Browsing by Author "Zapata, Alvaro"

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    Differences in rainfall interception among Eucalyptus genotypes
    (2023) Valverde, Juan Carlos; Rubilar, Rafael; Barrientos, Guillermo; Medina, Alex; Pincheira, Matias; Emhart, Veronica; Zapata, Alvaro; Bozo, Daniel; Espinoza, Yosselin; Campoe, Otavio C.
    Key messageHydrological indicators such as rainfall interception of Eucalyptus genotypes are essential to guarantee the water sustainability of forest plantations under climate change scenarios.Rainfall interception is a critical component of water balance in Eucalyptus plantations and may provide better water sustainability by reducing potential adverse effects under drought scenarios. This study evaluated rainfall interception of Eucalyptus globulus and E. nitens x globulus (high and low yield), E. nitens, E. badjensis, E. smithii, and E. camaldulensis x globulus. Rainfall, stemflow, throughfall, and interception (calculated as rainfall-stemflow-throughfall) were measured for 2 years (2020-2022) and correlated with plantation characteristics [diameter at breast height, total height, stem growth, and leaf area index (LAI)]. Our results showed an average rainfall of 1063.6 mm year(-1); only stemflow did not show differences among genotypes with an average value of 193.4 mm year(-1) (18.2% of annual rain). In contrast, throughfall and interception presented significant differences among genotypes, and both parameters showed a strong relationship with LAI. Therefore, three independent groups were obtained: E. badjensis and E. smithii showed the highest LAI (average 5.7 m(2) m(-2)) with 517.0 mm year(-1) of average interception and 427.6 mm year(-1) of average throughfall (48.6% and 40.2% respectively). For E. globulus (low-yield), E. nitens x globulus (low-yield), and E. nitens, that showed the lowest LAI (average 3.3 m(2) m(-2)), average throughfall reached 730.8 mm year(-1) (68.7%), and average interception reached 197.3 mm year(-1) (18.5%). Finally, E. globulus (high-yield), E. nitens x globulus (high-yield), and E. camaldulensis x globulus with an average LAI of 4.5 m(2) m(-2), average interception reached 345.2 mm year(-1) (32.5%), and average throughfall reached 602.7 mm year(-1) (56.7%). Our results suggest that understanding differences between taxas/genotypes may contribute to developing hydrological indicators that may improve estimates of plantation water sustainability under water scarcity climate change scenarios.
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    Rotation-age effects of subsoiling, fertilization, and weed control on radiata pine growth at sites with contrasting soil physical, nutrient, and water limitations
    (2023) Rubilar, Rafael; Bozo, Daniel; Albaugh, Timothy; Cook, Rachel; Campoe, Otavio; Carter, David; Allen, H. Lee; Alvarez, Jose; Pincheira, Matias; Zapata, Alvaro
    Although short- and medium-term responses to early silvicultural treatments have been documented, few studies show productivity gains or losses throughout a rotation across a range of soil types and resource availability. We evaluated the rotation length productivity responses of radiata pine to subsoiling, fertilization, and weed control in dry sand (DS), red clay (RC), and recent volcanic ash (RV) soils representing a gradient of physical, nutrient, and water limitations. Stands were planted in 2000 in a split-plot factorial design, with soil preparation (subsoiling vs. shovel planting) as the main plot and fertilization at planting (B only vs. NPKB) and weed control (none vs. 2-year banded application) as factorial randomized treatment plots within the main plots. Annual diameter at breast height, height, survival, and cumulative volume responses were measured. The rotation-age results for cumulative volume showed that early gains from weed control were maintained through at least 15 years of age. At rotation age, weed control increased the cumulative volume at the DS site (56 m3/ha, 20% gain), and the response over time was maintained at the RC site (28 m3/ha, 8% gain), whereas the volume was reduced at the RV site (-36 m3/ha, 7% loss). Fertilization resulted in the greatest response at the RC site (29 m3/ha, 8% gain); there were small responses at the DS site (5 m3/ha, 2% gain) and negative responses at the RV site (-18 m3/ ha, 4% loss). Interestingly, subsoiling resulted in null or negative responses at all sites, and negative effects increased over time, with volume responses ranging from -4 m3/ha (1% loss) and -27 m3/ha (7% loss) at the DS and RC sites, respectively, to -116 m3/ha (21% loss) at the RV site. Carrying capacity was reached at midrotation at the RV site and resulted in negative treatment effects at rotation age, suggesting the need for thinning or a younger harvest age at this site. Given the negative or null effects of soil preparation, a better understanding is needed for how this silvicultural treatment is affected by soil type and soil strength.