Browsing by Author "Ovalle, Juan F."

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    Climate and species stress resistance modulate the higher survival of large seedlings in forest restorations worldwide
    (WILEY, 2021) Andivia, Enrique; Villar Salvador, Pedro; Oliet, Juan A.; Puertolas, Jaime; Dumroese, R. Kasten; Molina Venegas, Rafael; Arellano, Eduardo C.; Li, Guolei; Ovalle, Juan F.; Ivetic, Vladan
    Seedling planting plays a key role in active forest restoration and regeneration of managed stands. Plant attributes at outplanting can determine tree seedling survival and consequently early success of forest plantations. Although many studies show that large seedlings of the same age within a species have higher survival than small ones, others report the opposite. This may be due to differences in environmental conditions at the planting site and in the inherent functional characteristics of species. Here, we conducted a global-scale meta-analysis to evaluate the effect of seedling size on early outplanting survival. Our meta-analysis covered 86 tree species and 142 planting locations distributed worldwide. We also assessed whether planting site aridity and key plant functional traits related to abiotic and biotic stress resistance and growth capacity, namely specific leaf area and wood density, modulate this effect. Planting large seedlings within a species consistently increases survival in forest plantations worldwide. Species' functional traits modulate the magnitude of the positive seedling size-outplanting survival relationship, showing contrasting effects due to aridity and between angiosperms and gymnosperms. For angiosperms planted in arid/semiarid sites and gymnosperms in subhumid/humid sites the magnitude of the positive effect of seedling size on survival was maximized in species with low specific leaf area and high wood density, characteristics linked to high stress resistance and slow growth. By contrast, high specific leaf area and low wood density maximized the positive effect of seedling size on survival for angiosperms planted in subhumid/humid sites. Results have key implications for implementing forest plantations globally, especially for adjusting nursery cultivation to species' functional characteristics and planting site aridity. Nursery cultivation should promote large seedlings, especially for stress sensitive angiosperms planted in humid sites and for stress-resistant species planted in dry sites.
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    Trade-Offs between Drought Survival and Rooting Strategy of Two South American Mediterranean Tree Species: Implications for Dryland Forests Restoration
    (MDPI, 2015) Ovalle, Juan F.; Arellano, Eduardo C.; Ginocchio, Rosanna
    Differences in water-acquisition strategies of tree root systems can determine the capacity to survive under severe drought. We evaluate the effects of field water shortage on early survival, growth and root morphological variables of two South American Mediterranean tree species with different rooting strategies during two growing seasons. One year-old Quillaja saponaria ( deep- rooted) and Cryptocarya alba ( shallow- rooted) seedlings were established under two watering treatments ( 2 L . week- 1 . plant- 1 and no water) in a complete randomized design. Watering improved the final survival of both species, but the increase was only significantly higher for the shallow- rooted species. The survival rates of deep- and shallow- rooted species was 100% and 71% with watering treatment, and 96% and 10% for the unwatered treatment, respectively. Root morphological variables of deep- rooted species such as surface area, volume, and diameter were higher under unwatered treatment. On the other hand, shallow- rooted species had a higher total root dry mass, length, surface area with watering treatments. Our findings suggest that deep- rooted species are highly recommended for reforestation in dry conditions, even under low soil water availability. Water supplements during the summer season can attenuate the differences between deep- and shallow- rooted species in their ability to survive drought during the early stage.