J Plant Ecol ›› 2018, Vol. 11 ›› Issue (1): 26-38.doi: 10.1093/jpe/rtx014

• Research Articles • Previous Articles     Next Articles

Understanding plant drought resistance in a Mediterranean coastal sand dune ecosystem: differences between native and exotic invasive species

Cristina Antunes1,2, Ana Júlia Pereira1,3, Patrícia Fernandes1, Margarida Ramos1, Lia Ascensão4, Otília Correia1 and Cristina Máguas1,*   

  1. 1 Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal; 2 PPG-Ecologia, Instituto de Biologia, CP 6109, Universidade Estadual de Campinas-UNICAMP, 13083-970 Campinas, São Paulo, Brazil; 3 SPBotânica-Botanical Society of Portugal, Travessa do Jardim 3, A-dos-Potes, 2615-018 Alverca do Ribatejo, Portugal; 4 CESAM-Centre for Environmental and Marine Studies, Faculdade de Ciências-CBV, Universidade de Lisboa, 1749-016 Lisboa, Portugal
  • Received:2016-05-18 Accepted:2017-02-18 Online:2018-01-19 Published:2018-01-18
  • Contact: Máguas, Cristina E-mail:cmhanson@fc.ul.pt

Abstract: Aims Mediterranean coastal dunes are habitats of great conservation interest, with a distinctive and rich flora. In the last century, Acacia spp., native from Australia, have been introduced in Portugal, with the objective of stabilizing sand dunes, and since have become dominant in numerous sand dune habitats. This invasion process led to the reduction of native plant species richness, changed soil characteristics and modified habitat's microclimatic characteristics. The aim of this research was to typify and compare, in Mediterranean sand dune ecosystems, the ecophysiological responses to drought of Helichrysum italicum and Corema album, two native species, and Acacia longifolia, an exotic invasive species. We addressed the following specific objectives: (i) to compare water relations and water use efficiencies, (ii) to evaluate water stress, (iii) to assess water use strategies and water sources used by plants and (iv) to evaluate the morphological adaptations at leaf and phyllode level.
Methods In order to obtain an integrative view of ecophysiological patterns, water relations and performance measuring methods have been applied: predawn (ψ PD) and midday (ψ MD) water potential, chlorophyll a fluorescence, oxygen isotopic composition of xylem, rain and groundwater (δ 18 O) and leaf carbon isotopic discrimination (Δ 13 C). The leaf characteristics of the three species, as well as the histochemistry of non-glandular trichome cell walls, were also studied to identify morpho-traits related to drought resistance.
Important findings The results support our initial hypothesis: although A. longifolia clearly possesses a degree of resistance to water stress, such ability is provided by a different water strategy, when compared to native species. Natives relied on morphological adaptations to restrict water loss, whereas the invasive species adjusted the water uptake as a way to balance their limited ability of restricting water loss. We corroborate that woody native species (i) have a conservative water-saving strategy and minor seasonal variations relative to invasive species, (ii) use enriched water sources during drought periods, indicating different water sources and root systems comparing with invasive species and (iii) present drought leaf morpho-functional adaptations related with limiting water loss. Comparing the physiological performance of invasive and native species can offer causal explanations for the relative success of alien plant invasions on sand dunes ecosystems.

Key words: ecophysiology, water use strategy, leaf morphology, Acacia longifolia, Corema album, Helichrysum italicum

摘要:
Aims Mediterranean coastal dunes are habitats of great conservation interest, with a distinctive and rich flora. In the last century, Acacia spp., native from Australia, have been introduced in Portugal, with the objective of stabilizing sand dunes, and since have become dominant in numerous sand dune habitats. This invasion process led to the reduction of native plant species richness, changed soil characteristics and modified habitat's microclimatic characteristics. The aim of this research was to typify and compare, in Mediterranean sand dune ecosystems, the ecophysiological responses to drought of Helichrysum italicum and Corema album, two native species, and Acacia longifolia, an exotic invasive species. We addressed the following specific objectives: (i) to compare water relations and water use efficiencies, (ii) to evaluate water stress, (iii) to assess water use strategies and water sources used by plants and (iv) to evaluate the morphological adaptations at leaf and phyllode level.
Methods In order to obtain an integrative view of ecophysiological patterns, water relations and performance measuring methods have been applied: predawn (ψ PD) and midday (ψ MD) water potential, chlorophyll a fluorescence, oxygen isotopic composition of xylem, rain and groundwater (δ 18 O) and leaf carbon isotopic discrimination (Δ 13 C). The leaf characteristics of the three species, as well as the histochemistry of non-glandular trichome cell walls, were also studied to identify morpho-traits related to drought resistance.
Important findings The results support our initial hypothesis: although A. longifolia clearly possesses a degree of resistance to water stress, such ability is provided by a different water strategy, when compared to native species. Natives relied on morphological adaptations to restrict water loss, whereas the invasive species adjusted the water uptake as a way to balance their limited ability of restricting water loss. We corroborate that woody native species (i) have a conservative water-saving strategy and minor seasonal variations relative to invasive species, (ii) use enriched water sources during drought periods, indicating different water sources and root systems comparing with invasive species and (iii) present drought leaf morpho-functional adaptations related with limiting water loss. Comparing the physiological performance of invasive and native species can offer causal explanations for the relative success of alien plant invasions on sand dunes ecosystems.

[1] Robert L. Fitch, Erin J. Questad and Edward G. Bobich. Soil resource availability and its effect on the ecophysiology and establishment of Stipa pulchra [J]. J Plant Ecol, 2019, 12(4): 603-614.
[2] Helena C. Serrano, Cristina Antunes, Manuel J. Pinto, Cristina Máguas, Maria Amélia Martins-Loução, Cristina Branquinho. The ecological performance of metallophyte plants thriving in geochemical islands is explained by the Inclusive Niche Hypothesis [J]. J Plant Ecol, 2015, 8(1): 41-50.
[3] Sonia Mediavilla, Maria Herranz, Patricia González-Zurdo, Alfonso Escudero. Ontogenetic transition in leaf traits: a new cost associated with the increase in leaf longevity [J]. J Plant Ecol, 2014, 7(6): 567-575.
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