Artículos Científicos

URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/14754

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Biomass allocation and gas exchange are affected by light conditions in endangered Cedrela salvadorensis (Meliaceae) seedlings
(Universidad de Costa Rica, 2016) Guzmán Quesada, Jose Antonio; Cordero Solórzano, Roberto A.; COREA ARIAS, EUGENIO
The determination of favorable light habitat conditions per species and life stage is transcendental, for both ex situ and in situ conservation strategies of endangered forest tree species, and for their utilization as plantation trees. This becomes especially important when planting material is scarce. We studied the multivariate responses in biomass allocation and in gas exchange to light and to CO2 in Cedrela salvadorensis seedlings, grown under similar light conditions as those this species faces in nature. During a period of 135 days, groups of ten seedlings were put under 75, 45, 15 and 3.5 % of full sun exposure obtained with neutral shade cloth, under nursery conditions. A series of biomass allocation variables and detailed gas exchange parameters (photosynthesis response curves to light and to internal carbon concentration) were measured at the end of the growth period in plants of the four treatments. According to the principal component analyses, highest values of gas exchange response were associated with the lower values of biomass allocation traits. These changes can be associated with resource-conservative and resource-acquisitive strategies, where the C. salvadorensis seedlings acclimatize their traits for the exploration and exploitation of light, to high or to dim light environment, respectively. The multivariate analyses also showed that the plants had a high performance at 45 % of light environments. These results suggest that 45 % of light environment was the optimal light habitat of this species at the tested developing stage. Our results have important implications to choose the best natural habitat for a successful establishment of C. salvadorensis. We propose practical considerations for programs of reforestation or reintroduction where this species be involved.
Climate reverses directionality in the richness–abundance relationship across the World’s main forest biomes
(Nature Comunications, 2020-12-01) Madrigal González, Jaime; Calatayud, Joaquín; Ballesteros Cánovas, Juan A.; Escudero, Adrián; Cayuela, Luis; Rueda, Marta; Ruiz Benito, Paloma; Herrero, Asier; Aponte, Cristina; Sagardia, Rodrigo; Plumptre, Andrew J.; Dupire, Sylvain; Espinosa, Carlos Ivan; Tutubalina, Olga; Myint, Moe; Pataro, Luciano; López Sáez, Jerome; Macia, Manuel J; Abegg, Meinrad; Zavala, Miguel A.; Quesada Román, Adolfo; Vega Araya, Mauricio; Golubeva, Elena; Timokhina, Yuliya; Stoffel, Markus
More tree species can increase the carbon storage capacity of forests (here referred to as the more species hypothesis) through increased tree productivity and tree abundance resulting from complementarity, but they can also be the consequence of increased tree abundance through increased available energy (more individuals hypothesis). To test these two contrasting hypotheses, we analyse the most plausible pathways in the richness-abundance relationship and its stability along global climatic gradients. We show that positive effect of species richness on tree abundance only prevails in eight of the twenty-three forest regions considered in this study. In the other forest regions, any benefit from having more species is just as likely (9 regions) or even less likely (6 regions) than the effects of having more individuals. We demonstrate that diversity effects prevail in the most productive environments, and abundance effects become dominant towards the most limiting conditions. These findings can contribute to refining cost-effective mitigation strategies based on fostering carbon storage through increased tree diversity. Specifically, in less productive environments, mitigation measures should promote abundance of locally adapted and stress tolerant tree species instead of increasing species richness

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