947 resultados para lowland forests
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Kelp forests represent some of the most productive and diverse habitats on Earth. Understanding drivers of ecological patterns at large spatial scales is critical for effective management and conservation of marine habitats. We surveyed kelp forests dominated by Laminaria hyperborea (Gunnerus) Foslie 1884 across 9° latitude and >1000 km of coastline and measured a number of physical parameters at multiple scales to link ecological structure and standing stock of carbon with environmental variables. Kelp density, biomass, morphology and age were generally greater in exposed sites within regions, highlighting the importance of wave exposure in structuring L. hyperborea populations. At the regional scale, wave-exposed kelp canopies in the cooler regions (the north and west of Scotland) were greater in biomass, height and age than in warmer regions (southwest Wales and England). The range and maximal values of estimated standing stock of carbon contained within kelp forests was greater than in historical studies, suggesting that this ecosystem property may have been previously undervalued. Kelp canopy density was positively correlated with large-scale wave fetch and fine-scale water motion, whereas kelp canopy biomass and the standing stock of carbon were positively correlated with large-scale wave fetch and light levels and negatively correlated with temperature. As light availability and summer temperature were important drivers of kelp forest biomass, effective management of human activities that may affect coastal water quality is necessary to maintain ecosystem functioning, while increased temperatures related to anthropogenic climate change may impact the structure of kelp forests and the ecosystem services they provide.
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Can social inequality be seen imprinted in a forest landscape? We studied the relationship between land holding, land use, and inequality in a peasant community in the Peruvian Amazon where farmers practice swidden-fallow cultivation. Longitudinal data on land holding, land use, and land cover were gathered through field-level surveys (n = 316) and household interviews (n = 51) in 1994/1995 and 2007. Forest cover change between 1965 and 2007 was documented through interpretation of air photos and satellite imagery. We introduce the concept of “land use inequality” to capture differences across households in the distribution of forest fallowing and orchard raising as key land uses that affect household welfare and the sustainability of swidden-fallow agriculture. We find that land holding, land use, and forest cover distribution are correlated and that the forest today reflects social inequality a decade prior. Although initially land-poor households may catch up in terms of land holdings, their use and land cover remain impoverished. Differential land use investment through time links social inequality and forest cover. Implications are discussed for the study of forests as landscapes of inequality, the relationship between social inequality and forest composition, and the forest-poverty nexus.
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The Alcantarilha lowland, partly barred by a well developed barrier, including foredunes covering Pleistocene-Holocene beachrock and aeolianite, develops across the Alcantarilha infilled estuary, the beach-dune extending further SE until the Salgados lagoon. A topographic and coring survey revealed a peculiar feature at the leeward toe of the dune ridge close to the inlet area: a sandy fan with location, shape and morphology suggesting emplacement by single or multiple overwash of the barrier tip rather than tidal forcing. Its storm or tsunami origin and age are under investigation, and the only time-constrain available at present is that it should post-date ca. 6600 cal BP, the most recent in situ aeolianite (Moura et al., 2007) dated so far. METHODS, DATA SET AND RESULTS The fan boundaries are distinctive in aerial photos and satellite images: it is roughly ellipsoidal, ~200 m wide and ~300 m elongated paralleling the shoreline, rising ~ 0.9-1.2 m above the surrounding floodplain surface. Detailed topography shows that its short axis aligns with SW-NE elongated (though irregular) depressions in the dune crest, which link the beach with the fan. This could have favoured funnelling of, or erosion by, water overtopping the barrier but, in either case, the fan should correspond to extreme and abrupt event(s) of coastal flooding. 18 trenches and cores were performed in the exposed area of the fan and nearby flood plain to obtain samples and data on its sedimentology, lithostratigraphy and geometry. The fan consists of well sorted and rounded sand (Fig. 2). It thins away and wedges out landwards of the apex (located near Alc29T) where it is partly covered by dune sand. Its lower boundary is undulating and marked by textural contrast between sand (fan) and underlying mud (alluvial/lagoonal); an accumulation of marine-sourced perforated pebbles showing limited lateral continuity may pinpoint this boundary near the foredune (core Alc 25, ca. 80 m westward of profile in Fig.1); mud-balls were also observed immediately above this surface in cores and trenches. As the washover was probably emplaced in a barred lagoonal/estuarine floodplain setting, the fan’s northern outer belt is enclosed by low-energy sediments (not shown in Fig. 2).
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This publication constitutes the fruits of National Science Centre research projects (grant no 2011/01/M/HS3/02142 – 6 articles) and the National Programme for the Development of the Humanities (grant no 0108/NPH3/H12/82/2014 – 3 articles). We would like to acknowledge and at the same time express our sincere gratitude for the generosity shown by the following at the Adam Mickiewicz University in making this publication possible: the Dean of the Department of History, Institute of Pre-history and the Eastern Institute.
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Shows cadastral and topographic data (land tracts with proprietors' names) in unurbanized areas.
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RBC donor (copy 2): Ernest Haywood Collection.
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Dissertação de Mestrado Integrado em Medicina Veterinária
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2016
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2016
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2016
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Introduction: Food availability and access are strongly affected by seasonality in Ethiopia. However, there are little data on seasonal variation in Infant and Young Child Feeding (IYCF) practices and malnutrition among 6-23 months old children in different agro-ecological zones of rural Ethiopia. Methods: Socio-demographic, anthropometry and IYCF indicators were assessed in post- and pre-harvest seasons among children aged 6–23 months of age randomly selected from rural villages of lowland and midland agro-ecological zones. Results: Child stunting and underweight increased from prevalence of 39.8% and 26.9% in post-harvest to 46.0% and 31.8% in pre-harvest seasons, respectively. The biggest increase in prevalence of stunting and underweight between post- and pre-harvest seasons was noted in the midland zone. Wasting decreased from 11.6% post-harvest to 8.5% pre-harvest, with the biggest decline recorded in the lowland zone. Minimum meal frequency, minimum acceptable diet and poor dietary diversity increased considerably in pre-harvest compared to post-harvest season in the lowland zone. Feeding practices and maternal age were predictors of wasting, while women’s dietary diversity and children age was predictor of child dietary diversity in both seasons. Conclusion: There is seasonal variation in malnutrition and IYCF practices among children 6-23 months of age with more pronounced effect in midland agro-ecological zone. A major contributing factor for child malnutrition may be poor feeding practices. Health information strategies focused on both IYCF practices and dietary diversity of mothers could be a sensible approach to reduce the burden of child malnutrition in rural Ethiopia.
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The seasonal climate drivers of the carbon cy- cle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combina- tion of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measure- ments and 35 litter productivity measurements), their asso- ciated canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonal- ity in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rain- fall is < 2000 mm yr-1 (water-limited forests) and to radia- tion otherwise (light-limited forests). On the other hand, in- dependent of climate limitations, wood productivity and lit- terfall are driven by seasonal variation in precipitation and evapotranspiration, respectively. Consequently, light-limited forests present an asynchronism between canopy photosyn- thetic capacity and wood productivity. First-order control by precipitation likely indicates a decrease in tropical forest pro- ductivity in a drier climate in water-limited forest, and in cur- rent light-limited forest with future rainfall < 2000 mm yr-1.
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Background: Managed forests are a major component of tropical landscapes. Production forests as designated by national forest services cover up to 400 million ha, i.e. half of the forested area in the humid tropics. Forest management thus plays a major role in the global carbon budget, but with a lack of unified method to estimate carbon fluxes from tropical managed forests. In this study we propose a new time- and spatially-explicit methodology to estimate the above-ground carbon budget of selective logging at regional scale. Results: The yearly balance of a logging unit, i.e. the elementary management unit of a forest estate, is modelled by aggregating three sub-models encompassing (i) emissions from extracted wood, (ii) emissions from logging damage and deforested areas and (iii) carbon storage from post-logging recovery. Models are parametrised and uncertainties are propagated through a MCMC algorithm. As a case study, we used 38 years of National Forest Inventories in French Guiana, northeastern Amazonia, to estimate the above-ground carbon balance (i.e. the net carbon exchange with the atmosphere) of selectively logged forests. Over this period, the net carbon balance of selective logging in the French Guianan Permanent Forest Estate is estimated to be comprised between 0.12 and 1.33 Tg C, with a median value of 0.64 Tg C. Uncertainties over the model could be diminished by improving the accuracy of both logging damage and large woody necromass decay submodels. Conclusions: We propose an innovating carbon accounting framework relying upon basic logging statistics. This flexible tool allows carbon budget of tropical managed forests to be estimated in a wide range of tropical regions