Growth, photosynthesis, and resource investment for vegetative and reproductive modules of Artemisia tridentata

• Published in: Ecology (Durham) Vol. 74; no. 5; pp. 1516 - 1528
• Main Authors: Evans, R. D., Black, R. Alan
• Format: Journal Article
• Language: English
• Published: Washington, DC The Ecological Society of America 01-07-1993; Ecological Society of America; Brooklyn Botanic Garden, etc
• Subjects: 550000 - Biomedical Sciences, Basic Studies; Animal and plant ecology; Animal, plant and microbial ecology; ARTEMISIA; Artemisia tridentata; Autoecology; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOMASS; Botany; CARBON; CHEMICAL REACTIONS; Construction costs; CRECIMIENTO; CROISSANCE; DROUGHT STRESS; ECOLOGIA VEGETAL; EFFICACITE; EFFICIENCY; EFICACIA; ELEMENTS; ENERGY SOURCES; ESTRES DE SEQUIA; FENOLOGIA; Flowers & plants; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; GROWTH; LEAVES; MOISTURE; NITROGEN; NONMETALS; PHENOLOGIE; PHENOLOGY; PHOTOCHEMICAL REACTIONS; PHOTOSYNTHESE; PHOTOSYNTHESIS; PHYTOECOLOGIE; PLANT ECOLOGY; Plant growth; PLANTS; Plants and fungi; PRODUCTION; RENEWABLE ENERGY SOURCES; REPRODUCTION; SEASONAL VARIATION; SHRUBS; Stems; STRESS DU A LA SECHERESSE; SYNTHESIS; TRANSPIRACION; TRANSPIRATION; USO DEL AGUA; UTILISATION DE L'EAU; VARIACION ESTACIONAL; VARIATION SAISONNIERE; WASHINGTON; WATER STRESS; WATER USE; Xylem; Radiolabelling; Growth; Resource allocation; Stomatal conductance; Environmental factor; Water use efficiency; Compositae; Ecophysiology; Nitrogen; Sexual reproduction; Water stress; Carbon cycle; Artemisia tridentata; Transpiration; Phenology; Dicotyledones; Angiospermae; Spermatophyta; Gas exchange; Photosynthesis; Drought; Small tree
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/1940079

Growth of vegetative and reproductive structures in Artemisia tridentata is temporally separated during the growing season; vegetative growth occurs during spring and early summer when soil moisture is most abundant, while reproductive growth occur during summer and fall when soil moisture may be limiting. Vegetative and reproductive structures may therefore exhibit contrasting efficiencies of resource acquisition and investment resulting from temporal differences in resource availability during their development. We examined the effect of water stress on growth, photosynthesis, and resource investment for vegetative and reproductive modules of Artemisia tridentata by applying supplemental water. No differences were observed in vegetative biomass between shrubs in the two watering treatments. Growth of vegetative structures occurred in the spring when water was not limiting, and shrubs in both watering treatments exerted little stomatal control over water loss. Conversely, reproductive growth occurred through the summer when water was limiting, and supplemental watering increased reproductive growth. Shrubs conserved water during summer by abscising leaves and lowering stomatal conductance of both vegetative and reproductive modules in response to decreases in xylem pressure potential and increases in evaporative demand. Leaf abscission can occur without decreasing the amount of carbon available for reproductive growth because inflorescences are capable of positive photosynthetic rates comparable to vegetative leaves. Water stress did not alter tissue construction costs or carbon and nitrogen contents for either vegetative or reproductive modules. Resource limitations were, however, reflected in the efficiency of water use during tissue construction; floral leaves and floral heads of shrubs not receiving supplemental water were produced with higher water-use efficiency. Conservative use of water during production of vegetative modules would offer no advantage to A. tridentata because neighboring species are also most active at this time. Reproductive growth in A. tridentata occurs during summer when neighboring species are largely dormant, and so efficient use of water may allow development of reproductive structures to continue throughout the summer even with limited supplies of water.