Life history variation in an annual plant under two opposing environmental constraints along an aridity gradient

Abstract

2006. Life history variation in an annual plant under two opposing environmental constraints along an aridity gradient. Á/ Ecography 29: 66 Á/74.Environmental gradients represent an ideal framework for studying adaptive variation in the life history of plant species. However, on very steep gradients, largely contrasting conditions at the two gradient ends often limit the distribution of the same species across the whole range of environmental conditions. Here, we study phenotypic variation in a winter annual crucifer Biscutella didyma persisting along a steep gradient of increasing rainfall in Israel. In particular, we explored whether the life history at the arid end of the gradient indicates adaptations to drought and unpredictable conditions, while adaptations to the highly competitive environment prevail at the mesic Mediterranean end. We examined several morphological and reproductive traits in four natural populations and in populations cultivated in standard common environment. Plants from arid environments were faster in phenological development, more branched in architecture and tended to maximize reproduction, while the Mediterranean plants invested mainly in vertical vegetative growth. Differences between cultivation and field in diaspore production were very large for arid populations as opposed to Mediterranean ones, indicating a larger potential to increase reproduction under favorable conditions. Our overall findings indicate two strongly opposing selective forces at the two extremes of the aridity gradient, which result in contrasting strategies within the studied annual plant species.M. Petrů and K. Tielbö rger (correspondence: Katja.Tielboerger@uni-tuebingen.de),

Separating the role of biotic interactions and climate in determining adaptive response of plants to climate change

“…Ecotypic differentiation along this or a similar climate gradient has been demonstrated for Bi. didyma (Petru˚et al 2006) and Br. distachyon (Liancourt and Tielbo¨rger 2011) …”

Biomass explains the intensity of facilitative – not competitive – interactions: three intraspecific tests with annuals

“…Separated by approximately 200 mm of average rainfall, the collection sites represent arid (A) semiarid (SA), Mediterranean (M) and mesic Mediterranean (MM) zones (Petrů et al, 2006). They are located over the same calcareous bedrock on south-facing slopes and experience similar average temperatures.…”

“…From previous studies we know that annual plant populations along the gradient differ in morphological and phenological traits as well as in competitive response ability (Petrů et al, 2006;Schiffers and Tielbörger, 2006;Liancourt and Tielbörger, 2009). To ensure natural breaking of summer dormancy, collected seeds were placed in bags of transparent, permeable synthetic fabric and attached to the ground surface at their respective sites of origin (as in Liancourt and Tielbörger, 2009).…”

The Use and Misuse of Climatic Gradients for Evaluating Climate Impact on Dryland Ecosystems - an Example for the Solution of Conceptual Problems

“…Grid-based, modular simulation models of vegetation dynamics are especially able to link information on differing scales (Jeltsch et al, 1996(Jeltsch et al, , 1997Jeltsch et al, 1999). However, in the type of climate change studies proposed in the present paper, phenomena on at least three different spatial scales have to be distinguished: (1) responses of individual plants, e.g., growth, seed production, mortality and, possibly, physiological adaptation mechanisms (e.g., Petru et al, 2006); (2) small-scale intra-and interspecific interactions between individuals of contrasting growth forms, among which interactions between herbaceous and woody vegetation, including competition and facilitation mechanisms, are of especial importance (Holzapfel et al, 2006); and (3) the effects of these interactions on vegetation pattern formation on the landscape level, with feedbacks to spatial processes such as runoff, soil moisture distribution and availability, fire, grazing, and other types of land use. At all these levels, the models need and use data obtained in the detailed field investigations and experiments, and thus also function as integrators of collected information.…”