In 1994, the wood wasp parasite Sirex noctilio was identified in Pinus spp. growing in the Calamuchita Valley of Cordoba, Argentina. This insect causes direct and indirect damage to trees, eventually causing death. The larval activity consisting of feeding and injecting a phytotoxic mucus, coincides with infection of the symbiotic pathogenic fungus Amilostereum areolatum. The "pine borer wasp" has a commercial impact, since the export of infested pinewood is prohibited by international agreement, thus affecting the regional economy based on pine forest products. A research project at the Universidad Nacional de Rio Cuarto dealing with the prevalence, distribution and incidence of Sirex in the region was begun in 1996. We are also studying the bioecology and natural enemies of the insect, as well as the convenience of introducing a parasite nematode, Deladenus sincidicola, to try to managing the problem. The "pine borer wasp" was declared an agricultural pest for the Province of Cordoba in 1997. En 1994 fue identificada Sirex noctilio F. (Hymenoptera-Siricidae) en las plantaciones de Pinus spp. (31.125 ha de Pinus elliottii, 3.738 ha de P. radiata y P. taeda) en el Valle de Calamuchita. La importancia de esta plaga radica en su acción directa por la actividad larval y los daños que indirectamente ocasiona por la inyección de un mucus fitotóxico y de esporas del hongo simbionte patogénico Amylostereum areolatum, lo que provoca que el árbol se seque. Además por tratarse de una plaga cuarentenana para los países que importan productos de nuestros bosques, su presencia restringirá la comercialización forestal con gran impacto en la economía local y regional. A partir del año 1996 en la Universidad Nacional de Rio Cuarto (UNRC) se comienza a investigar acerca de la presencia, distribución y grado de ataque en la región, su bioecología, controladores naturales e introducción del nemátodo Deladenus siricidicola, con el objetivo de establecer pautas de manejo de la "avispa barrenadora de los pinos". En 1997 se la declara "Plaga de la Agricultura" en la Provincia. Palabras claves: Sirex noctilio, manejo-impacto economico. INTRODUCCION El Valle de Calamuchita, provincia de Córdoba, según el Mapa de Aptitud Forestal (Izurieta et al. 1993) posee 36.202 ha de pinos, las que representan el 10% de las plantaciones de coniferas del país, estimándose la superficie potencialmente apta para la forestación en 250.000 a 300.000 ha Se-111 NOTAS TECNICAS Preliminary studies on Sirex noctilio (Hymenoptera-Siricidae) in pine plantations in the Calamuchita Valley,
In Prosopis caldenia forests, currently, the main activity is cattle rearing. Almost all research focuses on the herbaceous component, losing sight of the value of the forest resource and the implications of its management on the forage resource. The objective of this work is to evaluate forage availability based on forest cover, apply a model of diameter classes that allows predicting the evolution of forest mass and establish the relationship between the evolution of forest cover and forage availability. For this, forage availability was measured under and outside the projection of woody canopies, in two covers: open (10-15 m 2 ha -1 ) and closed (25-30 m 2 ha -1 ). Afterwards, through a model of diameter classes, it was sought to predict how the parameters of forest mass would evolve. The results of the herbaceous component showed that, up to 15 m 2 ha -1 of basal area (BA), there is no significant decrease in forage availability (approximately 2,700 kg ha -1 ). Regarding the forestry component, in a projected period of 10 years, 6.68 m 3 ha -1 would be obtained, representing 9.61 % of total standing volume. The relationship between canopy coverage and BA showed increase of 3.18 % per BA unit (R 2 = 0.96). This would allow projecting their participation by diameter class to propose improvement cuts that allow conducting these systems at coverage levels that do not significantly affect forage yield.
& Key message To be useful for silvicultural and forest management practices, the models of Site Index (SI) should be based on accessible predictor variables. In this study, we used spatially explicit data obtained from digital elevation models and climate data to develop SI prediction models with high local precision. & Context Predicting tree growth and yield is a key component to sustainable forest management and depends on accurate measures of site quality. & Aims The aim of this study was to develop both empirical models to predict site index (SI) from biophysical variables and a dynamic model of top height growth for plantations of Pinus elliottii Engelm. in Córdoba, Argentina. & Methods Site productivity described by SI was related to environmental characteristics, including topographic and climatic variables. Separate models were created from only topographic data and the combination of topographic and climate data. & Results Although SI can be adequately predicted through both types of models, the best results were obtained when combining topographic and climate variables (R 2 = 0.83, RMSE% = 7.02%, for the best-fitting model). The key factors affecting site productivity were the landscape position and the mean precipitation of the last 5 years before the reference age, both related to the amount of plant-available water in the soils. Furthermore, the top height growth models developed are fairly accurate, considering the proportion of variance explained (R 2 = 98%) and the precision of the estimates (RMSE % < 8%). & Conclusion The models developed here are likely to have considerable application in forestry, since they are based on accessible predictor variables, which make them useful for silvicultural and forest management practices, particularly for nonforest areas and for the young or uneven-aged stands.
Prosopis caldenia is a woody perennial species endemic to the temperate semi-arid phytogeographic region of central Argentina known as the Caldén district. Currently, some areas of this region are degraded because of livestock, fires, the advance of the agricultural frontier, and lack of forest management, among others. To improve the restoration of this important species within its natural distribution area and/or for the expansion of the wooded area, propagation methods must be developed that produce acceptable numbers of seedlings when seeds are put in conditions to germinate. The seeds of P. caldenia present an impermeable coat that prevents uniform imbibition. The literature is scarce regarding the study of scarification methods in this species. The objective of this work was to evaluate which pre-germination method (mechanical, chemical, or thermal) best adapts and improves the germination parameters. The seeds were placed in a germination chamber at a temperature of 30 ºC for 12 days and daily observations of germination, non-embedded seeds, non-germinated embedded seeds, root length, and germination indices were carried out. The results indicate that mechanical scarifying achieves the highest germination rate, germination indices, and root length (P < 0.05) followed by acid treatment. This research should be repeated in the nursery to verify whether the laboratory results are maintained under plant production conditions.
In the Valley of Calamuchita (Córdoba-Argentina), a forested area with 36,202 ha. of Pinus spp., it has been developed from 1996 a Geographical Information System (GIS) as a complementary tool for the study of the pest Sirex noctilio Fabricius. The objective is to store, to organize, to contrast and to analyze the obtained data of the study of Sirex noctilio F., with the purpose of generating new information that will serve as a basis in the definition of a strategy of pest management. In seven operative areas, were establishied points of sampling in permanent transects across different sites. In each one it was registered, degree attacks of the pest, management, density and age of the stand and its geographical position with GPS. The GIS was carried out with the data originated from the monitoring. The GIS was integrated by a space database and a database with thematic information. The result consisted on the elaboration of analogical maps by means of the visual analysis of pictures at 1:50.000 scale, digital prosessing of LandSat TM 5 satellite images and elaboration of thematic maps. In the conversion of analogical to digital information, it was used the vectorial system ARC/INFO. The pattern entity-relationship were the approache utylized for the generation of databases. The software used was the Visual dBASE, 1995. This information was modeled cartographically with the software ARCVIEW. As resulted of these activities is possible to have a data base from the last five sampling. It allows to understand not only the attack levels and their temporal variation, but also other aspects of the plantations like composition, management, density and estimated age.
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