ASSESSMENT OF SPOT SATELLITE DATA FOR TROPICAL VEGETATION INVENTORY AND MONITORING IN SUMATRA

Following  a  previous  vegetation  mapping  in  Sumatra  island  (Indonesia),  an  assessment  of  SPOT satellite capability to handle specific problems related to vegetation identification and monitoring from  remote sensing data has been undertaken. Results of visual interpretation and multispectral analysis have shown the usefulness of SPOT data  for the appraisal  of  tropical  vegetation  at medium  scale. This was  particularly  striking  for  the  swampy  vegetation types  including mangroves  and  for  the  secondary vegetation,  for which  significant  improvements have been brought by multispectral classifications. A 20 m ground resolution is neither sufficient  to provide information on  primary  forest  patterns,  nor  to  identify  properly  logged  over  areas.  Never theless,  several  degrees  of depletion  of  the  forest  and  all  the  serial  stages  have  been  identified,  which  is  a  considerable  progress compared with previous remote sensing means. SPOT is a very good alternative to medium scale aerial photographs for the production of medium  scale (1 : 100 000 to 1 : 250 000) vegetation and land-use maps

Assessment of Spot Satellite Data for Tropical Vegetation Inventory and Monitoring in Sumatra

Following a previous vegetation mapping in Sumatra island (Indonesia), an assessment of SPOT satellite capability to handle specific problems related to vegetation identification and monitoring from remote sensing data has been undertaken. Results of visual interpretation and multispectral analysis have shown the usefulness of SPOT data for the appraisal of tropical vegetation at medium scale. This was particularly striking for the swampy vegetation types including mangroves and for the secondary vegetation, for which significant improvements have been brought by multispectral classifications. A 20 m ground resolution is neither sufficient to provide information on primary forest patterns, nor to identify properly logged over areas. Never theless, several degrees of depletion of the forest and all the serial stages have been identified, which is a considerable progress compared with previous remote sensing means. SPOT is a very good alternative to medium scale aerial photographs for the production of medium scale (1 : 100 000 to 1 : 250 000) vegetation and land-use maps

Suitability of Local Resource Management Practices Based on Supernatural Enforcement Mechanisms in the Local Social-cultural Context

Environmental anthropological studies on natural resource management have widely demonstrated and thematized local resource management practices based on the interactions between local people and supernatural agencies and their role in maintaining natural resources. In Indonesia, even though the legal status of local people's right to the forest and forest resources is still weak, the recent transition toward decentralization presents a growing opportunity for local people to collaborate with outsiders such as governmental agencies and environmental nongovernmental organizations in natural resource management. In such situations, in-depth understanding of the value of local resource management practices is needed to promote self-directed and effective resource management. Here, we focus on local forest resource management and its suitability in the local social-cultural context in central Seram, east Indonesia. Local resource management appears to be embedded in the wider social-cultural context of the local communities. However, few intensive case studies in Indonesia have addressed the relationship between the Indigenous resource management practices closely related to a people's belief in supernatural agents and the social-cultural context. We illustrate how the well-structured use of forest resources is established and maintained through these interactions. We then investigate how local resource management practices relate to the social-cultural and natural resources context of an upland community in central Seram and discuss the possible future applications for achieving conservation

The effect of pressure and water concentration on the electrical conductivity of dacitic melts: Implication for magnetotelluric imaging in subduction areas

International audienceSilica-rich hydrous magmas are commonly stored in crustal reservoirs, but are also present at mantle depths in subduction contexts as a result of slab melting in the presence of considerable amounts of water and other vol-atile species. Magnetotelluric surveys frequently identify highly conductive zones at crustal or mantle depths possibly revealing the presence of such silica-rich melts and this can be used to trace the cycling of water in sub-duction zones and its relationship with arc-magmatism. The achievement of such a purpose is impeded by poor knowledge of the electrical conductivity of both dry and hydrous silica-rich melts at pressure. To fill this gap, we performed in situ electrical conductivity measurements on a dacitic melt using a 4-wire set up to 1300 °C, 3.0 GPa and H 2 O content up to 12 wt.%. Melt conductivity is strongly correlated with its water content, and we reveal a complex effect of pressure being relatively small at low water contents and major at high water contents: with increasing water content, the activation volume ranges between 4 (dry) and 25 cm 3 /mol (H 2 O = 12 wt.%) and the activation energy decreases from 96 kJ (dry) to 62 kJ (12 wt.% H 2 O). By comparison with diffusivity data, so-dium appears to be the main charge carrier, even at high (12 wt.%) water content. A T–P–[H 2 O] model predicting the conductivity of dacitic melts shows that crustal and mantle wedge conductive bodies can be interpreted by the presence of silica-rich, hydrous, partially crystallized magma