Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Master → Etats Unis → 1999 → Lessingia glandulif era A. Gray (Asteraceae) in the Mojave Desert : Habitat Selection in a Summer-Blooming Annual

California State Polytechnic University, Pomona (1999)

Lessingia glandulif era A. Gray (Asteraceae) in the Mojave Desert : Habitat Selection in a Summer-Blooming Annual

Bogdanoff-Lord, Judith J.

Titre : Lessingia glandulif era A. Gray (Asteraceae) in the Mojave Desert : Habitat Selection in a Summer-Blooming Annual

Auteur : Bogdanoff-Lord, Judith J.

Université de soutenance : California State Polytechnic University, Pomona

Grade : Master of Science In Biological Sciences 1999

Résumé
Lessingia glandulifera A. Gray (Asteraceae) is a summer-blooming annual found in the Mojave Desert, as well as in coastal and pine forest habitats. It reaches reproduc tive maturity in the desert during the season when temperatures are at their highest and water availability is at its lowest. The purpose of this study was to investigate the survival, growth, reproduction and anatomy of this species in relation to five environmental factors (light, air and soil temperature, soil water and organic matter) to ascertain whether the populations had undergone habitat selection. Habitat selection in plants is the net result of adjustments to, and integration within, an ecosystem so that the plants can survive and function in that environment. The results of the two-sample t-tests indicate that L. glandulifera selects for high light environments but not for high soil water content. Additionally, soil organic matter was significantly lower at the focal plants than for the overall environment during most of the summer. Analysis of the demography data indicates that abiotic factors, particularly lack of rain, lead to the highest number of deaths . There was no evidenc e of her bivory, which may be deterred by chemicals in the phyllary glands. The anatomical portion of this study revealed that L. glandulifera stems possess reinforcing fibers and undergo secondary growth. Tracheids and parenchyma surround the vessels in the vascular bundles, an arrangement which provides a water jacket that would minimize embolisms. These features help enable the plant to persist in the desert.

Mots clés : Mojave Desert ; habitat selection in plants ; environmental factors ; ecosystem

Présentation

Version intégrale (3,96 Mb)

Page publiée le 3 janvier 2015, mise à jour le 8 septembre 2018