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Author: Rubilar, Rafael ×

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  • Artículo de revista
    Nitrogen loading of Eucalyptus globulus seedlings: nutritional dynamics and influence on morphology and root growth potential
    Achieving successful outplanting of trees on increasingly harsher sites is a global concern. In Chile, for example, new Eucalyptus globulus plantations are being targeted to poorer, low fertility sites where additional stresses often negatively affect seedling performance during the first field season. Nitrogen-loading during the later stages of nursery production can, however, significantly improve seedling physiological performance on harsher sites by increasing plant growth and nutrient storage reserves for subsequent root growth after outplanting. Maximizing these benefits, and applying the concept of loading throughout the entire crop cycle, requires a better understanding of nitrogen (N) dynamics. Thus, for container E. globulus, considered one of the most important plantation species worldwide, we evaluated the effects of increasing N supply (50 to 600 mg N L−1) on seedling morphological traits, biomass production, root growth potential, and foliar N. After 15 weeks of N application, seedlings showed an increase in all growth variables evaluated up to 300 mg N L−1, whereas higher rates allowed luxury consumption. Modeling growth responses revealed, however, an apparent ammonium antagonism with other macronutrient cations suggests that high rates of this N-form may negate the potential benefits of N-loading, or that other modifications to the fertilizer solution may promote additional growth at higher N rates. Foliar N concentration, which was easily and accurately measured with a leaf chlorophyll meter, showed a gradient from basal to apical leaves suggesting a strong translocation of N in E. globulus seedlings. Our results suggest nursery management that supplies 300 mg L−1 of N through the entire growing season could improve seedling nutritional status, morphological attributes, and growth of new roots, attributes that may improve establishment on low fertility sites.
    Acevedo Tapia, Manuel-Rubilar, Rafael-Dumroese, R. Kasten-Ovalle, Juan F.-Sandoval, Simón-Chassin-Trubert Fuentealba, Rodrigo Andrés
    2020
  • Artículo de revista
    Hillslope soil erosion and mobility in pine plantations and native deciduous forest in the coastal range of south‐Central Chile
    Significant areas of Latin America, and especially of Chile, have been forested with forest plantations to provide timber and fiber and to decrease soil erosion after deforestation. Despite their potential contribution to reducing erosion processes, the magnitude of this decline has not been adequately assessed. In this study, we estimated soil loss and mobility for one year on steep hillslopes using the traditional erosion‐pin approach at five micro‐catchments planted with Pinus radiata with different stand ages and compared them to an adjacent secondary broadleaf Nothofagus sp. native forest. Annual net soil loss (ASL) positively correlated with cumulative rainfall (R2 = .49, p < .001). ASL averaged 65.03 ± 9.8 mg ha−1 yr−1, with the lowest ASL in the natural forest with 21.4 ± 3.1 mg ha−1 yr−1 and the highest in one of the 1‐year‐old plantation micro‐catchments (88.9 ± 9.3 mg ha−1 yr−1). ASL under plantation stands of different ages displayed no significant differences. All areas showed similar net soil loss index values, averaging 83.0 ± 1%, suggesting that most of the sediment left the hillslope. The RUSLE model predicted ASL moderately well across all sites and conditions (0.41, p = .018), but it tends to underestimate ASL, particularly for native forests. On average, soils on hilly terrain under plantation forest may suffer losses up to four times greater than natural forests. The latter stresses the need to improve our understanding of erosive processes that may be still active under planted forest, and to better assess the effect of management practices on soil erosion, particularly on previously highly degraded and erodible soils.
    Aburto, Felipe-Cartes Rodríguez, Eduardo-Mardones, Oscar-Rubilar, Rafael
    2021