31,884 research outputs found

    Harvesting natural resources: management and conflicts

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    It is reasonable to consider the stock of any renewable resource as a capital stock and treat the exploitation of that resource in much the same way as one would treat accumulation of a capital stock. This has been done to some extent in earlier papers containing a discussion of this point of view. However, the analysis is much simpler than it appears in the literature especially since the interaction between markets and the natural biology dynamics has not been made clear. Moreover renewable resources are commonly analyzed in the context of models where the growth of the renewable resource under consideration is affected by two factors: the size of the resource itself and the rate of harvesting. This specification does not take into account that human activities other than harvesting can have an impact on the growth of the natural resource. Furthermore, natural resource harvesting are not productive factories. Fishery economic literature (based on the foundations of Gordon, 1954; Scott, 1955; and Smith, 1963) suggests particular properties of the ocean fishery which requires tools of analysis beyond those supplied by elementary economic theory. An analysis of the fishery must take into account the biological nature of fundamental capital, the fish and it must recognize the common property feature of the open sea fishery, so it must allow that the fundamental capital is the subject of exploitation. The purpose of this paper is the presentation of renewable resources dynamic models in the form of differential games aiming to extract the optimal equilibrium trajectories of the state and control variables for the optimal control economic problem. We show how methods of infinite horizon optimal control theory may be developed for renewable resources models.Renewable resources; exploitation of natural resources; dynamic optimization; optimal control

    Carbon Sequestration under different land uses and soils in the State of Quintana Roo, Mexico

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    Rising in global temperature is evidently related to atmospheric carbon dioxide (CO2) and methane (CH4) concentrations; this has become an environmental problem. The use of renewable energy, the development of eco-friendly merchandise and the enforcement of biomass management have been proposed to mitigate the issue. In the ecosphere, the pedosphere stores 1,500 to 2,500 PgC, which is four times more than the carbon stored in biomass; hence, it is very important to carry out soil carbon studies because of more long-term stability of such storage. In the study, soil carbon quantification was applied to the entire state of Quintana Roo, using a purpose oriented sampling, to observe the dynamic between land uses and soils, relating all relevant characteristics and properties of the landscape. To study the carbon content stored in soils, total carbon was estimated through loss-on-ignition, organic carbon by Walkley-Black method and inorganic carbon by calcium carbonate determination. The result portrays that the coastal dune vegetation-Arenosol (1,256 Mg C ha-1) is the combination with the highest soil carbon density, while Leptosol is the soil type with the highest storage capacity (852 MtC). Consequently, the soil carbon storage not only relates to soil properties but also associates with the surface area occupied by the specific soil type. In addition, the characteristics of the landscape play an important role in the storage of soil carbon. Due to that, soil carbon storage can be explained by biogeomorphoedaphic factors.Evidentemente, el incremento en la temperatura global está relacionado con la concentración de dióxido de carbono (CO2) y metano (CH4) en la atmosfera. Esto ya se volvió un problema ambiental. El uso de energía renovable, el desarrollo de mercados eco-amables y el manejo de la biomasa han sido alternativas de mitigación. En la ecosfera, la pedosfera ocupa 1,500 a 2,500 PgC y captura cuatro veces más CO2 que la biomasa. Debido a la gran estabilidad del almacenamiento de CO2 a largo plazo en suelo es muy importante llevar a cabo un estudio del carbono (C) almacenado en el suelo. En el presente estudio, se presenta la cuantificación de carbono en suelos del Estado de Quintana Roo, utilizando un muestreo dirigido, con la finalidad de observar la dinámica de los cambios uso de suelo relacionados con las características y propiedades del paisaje. Para estimar la magnitud del almacenamiento, se cuantificó el carbono total con el método de calcinación, se obtuvo el carbono orgánico a través del método de Walkley-Black, y se estimó el carbono inorgánico por la determinación de carbonato de calcio. El resultado muestra que la duna costera-Arenosol (1,256 Mg C ha-1) es la combinación con la mayor densidad del carbono en el suelo por acumulación de materiales exógenos, mientras Leptosol es el suelo que representa la mayor capacidad en el secuestro de carbono (852 MtC). Por lo tanto, el almacenamiento de carbono en el suelo no solo se relaciona con las propiedades del suelo sino también se asocia con la superficie ocupada por el tipo de suelo. Además, las características del paisaje juegan un papel importante en la conservación de los inventarios de carbono en el suelo. Esto indica que, el almacenamiento de carbono en el suelo se puede ser explicado al menos parcialmente por los factores biogeomorfoedáficos del territorio.Nach derzeitigen wissenschaftlichen Erkenntnissen stehen die steigenden globalen Temperaturen in ursächlichem Zusammenhang mit den Konzentrationen von Treibhausgasen, insbesondere Kohlendioxid (CO2) und Methan (CH4), in der Atmosphäre. Dies ist zu einem großen Umweltproblem geworden. Um das Problem zu mildern, wurden die Nutzung erneuerbarer Energien, die Entwicklung umweltfreundlicher Technologien und Waren und die Implementierung eines Biomasse-Managements vorgeschlagen. In der Ökosphäre speichert die Pedosphäre zwischen 1,500 und 2,500 PgC. Dies ist in etwas viermal so viel wie in dergesamten Biomasse gespeichert wird. Daher ist es sehr wichtig, Studien über den Gehalt von Kohlenstoff im Boden durchzuführen, da dieser eine langfristige Speicherung ermöglicht. In der Studie wurde eine Kohlenstoffquantifizierung für den gesamten mexikanischen Bundesstaat Quintana Roo vorgenommen, wobei mehrere Stichproben verwendet wurden, um die Dynamik zwischen Landnutzungen und Böden zu beobachten, in Verbindung mit allen Merkmalen und Eigenschaften der Landschaft. Um den in den Böden gespeicherten Kohlenstoffgehalt zu untersuchen, wurde der Gesamtkohlenstoff durch das Verfahren der Kalzinierung ermittelt, der Gehalt des organischen Kohlenstoffs wurde mit Hilfe der Walkley-Black-Methode geschätzt, während der Gehalt des anorganischen Kohlenstoffs mit Hilfe der Bestimmung des Calciumcarbonatgehalts festgestellt wurde. Das Ergebnis zeigt, dass Küstendünen-Arenosole (1,256 Mg C ha-1) die höchsten Kohlenstoffdichte besitzen, während Leptosol der Bodentyp mit der höchsten Speicherkapazität für Kohlenstoff (852 MtC) ist. Folglich hängt die Speicherkapazität des Bodens nicht nur von den Bodeneigenschaften ab, sondern auch von der Fläche, auf der dieser Bodentyp zu finden ist. Darüber hinaus spielen die Merkmale der Landschaft eine wichtige Rolle bei der Erhaltung des Vorkommens von Kohlenstoff im Boden. Dadurch kann die Speicherung von Kohlenstoff in den Böden durch biogeomorphoedaphische Faktoren erklärt werden.近年來全球環境問題凸顯,二氧化碳(CO2)和甲烷(CH4)的濃度引起了全球溫度上升。因此,再生能源的開發、生態環保商品的使用和生物量管理成為應對這一問題的重要方案。在生態圈中,土壤可儲存一萬五千至二萬五千億噸的碳,比植物多出了四倍,這表明土壤儲量更加長久穩定,所以對土壤碳的研究極為重要。本研究區域位於墨西哥金塔納羅奧州,採用目地性的抽樣方式來觀察與景觀特征和性質相關的動態土地使用與土壤碳存量。通過強熱減量統計 (總土壤碳),採用了Walkley-Black (有機碳) 和碳酸鈣 (無機碳) 的測定以研究土壤中儲存的碳含量。結果表明,沿海沙丘和Arenosol土壤類型的組合 (1,256 Mg C ha-1) 的碳含量是最高的,Leptosol 土壤類型的碳儲存量能力是最強的 (852 MtC)。因此,土壤碳儲存不僅與土壤性質有關,而且與土壤類型占據的面積有關。此外,景觀特徵在保持與獲取土壤碳中起了重要作用,所以土壤碳儲存可以通過生物、地質、地形與土壤因素來解釋

    Dynamic optimization in natural resources management

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    Dynamic modeling is general and recently the most interesting perspective to solve a dynamic economic problem based on Pontryagin’s maximum principle. Moreover traditional economic theory, up to the middle of twentieth century, builds up the production functions regardless the inputs’ scarcity. Nowadays it is clear that both the inputs are depletable quantities and a lot of constraints are imposed in their usage in order to ensure economic sustainability. For example the input “oil” used in the production is a non renewable resource so it can be exhausted. In a same way every biomass resides in ecosystems is a resource that can be used in a generalized production function for capital accumulation purposes but the latter resource is a renewable one. The purpose of this paper is the presentation of some natural resources dynamic models in order to extract the optimal trajectories of the state and control variables for the optimal control economic problem. We show how methods of infinite horizon optimal control theory developed for natural resources models.Dynamic optimization; optimal control; maximum principle; natural resources

    Potential of Using Morphological and Functional Traits of Woody Species as Indicators of Dry Conditions in the Transition Zone of the Atlantic Forest (Mata Atlântica) in the Rio De Janeiro State, Brazil

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    Plants have certain characteristics which allow them to respond to various environmental conditions, like changes in climate, water loss in the soil, lack of minerals; among others. In some of these so-called traits, the responses to climatic phenomena such as drought can be evidenced through morphological adaptations (spines, succulent tissues, trichomes, among others) or physiological adaptations (regulation of water potential at the cellular level, the concentration of nutrients, etc.) In certain areas of Brazil such as the Mata Atlântica biome, drought events are increasingly occurring and affecting human activities and the environment, and it is required to understand if tree species with traits adapted to dry conditions are occurring in drought-prone areas. For this reason, it is intended to find out the potential of using morphological functional traits of woody species as indicators of dry conditions in the transition zone of the Atlantic Forest. RJ Brazil. Therefore, this work was carried out considering a field phase in a drought-prone area known as “Mata de Tabuleiros” or Semideciduous Seasonal Lowland Forest that belongs to the domain of the Mata Atlântica, there were selected morphological traits in order to know which of them can give a hint as drought tolerant traits. On the other side, there was searched in the Rio de Janeiro Botanical Garden JABOT database for species with recorded characteristics related to drought adaptations. For the traits in the field, and the selected species from the database was elaborated a Species Distribution Model SDM in order to know how some climatic variables allow the distribution of species and morphological traits. As main result there was elaborated a set of trait indicators that can be considered for further analysis in the region; and also the results of the SDM obtained at large scale for the Mata Atlântica for the species selected from the database, and the SDM for the traits analyzed in the field in the Mata de Tabuleiros. Besides that, the consultations with experts in the subject were an important input that allowed to carry out this research. The use of morphological and functional traits is important to understand the interactions between organisms and their environment, in this case, to cope and tolerate a climate phenomenon like drought. Keywords: Mata de Tabuleiros, Drought tolerance, Morphological traits, Species Distribution Modelin

    Hydrological Drought Assessment in the Tempisque-Bebedero Catchment System in Costa Rica

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    The present thesis research was focused on the assessment of hydrological drought in the Tempisque-Bebedero catchment system in Costa Rica as part of the TropiSeca project framework. The study area is in the province of Guanacaste and has an extension of 5449.94 Km2, the region is characterized by a defined wet and dry season resulting in a marked seasonality in precipitation and streamflow regime which provokes frequent periods of water deficits considered as drought. The main objective of this research is to conduct an analysis on hydrological drought in the study area through the understanding of the behavior of hydrological cycle and its implications for the rice sector by applying different drought indices such as Standardized Precipitation Index (SPI) and Streamflow Drought Index (SDI). From the values obtained in the calculation of drought indices were studied the temporal distribution and spatial distribution based on the characterization of drought periods in terms of frequency, severity, duration, and seasonality. For the characterization of meteorological drought in the study area an approach based on area average precipitation was implemented to calculate a regional representative SPI for each sub-basin, in contrast, hydrological drought was assessed using only two streamflow gauges data provided by the ICE from 1973 until 2003. As result, Tempisque showed longer drought periods in comparison with Bebedero whose mean duration was lower but the number of drought events were more frequent. In terms of spatial distribution, it could be found that the upper basin experienced extreme meteorological drought periods at high time scales tied to a severe streamflow deficit probably justified by its low permeability due to geological characteristics that allow a slow movement of groundwater. Additionally, one of the aims of this thesis was to analyze the existence of correlation between precipitation and streamflow anomalies with rice yield and, to determine the influence of ENSO in climate variability using Sea Surface Temperature indices; in this phase of the research was found that climate patterns in the catchment system exhibited a significant influence by ENSO events with a significance level of 99% (r > 0.7) showing an important dependence of meteorological drought periods presented during the period 1980-2016. In terms of temporal behavior of rice yield anomalies was revealed moderate correlation coefficients (r < 0.4) in both watersheds due to in most of the cases the response of water deficit did not have significant impact in terms of magnitude as expected; in some periods in which drought period was present categorized as mild-drought, rice yield had a considerable decreasing compared with those in which was categorized as extreme event; these differences can be justified mostly because crop yield depends not only on weather, but also on variety of seed used and its coping capacity to periods of water scarcity, fertilizers, soil moisture, farming techniques, sowing date, temperature, irrigation, use of pesticides etc. The results of this thesis can be used to motivate future researches in the elaboration of crop models to predict yields based on physiological processes during plant development considering water requirement to take enough measures to mitigate the effects of drought periods. Furthermore, it should be considered to implement a drought monitor system in the area as an important tool of early warning system and as an indicator for the efficient water resources management

    The geographical information system and the natural resources management

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    The Geographical Information System (GIS) works on databases that contain different kinds of information (town-planning, geographical and environmental). It is able to correlate, to integrate and to consult them just using simple or complex inquiries allowing in any moment the introduction of new data or the updating of those available. The management of the natural resources well it is lent to be done through the creation of a GIS : natural resources are connected to the punctual knowledge of the territory but have to be referred to lots of other factors, primarily linked to human activities, that contributes to organize and transform them. It is needed a suitable cartography containing the basic dates and the general subjects to overlap to the whole other series of information, different for origin and contents. The aim is to represent the natural and human structure of the territory, to know the spontaneous or induced events, to manage the norms and to plan the existing resources: from the integration of all the information it is created an adding value. A concrete example of this statement is represented by a project, in course of elaboration, promoted by the province of Rome for the Realization of an Ecological Network in the mountainous complex of the Lucretili-Simbruini-Ruffi. The study area is situated in the centre of Italy and more precisely in Lazio region throw the border with Abruzzo. The location of this place makes it to be a key element in the environmental continuity at territorial scale, therefore the study of the same one will be made analysing more levels, beginning from the landscape, in its components natural and human, continuing with the definition of the functional ecological network, and concluding with the aspects of managerial nature, that more than the others will receive advantages from the creation of the GIS. There are essential elements able to suggest guidelines for planning and maintaining with ecological criteria: it means to verify the planning instruments, to point out the areas with different kind of constraints and to analyze the incongruities and the conflict points that will become the most important in the new action-plan.

    Changes in Beliefs and Perceptions about the Natural Environment in the Forest-Savanna Transitional Zone of Ghana: The Influence of Religion

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    The potential of traditional natural resources management for biodiversity conservation and the improvement of sustainable rural livelihoods is no longer in doubt. In sub-Saharan Africa, extensive habitat destruction, degradation, and severe depletion of wildlife, which have seriously reduced biodiversity and undermined the livelihoods of many people in rural communities, have been attributed mainly to the erosion of traditional strategies for natural resources management. In Ghana, recent studies point to an increasing disregard for traditional rules and regulations, beliefs and practices that are associated with natural resources management. Traditional natural resources management in many typically indigenous communities in Ghana derives from changes in the perceptions and attitudes of local people towards tumi, the traditional belief in super natural power suffused in nature by Onyame, the Supreme Creator Deity. However, this is closely entwined with ecological, demographic and economic factors. Whilst these factors have driven the need to over-exploit natural resources, a situation which threatens the sustainability of community forests including sacred groves, religion has been used to justify such actions. This paper explores changes in tumi and the sustainability of sacred groves in the forest-savanna transitional zone in Ghana. It would confirm that changes in traditional animist beliefs, such as tumi, which informs the worldview of local people and underlies traditional natural resources management, is mainly due to the advances made by Christianity and Islam.Tumi, Sacred Groves, Forest-Savanna Transition, Sustainability, Traditional, Christianity, Islam

    Environmental and Natural Resources Management: Lessons from City Program Innovations

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    The enactment of the 1991 Local Government Code has brought greater responsibilities for local government units to manage their natural resources and the environment. This move has encouraged greater dynamism and innovation in some Philippine cities. Strategies employed and programs undertaken by various cities largely depend on the stage of development and their respective focus and priorities. For large urban cities, environmental problems are associated with growth and economic activity and thus, a special attention is given for a clean air and a healthy environment. This paper aims to draw lessons from selected cities that have undertaken innovative environmental programs and to highlight key elements that have made their programs successful and sustainable.metropolitan structure, environmental issues, metropolitan planning and development, environmental management

    Harnessing Wisdom for Managing Watersheds: Honey Bee Perspective on Innovations, Institutions and Policies for Marginal Environments

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    Participatory approaches for watershed management are now considered essential for sustainable natural resources management and yet there is very little opportunity for intellectual participation by the people. This requires understanding of the local knowledge systems and their institutional context. In this paper, we provide an overview of the conceptual framework which can facilitate such participation. The full report being published separately includes case studies of farmers’ innovations in natural resources management.

    Environmental and Natural Resources Management: Lessons from City Program Innovations

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    The enactment of the 1991 Local Government Code has brought greater responsibilities for local government units to manage their natural resources and the environment. This move has encouraged greater dynamism and innovation in some Philippine cities. Strategies employed and programs undertaken by various cities largely depend on the stage of development and their respective focus and priorities. For large urban cities, environmental problems are associated with growth and economic activity and thus, a special attention is given for a clean air and a healthy environment. This paper aims to draw lessons from selected cities that have undertaken innovative environmental programs and to highlight key elements that have made their programs successful and sustainable.metropolitan structure, environmental issues, metropolitan planning and development, environmental management
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