Analysis of the vegetation-soil-water interaction and external factors on the water availability in a rain forest
Ramos J.1*, Gracia J.1, Ortiz S.1, González-Chávez, J. L.2, Iturbe R.1, Rodríguez-Martínez T.1
1 Instituto de Ingeniería, UNAM 2 Facultad de Química, UNAM
In general, degradation of water quality due to human and natural (less common) causes leads to the loss of the environmental value of the ecosystem which is vital to the survival of its habitats. Different forms of nature degradation (biological, physical and chemical among others), particularly those linked to humans, could reduce the capacity of the system to get a gradual recovering or adaptation (resilience). Sometimes, many of the changes that occur are not detected on time or these increase quickly imposing pressure in the system unable to recover by itself, thus human intervention is required in order to return the ecosystem to its own value. In the case of water, availability depends on several factors in order to cover water demands to maintain or restore the benefits that humans receive, and to define hydrological aspects that define the ecosystems. The above involves both ecological interactions as well as external factors such as the presence of humans, changes in seasonal patterns of flow, physicochemical characteristics of water bodies, and the type and amount of pollutants entering these water bodies. Thus, the aim of this paper is to establish how the changes of land use have a major impact affecting water quality and therefore availability considering also soil type and vegetation. For this, nine aguadas (a type of cenotes) were monitored at the Natural Protected area Calakmul Biosphere Reserve, whose importance is based on sustaining the ecosystem for different species, as well as being used as a source of supply water for animals and humans. Particularly, the paper assesses the effect on the quality of the aguadas with and without direct human impact. Results show that deforestation around bodies of water, transforming jungle into agricultural area, has been crucial since it creates a climatic transition zone affecting the water characteristics and conditions. Direct effects such as the erosion which drags nutrients and soil materials into the water bodies are also considered. Additionally, the presence of microorganisms (total coliforms) due to the combined use in situ of water for human and animal was observed. The natural influence by rock washing or erosion in the subsurface and surface has an effect on production systems due to the presence of carbonates, sodium, calcium, magnesium and potassium by the type of soil. Also, strontium levels (<0.5 mg/l) were found at a concentration related to natural soil sources in the zone. Although, human activities are pressing the ecosystem, its resilience capability helps to recover the resource maintaining some water quality for drinking and direct use. However, if the tendency of destruction continue, short-term water goals and targets will not be sufficient for the conservation and sustainable use of biodiversity and ecosystems. Thus, in order to regulate human relationship with nature activities, it is necessary to predict the consequences of changes in drivers for biodiversity, ecosystem functions, and ecosystem services, together with the improved measures of biodiversity, thus these will help to maintain a sustainable system looking at the long term and at different scales.
The main aim of the present study was to assess the impact of Eucalyptus rubida plantation on soil moisture and ground vegetation cover in lesotho. Since forestry is about the people as well as the environment, the methodology that was adopted in this study included questionnaire survey, soil moisture monitoring and vegetation survey. Local people between the ages of 40 to over 70 years were interviewed and the assumption was that people in these age category know better the impacts of the eucalypts in the area over the years. Three land-use types (eucalypts plantation, indigenous forest and grassland/rangeland) on the same topography, aspect and soil type were identified and studied and the results of soil moisture status after a rainfall event (over 5 days period) and ground vegetation cover were compared. The indigenous forest comprised of a mixture of tree species that include Leucosidea sericea, Buddleja salviifolia, Rhus dentata, Rhus divaricata, Rhmnus prinoides, Euclea coriacea and Olea Africana while the rangeland was mainly eragrostis/aristida grassland. The rate of soil moisture decrease between the three land-use types was significant and was in the following order: eucalypts plantation (3.37% per day) > indigenous forest (1.63% per day) > grassland/rangeland (1.56% per day). The high rate of soil moisture decrease of 3.37% per day could be attributed to high evapotranspiration rate of the eucalypts plantation. The frequency of ground flora of forbs, grasses and brush was found to be highest under the grassland followed by the indigenous forest and then eucalypts plantation. The land under the eucalypts plantation was mostly bare and had the highest frequency of litter and rockiness compared to both the indigenous forest and the grassland/rangeland. The presence of invader species such as Chrysocoma cilliata, Anthanasia thodei, Gnaphalium undulatum, Scabiosa columbaria, Aster fillifolis, Passerina montana, Erica maesta and Artemisia afra under the eucalypts plantation was also an indication of degradation while the high presence of litter and rockiness could be due to anthropogenic pressures such as human movement which could have limited the growth of ground flora.
The Guaratinguetá region in São Paulo, Brazil, located in the Vale do Paraíba, a strategic economic region given its location in the industrial/technological hub between the cities of Rio de Janeiro and São Paulo. It features tropical climate and distribution of rainfall influenced by frontal systems, orography, convective rainfall, the continental influence and sea breezes, thus making it a highly productive region nationwide. The purpose of this article is to subsidize planning management of water resources, and the exploitation of water in various sectors, as well as serve as a reference for civil works and climate studies, looking to improve the use of activities that depend on the utilization of water in the region, therefore improving the quality of life of the population.
The used and properly compiled meteorological data were obtained from the Aeronautics Ministry Meteorological Station, the Department of Water and Energy of the State of São Paulo and the National Institute for Space Research. The data were analyzed according to the Gumbel distribution/methodology. The study was performed by addressing the overall period (1974-2012), the period in decades, and the seasonal period (1962-1991). The results show an increasing trend of average rainfall through the detailing in decades. The interval also showed an average cyclic rainfall, high and low cycles that alternate. In the second set of details, based on the seasons of the year, the averages behave according to the season for highland tropical climate, with summer having greater rainfall, followed by spring and autumn and winter with the least rainfall.
Knowing that there is a change of the rainfall regime, it is necessary to have better forecast of works in the region, more detailed monitoring, as well as government precaution tools. The major concern with global warming, and with water scarcity already pointed out in several regions of the world, makes it necessary nowadays to get a response based on microclimates, considering this effect. As the planning management of water resources, and the exploitation of water in various sectors are normally of the competence of public entities, the aim is to cooperate and provide data for such entities.
The quick eucalyptus expansion together with its big species number and their great adaptability to the most varied ecological conditions lead to the need for studies to identify areas with climate fitness for different species implementation and development. Therefore, this study aimed to verify areas suitability for planting two eucalyptus species in Espírito Santo state, using Geographic Information Systems supported by strategic decision analysis. In the analysis, the data used as decision factors were average precipitation, average temperature, hydric deficit and Espírito Santo’s declivity. These factors were submitted to fuzzy standardization, aggregated and compensated by the Weighted Linear Combination process (WLC), resulting in the final fitness mapping. For the species conflict areas conciliation it was used the module for Multi-objective Land Allocation (MOLA), thus maximizing the land suitability for the purpose. The WLC analysis identified the areas suitability and using MOLA module it was able to solve the suitability conflict between the two eucalyptus species. Great part of Espírito Santo state has high suitability for the species development, and the northwest and part of the northern regions have presented the lower fitness for both eucalyptus species analyzed. Considering the 10,000 km2 most adaptable area to eucalyptus cultivation in the state it was found that the most suitable areas for cultivating both eucalyptus species are located in the mountainous region, part of the south region and near the northeast coast.