Transfer of Virtual Water of Woody Forest Products from China

Global freshwater resources are under increasing pressure. It is reported that international trade of water-intensive products (the so-called virtual water trade) can be used to ease global water pressure. In spite of the significant amount of international trade of woody forest products, virtual water of woody forest products (VWWFP) and the corresponding international trade are largely ignored. However, virtual water research has progressed steadily. This study maps VWWFP and statistically analyzes China’s official data for the period 1993–2014. The results show a rapid increase in the trend of VWWFP flow from China, reaching 7.61 × 1012 m3 or 3.48 times annual virtual water trade for agricultural products. The export and import volumes of China are respectively 1.27 × 1012 m3 and 6.34 × 1012 m3 for 1993–2014. China imported a total of 5.07 × 1012 m3 of VWWFP in 1993–2014 to lessen domestic water pressure, which is five times the annual water transfer via China’s South–North Water Transfer project. Asia and Europe account for the highest contribution (50.52%) to China’s import. Other contributors include the Russian Federation (16.63%), Indonesia (13.45%), Canada (13.41%), the United States of America (9.60%), Brazil (7.23%) and Malaysia (6.33%). China mainly exports VWWFP to Asia (47.68%), North America (23.24%), and Europe (20.01%). The countries which export the highest amount of VWWFP include the United States of America, Japan, Republic of Korea and Canada. Then the countries which import the highest amount of VWWFP include the Russian Federation, Canada, United States of America, and Brazil. The VWWFP flow study shows an obvious geographical distribution that is driven by proximity and traffic since transportation cost of woody forest products could be significant

Monitoring Land-Use/Land-Cover Changes at a Provincial Large Scale Using an Object-Oriented Technique and Medium-Resolution Remote-Sensing Images

An object-based image analysis (OBIA) technique is replacing traditional pixel-based methods and setting a new standard for monitoring land-use/land-cover changes (LUCC). To date, however, studies have focused mainly on small-scale exploratory experiments and high-resolution remote-sensing images. Therefore, this study used OBIA techniques and medium-resolution Chinese HJ-CCD images to monitor LUCC at the provincial scale. The results showed that while woodland was mainly distributed in the west, south, and east mountain areas of Hunan Province, the west had the largest area and most continuous distribution. Wetland was distributed mainly in the northern plain area, and cultivated land was distributed mainly in the central and northern plains and mountain valleys. The largest impervious surface was the Changzhutan urban agglomerate in the northeast plain area. The spatial distribution of land cover in Hunan Province was closely related to topography, government policy, and economic development. For the period 2000⁻2010, the areas of cultivated land transformed into woodland, grassland, and wetland were 183.87 km2, 5.57 km2, and 70.02 km2, respectively, indicating that the government-promoted ecologically engineered construction was yielding some results. The rapid economic growth and urbanization, high resource development intensity, and other natural factors offset the gains made in ecologically engineered construction and in increasing forest and wetland areas, respectively, by 229.82 km2 and 132.12 km2 from 2000 to 2010 in Hunan Province. The results also showed large spatial differences in change amplitude (LUCCA), change speed (LUCCS), and transformation processes in Hunan Province. The Changzhutan urban agglomerate and the surrounding prefectures had the largest LUCCA and LUCCS, where the dominant land cover accounted for the conversion of some 189.76 km2 of cultivated land, 129.30 km2 of woodland, and 6.12 km2 of wetland into impervious surfaces in 2000⁻2010. This conversion was attributed to accelerated urbanization and rapid economic growth in this region

Modeling the Effect of Climate Change on Water Stored above a Micro-Dam in an Inland Valley Swamp in Sierra Leone, Using SWAT

Many societies have experienced water scarcity resulting from population growth, increased urbanization and industrialization, increased irrigation associated with advances in agriculture productivity, desertification, global warming, or poor water quality. Climate change, and soil heterogeneity has a direct impact on the discharges of many rivers in and around the world. Various hydrological models have been used to characterize the impact of climate and soil properties on hydrology and water resources. The SWAT (Soil and Water Assessment Tool) water balance model, one such model, has been used at a variety of scales. In this instance it was used to model the impact of climate change on water storage in a reservoir at the downstream end of a small (75 ha) watershed. The watershed is the major component of an inland valley swamp, with a valley bottom that receives runoff from the watershed. The SWAT model was calibrated using storage data from 2014/15 and validated with data from 2015/16. Using future ensemble values derived from GCMs, the model predicted a reduction in the storage volume at the beginning of December of every dry season, with the 100-year storage volume down from 10,000 to 6900 cubic meters

Effect of Biochar Application Depth on Crop Productivity Under Tropical Rainfed Conditions

Although inherently fertile, tropical soils rapidly degrade soon after cultivation. The period of time for which crops, mulch, compost, and manure provide nutrients and maintain mineral fertilizers in the soil is relatively short. Biochar, on the other hand, has the potential to maintain soil fertility and sequester carbon for hundreds or even thousands of years. This study determined the effect of biochar application depth on the productivity of NERICA-4 upland rice cultivar under tropical rainfed conditions. A fixed biochar–soil ratio of 1:20 (5% biochar) was applied in three depths—10 cm (TA), 20 cm (TB), and 30 cm (TC) with a non-biochar treatment (CK) as the control. The study showed that while crop productivity increased, root penetration depth decreased with increasing biochar application depth. Soil moisture was highest under TA (probably due to water logging in sunken-bed plots that formed after treatment) and lowest under TC (due to runoff over the raised-bed plots that formed too). Grain yield for the biochar treatments was 391.01–570.45 kg/ha (average of 480.21 kg/ha), with the potential to reach 576.47–780.57 kg/ha (average of 695.73 kg/ha) if contingent field conditions including pest damage and runoff can be prevented. By quantifying the effect of externalities on the field experiment, the study showed that biochar can enhance crop productivity. This was good for sustainable food production and for taking hungry Africa off the donor-driven food ration the nation barely survives on