Erosion and Nutrient Loss on Sloping Land under Intense Cultivation in Southern Vietnam

To help improve the well‐being of the local people, a joint Vietnamese‐UK team set out to establish a way of estimating soil and nutrient losses under different land management scenarios, using field data extrapolated through remote sensing and GIS, to obtain catchment‐wide estimates of the impact of land cover change. Immigration from remote provinces to the Dong Phu District of Binh Phuóc Province, about 120 km north of Ho Chi Minh City, has led to disruption of soil surface stability on easily eroded clayey sandstones, creating rapid nutrient depletion that affects crop yields and siltation in the channel of the Rach Rat river downstream. The poor farmers of the areas see crop yields drop dramatically after two or three years of cultivation due to the fertility decline. Soil loss varies dramatically between wet season and dry season and with ground cover. Erosion bridge measurements showed a mean loss of 85.2 t ha^?1 y^?1 under cassava saplings with cashew nuts, 43.3 t ha^?1 y^?1 on uncultivated land and 41.7 t ha^?1 y^?1 under mature cassava. The rates of erosion were higher than those reported in many other parts of Vietnam, reflecting the high erodibility of the friable sandy soils on the steep side‐slopes of the Rach Rat catchment. However, although the actual measurements provide better soil loss data than estimates based on the parameters of soil loss equations, a large number of measurement sites is needed to provide adequate coverage of the crop and slope combinations in this dissected terrain for good prediction using GIS and remote sensing.     

THE ROLE OF DAGGERS IN EARLY BRONZE AGE BRITAIN: THE EVIDENCE OF WEAR ANALYSIS

Summary. This paper examines the detailed condition of 55 Early Bronze Age daggers from central southern England. It appears that the more elaborate weapons had remained in circulation for a longer period than other examples.     

CLIMATE CHANGE and RECREATION IN NAHANNI NATIONAL PARK RESERVE

Prospects of global climatic change may present challenging physical, biological and managerial problems for Canadian national parks. A study was undertaken to assess the possible implications of climatic warming on water-based recreation activities of Nahanni National Park Reserve (nnpr). Significant increases in mean annual temperature and moderate increases in precipitation totals are expected for the park under a doubling of co₂. Under such conditions, hydrological changes would have little effect on the execution of river recreation, whereas forest fire and ecological changes would likely ha ve significant impacts on the experience of river recreation. Two complementary management strategies, ecological and visitor monitoring, are proposed to respond to uncertainties associated with environmental change.
Le changement global du climat peut poser de nou veaux problèmes d'ordre physique, biologique et dans l'aménagement des Pares Nationaux Canadiens. Une étude a été entreprise pour étudier les impacts possibles du rechauffement global sur la récréation aquatique dans la réserve nationale Nahanni (nnpr). Une augmentation significative de la température moyenne est accompagnée d'une légère augmentation de la précipitation comme nous l'espérions en cas de doublement de CO₂. if y aura peu d' effets sur l'utilisation des rivières à des fins récréatives. Les feux de forêts ainsi que le changement écologique auront des impacts plus significatifs. Deux stratégies d'aménagement, l'une écologique et l'autre au niveau des visiteurs, sont proposées pour répondre au changement environnemental dans le Pare.