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Instituto Potosino de Investigación Científica y Tecnológica (IPICYT) 2016

Effect of induced global warming on survival and performance of succulent species from Southern Chihuahuan Desert

Aragón Gastélum, José Luis

Titre : Effect of induced global warming on survival and performance of succulent species from Southern Chihuahuan Desert

Auteur : Aragón Gastélum, José Luis

Etablissement de soutenance : Instituto Potosino de Investigación Científica y Tecnológica (IPICYT)

Grade : Doctor en Ciencias Aplicadas 2016

Résumé
"Numerous ecological studies have assessed the potential consequences of climate warming within several ecosystems worldwide. However, the impact of global warming on desert plants is still little studied. Most predictions of global change in desert species have been suggested for adult plants, neglecting other plant development phases, such as seeds, seedlings or young plants, which are often more susceptible to temperatures, drought and anthropogenic stresses than mature plants. The Chihuahuan Desert is largest warm desert of North America ; it expands from southwestern United States to the Central Mexican Highlands. Global change predictions for this region indicate that summer temperatures (June–September) will increase by 1–2oC by 2030. However, the greatest temperature increase is predicted to occur during the winter months (January–March), when monthly average temperatures might increase by up to 6oC. This critical scenario has created strong uncertainty for conservation biologists because the southernmost section of the Chihuahuan Desert harbors an elevated richness of succulent plants, especially globose cacti, most of them protected by the Mexican environmental laws. Nevertheless, there is still little information about the thermal tolerance thresholds for plant species of this area. Passive open top-chambers (OTCs) are the most common and simplest tool to evaluate the responses of plants to climate warming in the field. The main goal of this research was to assess survival rate and tolerance mechanisms of several succulent species from the Cactaceae and Asparagaceae families in the earlier stages of their life cycles (seeds, seedlings and young plants) under a potential scenario of global warming in the Southern Chihuahuan Desert, within the state of San Luis Potosí, México. In our induced global warming scenario using OTCs, the mean air temperature was higher and relative humidity was lower than in the control plots. These temperature increases and relative humidity decreases promoted the rise of the mean soil temperature within OTCs compared to open spaces. We hypothesize that this physical stress rises will have a severe detrimental effect in seeds, seedlings and young plants of the studied species. Differential responses were observed, which were in function of the development state and the analyzed species.

Mots clés : Anatomía funcional Asparagaceae Banco de semillas del suelo Cactaceae Calentamiento global Cámaras de techo abierto Desierto Chihuahuense Ecofisiología GCCA Germinación de semillas Juveniles Plántulas Supervivencia.

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