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Accueil du site → Doctorat → Mexique → Influencia de altitud en la germinación de semillas y establecimiento de plántulas de matorral en el noreste de México

Universidad Autonoma de Nuevo Leon (2006)

Influencia de altitud en la germinación de semillas y establecimiento de plántulas de matorral en el noreste de México

García Pérez, Jaime Francisco

Titre : Influencia de altitud en la germinación de semillas y establecimiento de plántulas de matorral en el noreste de México

Auteur : García Pérez, Jaime Francisco

Université de soutenance : Universidad Autonoma de Nuevo Leon

Grade : DOCTOR EN CIENCIAS CON ESPECIALIDAD EN MANEJO DE RECURSOS NATURALES 2006

Résumé partiel
The potential upslope movement of plant species according to climate change predictions was explored. On one experiment seed germination and seedling growth of four species was carried out on an elevation gradient ranging from 90 to 1960 m above sea level. Species used were Cordia boissieri, Ebenopsis ebano and Caesalpinia mexicana (native to northeastern Mexico) and Melia azederach a naturalized exotic tree. Seeds of four species were set to germinate in containers on four occasions and five elevations (spring, 2003 and 2004, autumn 2003 and 2004 at 90, 350, 520, 1600 and 1960 m above sea level). The three lowest elevations used include the current distribution range of the species, and in these is where higher germination values and seedling growth were obtained across species. On a second study, the same variables form the first experiment were measured in the same elevation gradient, but without irrigation and with seeds sown directly in the local soil. Seeds were sown on 1 m2 . Seedling emergency across species occurred mainly in summer and early autumn ; although a small percentage of seeds germinated during spring. Results suggest that germination was inhibited by low temperatures. High temperature and drought in summer, as well as lack of moisture in winter caused seedling mortality. Seedling length and number of leaves were greater at elevations with higher seedling survival. To evaluate the potential role of nurse plants in seedling establishment, seedling emergence and survival were evaluated under the canopy of three native woody plants (Caesalpinia mexicana Gray ; Cordia boissieri A. DC and Ebenopsis ebano (Berl.) Barneby I J.W. Grimes, at four elevations (90, 350, 540 and 670 m above sea level). There were 42 species germinating under the canopy of studied plants across altitudes. Under Caesalpinia mexicana 33 species germinated (6 grasses, 20 forbs and 7 woody plants) ; under the canopy of Cordia boissieri there were 36 species germinating (6 grasses, 22 forbs and 8 woody plants) and ; under Ebenopsis ebano there were 38 species germinating (5 grasses, 23 forbs and 10 woody species).

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