scholarly journals Parameterization of the Stomatal Component of the DO3SE Model for Mediterranean Evergreen Broadleaf Species

2007 ◽  
Vol 7 ◽  
pp. 119-127 ◽  
Author(s):  
Roccío Alonso ◽  
Susana Elvira ◽  
María J. Sanz ◽  
Lisa Emberson ◽  
Benjamín S. Gimeno
Keyword(s):  
Quercus Ilex ◽  
Measured Data ◽  
Holm Oak ◽  
Accurate Estimation ◽  
Soil Parameters ◽  
Summer Drought ◽  
Moisture Deficit ◽  
Broadleaf Species ◽  
Mapping Exercise ◽  
Good Agreement

An ozone (O3) deposition model (DO3SE) is currently used in Europe to define the areas where O3concentrations lead to absorbed O3doses that exceed the flux-based critical levels above which phytotoxic effects would be likely recorded. This mapping exercise relies mostly on the accurate estimation of O3flux through plant stomata. However, the present parameterization of the modulation of stomatal conductance (gs) behavior by different environmental variables needs further adjustment if O3phytotoxicity is to be assessed accurately at regional or continental scales. A new parameterization of the model is proposed for Holm oak (Quercus ilex), a tree species that has been selected as a surrogate for all Mediterranean evergreen broadleaf species. This parameterization was based on a literature review, and was calibrated and validated using experimentally measured data of gsand several atmospheric and soil parameters recorded at three sites of the Iberian Peninsula experiencing long summer drought, and very cold and dry winter air (El Pardo and Miraflores) or milder conditions (Tietar). A fairly good agreement was found between modeled and measured data (R2= 0.64) at Tietar. However, a reasonable performance (R2= 0.47–0.62) of the model was only achieved at the most continental sites when gsand soil moisture deficit relationships were considered. The influence of root depth on gsestimation is discussed and recommendations are made to build up separate parameterizations for continental and marine-influenced Holm oak sites in the future.

scholarly journals Cavitation Limits the Recovery of Gas Exchange after Severe Drought Stress in Holm Oak (Quercus ilex L.)

Forests ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 443 ◽  
Author(s):  
José Peguero-Pina ◽  
Óscar Mendoza-Herrer ◽  
Eustaquio Gil-Pelegrín ◽  
Domingo Sancho-Knapik
Keyword(s):  
Drought Stress ◽  
Quercus Ilex ◽  
Stomatal Closure ◽  
Maximum Velocity ◽  
Holm Oak ◽  
Severe Drought ◽  
Summer Drought ◽  
Co2 Uptake ◽  
Partial Recovery ◽  
Xylem Embolism

Holm oak (Quercus ilex L.) is a Mediterranean species that can withstand intense summer drought through a high resistance to cavitation far beyond the stomatal closure. Besides stomatal limitations, both mesophyll and biochemical limitations to CO2 uptake could increase in holm oak under drought. However, no studies have addressed how hydraulic and non-hydraulic factors may limit the recovery of photosynthesis when re-watering after inducing 50% loss of hydraulic conductivity. We measured photosynthetic traits, xylem embolism, and abscisic acid (ABA) in holm oak with increasing levels of drought stress and seven days after plant re-watering. Drought stress caused a sharp decrease in net CO2 assimilation (AN), stomatal and mesophyll conductance (gs and gm), and maximum velocity of carboxylation (Vcmax). The stomatal closure could be mediated by the rapid increase found in ABA. The high level of xylem embolism explained the strong down-regulation of gs even after re-watering. Therefore, only a partial recovery of AN was observed, in spite of non-hydraulic factors not limiting the recovery of AN, because i/ABA strongly decreased after re-watering, and ii/gm and Vcmax recovered their original values. Therefore, the hydraulic-stomatal limitation model would be involved in the partial recovery of AN, in order to prevent extensive xylem embolism under subsequent drought events that could compromise holm oak survival.

scholarly journals Regeneration dynamics in fragmented landscapes at the leading edge of distribution: Quercus suber woodlands as a study case

2021 ◽  
Author(s):  
Jorge Luis Montero-Muñoz ◽  
Carmen Ureña ◽  
Diego Navarro ◽  
Valentín Herrera ◽  
Pilar Alonso-Rojo ◽  
...  
Keyword(s):  
Tree Growth ◽  
Quercus Suber ◽  
Forest Recovery ◽  
Tree Cover ◽  
Distribution Area ◽  
Soil Parameters ◽  
Old Fields ◽  
Summer Drought ◽  
Regeneration Dynamics ◽  
Positive Effect

Abstract Aims We studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits of rainfall and temperature. Two hypotheses were established: (1) regeneration of Quercus species is strongly favored by the presence of tree cover; and (2) growth of Q. suber is driven by the climatic variables that represent the lower ecological limit of its leading distribution edge. Methods We selected woodlands and old fields with and without tree remnants (n = 3 per type), and analyzed stand structure, soil parameters and tree growth. Results Succession was arrested in old fields without tree remnants. By contrast, remnant trees were accelerators of forest recovery in old fields. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation that mitigate the effects of summer drought on seedlings. Also, tree cover improved soil parameters (e.g., organic matter) that are important factors for understanding differences in regeneration. Winter/spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September. Conclusions Regeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover.

Structure, biomass and production of a resprouted holm-oak (Quercus ilex L.) forest in NE Spain

Vegetatio ◽  
1992 ◽  
Vol 99-100 (1) ◽  
pp. 51-59 ◽  
Author(s):  
M. J. Lled� ◽  
J. R. S�nchez ◽  
J. Bellot ◽  
J. Boronat ◽  
J. J. Iba�ez ◽  
...  
Keyword(s):  
Quercus Ilex ◽  
Holm Oak ◽  
Ne Spain

Use of a three-dimensional model to predict heavy metal (copper) fluxes in the Oujiang estuary

2014 ◽  
Vol 69 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
Shasha Lu ◽  
Ruijie Li ◽  
Xiaoming Xia ◽  
Jun Zheng
Keyword(s):  
River Discharge ◽  
Water Surface ◽  
Three Dimensional ◽  
Measured Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Pollutant Concentrations ◽  
Suspended Sediment Concentrations ◽  
Adsorption Desorption ◽  
Good Agreement

Measuring pollutant concentrations in major tributaries is the standard method for establishing pollutant fluxes to the sea. However, this method is costly and difficult, and may be subject to a great deal of uncertainty due to the presence of unknown sources. This uncertainty presents challenges to managers and scientists in reducing contaminant discharges to water bodies. As one less costly method, a three-dimensional model was developed and used to predict pollutant fluxes to the sea. The sorptive contaminant model was incorporated into hydrodynamic and sediment models. Adsorption–desorption of copper by sediments in the Oujiang estuary were described using Henry's law. The model was validated using measured data for water surface elevations, flow velocity/direction, suspended sediment concentrations, and the proportion of copper sorbed to sediment. The validated model was then applied to predict fluxes of copper. Combined with the measured data, the copper concentration in the Oujiang River discharge was calculated as 13.0 μg/L and copper fluxes were calculated as 52 t in 2010. This copper flux prediction was verified using measured dissolved copper concentrations. Comparisons between the modeled and measured results showed good agreement at most stations, demonstrating that copper flux prediction in the Oujiang estuary was reasonably accurate.

scholarly journals Drought reduced monoterpene emissions from the evergreen Mediterranean oak <i>Quercus ilex</i>: results from a throughfall displacement experiment

2009 ◽  
Vol 6 (7) ◽  
pp. 1167-1180 ◽  
Author(s):  
A.-V. Lavoir ◽  
M. Staudt ◽  
J. P. Schnitzler ◽  
D. Landais ◽  
F. Massol ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Quercus Ilex ◽  
Photochemical Efficiency ◽  
Leaf Water ◽  
Control Treatment ◽  
Summer Drought ◽  
Drought Period ◽  
Significant Difference ◽  
Monoterpene Emission

Abstract. The effects of water limitations on the emission of biogenic volatile organic compounds are not well understood. Experimental approaches studying drought effects in natural conditions are still missing. To address this question, a throughfall displacement experiment was set up in a natural forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature trees were exposed in 2005 and 2006 either to an additional drought, to irrigation or to natural drought (untreated control). In both years, absolute monoterpene emission rates as well as the respective standard factors of the trees exposed to normal and additional drought strongly declined during the drought periods. Monoterpene emissions were lower in year 2006 than in year 2005 (factor 2) due to a more pronounced summer drought period in this respective year. We observed a significant difference between the irrigation and additional drought or control treatment: irrigated trees emitted 82% more monoterpenes during the drought period 2006 than the trees of the other treatments. However, no significant effect on monoterpene emission was observed between normal and additional drought treatments, despite a significant effect on leaf water potential and photochemical efficiency. During the development of drought, monoterpene emissions responded exponentially rather than linearly to decreasing leaf water potential. Emissions rapidly declined when the water potential dropped below −2 MPa and photosynthesis was persistently inhibited. Monoterpene synthase activities measured in vitro showed no clear reduction during the same period. From our results we conclude that drought significantly reduces monoterpene fluxes of Mediterranean Holm oak forest into the atmosphere due to a lack of primary substrates coming from photosynthetic processes.

Habitat selection patterns of common cranes Grus grus wintering in holm oak Quercus ilex dehesas of central Spain: Effects of human management

1996 ◽  
Vol 75 (2) ◽  
pp. 119-123 ◽  
Author(s):  
Mario Díaz ◽  
Elvira González ◽  
Rodrigo Muñoz-Pulido ◽  
Miguel Angel Naveso
Keyword(s):  
Habitat Selection ◽  
Quercus Ilex ◽  
Holm Oak ◽  
Central Spain ◽  
Grus Grus ◽  
Human Management

scholarly journals Regeneration Dynamics in Fragmented Landscapes at the Leading Edge of Distribution: Quercus Suber L. as A Study Case

2021 ◽  
Author(s):  
Jorge Montero-Muñoz ◽  
Carmen Ureña ◽  
Diego Navarro ◽  
Valentín Herrera ◽  
Pilar Alonso-Rojo ◽  
...  
Keyword(s):  
Tree Growth ◽  
Quercus Suber ◽  
Forest Recovery ◽  
Tree Cover ◽  
Distribution Area ◽  
Soil Parameters ◽  
Old Fields ◽  
Summer Drought ◽  
Regeneration Dynamics ◽  
Positive Effect

Abstract AimsWe studied the regeneration dynamics of woodlands and abandoned old fields in a landscape dominated by Quercus suber in its lower limits for rainfall and temperature. Two hypotheses were established: (1) recruitment of Q. suber is restricted more by abiotic variations than other species adapted to more extreme Mediterranean conditions; and (2) decreases in precipitation reduce growth, but temperature positively affects growth in the leading cold edge of this species distribution area.MethodsWe selected nine sites containing forest stands and old fields with and without tree remnants, and analyzed stand structure, soil parameters and tree growth.ResultsSuccession was arrested in plots without tree remnants after cultivation abandonment. By contrast, remnant trees were accelerators of forest recovery. Tree cover played a fundamental role in Quercus recruitment throughout seed dispersal and facilitation effects that ameliorate summer drought. However, soil variables also significantly explained much of the variance observed and are important for understanding differences in regeneration. Winter and spring precipitation exerted a positive effect on tree growth, as well as temperatures during winter/spring and September.ConclusionsRegeneration dynamics are modeled by the density of tree cover in the cold and dry edge of the distribution area of Q. suber where Q. ilex is increasing in abundance. Although temperature has a positive effect on the tree growth of Q. suber, when demographic processes are considered, decreases in water availability likely play a critical role in Q. ilex recruitment. This in turn changes dominance hierarchies, especially in abandoned areas with little or no tree cover.

scholarly journals Decline in holm oak coppices (Quercus ilex L. subsp. ballota (Desf.) Samp.): biometric and physiological interpretations

2017 ◽  
Vol 26 (2) ◽  
pp. e06S ◽  
Author(s):  
Rafael Serrada ◽  
Valentín Gómez-Sanz ◽  
María J. Aroca ◽  
Javier Otero ◽  
J. Alfredo Bravo-Fernández ◽  
...  
Keyword(s):  
Quercus Ilex ◽  
Holm Oak
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