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Accueil du site → Doctorat → États-Unis → 2002 → Effects of mineral nutrient deficiencies on plant performance in the desert shrubs Chrysothamnus nauseosus ssp. consimilis and Sarcobatus vermiculatus

University of California, Davis (2002)

Effects of mineral nutrient deficiencies on plant performance in the desert shrubs Chrysothamnus nauseosus ssp. consimilis and Sarcobatus vermiculatus

Drenovsky, Rebecca E

Titre : Effects of mineral nutrient deficiencies on plant performance in the desert shrubs Chrysothamnus nauseosus ssp. consimilis and Sarcobatus vermiculatus

Auteur : Drenovsky, Rebecca E

Université de soutenance : University of California, Davis

Grade : Doctor of Philosophy (PhD) 2002

Résumé
Nutrient limitations, although often overlooked in deserts, can influence plant success and community composition. My objective was to link low nutrient availability to desert shrub performance in the Mono Lake basin, CA. At this site, long and short-term lake level changes have exposed lake bed surfaces, creating a dune chronosequence varying in salinity, nutrient availability, and community composition. The non-mycorrhizal shrub Sarcobatus is most dominant on younger, more saline dunes. In contrast, the mycorrhizal shrub Chrysothamnus is most dominant on less saline, older dunes. The relationships between nutrient limitation and plant performance were explored in four experiments. (1) Sarcobatus is most successful on saline sites where leaf N is high, suggesting Na and N interactions stimulate Sarcobatus performance. Contrary to expectations, high N availability did not induce salt-stimulated growth or increase Sarcobatus salinity tolerance in a greenhouse experiment. (2) Sarcobatus leaf nutrients, seed production, recruitment, and community dominance decrease with substrate age. Although multiple limiting nutrients were expected, N addition, alone, increased Sarcobatus growth, seed production, filled seed weight, and leaf N. Nitrogen limitations may reduce Sarcobatus fitness, contributing to observed successional changes in these alkaline dunes. (3) Based on mycorrhizal status, leaf N and P concentrations, and critical foliar N:P values, I predicted N limits Chrysothamnus and P limits Sarcobatus . However, following nutrient addition, only P and water additions increased Chrysothamnus growth, where as only N additions increased Sarcobatus growth. Hypotheses were explored regarding these unpredicted responses to nutrient addition. (4) Differential N and P losses were estimated in Chrysothamnus and Sarcobatus by measuring leaf nutrient resorption in conjunction with aboveground N and P pools. Chrysothamnus resorbed significantly more N than Sarcobatus , where as Sarcobatus resorbed significantly more P than Chrysothamnus . As leaf N and P pools were approximately 50% of both species’ aboveground N and P pools, resorption from senescing leaves can contribute significantly to nutrient retention. Annual N and P litterfall losses may lead to N limitation in Sarcobatus and P limitation in Chrysothamnus . Together, these data suggest nutrient limitations and plant adaptations to these adverse conditions strongly influence desert plant performance, population dynamics, and community composition.

Mots clés : Ecology, Sarcobatus vermiculatus, Shrubs, Chrysothamnus nauseosus, Desert, Biological sciences Nutrient deficiencies, Botany

Annonce (WorldCat)

Accès au document : Proquest Dissertations & Theses

Page publiée le 18 février 2015, mise à jour le 8 janvier 2017