Browsing by Author "Castillo, Miguel"

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    Biocontrol of Sirex noctilio by the parasitic nematode Deladenus siricidicola : a five season field study in southern Chile
    (2018) Castillo, Miguel; Sanfuentes, Eugenio; Angulo, Andrés; Becerra, José; Romero Romero, Jesús L.; Arce Johnson, Jorge Patricio
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    Detection of Phytophthora cinnamomi on declining Araucaria araucana forests
    (2022) Sanfuentes, Eugenio; Gonzalez, Mariela; Castillo, Miguel; Rubilar, Rafael; Besoain, Ximena; Sanhueza, Claudia; Smith, Milena
    Since 2016, crown death and mortality of Araucaria araucana trees have been observed at different localities of the Nahuelbuta Coastal Range, Chile. The objective of this study was to determine the presence of Phytophthora spp. in the rhizosphere of A. araucana trees that may explain its decline. Samples of soil rhizosphere were collected from trees with crown death as well as from asymptomatic trees at two visually contrasting severity areas. Phytophthora detection from soil samples was carried out using leaf bait technique, and isolates were identified by morphology and molecular methods. Recovered Phytophthora isolates were used in pathogenicity tests with A. araucana plants. From rhizosphere soil samples of 30 A. araucana trees, 56 isolates of Phytophthora cinnamomi were obtained. Isolations were more frequent in the rhizosphere of trees with severe crown symptoms and originated exclusively from the selected area showing severe crown symptoms. Plant stem inoculation with P. cinnamomi isolates caused 100% mortality; however, through root infestation, mortality was variable depending on the specific isolate. These results are the first report of the pathogenicity of P.cinnamomi A2 in natural forests of A. araucana in Chile.
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    The Large-Scale Effect of Forest Cover on Long-Term Streamflow Variations in Mediterranean Catchments of Central Chile
    (2022) Pizarro, Roberto; Valdes-Pineda, Rodrigo; Garcia-Chevesich, Pablo A.; Ibanez, Alfredo; Pino, Juan; Scott, David F.; Neary, Daniel G.; McCray, John E.; Castillo, Miguel; Ubilla, Patricio
    Forest ecosystems play an important role in hydrological processes as surface and subsurface runoff, as well as the storage of water at the catchment scale. Therefore, it is important to have a greater understanding of the effects of forests in the long-term water balance of Mediterranean catchments. In this sense, this study evaluates the effect of native forests, forest plantations, and the combination of both, on long-term streamflow variations in central Chile, an unusual area of Mediterranean climate characterized by a well-marked annual cycle with dry summers and wet winters. Thus, the temporal pattern of monthly streamflow was evaluated for mean flow (Qmean), maximum flow (Qmax), and minimum flow (Qmin) in 42 large-scale (>200 km(2)) Mediterranean catchments. Each series of monthly streamflow data was QA/QC, and then evaluated using the Mann-Kendall's non-parametric statistical test to detect temporal variations between 1994 and 2015. In addition to the previous analysis, the monthly series were grouped into wet seasons (April-September) and dry seasons (October-April), to determine if there were any significant differences within the annual hydrological cycle. The areas covered with native and forest plantations and their relative changes were evaluated for each catchment through streamflow variations and forest cover indicators. Results revealed that streamflow variations are positive and significant when more forest cover exists. The intra-catchment relationships assessed for both species revealed the significant role of native forests and mixed masses as key ecosystems for the long-term conservation of summer streamflow in Mediterranean catchments of central Chile. These findings encourage an urgent need to create highland afforestation programs on degraded areas of central Chile, to maximize water storage in a region that is quickly drying out due to unsustainable water and land use management practices and the effects of global warming.