An integrated approach shows different use of water resources from Mediterranean maquis species in a coastal dune ecosystem

Abstract

Abstract. An integrated approach has been used to analyse the dependence of three Mediterranean species, A. unedo L., Q. ilex L., and P. latifolia L. co-occurring in a coastal dune ecosystem on two different water resources: groundwater and rainfed upper soil layers. The approach included leaf level gas exchanges, sap flow measurements and structural adaptations between 15 May and 31 July 2007. During this period it was possible to capture different species-specific response patterns to an environment characterized by a sandy soil, with a low water retention capacity, and the presence of a water table. The latter did not completely prevent the development of a drought response and, combined with previous studies in the same area, response differences between species have been partially attributed to different root distributions. Sap flow of A. unedo decreased rapidly with the decline of soil water content, while that of Q. ilex decreased only moderately. Midday leaf water potential of P. latifolia and A. unedo ranged between −2.2 and −2.7 MPa throughout the measuring period, while in Q. ilex it decreased down to −3.4 MPa at the end of the season. A. unedo was the only species that responded to drought with a decrease of its leaf area to sapwood area ratio from 23.9±1.2 (May) to 15.2±1.5 (July). While A. unedo also underwent an almost stepwise loss on hydraulic conductivity, such a loss did not occur for Q. ilex, whereas P. latifolia was able to slightly increase its hydraulic conducitivity. These differences show how different plant compartments coordinate differently between species in their responses to drought. The different responses appear to be mediated by different root distributions of the species and their relative resistances to drought are likely to depend on the duration of the periods in which water remains extractable in the upper soil layers.

Plant-soil interactions in Mediterranean forest and shrublands: impacts of climatic change

“…The avoidance of overlapping structures of the root system has been widely observed among different types of plants, such as between trees and grasses (Silva and Rego 2003;Lefi et al 2004a, b;Mattia et al 2005;Moreno et al 2005) or among more similar types, such as between woody evergreens (Filella and Peñuelas 2003b;Silva and Rego 2003;Mattia et al 2005;Mereu et al 2009). This differential capacity of plant species to exploit soil sources at different depths of soil has beneficial effects for the coexistence of species.…”

“…During drought, different plant species of the same community exhibit differential decreases in the growth of aboveground biomass (Mamolos et al 2001;Ogaya and Peñuelas 2007b;Prieto et al 2009a, b), changes in foliar nutrient concentrations and contents Sardans et al 2008a, b, e, f;Sardans and Peñuelas 2008), and effects on hydraulic conductivity (Mereu et al 2009) (Table 3). These differences in growth and nutrient uptake during drought are related to species differences in the capacity to maintain ecophysiological traits, such as photosynthetic rate, WUE, regulation of foliar gas exchange Llorens et al 2003a, b;Ozturk et al 2010;Vilagrosa et al 2010;Galle et al 2011 The relationships between hydraulic architecture and leaf area are a key factor determining drought adaption success.…”

“…Deep root systems enable the uptake of water from deep soil layers in drought seasons when the upper layers are water depleted (Veneklas and Poot 2003;Baldocchi and Xu 2007;Hernández-Santana et al 2008). Moreover, in Mediterranean plant communities, plant species with root-systems that tend to occupy different soil layer usually coexist avoiding the root systems overlapping and consequently diminishing the competition intensity, and also allowing to exploit the sources throughout all the soil depth (Castell et al 1994;Silva and Rego 2003;Lefi et al 2004a, b;Mattia et al 2005;Moreno et al 2005;Filella and Peñuelas 2003b;Silva and Rego 2003;Mattia et al 2005;Mereu et al 2009). Plants with deep-roots have proved to resist better drought events than species with shallow-root systems West et al 2012).…”

Mapping and Assessment of PM10 and O3 Removal by Woody Vegetation at Urban and Regional Level

“…where FO 3 represents the instant stomatal O 3 flux in the leaf, expressed in nmol m −2 ·s −1 , g s is the stomatal conductance to water vapor of each forest ecosystem, derived from a review of the literature and from experimental measures performed on the prevalent species [44,[63][64][65][66][67][68], [O 3 ] is the O 3 concentration in the air (ppb), and 0.613 is the diffusibility ratio between water vapor and O 3 .…”

Rainfall pattern greatly affects water use by Mongolian Scots pine on a sandy soil, in a semi-arid climate

“…The rapidly 280 depleted soil moisture is responsible for the frequent drought to which the time with degrees of moderate drought, severe drought and extreme drought accounted for about 38 %, 26 % and 3 % of the whole trial period, respectively. Consequently, the sap flux declines very quickly in this partially desiccated root system (Mereu et al, 2009). …”