channels that dissect landslide bodies breach these closed depressions, the wetlands there progress rapidly from ponds to peat bogs. Landslide activities can create wetlands of various ages, and the dissection of landslide bodies controls the developmental stages of these wetlands. Therefore, a large landslide may contain coexisting wetlands of various ages and types.
Tributaries of Lake Tonle Sap in the Lower Mekong Basin are strongly influenced by seasonal changes of water level in Lake Tonle Sap and discharge of the Mekong River. The aim of this research was to gain a better understanding of the fluvial geomorphology of the Stung Sen River, a tributary of Lake Tonle Sap. We used stereopairs of aerial photographs and satellite images to identify the microtopography of the floodplain and riverbed, and field surveys to observe bankside topography and deposits. We recognized four types of channel bar in the lower Stung Seng River: lateral bars (type A), point bars (type B), concave-bank benches (type C), and diagonal and island bars (type D). Type A appears to have a complementary relationship with type D. In some instances types A and D bars transition to type B bars and, in rare instances, into type C bars. These changes are probably related to channel sinuosity and changes in the volume of transported sediment. Sediment transport and construction of the channel bars appears to be controlled by shifts of the flow regime of the Stung Sen River related to differences in the rate of water level rise in the river compared to those in Lake Tonle Sap. The riverine environment differs greatly from that of the floodplain, where sediment is deposited from suspension during periods of inundation.
The possible changes of Net Ecosystem Exchange (NEE) of CO2 and evapotranspiration (E) of a tropical rain forest due to climate change are described using a process-based CO2/H2O exchange model (Mixfor-SVAT). Projections of future climate conditions are provided by a global ECHAM5 model for the Special Report on Emission Scenarios (SRES) A1B. As a key region for this study, the tropical rain forest situated in Lore-Lindu National park in Central Sulawesi in Indonesia was selected. Results of the modeling experiments showed a very high sensitivity of NEE and E of this tropical rain forest to both the projected climate changes and the possible reduction of nutrients in plants due to the impact of gradually elevated CO2 in the air and depletion of soil nutrient resources. Under optimal conditions for carbon assimilation and biomass production, i.e. when the CO2 increase in the air is strictly balanced with nutrient supply, the projected climate changes will lead to increase of Gross Primary Production (GPP) by 21.3%, insignificant change of annual NEE and decrease of E by 18%. The ratio of E and precipitation, which determines the surface moisture conditions, decreases by 29.9% (from 0.78 to 0.55). It can lead to increases of soil wetness, ground water level and surface runoff in the study area in future. Limited nutrient supply can significantly reduce GPP, NEE and E. In particular the decrease of nutrient supply of about 20% can completely offset the possible GPP increase due to projected increases of temperature and CO2 concentration in the air.
This study examines the effects of a climate event on livelihood assets of households in upland northern Laos, when the early onset of the rainy season as a result of climate change led to a failure to burn swidden systems. A Sustainable Livelihoods Framework is applied to estimate rural livelihood assets associated with differences in climate conditions, such as the 2010 normal climate and the 2011 climate event, and to compare household strategies in each climate condition. The findings indicate that natural capital had the highest index value in the 2010 normal climate, whereas human capital had the highest value in the 2011 climate event. Financial capital had the lowest index in both climate conditions. Residents at the research site were better off in terms of natural capital but worse off in terms of financial capital. This indicates that the government and other rural development agencies should not only manage natural resources; income-generation activities are also needed. We conclude that natural resources, as well as non-timber forest product (NTFP) gathering and off-farm activity, were the most important strategies for the entire research site under the normal climate condition. NTFP gathering and outside work are important in meeting subsistence needs and augmenting income levels in households when the rainy season begins early as a result of climate change. Outside employment was an additional strategy in households to achieve their livelihood goals, including food security and household income generation, under conditions of economic change and climate events.