Multi-objective models for the forest harvest scheduling problem in a continuous-time framework

In this study we present several multi-objective models for forest harvest scheduling in forest with single-species, even-aged stands using a continuous formulation. We seek to maximize economic profitability and even-flow of timber harvest volume, both for the first rotation and for the regulated forest. For that, we design new metrics that allow working with continuous decision variables, namely, the harvest time of each stand. Unlike traditional combinatorial formulations, this avoids dividing the planning horizon into periods and simulating alternative management prescriptions before the optimization process. We propose to combine a scalarization technique (weighting method) with a gradient-type algorithm (L-BFGS-B) to obtain the Pareto frontier of the problem, which graphically shows the relationships (trade-offs) between objectives, and helps the decision makers to choose a suitable weighting for each objective. We compare this approach with the widely used in forestry multi-objective evolutionary algorithm NSGA-II. We analyze the model in a Eucalyptus globulus Labill. forest of Galicia (NW Spain). The continuous formulation proves robust in forests with different structures and provides better results than the traditional combinatorial approach. For problem solving, our proposal shows a clear advantage over the evolutionary algorithm in terms of computational time (efficiency), being of the order of 65 times faster for both continuous and discrete formulationsS

Forecasting variations in profitability and silviculture under climate change of radiata pine plantations through differentiable optimization

Climate change might entail significant alterations in future forest productivity, profitability and management. In this work, we estimated the financial profitability (Soil Expectation Value, SEV) of a set of radiata pine plantations in the northwest of Spain under climate change. We optimized silvicultural interventions using a differentiable approach and projected future productivity using a machine learning model basing on the climatic predictions of 11 Global Climate Models (GCMs) and two Representative Concentration Pathways (RCPs). The forecasted mean SEV for future climate was lower than current SEV (∼22% lower for RCP 4.5 and ∼29% for RCP 6.0, with interest rate = 3%). The dispersion of the future SEV distribution was very high, alternatively forecasting increases and decreases in profitability under climate change depending on the chosen GCM. Silvicultural optimization considering future productivity projections effectively mitigated the potential economic losses due to climate change; however, its ability to perform this mitigation was strongly dependent on interest rates. We conclude that the financial profitability of radiata pine plantations in this region might be significantly reduced under climate change, though further research is necessary for clearing the uncertainties regarding the high dispersion of profitability projectionsS

Simultaneous optimization of even flow and land and timber value in forest planning: a continuous approach

Background: Forest management planning involves deciding which silvicultural treatment should be applied to each stand and at what time to best meet the objectives established for the forest. For this, many mathematical formulations have been proposed, both within the linear and non-linear programming frameworks, in the latter case generally considering integer variables in a combinatorial manner. We present a novel approach for planning the management of forests comprising single-species, even-aged stands, using a continuous, multi-objective formulation (considering economic and even flow) which can be solved with gradient-type methods. Results: The continuous formulation has proved robust in forest with different structures and different number of stands. The results obtained show a clear advantage of the gradient-type methods over heuristics to solve the problems, both in terms of computational time (efficiency) and in the solution obtained (effectiveness). Their improvement increases drastically with the dimension of the problem (number of stands). Conclusions: It is advisable to rigorously analyze the mathematical properties of the objective functions involved in forest management planning models. The continuous bi-objective model proposed in this paper works with smooth enough functions and can be efficiently solved by using gradient-type techniques. The advantages of the new methodology are summarized as: it does not require to set management prescriptions in advance, it avoids the division of the planning horizon into periods, and it provides better solutions than the traditional combinatorial formulations. Additionally, the graphical display of trade-off information allows an a posteriori articulation of preferences in an intuitive way, therefore being a very interesting tool for the decision-making process in forest planningS

CÉSTODOS DEL TIBURÓN TORO CARCHARHINUS LEUCAS EN PLAYA CHACHALACAS, VERACRUZ, MÉXICO

The spiral valve (intestine) of a bull shark Carcharhinus leucas (Valenciennes, 1841) caught by artisanal fisheries at Chachalacas Beach, Veracruz Mexico was examined for helminth parasites. A total of 303 collected cestodes belonging to eight species: Callitetrarhynchus cf. gracilis (Rudolphi, 1819); Cathetocephalus cf. thatcheri Dailey & Overstreet, 1973; Eutetrarhynchidae sp.; Otobothrium sp. 1; Otobothrium sp. 2; Paraorygmatobothrium sp. 1; Paraorygmatobothrium sp. 2 and Phoreiobothrium sp. The bull shark feeds on a wide range of prey mainly bony fish. This is the first record of cestodos in the bull shark off the coast of Veracruz Mexico.La válvula espiral (intestino) de un tiburón toro Carcharhinus leucas (Valenciennes, 1841) capturado en la pesca artesanal de playa Chachalacas, Veracruz México fue examinado en busca de helmintos parásitos. Se colectaron 303 céstodos pertenecientes a ocho especies: Callitetrarhynchus cf. gracilis; Cathetocephalus cf. thatcheri; Eutetrarhynchidae sp.; Otobothrium sp. 1; Otobothrium sp. 2; Paraorygmatobothrium sp. 1; Paraorygmatobothrium sp. 2 y Phoreiobothrium sp. El tiburón toro se alimenta de una amplia gama de presas principalmente peces óseos, llegando a albergar un gran número de especies de cestodos. Este es el primer registro de céstodos en el tiburón toro para las costas de Veracruz México

HELMINTOS PARÁSITOS INTESTINALES DEL TIBURÓN PUNTAS NEGRAS CARCHARHINUS LIMBATUS (MÜLLER & HENLE, 1839) (CARCHARHINIFORMES: CARCHARHINIDAE), EN PLAYA CHACHALACAS, VERACRUZ, MÉXICO

Se examinaron 39 válvulas espirales de tiburón puntas negras Carcharhinus limbatus (Müller & Henle, 1839) capturados por la pesca artesanal en la localidad de Playa Chachalacas, Veracruz. Se encontró un total de 7029 helmintos, de los cuales el 99% pertenecieron a los cestodos y 1% a los nematodos. Cada helminto colectado fue procesado mediante las técnicas específicas para cada grupo. Registramos 21 especies de helmintos, de las cuales 20 fueron céstodos y una de nemátodo. Los céstodos Paraorygmatobothrium cf sinuspersicense (Malek, Caira & Haseli, 2010) y Nybelinia sp. 1 (Poche, 1926), presentaron los mayores valores de prevalencia e intensidad promedio de infección. Se registra a C. limbatus como nuevo hospedero para P. cf sinuspersicense; Anthobothrium laciniatum (Linton, 1890); Rhinebothrium sp. (Linton, 1889); Thysanocephalum thysanocephalum (Linton, 1899); Cathetocephalus thatcheri (Daily & Overstreet, 1973); Oncomegas cf wageneri (Palm, 1995); Disculiceps pileatus (Linton, 1891); Poecilancistrum caryophyllum (Diesing, 1850) y Hysterotylacium sp. Ward & Magath, 1917. Todos los helmintos encontrados en el tiburón puntas negras C. limbatus representan nuevos registros para la zona costera del estado de Veracruz, México

Diet and environment in southeastern Iberia during the Bronze Age based on isotope analysis of human remains

A large sample of human bones from a series of archaeological sites in the south-eastern Iberian Peninsula was selected for δ13C and δ15N stable isotope analysis. Except for some contrast samples, the remains date from the first half of the second millennium cal BC and are ascribed to the Argar Culture, which developed during the Bronze Age in south-eastern Iberia. Most authors have considered that this region reached a high degree of social hierarchical organization at this time, as demonstrated by the funerary record, both with regard to the grave goods and to the evidence of physical effort and diseases on the human remains. Results of the isotope analysis revealed the existence of differences among the settlements studied, as well as differences over time within every settlement and among the various individuals tested. Some variances can be assigned to social classes/status and others are linked to chronological factors. In particular, changes in δ13C can be explained by the increasing aridity of the first half of the second millennium cal BC, although other causes can be put forward too.This work was supported by the Consejería de Innovación y Empresa de la Junta de Andalucía (project HUM-061658) and by the Spanish Ministerio de Ciencia e Innovación (project HAR2016-80057-P)Departamento de Historia II y Geografí

Small and medium hotels cluster analysis in Huatulco, Mexico, as a tool to develop a cross sector network

En este estudio se realiza un diagnóstico sobre el sistema de calidad implantado en hoteles pequeños y medianos. A partir del mismo se realiza un análisis cluster para segmentar los mismos, como paso previo para desarrollar una estrategia común de calidad como primer escalón para desarrollar una red turística multiagente de destino. Bahías de Huatulco, México se presenta como estudio de caso.In order to develop a cross sector network hotels within the region must foster it due to their comparative size. This paper presents an investigation on the quality system implemented in small and medium hotels in the Bahias de Huatulco area. Segmentation is based on a cluster analysis. This is considered the first step in order to develop a cross sector network. Bahías de Huatulco, México, is a study case

The structure of an endogenous Drosophila centromere reveals the prevalence of tandemly repeated sequences able to form i-motifs

Centromeres are the chromosomal loci at which spindle microtubules attach to mediate chromosome segregation during mitosis and meiosis. In most eukaryotes, centromeres are made up of highly repetitive DNA sequences (satellite DNA) interspersed with middle repetitive DNA sequences (transposable elements). Despite the efforts to establish complete genomic sequences of eukaryotic organisms, the so-called 'finished' genomes are not actually complete because the centromeres have not been assembled due to the intrinsic difficulties in constructing both physical maps and complete sequence assemblies of long stretches of tandemly repetitive DNA. Here we show the first molecular structure of an endogenous Drosophila centromere and the ability of the C-rich dodeca satellite strand to form dimeric i-motifs. The finding of i-motif structures in simple and complex centromeric satellite DNAs leads us to suggest that these centromeric sequences may have been selected not by their primary sequence but by their ability to form noncanonical secondary structures.Peer Reviewe