Papers by Jorge Lopez-Portillo
Madera Y Bosques, Dec 13, 2019
El transporte de agua en las plantas vasculares terrestres es pasivo y está determinado por la tr... more El transporte de agua en las plantas vasculares terrestres es pasivo y está determinado por la transpiración o pérdida de agua a través de las hojas. La teoría de la cohesión-tensión es la más aceptada para explicar este proceso, y se complementa con la analogía de la ley de Ohm, que analiza el flujo del agua como un proceso catenario. La resistencia al estrés hídrico y a la cavitación está fuertemente asociada con las características anatómicas del xilema, de las punteaduras intervasculares y de sus membranas, estas últimas se alteran en función de las propiedades químicas de la solución acuosa que fluye a través de ellas. Con base en estas premisas, esta revisión aborda el fenómeno del ascenso del agua en las plantas vasculares terrestres y analiza los conceptos, las teorías y los métodos más usados en el estudio de la arquitectura hidráulica. Además, señala las diferencias en la estructura del xilema y el transporte del agua entre dicotiledóneas y monocotiledóneas. PALABRAS CLAVE: cavitación, cohesión-tensión, estrés hídrico, potencial hídrico, transporte de agua en las plantas, xilema.
Foliar Water Uptake in Eight Mangrove Species: Implications of Morpho-Physiological and Anatomical Traits
SSRN Electronic Journal, 2022
Functional anatomy and xylem cavitation resistance of three species of monocotyledons grown on flooded substrates
Physiologia Plantarum, 2020
There are few investigations that analyze the xylem functional anatomy of monocotyledons, as the ... more There are few investigations that analyze the xylem functional anatomy of monocotyledons, as the methods have been developed for woody plants. This study describes the root, rhizome and aerial stem xylem anatomy and functional anatomy ofCanna indica,Cyperus papyrusandPhragmites communisgrown on flooded substrates; and it aims to evaluate the relationship between the xylem anatomy and its cavitation resistance. To calculate the indexes of vulnerability, mesomorphy, collapse and relative hydraulic conductivity in the three organs mentioned, the diameter, number of vessels per mm2, thickness of the walls and the length of the tracheal elements were recorded. In addition, the xylem specific conductivity of the aerial stem was measured with the pipette method, and its resistance to cavitation was determined experimentally by the air injection technique. The protoxylem is xeromorphic, it has longer vessel elements, smaller diameters, thin walls and scalariform perforation plates, whereas ...
Regional Distribution and Change Dynamics of Mangroves in México between 1970/80 and 2015
Wetlands, 2020
We use the maps elaborated within the Mexican Mangrove Monitoring System (MMMS) project of the Na... more We use the maps elaborated within the Mexican Mangrove Monitoring System (MMMS) project of the National Commission for Knowledge and Use of Biodiversity (CONABIO) to analyze the changes in mangrove area distribution during the last 45 years, within the framework of the coastal regional characteristics in Mexico. We found that 19% of the primary mangrove area identified in 1970/1980 was lost and that 9.4% was gained as secondary mangrove forests due to the colonization of new or disturbed areas. Using location and residence stability indexes, we identified two main change dynamics within three periods (1970/1980–2005, 2005–2010 and 2010–2015): (1) the dominant effect of climate change, especially in northwest Mexico and (2) the dominant effect of anthropic activities, mainly in the Gulf of Mexico. Significant differences in changes in the area of mangroves between regions over time highlight the relevance of more detailed and local studies to understand the processes leading to the degradation or conservation of mangroves.
Research Square (Research Square), Dec 1, 2020
The occurrence of natural root grafts, the functional union of roots of the same or different tre... more The occurrence of natural root grafts, the functional union of roots of the same or different trees , is common and shared across tree species 2 . However, their significance for forest ecology remains little understood. While early research suggested negative effects of root grafting (i.e. increases the risk of pathogen transmission) , recent evidence supports the hypothesis that it is an adaptive strategy that reduces stress by facilitating resource exchange . Here by analysing mangrove root graft networks, we show evidence of cooperation-associated benefits of root grafting. Grafted trees were found to dominate the upper canopy of the forest, and as the probability of grafting and the frequency of grafted groups increased with a higher environmental stress, the mean group size (number of trees within grafted groups) decreased. While root networks could form randomly (i.e. trees do not actively 'choose' neighbours to graft to) , the increased frequency and reduced group sizes of connected trees in higher-stress environments point to the existence of underlying mechanisms that regulate 'optimal size' group selection related to resource use within cooperating groups . This work calls for further studies to better understand tree interactions (i.e. network hydraulic redistribution) 15 and their consequences for individual tree and forest stand resilience and water-use efficiency.
Functional Ecology, Oct 23, 2018
Sustainability, Dec 18, 2020
Tree Physiology, Sep 2, 2016
Salinity tolerance in plant species varies widely due to adaptation and acclimation processes at ... 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 (Ψ s ), stomatal conductance (g s ), whole-plant hydraulic conductance (K plant ) and predawn disequilibrium between xylem and substrate water potentials (Ψ pdd ). We expected that, for all three species, salinity increments would result in coordinated declines in Ψ s , g s and K plant , and that the Ψ pdd would increase with substrate salinity and time of exposure. In concordance with our predictions, reductions in substrate water potential promoted a coordinated decline in Ψ s , g s and K plant , whereas the Ψ pdd increased substantially during the first 4 days but dissipated after 7 days, indicating a time lag for equilibration after a change in substratum salinity. Our results show that mangroves confront and partially ameliorate acute salinity stress via simultaneous reductions in Ψ s , g s and K plant , thus developing synergistic physiological responses at the cell and whole-plant scales.
Communications biology, May 5, 2021
The occurrence of natural root grafts, the union of roots of the same or different trees, is comm... more The occurrence of natural root grafts, the union of roots of the same or different trees, is common and shared across tree species. However, their significance for forest ecology remains little understood. While early research suggested negative effects of root grafting with the risk of pathogen transmission, recent evidence supports the hypothesis that it is an adaptive strategy that reduces stress by facilitating resource exchange. Here, by analysing mangrove root graft networks in a non-destructive way at stand level, we show further evidence of cooperation-associated benefits of root grafting. Grafted trees were found to dominate the upper canopy of the forest, and as the probability of grafting and the frequency of grafted groups increased with a higher environmental stress, the mean number of trees within grafted groups decreased. While trees do not actively 'choose' neighbours to graft to, our findings point to the existence of underlying mechanisms that regulate 'optimal group size' selection related to resource use within cooperating networks. This work calls for further studies to better understand tree interactions (i.e. network hydraulic redistribution) and their consequences for individual tree and forest stand resilience.
Latin American Journal of Aquatic Research
The biological importance of rhizosphere sediment-associated fungi in mangroves is poorly underst... more The biological importance of rhizosphere sediment-associated fungi in mangroves is poorly understood, especially when they are affected by high salinity and anaerobiosis in disturbed areas. This study evaluated the fungal diversity in the rhizosphere sediments of three mangrove species associated with three conservation conditions of mangrove forests in preserved, semi-preserved, and deteriorated areas. In addition, fungal bioactivity was correlated to the fungal diversity found in mangrove species from each area. We isolated 50 fungal strains belonging to three phyla, seven classes, and 10 orders. The fungal diversity was higher in the preserved area (H' = 2.22) than in the semi-preserved (H' = 1.73) and deteriorated areas (H' = 1.68); the redundancy analysis showed a tendency of fungal accumulation towards the rhizosphere of Rhizophora mangle and Avicennia germinans in the preserved and semi-preserved areas. In addition, the redundancy analysis showed that 10 bioactive...
Allometry of two columnar cacti in a tropical deciduous forest
Brazilian Journal of Botany
5th International Mangrove, Macrobenthos and Management Meeting: Book of abstracts, 2019
Global Ecology and Biogeography, 2020
AimTree crowns determine light interception, carbon and water exchange. Thus, understanding the f... more AimTree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling and for the calibration of remote sensing products. Nevertheless, we know little about large‐scale variation and determinants in tropical tree crown allometry. In this study, we explored the continental variation in scaling exponents of site‐specific crown allometry and assessed their relationships with environmental and stand‐level variables in the tropics.LocationGlobal tropics.Time periodEarly 21st century.Major taxa studiedWoody plants.MethodsUsing a dataset of 87,737 trees distributed among 245 forest and savanna sites across the tropics, we fitted site‐specific allometric relationships between crown dimensions (crown depth, diameter and volume) and stem diameter using power‐law models. Stand‐level and environmental drivers of crown allometric re...
Mangrove Forest Restoration and Rehabilitation
Mangrove Ecosystems: A Global Biogeographic Perspective, 2017
We analyzed current best practices and recommendations used in the implementation of mangrove reh... more We analyzed current best practices and recommendations used in the implementation of mangrove rehabilitation and restoration (R/R) projects in the Atlantic-East Pacific (AEP) and the Indo-West Pacific biogeographic regions during the last 20 years. Comprehensive literature and World Wide Web searches were performed identifying 90 sites around the world where R/R actions have been implemented. For each site, we analyzed the sources of damage/impact and classified the origin as natural (siltation, erosion, the direct and indirect effect of tropical storms or tsunamis) or anthropogenic (pollution, land use policies, overharvesting, aquaculture, altered hydrology and hydroperiod). In most cases, the causes of damage were a complex mixture associated to erosion, hydrological impairment, deforestation, siltation, and land conversion for aquaculture and other land uses. The area extension of mangrove sites undergoing restoration or just afforestation ranged from few square meters to several thousand hectares. Numerous projects were implemented without an underlying science-based approach and were often ill-prepared and unsuccessful. Although there is no “one-size-fits-all” solution to restore or rehabilitate mangrove wetlands, published studies (particularly peer reviewed) provide useful insights into designing R/R projects with clearly defined and prioritized management objectives based on a diagnostic of the source of damage/deterioration. A critical step is to develop a decision tree that serves as a guide to optimize the use of available funding in the development, implementation, and monitoring of R/R protocols to set clear objectives, goals and deadlines. These steps should be part of a robust research agenda based on sound ecological theory and reliable monitoring practices, including the participation of local communities. Any monitoring and reporting program should address spatial and temporal replication that explicitly includes reference sites near the target restoration site. The results of each R/R project, whether successful or not, should be published, as they are critical sources of data and information for further development of mangrove R/R practices and methods within the community of restoration ecology science. We urge the continental level implementation of guidelines to advance international initiatives aimed to protect and conserve one the most productive and threatened coastal ecosystems in the world.
Sustainability, 2020
The coastal zone is in a critical state worldwide, due to the loss and fragmentation of its ecosy... more The coastal zone is in a critical state worldwide, due to the loss and fragmentation of its ecosystems. Much of this is caused by long-term anthropic local, regional, or global actions, which drive coastal squeeze processes. Most of the criteria to evaluate the effects of coastal squeeze are focused on merely identifying its effect on the coastal zone. Here, we propose a framework to manage (identify, analyze, quantify, and tackle) the effect of coastal squeeze. This DESCR framework examines the relations between Drivers, Exchanges, and States of the environment to subsequently evaluate the chronic, negative Consequences and determine possible Responses. To illustrate the application of the DESCR framework, the coastal zone of Puerto Morelos, in the Mexican Caribbean, was studied using this approach. We analyzed the systemic interactions among the coastal ecosystems in this area, such as coral reefs, seagrass beds, beach, coastal dunes, and mangroves, which have been altered over th...
PLOS ONE, 2020
The restoration of mangroves has gained prominence in recent decades. Hydrological rehabilitation... more The restoration of mangroves has gained prominence in recent decades. Hydrological rehabilitation has been undertaken to connect impaired mangroves with the sea, lagoons or estuaries. Because mangrove hydrodynamics occurs on the surface and interstitial spaces in the sediment, we propose to determine the hydrological flow paths to restore the hydrological regimes of the impaired mangroves. The hydrological flow paths were determined through a micro basin analysis based on microtopographic data to generate a digital elevation model. Applying this methodological approach, the hydrology of an impaired area on a barrier island in the Gulf of Mexico was restored by excavating, desilting or clearing the channels on the identified hydrological flow paths. This area was compared to one in which impaired mangroves were reconnected to the marine lagoon but disregarding the flow paths. Data collected in both areas were evaluated by flood level analysis, using two methods: (i) a simple linear regression model (SLRM) and (ii) spectral analysis (SA), also known as dominant frequency analysis. The results suggest that restoration based on the hydrological flow paths was more effective than the direct opening to the nearest main water body without accounting for the microtopography. In both areas, soil salinity and sulfides decreased after hydrological reconnection. However, a greater efficiency in the investment of time and human resources was achieved when preferential flow paths were identified and taken into account. The methodological procedures described in this study are of universal application to other mangrove restoration programs.
Journal of Coastal Research, 2019
Conservation of mangrove ecosystems is one of the major global environmental challenges of this c... more Conservation of mangrove ecosystems is one of the major global environmental challenges of this century. To propose viable strategies for its conservation, it is necessary to produce an adequate cartography that enables, among other things, accurate differentiation among plant communities. Google Earth Pro (GEP) images were evaluated as a tool to classify different mangrove communities and were compared to RapidEye satellite (RE) images. The accuracy of the following classifications were compared: (1) one based on the normalized difference vegetation index (NDVI) of a RE image, (2) one based on a mosaic of 141 GEP images, both using object-based image analysis (OBIA) and (3) one based on the visual interpretation (VI) of the same GEP mosaic. It was possible to distinguish ten mangrove communities in 2436 ha, six of them dominated or codominated by the white mangrove Laguncularia racemosa, suggesting that this estuary has a strong riverine influence and low salinities. There was a 97% accuracy on the VI of GEP mosaic, significantly higher than the OBIA classifications done on RE (88%) or GEP (80%) images. These results indicate that GEP, an open access resource, provides similar accuracy when mapping mangrove communities compared to commercial images such as RE, and that the accuracy is greater when using VI. GEP images are very important tools to generate accurate and detailed large scale maps of mangrove communities and represent a great opportunity to move along in the challenge of identification, mapping and monitoring these valuable ecosystems.
Biotropica, 2019
Rhizophora mangle is the most common species of mangrove within its range and a major component o... more Rhizophora mangle is the most common species of mangrove within its range and a major component of coastal ecosystems in the tropics and subtropics. Its phenology is affected by seasonal variations in temperature, salinity, and precipitation, all of which may be altered by impending climate change. In this work, the monthly leaf, flower, and fruit phenology of R. mangle was assessed at three sites, along a natural salinity gradient for 12 months. We assessed phenological states using litter traps installed in mangrove stands, and by direct observation of leaf production at two sites, and flower, and fruit production at a single site. Phenological events were compared with seasonal climatic variations (in wind, rain, and temperature) to explore potential abiotic controls on the phenology of this species. Leaf shedding was lowest at the low salinity site. Leaf and stipule production showed a seasonal trend, decreasing during the cool and dry winter months. Flowering was highly seasona...
Scientia Fungorum, 2018
Antecedentes: Los hongos de los bosques de manglar representan un gran potencial para la bioprosp... more Antecedentes: Los hongos de los bosques de manglar representan un gran potencial para la bioprospección de nuevos metabolitos bioactivos. La rizósfera de varias regiones del mundo ha sido ampliamente estudiada, no obstante, no existen estudios sobre la biodiversidad de los manglares mexicanos. Objetivos: Evaluar la actividad anti-proliferativa de extractos de hongos aislados de sedimentos acumulados en la rizósfera de tres especies de mangles distribuidos en tres zonas con diferentes grados de salinidad en México. Métodos: Los hongos aislados se identificaron a nivel de género, mediante claves taxonómicas. Se determinó la actividad anti-proliferativa mediante el ensayo SRB y se identificaron molecularmente las cepas con valores de GI 50 <100 µg.mL -1 . Resultados y conclusiones: Seis extractos de cuatro cepas presentaron valores de GI 50 <100 µg.mL -1 en al menos una línea celular cancerosa. Una cepa de Aspergillus pulverulentus aislada de una zona perturbada de Avicennia germinans mostró la mayor actividad anti-proliferativa con seis líneas celulares de cáncer diferentes. Los valores de GI 50 variaron de 40 a 83 µg.mL -1 en extractos de biomasa y de 6 a 28 µg.mL -1 en extractos de caldo de cultivo. Este trabajo es el primer estudio de bioprospección de hongos que muestran actividad anti-proliferativa en sedimentos de manglar en México.
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Papers by Jorge Lopez-Portillo