Drought prolongs leaf life span in the herbaceous desert perennial Cryptantha flava

Abstract

Summary1. Drought-deciduous leaves are common in habitats with predictable, seasonal drought, and a reduction in transpirational surface area is generally considered an important drought-response strategy. Yet leaf demographic responses to unpredictable drought events that can occur at any time during the growing season have been little studied in ecological systems. 2. We created drought in a natural population of the herbaceous desert perennial Cryptantha flava (A. Nels.) Payson (Boraginaceae) in north-eastern Utah, USA, by installing rainout shelters just before and during the early part of the growing season, from 1 March until mid-June in 1998, and from 1 March until mid-May in 1999. 3. Droughted plants exhibited water stress through lower rates of midday photosynthesis and conductance, and by producing leaves with a smaller surface area and greater specific mass than plants exposed to ambient precipitation. 4. Under drought, leaf life span increased on flowering stalks and vegetative rosettes and new leaf production decreased, reducing leaf turnover and increasing standing leaf crop in droughted plants. 5.A larger number of leaves under drought conditions compensated in area for their smaller size, which means that transpirational surface area was not reduced. 6. The reduction in photosynthetic rate and the increase in leaf life span are consistent with a more general pattern in response to other low resource conditions, paralleling leaf-level responses to shortages of nutrients and light. 7. Plants in the drought and ambient precipitation treatments responded to lateseason rainfall with increased leaf production, providing an additional example of developmental plasticity in response to temporal heterogeneity in water availability.

Components of the leaf area index of marandu palisadegrass swards subjected to strategies of intermittent stocking

“…This is an opposite pattern of variation in relation to leaf lifespan, which increased from summer to winter 2005 (Zeferino, 2006), but it is in accordance with the reports of several authors that there is an inverse relationship between SLA and leaf lifespan (Casper et al, 2001). This same pattern of response was also recorded on swards managed at 95% LI for both basal and aerial tillers, indicating that aerial tillers function in a similar manner to basal tillers.…”

Funtional Ecology of fronds in Iberian saxicolous ferns

“…This pattern has been observed before in other studies of terrestrial plants, observing a decrease in the growth rate and, so that, in the foliar area under water stress conditions (Casper et al 2001). This statement seems logical, as the lack of water reduces the photosynthetic rate per area unit and, finally, the foliar area (McCree, 1986), variable that is used in the calculation of SLA.…”

Compensação tamanho/densidade populacional de perfilhos em pastos de capim-marandu

“…Diversos autores têm apontado a existência de relação inversa entre área foliar específica e longevidade de folhas em diferentes espécies (Van der Werf et al, 1998;Ryser & Urbas, 2000;Casper et al, 2001). Sbrissia (2004) também observou correlação inversa (-0,74) significativa entre essas variáveis para o capim-marandu e sugeriu um mecanismo de "economia de recursos" em épocas de estresse causado por variáveis ambientais.…”