Forestry processors productivity models in northeastern Argentina

O presente estudo analisou a performance de três processadores florestais operando em plantações de Pinus taeda no nordeste da Argentina e foi desenvolvido um modelo geral para determinar as características dos equipamentos e combinações de produtos processados que afetam a produtividade e os custos operacionais. Foram avaliados por meio de um estudo de tempos e movimentos, um processador florestal John Deere 2154 D equipado com cabeça Waratah HTH 622B, um processador florestal Caterpillar 320D FM equipado com cabeça Log Max 7000b e uma escavadora John Deere 200D LC equipada com cabeça Log Max 7000c. Os equipamentos operaram realizando corte raso em florestas de 13 anos, com volumes médios variando entre 0,42 e 0,57 m3. Foi analisada a potencia dos equipamentos e o desenvolvimento de combinações de productos: toras trituráveis e toras trituráveis e serráveis. Foi ajustado um modelo de misto de efeitos fixos alcançando um coeficiente de R2 de 0,7. O delineamento florestal afetou positivamente a produtividade efetiva implicando também um aumento no custo de produção. A potência apresentou uma interação com o volume das árvores, afetando a produtividade para volumes a 0,5 m3. O desenvolvimento de varios productos afetou negativamente a produtividade.This study analyzed the performance of three forest processors working in Pinus taeda clear-cutting of plantations in the Northeast of Argentina and development a general model for determining how the characteristics of machines and the products sorting affected the productivity and cost of the operation. We evaluated, by a time and motion study, a John Deere 2154 D forestry processor equipped with a head Waratah HTH 622B, a Caterpillar 320D FM forestry processor equipped with a head Log Max 7000B and a John Deere 200D LC excavator hybrid processor equipped with a head Log Max 7000C. The machines clearcut a forest plantation of 13 years, with average volumes between 0.42 and 0.57 m3. Analyzed were the influence of the power of the equipment and the development of two product combinations: pulpwood, and pulpwood and saw timber. The general predictive model resulted in a coefficient of determination (R2) of 0.7. The forest design positively affected the productivity, also involving an increase in the cost of production. The power provided an interaction with the volume of trees, affecting productivity for larger volumes to 0.5 m3. The development of various products negatively affected productivity.Fil: Hildt, Eduardo. Universidad Nacional de Misiones. Facultad de Ciencias Forestales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mac Donagh, Patricio Miguel. Universidad Nacional de Misiones. Facultad de Ciencias Forestales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Observaciones sobre las especies de truchas criollas.

The genus Percichthys (Serranidae) includes three nominal species in Argentina, trucha, vinciguerrae and altispinis. The authors of this paper examine materials from: 1: the Río Negro river in its inferior course, in front of Viedma; 2: lake Pellegrini, near Neuquén, where the rivers Neuquén and Limay meet and form the Negro; 3: Plottier, near the place just named; 4: Colorado river, in Fortín Uno; 5: Curacó river, a tributary to the Colorado, now cut into separate sections since years ago on account of the lack of water; this river normally would connect the Colorado with the rivers up to the San Juan where the « trucha » lives; 6: Luro or La Salada lagoon, formed by the Colorado river near its mouth; 7: Argentino lake, in the southern Patagonia. These fishes are known as « trucha criolla » or « native trout » although the old Spanish name was « perca », more appropiate. Percichthys altispinis Regan 1905 is a good species ; it has been re-found in the Colorado river, at Fortín Uno. An illustration of it is given, characters of four specimens and a note on its scales. P. trucha C. V. reveeals itself on close examination as a complex species or linnean species (linneon) ; with several combinations of characters, but even more materials are needed to establish if there are geographical races (subspecies). A new examination of the Chilean materials is required (former authors considered them jointly with the Atlantic versant or Argentine materials). Some of the infraspeciíic forms are prognathous, and low finned ; others, the contrary; the head may be normal, or conical and bony; etc. As to P. vinciguerrae its standing as a valid species is doubtfull; perhaps, with P. laevis Jenyns it is a southern form. In the same reduced habitat (lagoon, or isolated course) diversified forms are present; some show parallelism with those of other places ; it is supposed that they show ecological influences according to the year or season of birth or developpment. A thorough study of the scales is given, with epidological characteristics and general conciusions as to the method of measuring and comparing their « reading». There are some marked differences even in the same habitat

Colonization of a Neotropical Reservoir (Córdoba, Argentina) by Ceratium hirundinella (O. F. Müller) Bergh

Blooms of Ceratium hirundinella (O. F. Müller) Bergh. have been detected in different water bodies in the Neotropical Region since 1990. The colonization began in southern lakes, and during the last decade the dinoflagellate arrived and bloomed in subtropical reservoirs. In this context the colonization of C. hirundinella and its population development have been analyzed from its first record in the Río Tercero Reservoir (February 1999 to February 2001). Phytoplankton and physicochemical samples were obtained from three sampling stations at the Reservoir, one in the outlet of the water cooling channel of the nuclear power plant, and one in the nearest tributary (Quillinzo River). Two blooms of C. hirundinella were detected during the warm seasons with temperatures higher than 18°C, and pH ranging between 8.5 and 8.9. Environmental conditions such as certain light intensity range and percentage of dissolved oxygen mentioned as favorable for Ceratium development were always recorded in Río Tercero Reservoir. Cysts were observed in spring and summer months. Another dinoflagellate (Peridinium gatunense Nygaard) bloomed in previous summer in this water body but its population density decreased during the invasive phase of colonization of C. hirundinella. Asplanchna girodi, became the dominant zooplankter after the first bloom of C. hirundinella. We believe that the presence of this dinoflagellate in the Neotropical Region could be a regional phenomenon associated with some dispersal mechanisms and favorable local conditions for its proliferation like those recorded in the Rio Tercero ReservoirFil: Mac Donagh, María Elicia. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casco, Maria Adela. Universidad Nacional de La Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Claps, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Sobre dos palometas (Pirañas) y un pacucito (Pisces: Characinidae)

Fil: Mac Donagh, Emiliano. Museo de La Plata. (UNLP) Paseo del Bosque s/n. (1900) La Plata, ArgentinaFil: Fuster de Plaza, María Luisa

ESTRUCTURA POBLACIONAL DE Ocotea puberula EN UN BOSQUE SECUNDARIO Y PRIMARIO DE LA SELVA MIXTA MISIONERA

El objetivo de este trabajo fue estudiar la estructura de la población de Ocotea puberula (Nees et Mart.) Nees (Lauraceae), en bosques de sucesión secundaria y primaria en el Nordeste de Misiones en Argentina, a 26º 15´S y 54º 15´W. Dos parcelas permanentes de muestreo de 3 hectáreas cada una fueron instaladas en el bosque secundario y primario, respectivamente. Cada parcela fue dividida en 75 subparcelas de 20 x 20 m, donde todos los individuos de Ocotea puberula de tamaño igual o superior a 20 centímetros de altura fueron registrados. Se estudió la estructura de tamaño y la distribución espacial. Ocotea puberula mostró ser una especie secundaria con un número abundante de individuos en la fase de regeneración natural en el bosque secundario, y solamente árboles adultos en el bosque primario. La especie presentó en ambos bosques un patrón agrupado de distribución espacial

Pinus taeda L. : plantation density and yield

Este artículo muestra los primeros resultados de un ensayo para testear hipótesis sobre los efectos combinados de la densidad inicial y los tratamientos de aclareos sucesivos, la altura de poda final y el número de levantes de la poda sobre el rendimiento de la masa de Pinus taeda L. Las variables de la masa para analizar el rendimiento fueron el volumen total por unidad de superficie, el volumen total individual, el diámetro a la altura de pecho, la altura media y la altura dominante. Al 4° año se evaluó el efecto de la densidad sobre el rendimiento de la masa. Los tres niveles adoptados fueron: D1 = 567,13; D2 = 810,72 y D3 =1.691,18 arb/ha. El volumen total por unidad de superficie promedio de D3 resultó superior al de D2 y, a su vez, éste superó al de D1. Los volúmenes individuales y los diámetros a la altura de pecho promedio de las densidades D1 y D2 resultaron estadísticamente homogéneos entre sí y superiores al de D3. No se encontraron diferencias significativas entre las alturas totales promedio registradas en los 3 niveles de densidad.This paper show the firts results of a trial that have as objectives to test hypotesis about the effects of combinations of stand original density, treatments of sucessive thinnings, final prune heigth and number of raise of prune about the stand yield of Pinus taeda L. The yield of stands variables analized were volume per unity of surface, individual volume, diameter at breast heigth (dbh), mean heigth and dominant heigth. At 4th year, were tested the effects of density about the stand yield, dealing with three density levels that were: D1 = 567,13; D2 = 810,72 and D3 = 1.691,18 tree/ha. The mean volume per unity of surface of the D3 results higher than D2 and this higher than D1. The means of individual volume and diameter at breast heigth in D1 and D2 results statistically equals and both higher than D3. About mean heigth and dominant heigth it wasn't found effects of density.Fil: Costas, Rubén. Universidad Nacional de MisionesFil: Mac Donagh, Patricio. Universidad Nacional de MisionesFil: Weber, Elizabeth. Universidad Nacional de MisionesFil: Irschick, Pedro. Universidad Nacional de MisionesFil: Palavecino, José. Universidad Nacional de Misione

The fishes from the lagoons of Buenos Aires

The plan that guided my studies of the freshwater Fishes in the Buenos Aires province was the completion of the facts assembled by Holmberg, Berg, Perugia und Eigenmann but which had not given a thorough notion of the zoogeography and ecology of the region involved. I can now state that the southern limit of the distribution of the Fishes of the Family Characidae is the Cochicó lagoon and the Sauce Grande river, which forms the lagoon of the same name. This changes completely the notion repeatedly published by Eigenmann whose maps in the famous Princeton University Expedition Report marked the Rio Salado as the limit.Facultad de Ciencias Naturales y Muse