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Jorge Lopez-Portillo

    Jorge Lopez-Portillo

    Salinity tolerance in plant species varies widely due to adaptation and acclimation processes at the cellular and whole-plant scales. In mangroves, extreme substrate salinity induces hydraulic failure and ion excess toxicity and reduces... more
    Salinity tolerance in plant species varies widely due to adaptation and acclimation processes at the cellular and whole-plant scales. In mangroves, extreme substrate salinity induces hydraulic failure and ion excess toxicity and reduces growth and survival, thus suggesting a potentially critical role for physiological acclimation to salinity. We tested the hypothesis that osmotic adjustment, a key type of plasticity that mitigates salinity shock, would take place in coordination with declines in whole-plant hydraulic conductance in a common garden experiment using saplings of three mangrove species with different salinity tolerances (Avicennia germinans L., Rhizophora mangle L. and Laguncularia racemosa (L.) C.F. Gaertn., ordered from higher to lower salinity tolerance). For each mangrove species, four salinity treatments (1, 10, 30 and 50 practical salinity units) were established and the time trajectories were determined for leaf osmotic potential (Ψs), stomatal conductance (gs), ...
    Although several damaged mangrove ecosystems have been restored worldwide, so far, it has not been established whether a restored mangrove system regains all the functional properties of preserved mangroves. This study measured nitrogen... more
    Although several damaged mangrove ecosystems have been restored worldwide, so far, it has not been established whether a restored mangrove system regains all the functional properties of preserved mangroves. This study measured nitrogen fixation as an indicator of whether disturbed mangroves that were reforested or naturally regenerated fully recovered from this disturbance at a functional level. Rates of nitrogen fixation were measured for one year in impaired, preserved, reforested, and naturally regenerated mangroves dominated by the black mangrove (Avicennia germinans). There was no significant difference in rates of nitrogen fixation among preserved and adjacent reforested and naturally regenerated mangroves, but a significant reduction occurred in an impaired mangrove. Nitrogen fixation was mainly controlled by pH, salinity, and temperature. The highest rates of nitrogen fixation occurred in summer at pH values less than 6.4, whereas the impaired mangrove had higher pH and salinity and had very low nitrogen fixation activity. These results suggest that nitrogen fixation can be used as an ecological indicator of the success of reforestation and as a sensitive measure of perturbations in mangroves.
    ... Article Outline. 1. Introduction; 2. Materials and methods; 2.1. Study area; 2.1.1. Climate; 2.1.2. Geology; 2.1.3. Geomorphology; 2.1.4. Hydrology; 2.1.5. Soils; 2.1.6. Vegetation and land use. 2.2. Evolution of the deltaic fan; 2.3.... more
    ... Article Outline. 1. Introduction; 2. Materials and methods; 2.1. Study area; 2.1.1. Climate; 2.1.2. Geology; 2.1.3. Geomorphology; 2.1.4. Hydrology; 2.1.5. Soils; 2.1.6. Vegetation and land use. 2.2. Evolution of the deltaic fan; 2.3. Cartography and fieldwork; 2.4. ...
    ... Baton Rouge, LA 70803, USA. *Correspondence: Rodrigo Méndez-Alonzo,. *Correspondence: Corresponding author; e-mail: rodrigo.mendez@posgrado.inecol. edu.mx. Publication History. Issue published online: 8 JUL 2008; ...
    Nectar production has been proposed as an adaptation to attract pollinators that benefit from this resource. Energetic investments may be expensive, so some species such as Prosopis glandulosa have developed a dimorphic system of nectar... more
    Nectar production has been proposed as an adaptation to attract pollinators that benefit from this resource. Energetic investments may be expensive, so some species such as Prosopis glandulosa have developed a dimorphic system of nectar production, which is expected to affect floral visitor behaviour and then plant fitness. We quantified bee diversity during a 2 year period in a population of the honey mesquite in order to determine changes in bee diversity due to the presence of nectar, bee preferences to collect either nectar of pollen, and to determine between year variations of bee faunas. Floral visitors were captured at three different times of the day during the flowering seasons of 1994 and 1995, in a population of Prosopis glandulosa which has a 1:1 proportion of nectar: nectarless individuals. Pollinators were clearly distinct between nectar morphs, bee species diversity and relative abundance of visits were significantly greater on nectarful than on nectarless plants, with species on nectarless individuals being a subset of those in the nectarful morph. Our results suggest differences in the function of floral rewards (i.e., nectar and pollen) to attract floral visitors. For the Chihuahuan arid environment, mesquite provides floral rewards with ease, quantity and quality for close to 10% of all bee fauna making them important components of these communities.
    Rhizophora species of mangroves have a conspicuous system of stilt-like roots (rhizophores) that grow from the main stem and resemble flying buttresses. As such, the development of rhizophores can be predicted to be important for the... more
    Rhizophora species of mangroves have a conspicuous system of stilt-like roots (rhizophores) that grow from the main stem and resemble flying buttresses. As such, the development of rhizophores can be predicted to be important for the effective transmission of dynamic loads from the top of the tree to the ground, especially where the substrate is unstable, as is often the case in the habitats where Rhizophora species typically grow. This study tests the hypothesis that rhizophore architecture in R. mangle co-varies with their proximity to the main stem, and with stem size and crown position. The allometry and wood mechanical properties of R. mangle (red mangrove) trees growing in a mangrove basin forest within a coastal lagoon in Mexico were compared with those of coexisting, non-buttressed mangrove trees of Avicennia germinans. The anatomy of rhizophores was related to mechanical stress due to crown orientation (static load) and to prevailing winds (dynamic load) at the study site. ...
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    Resumen La heterogeneidad del paisaje varía en el espacio dependiendo de la proporción entre polígonos y unidades tipológicas. La alta variabilidad del espacio geográfico le confiere una elevada connotación ecológica, lo cual sugiere una... more
    Resumen La heterogeneidad del paisaje varía en el espacio dependiendo de la proporción entre polígonos y unidades tipológicas. La alta variabilidad del espacio geográfico le confiere una elevada connotación ecológica, lo cual sugiere una estrecha relación con la ...
    ... deriva deun vocablo guaraníque Los manglares corresponden a la vegetación arbórea de la zona de mareas que corresponde al ecotono entre los ... los 28° 53´19.98” N; 113° 31´17.5”W. El límite Insular de costa este del Mar de Cortés:... more
    ... deriva deun vocablo guaraníque Los manglares corresponden a la vegetación arbórea de la zona de mareas que corresponde al ecotono entre los ... los 28° 53´19.98” N; 113° 31´17.5”W. El límite Insular de costa este del Mar de Cortés: Isla Tiburón, Sonora, aproximadamente a ...
    SUMMARY The mangrove ecosystems which surround the La Mancha la- goon in Veracruz, Mexico, are characterized by the high com- plexity of its landscapes in conditions of adequate conservation. This work deals on the structure and... more
    SUMMARY The mangrove ecosystems which surround the La Mancha la- goon in Veracruz, Mexico, are characterized by the high com- plexity of its landscapes in conditions of adequate conservation. This work deals on the structure and composition of the geocomplexes of this area. The use of structural-genetic and his- torical-evolutionary principles permitted the survey, classification and cartography of mangrove landscapes
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    Research Interests:
    We examined the concept that high vessel number provides xylem safety and also show that under certain circumstances high vessel number may increase rather than decrease the probability of mortality. The independ-ent variable was the... more
    We examined the concept that high vessel number provides xylem safety and also show that under certain circumstances high vessel number may increase rather than decrease the probability of mortality. The independ-ent variable was the number of vessels per organ ...
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