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Bautista F.,National Autonomous University of Mexico | Zinck J.A.,International Institute for Geo information Science and Earth Observation
Journal of Ethnobiology and Ethnomedicine | Year: 2010

Background: Mayas living in southeast Mexico have used soils for millennia and provide thus a good example for understanding soil-culture relationships and for exploring the ways indigenous people name and classify the soils of their territory. This paper shows an attempt to organize the Maya soil knowledge into a soil classification scheme and compares the latter with the World Reference Base for Soil Resources (WRB).Methods: Several participative soil surveys were carried out in the period 2000-2009 with the help of bilingual Maya-Spanish-speaking farmers. A multilingual soil database was built with 315 soil profile descriptions.Results: On the basis of the diagnostic soil properties and the soil nomenclature used by Maya farmers, a soil classification scheme with a hierarchic, dichotomous and open structure was constructed, organized in groups and qualifiers in a fashion similar to that of the WRB system. Maya soil properties were used at the same categorical levels as similar diagnostic properties are used in the WRB system.Conclusions: The Maya soil classification (MSC) is a natural system based on key properties, such as relief position, rock types, size and quantity of stones, color of topsoil and subsoil, depth, water dynamics, and plant-supporting processes. The MSC addresses the soil properties of surficial and subsurficial horizons, and uses plant communities as qualifier in some cases. The MSC is more accurate than the WRB for classifying Leptosols. © 2010 Bautista and Zinck; licensee BioMed Central Ltd. Source

Zhang Y.,Free University of Berlin | Guanter L.,Free University of Berlin | Berry J.A.,Carnegie Institution for Science | Joiner J.,NASA | And 5 more authors.
Global Change Biology | Year: 2014

Photosynthesis simulations by terrestrial biosphere models are usually based on the Farquhar's model, in which the maximum rate of carboxylation (Vcmax) is a key control parameter of photosynthetic capacity. Even though Vcmax is known to vary substantially in space and time in response to environmental controls, it is typically parameterized in models with tabulated values associated to plant functional types. Remote sensing can be used to produce a spatially continuous and temporally resolved view on photosynthetic efficiency, but traditional vegetation observations based on spectral reflectance lack a direct link to plant photochemical processes. Alternatively, recent space-borne measurements of sun-induced chlorophyll fluorescence (SIF) can offer an observational constraint on photosynthesis simulations. Here, we show that top-of-canopy SIF measurements from space are sensitive to Vcmax at the ecosystem level, and present an approach to invert Vcmax from SIF data. We use the Soil-Canopy Observation of Photosynthesis and Energy (SCOPE) balance model to derive empirical relationships between seasonal Vcmax and SIF which are used to solve the inverse problem. We evaluate our Vcmax estimation method at six agricultural flux tower sites in the midwestern US using spaced-based SIF retrievals. Our Vcmax estimates agree well with literature values for corn and soybean plants (average values of 37 and 101 μmol m-2 s-1, respectively) and show plausible seasonal patterns. The effect of the updated seasonally varying Vcmax parameterization on simulated gross primary productivity (GPP) is tested by comparing to simulations with fixed Vcmax values. Validation against flux tower observations demonstrate that simulations of GPP and light use efficiency improve significantly when our time-resolved Vcmax estimates from SIF are used, with R2 for GPP comparisons increasing from 0.85 to 0.93, and for light use efficiency from 0.44 to 0.83. Our results support the use of space-based SIF data as a proxy for photosynthetic capacity and suggest the potential for global, time-resolved estimates of Vcmax. © 2014 John Wiley & Sons Ltd. Source

van Gils H.,International Institute for Geo information Science and Earth Observation | Odoi J.O.,Nature Today | Andrisano T.,Aquila
Forest Ecology and Management | Year: 2010

Alternative hypotheses on post-fire successions of monospecific European beech (Fagus sylvatica L.) and black pine (Pinus nigra Arnold) forests are investigated. The research area is located in the centre of the Apennine montane belt, Italy and covers portions of the Roccamorice and Lettomanoppello municipalities within the Majella National Park. Temporal moderate-resolution (MODIS) and spatial mid-resolution (ASTER) imagery are combined for the assessment of the 2007-fire features. Tree seedlings were surveyed on the ground in post-fire forests and their unburnt equivalents during September 2008. The satellite imagery analysis provides records on spread, intensity, location and extent of the forest fires. The evidence suggests an abandoned farmland fire spreading secondarily uphill into the forests. The early post-fire beech forest manifests primarily beech seedlings and beech sprouts, rarely interspersed with seedlings of maples (Acer spp.) and manna-ash (Fraxinus ornus L.), indicating a low probability of succession to mixed forest. The post-fire pine plantation appears to convert to a manna-ash bush-woodland, whereas the unburnt pine manifests succession to a mixed forest with beech and maples. Based on our findings, specific fire control and silvicultural interventions are recommended. © 2009 Elsevier B.V. All rights reserved. Source

Damen M.C.J.,International Institute for Geo information Science and Earth Observation
Journal of Marine Systems | Year: 2010

The Pearl River delta area in Guangdong Province has one of the highest economic development rates of China. Rapid industrialization and urbanization has resulted in extensive changes in land use, including the construction of harbours and embankments. The lack of sustainable coastal zone management has caused severe environmental problems, such as land subsidence, intrusion of sea water, siltation of river channels and coastal erosion. For the analysis of the changes of the coastlines, multi-temporal Landsat images and a SPOT scene have been used, in combination with topographical and nautical data. From the change analysis, it can be concluded that the largest variations in the position of the coastline over time occurred in the Nansha Development Zone, situated in the Northern part of Lingdingyang bay. Sedimentation and land reclamation was responsible for the growth of the islands in the period 1960 to 2000, which however decreased slightly in the years after. Various large changes occurred also in the East of the bay along the coast of Shekou peninsula, caused by extensive harbour construction and growth of polder systems. Based on the research of the coastline change in recent decades, suspended sediment plume distribution and its sedimentation, it is suggested that the western part of the waterway in the estuary may not be suitable for large number of construction for harbours, due to the sedimentation and fill up. One of the most important impacts of the coastline changes in the Pearl River Estuary is the narrowing down and extension of river channel which results in more floods in the upper part of the river. © 2010 Elsevier B.V. Source

Blahut J.,University of Milan Bicocca | Blahut J.,CNR Institute for the Dynamics of Environmental Processes | van Westen C.J.,International Institute for Geo information Science and Earth Observation | Sterlacchini S.,CNR Institute for the Dynamics of Environmental Processes
Geomorphology | Year: 2010

For the generation of susceptibility maps on medium scales (1:25,000 to 1:50,000) using statistical techniques, a reliable landslide inventory is needed, together with factor maps used as inputs. This paper compares landslide susceptibility maps obtained with the same methodology but using different landslide inventories: the official Italian landslide inventory GeoIFFI for the Lombardy Region and a recently mapped inventory (DF2001). The analysis included four main steps: (i) preparation of debris flow inventories using both random and spatial partitions and factor maps as explanatory variables; (ii) calculation of accountability and reliability indices for a preliminary susceptibility analysis and selection of an appropriate combination of the factor maps for detailed analysis; (iii) evaluation and validation of the obtained susceptibility maps; and (iv) comparison of the results and selection of the final map. The study area is located in the Valtellina Valley in the Central Italian Alps. The analysis identified highly susceptible areas of shallow landslides that may generate debris flows. It was demonstrated that more precisely delimited source areas for landslide-induced debris flows produce better susceptibility maps. However, the improvement of these maps was relatively limited when the inventories were randomly subdivided. Higher improvements were observed after the subdivision of the inventories into three geographical parts with different geomorphological characteristics. Although the modelling showed very similar results if evaluation is made using standard techniques, the spatial pattern of the susceptibility maps was highly variable and dependent on the combination of the factor maps used. © 2010 Elsevier B.V. Source

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