Plant Effects on Soils in Drylands: Implications for Community Dynamics and Ecosystem Restoration

DOI: 10.1007/1-4020-3447-4_6
Download full-text


Available from: Jordi Cortina, Sep 30, 2015
1 Follower
86 Reads
  • Source
    • "Nevertheless, a shift from facilitation to competition under high-abiotic-stress conditions may occur when the levels of the most limiting resource are so low that the benefits provided by the facilitator cannot overcome its own resource uptake (Maestre and Cortina, 2004). Thus, despite the fact that in water-limited environments, plants generally improve soil fertility and microclimate under their canopies (Cortina and Maestre, 2005), these changes do not always translate into increased water availability in their immediate vicinity (Sala et al., 1989; Valladares and Pearcy, 2002). Canopy interception can reduce the amount of water reaching the soil, and root competition for water can make the understorey drier than open patches (Abrams and Mostoller, 1995; Valladares and Pearcy, 2002; Hamerlynck et al., 2011). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Water relations are essential in plant–plant interactions, particularly in Mediterranean coastal sand dunes, owing to marked drought periods and the possibility of groundwater (GW) salinization. In this study, seasonal water use dynamics were explored in the interaction between a native–invasive species, Retama monosperma, and the endangered Thymus carnosus, in south-western Spain. The following variables were measured: xylem water isotopic composition to determine water sources, predawn and midday stem water potential and free leaf proline content as stress indicator. GW electrical conductivity and stable isotopes were also analysed to assess water table salinity. In late summer and spring, the warmest seasons, Thymus beneath Retama displayed significantly lower water potential and higher leaf proline content than isolated Thymus, whereas Retama showed the highest proline content in autumn and winter. Water sources showed different patterns depending on the Thymus situation: Isolated ones always matched the brackish GW, as well as Retama plants, whereas Thymus beneath Retama switched among rainfall, soil and water table, showing a seasonal change in the water-harvesting strategy. Overall, competition for water sources between both species was discovered, which led to a shift in water use and water uptake strategies of understorey Thymus. The results also demonstrate the importance and potential use of species interaction studies in the development of threatened species management strategies. Copyright © 2013 John Wiley & Sons, Ltd.
    Ecohydrology 04/2014; 7(2). DOI:10.1002/eco.1401 · 2.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Shrubs often dominate early successional stages in areas that are suitable for the establishment of forests. Under a dense shrub canopy, the density of seedlings of late successional tree species can be low, suggesting that colonisation by forest species may be hampered. In contrast, several studies have shown that positive interactions may offset the negative effects of competition when environmental conditions are limiting. We have evaluated the effect of different types of shrubland clearing and planting location on the establishment of Quercus suber seedlings under Mediterranean conditions. Clearing a 2-m spot around planted seedlings had a weak effect on seedling performance. Seedlings planted on highly exposed microsites showed 65% increase in survival as compared to seedlings planted in undisturbed shrubland. Seedling growth showed a similar trend. For example average stem height in seedlings planted in open sites was 39.60 cm as compared to 29.59 cm in seedlings planted on undisturbed shrubland. Increased soil water availability may be responsible for the positive effect of shrubland clearing. Seedling survival was negatively correlated with the abundance of obligate seeders such as Cistus salviifolius, and positively correlated with the abundance of sprouting species such as Erica arborea suggesting that the interaction between Q. suber seedlings and extant vegetation may be species dependent.
    Forest Ecology and Management 03/2008; 255(3-4-255):374-382. DOI:10.1016/j.foreco.2007.09.074 · 2.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Exotic species have been widely used in reforestation in arid areas in northern Africa, as they provide ecosystem services that native species may be unable to supply. But information on their effect on ecosystem function and composition is scarce. We have evaluated the effect of 20-year-old Acacia saligna (Labill.) H.L. Wendl. plantations on the soil surface conditions and vascular plant composition in central Tunisia. Landscape function analysis (LFA) indices of soil stability, infiltration, and nutrient recycling underneath A. saligna increased by 1%, 138%, and 148%, respectively, in comparison to bare areas. This species, however, did not affect indicators of soil surface functionality, the spatial pattern of resource sinks-sources, or vascular plant species composition at a plot scale. This was probably due to low A. saligna cover, and a limited degree of litter incorporation into the soil surface. Our results suggest that the potential for improving ecosystem function and fostering succession by using this species seems to be limited in this arid environment.
    Arid Land Research and Management 01/2009; 23(1-1):28-46. DOI:10.1080/15324980802599209 · 0.80 Impact Factor
Show more