Transición socio-ecológica y su reflejo en un agroecosistema del sureste español (1752-1997)

Este artículo parte del supuesto de que el metabolismo social configura de una manera concreta a los agroecosistemas. En términos territoriales, el metabolismo social imprime una particular huella sobre el territorio, configurando paisajes específicos. Por ello, es conveniente distinguir entre la huella visible que todo metabolismo agrario tiene sobre el agroecosistema y la huella oculta, que es aquella parte del territorio, a veces muy distante, del que provienen recursos naturales o funciones ambientales que resultan imprescindibles para el funcionamiento del metabolismo estudiado. A partir de información etno-histórica, el presente artículo analiza la transición socio-ecológica de un agroecosistema en el sureste de España, el municipio de Santa Fe, considerando los cambios operados en el metabolismo agrario a lo largo de doscientos cincuenta años (1752-1997). El artículo muestra los distintos arreglos territoriales de las dos grandes formas de organización del metabolismo social que han existido desde mediados del siglo XVIII, dependientes del suelo o del subsuelo, según hayan tenido en la energía solar o en los combustibles fósiles su fuente de aprovisionamiento. Se concluye que el crecimiento agrario, esto es el aumento sostenido de la productividad de la tierra y del trabajo, sólo es posible mediante el aumento correlativo de la huella oculta, es decir mediante la importación de energía y materiales.This article is based on the premise that social metabolism shapes agro-ecosystems in a particular way. In territorial terms, the social metabolism leaves its own distinctive footprint on the territory, thus shaping specific types of landscape. It is therefore important to distinguish between the visible footprint, which all forms of agricultural metabolism make within the agro-ecosystem and the hidden footprint, which refers to that (often very distant) part of the territory from which the natural resources or environmental functions essential to the functioning of the metabolism under study originate. This article analyzes the socio-ecological transition of an agro-ecosystem in the south-east of Spain, the municipality of Santa Fe, and studies the changes undergone in the agricultural metabolism over a period of two hundred and fifty years (1752-1997). The study shows the different territorial arrangements of the two main forms of organization of the social metabolism which have existed since the mid-eighteenth century, dependent either on the soil or subsoil, according to whether their main source of energy is solar or from fossil fuels. It concludes that agricultural growth (i.e. a sustained increase in land productivity and work) is only possible through a correlative increase of the hidden footprint; that is to say, through the importation of energy and materials

Sobre las posibilidades de crecimiento agrario en los siglos XVIII, XIX y XX. Un estudio de caso desde la perspectiva energética

This article analyses the functioning of agricultural systems based on organic energy in contrast with the present situation. To accomplish it, an example has been taken from the mid-18th and 19th centuries in the Southern Iberian Peninsula (Santa Fe), before the spread of chemical fertilizers. The analysis is centred on energy flows and looks at territorial changes occurred in the system at that time. In order to show the contrast, recent data (1997) has also been included in some 01 the tables. The structure, functioning and organization of both agrarian systems is different, showing distinct scales in both forms of production together with environmental Iimits where established. The conventional measuring instruments are designed in such a way that favour, given their plot focus, those farmers that manage to maximise the relation between soil, nutrition, and plant, subordinating the whole agricultural system to this aim and subsidizing it with energy and external nutrients

Bridge transformation for continuation call-based tabled execution.

The advantages of tabled evaluation regarding program termination and reduction of complexity are well known —as are the significant implementation, portability, and maintenance efforts that some proposals (especially those based on suspension) require. This implementation effort is reduced by program transformation-based continuation call techniques, at some efficiency cost. However, the traditional formulation of this proposal by Ramesh and Cheng limits the interleaving of tabled and non-tabled predicates and thus cannot be used as-is for arbitrary programs. In this paper we present a complete translation for the continuation call technique which, using the runtime support needed for the traditional proposal, solves these problems and makes it possible to execute arbitrary tabled programs. We present performance results which show that CCall offers a useful tradeoff that can be competitive with state-of-the-art implementations

Towards a Complete Scheme for Tabled Execution Based on Program Transformation

The advantages of tabled evaluation regarding program termination and reduction of complexity are well known —as are the significant implementation, portability, and maintenance efforts that some proposals (especially those based on suspension) require. This implementation effort is reduced by program transformation-based continuation call techniques, at some efficiency cost. However, the traditional formulation of this proposal [1] limits the interleaving of tabled and non-tabled predicates and thus cannot be used as-is for arbitrary programs. In this paper we present a complete translation for the continuation call technique which, while requiring the same runtime support as the traditional approach, solves these problems and makes it possible to execute arbitrary tabled programs. We also present performance results which show that the resulting CCall approach offers a useful tradeoff that can be competitive with other state-of-the-art implementation

Transición socio-ecológica y su reflejo en un agroecosistema del sureste español (1752-1997)

Este artículo parte del supuesto de que el metabolismo social configura de una manera concreta a los agroecosistemas. En términos territoriales, el metabolismo social imprime una particular huella sobre el territorio, configurando paisajes específicos. Por ello, es conveniente distinguir entre la huella visible que todo metabolismo agrario tiene sobre el agroecosistema y la huella oculta, que es aquella parte del territorio, a veces muy distante, del que provienen recursos naturales o funciones ambientales que resultan imprescindibles para el funcionamiento del metabolismo estudiado. A partir de información etno-histórica, el presente artículo analiza la transición socio-ecológica de un agroecosistema en el sureste de España, el municipio de Santa Fe, considerando los cambios operados en el metabolismo agrario a lo largo de doscientos cincuenta años (1752-1997). El artículo muestra los distintos arreglos territoriales de las dos grandes formas de organización del metabolismo social que han existido desde mediados del siglo XVIII, dependientes del suelo o del subsuelo, según hayan tenido en la energía solar o en los combustibles fósiles su fuente de aprovisionamiento. Se concluye que el crecimiento agrario, esto es el aumento sostenido de la productividad de la tierra y del trabajo, sólo es posible mediante el aumento correlativo de la huella oculta, es decir mediante la importación de energía y materiales.Agroecología, Sustentabilidad agraria, Agricultura tradicional, Metabolismo social, Balances de energía.

A general implementation framework for tabled CLP

This paper describes a framework to combine tabling evalua- tion and constraint logic programming (TCLP). While this combination has been studied previously from a theoretical point of view and some implementations exist, they either suffer from a lack of efficiency, flex- ibility, or generality, or have inherent limitations with respect to the programs they can execute to completion (either with success or fail- ure). Our framework addresses these issues directly, including the ability to check for answer / call entailment, which allows it to terminate in more cases than other approaches. The proposed framework is experimentally compared with existing solutions in order to provide evidence of the mentioned advantages

A simulation study on parallel backtracking with solution memoing for independent and-parallelism

Goal-level Independent and-parallelism (IAP) is exploited by scheduling for simultaneous execution two or more goals which will not interfere with each other at run time. This can be done safely even if such goals can produce multiple answers. The most successful IAP implementations to date have used recomputation of answers and sequentially ordered backtracking. While in principle simplifying the implementation, recomputation can be very inefficient if the granularity of the parallel goals is large enough and they produce several answers, while sequentially ordered backtracking limits parallelism. And, despite the expected simplification, the implementation of the classic schemes has proved to involve complex engineering, with the consequent difficulty for system maintenance and expansion, and still frequently run into the well-known trapped goal and garbage slot problems. This work presents ideas about an alternative parallel backtracking model for IAP and a simulation studio. The model features parallel out-of-order backtracking and relies on answer memoization to reuse and combine answers. Whenever a parallel goal backtracks, its siblings also perform backtracking, but after storing the bindings generated by previous answers. The bindings are then reinstalled when combining answers. In order not to unnecessarily penalize forward execution, non-speculative and-parallel goals which have not been executed yet take precedence over sibling goals which could be backtracked over. Using a simulator, we show that this approach can bring significant performance advantages over classical approaches

Guideline for constructing nutrient balance in historical agricultural systemes (and its application to three case-studies in southern Spain)

The purpose of this paper is to provide interested researchers with a simple tool to evaluate the efficacy of different methods of fertility replenishment that have accompanied and made possible the contemporary agriculture. We propose a nutrient balance model created especially to be applied to the past. In the first part of this working paper each term in the balance is defined and specified the information the user must input into the model. The second part of this paper reports on the application of this methodology based on the balances of nutrients to the evolution of Andalusian agriculture since the mid 18th Century. The nutrient balances show the effects of agrarian growth in an environmentally limited context, offering reasonable doubt regarding the medium and long-term stability of certain forms of cultivation. The balances show that in the last decades of the 19th Century, productive intensification had reached its ceiling, with livestock numbers levelling off or clearly declining. The deficits of nutrients even began to exceed the fertilisation capacity of the available livestock. The intensification applied in unfertilised rotations and crops had to be sustained through the extraction of soil reserves.Soil fertility management, Nutrient balances, Past organic agricultures, Agrarian growth, Socio-ecological transition, Agricultural change

An Improved Continuation Call-Based Implementation of Tabling

Tabled evaluation has been proved an effective method to improve several aspects of goal-oriented query evaluation, including termination and complexity. Several “native” implementations of tabled evaluation have been developed which offer good performance, but many of them require significant changes to the underlying Prolog implementation, including the compiler and the abstract machine. Approaches based on program transformation, which tend to minimize changes to both the Prolog compiler and the abstract machine, have also been proposed, but they often result in lower efficiency. We explore some techniques aimed at combining the best of these worlds, i.e., developing an extensible implementation which requires minimal modifications to the compiler and the abstract machine, and with reasonably good performance. Our preliminary experiments indicate promising results