Publications

@article{Martínez2021c,

title = {Ephemeral visitors or permanent residents? — Decadal change in the ruderal vegetation from a periurban university campus},

author = {D. N. Martínez and L. López-Toledo and F. Espinosa-García and M. Camacho-Cervantes and E. de la Barrera},

url = {https://www.sciencedirect.com/science/article/pii/S161886672100399X},

doi = {10.1016/j.ufug.2021.127372},

year  = {2021},

date = {2021-10-11},

urldate = {2021-10-11},

journal = {Urban Forestry and Urban Greening},

volume = {65},

pages = {127372},

abstract = {Highlights

• Anthropogenic disturbance (built area) increased in the study site over the years.

• Species richness and the proportion of exotic species increased with disturbance.

• The most diverse families of ruderal flora were Asteraceae, Fabaceae, and Poaceae.

• The 16 species that disappeared after 2008 were native.

• Thirteen of the exotic species found in the study site are invasive in Mexico.



Abstract

Urbanization creates environmental conditions that hinder the growth of natural vegetation. We surveyed the ruderal vegetation from a periurban university campus in west-central Mexico during the rainy seasons of 2008 and 2016–2018, time during which the campus underwent intensive construction. The built area grew from 4 ha in 2009 to 12.6 ha in 2017. We identified 234 different Angiosperms belonging to 165 genera and 43 families and the community composition changed over time. For example, Asteraceae was replaced by Poaceae as the richest family in 2018. Also, 16 native species found in 2008 disappeared from the study site, 9 of which have been related with low disturbance. In contrast, 98 new species were observed in the latter years, including some that are commonly found in cities. Overall, species richness increased with time, including that of exotic species that increased from 16 % of the total species in 2008 to 24 % in 2018. Thirteen of such exotic species are invasive in Mexico, including Digitaria velutina, Asphodelus fistulosus, Mercurialis annua, and Senecio inaequidens, for which this was their first record in the city of Morelia (population 849,053), where the campus is located. These results suggest that environmental conditions imposed by disturbance can favor the proliferation of various species, especially grasses and several exotic species of different families.},

keywords = {anthropocene, biodiversity, biodiversity threats, Bioindicator, disturbance, invasive species, land-use change, urban ecology, urban sprawl},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2020b,

title = {Isotopic biomonitoring of anthropic carbon emissions in a megalopolis},

author = {E. A. Díaz-Álvarez and E. de la Barrera},

doi = {10.7717/peerj.9283},

issn = {2167-8359},

year  = {2020},

date = {2020-05-29},

journal = {PeerJ},

volume = {8},

pages = {e9283},

abstract = {Atmospheric pollution has become a serious threat for human health and the environment. However, the deployment, operation, and maintenance of monitoring networks can represent a high cost for local governments. In certain locations, the use of naturally occurring plants for monitoring pollution can be a useful supplement of existing monitoring networks, and even provide information when other types of monitoring are lacking. In this work, we i) determined the tissue carbon content and the δ13C values for the epiphytic CAM bromeliad Tillandsia recurvata and the relationship of both parameters with the existing CO concentrations in the Valley of Mexico basin, and ii) mapped the spatial distribution of such elemental and isotopic composition for this plant within the basin, in order to assess its potential as an atmospheric biomonitor of carbon monoxide, a pollutant with important repercussions on public health. The CO concentrations in the basin ranged from 0.41 ppm at rural locations to 0.81 ppm at urban sites. The carbon content of T. recurvata which averaged 42.9 ± 0.34% (dry weight), was not influenced by the surrounding CO concentration. In contrast, the δ13C depended on the sites where the plants were collected. For example, the values were ‒13.21‰ in rural areas and as low as –17.47‰ in an urban site. Indeed, the isotopic values had a positive linear relationship with the atmospheric CO concentrations. Given the close relationship observed between the isotopic composition of T. recurvata with the CO concentrations in the Valley of Mexico, the δ13C values can be useful for the detection of atmospheric carbonaceous emissions.},

keywords = {atmospheric pollution, biomonitoring, biomonitors, stable isotopes, Tillandsia, urban ecology},

pubstate = {published},

tppubtype = {article}

}

@article{Martínez2020,

title = {Germination ecophysiology for three peri-urban ephemeral weeds},

author = {D. N. Martínez and E. de la Barrera },

url = {https://lagranja.ups.edu.ec/index.php/granja/article/view/31.2020.03},

doi = {10.17163/lgr.n31.2020.03},

year  = {2020},

date = {2020-02-28},

journal = {La Granja (Revista de Ciencias de la Vida)},

volume = {31},

pages = {03},

abstract = {The environmental requirements leading to germination were determined by three common species found during the June-October 2009 rainy season in a peri-urban site from Morelia, Michoacán, Mexico, where the construction of a campus of Universidad Nacional Autónoma de México (UNAM) was underway. In particular, the responses were evaluated in the laboratory to low-temperature stratification, as well as day/night air temperature, and water potential for the native Onagraceae Lopezia racemosa and Ludwigia octovalvis, and the exotic Polygonaceae Rumex crispus. Low-temperature stratification had no effect on germination by L. racemosa, for which maximum germination averaging 88% was optimal at 25/15 and 30/20 ºC. Germination at 21 d was halved at –0.5 MPa and completely inhibited at –1.0 MPa. The seeds of L. octovalvis were also insensitive to low temperature stratification and their germination never exceeded 70%, with the two highest temperatures of 30/20 and 35/25 ºC being the optimum. For this species germination was maximal at 0.0 MPa, decreasing significantly under every treatment with a minimum germination of 21% for seeds incubated at –0.1 MPa. Germination for the exotic R. crispus was delayed by low-temperature stratification, although all its seeds germinated regardless of the temperature or water potential treatment. While the environmental requirements for germination of ephemeral species often match the typical climate of their growing season, the differential responses found for the species considered in the present study provide some insight into the mechanisms leading to changes in species composition for communities from disturbed environments, including the displacement of native species and the proliferation of exotic, potentially invasive plants. },

keywords = {invasive species, reproductive ecophysiology, temperature, urban ecology, water relations},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2019b,

title = {Bryophyte enzymatic responses to atmospheric nitrogen deposition: A field validation for potential biomonitors},

author = {E. A. Díaz-Álvarez and E. de la Barrera and A. Arciga-Pedraza and M. Arróniz-Crespo},

doi = {10.1639/0007-2745-122.3.396},

year  = {2019},

date = {2019-08-19},

journal = {The Bryologist},

volume = {122},

number = {3},

pages = {396-403},

abstract = {The monitoring of atmospheric nitrogen deposition is necessary considering that this kind of environmental pollution is among the leading causes of global biodiversity loss. However, deploying and operating monitoring networks can be cost-prohibitive; the use of naturally occurring biomonitors can be a viable alternative for characterizing such nitrogenous pollution, with bryophytes being of particular promise. For instance, a previous dose-response greenhouse experiment evaluating potential biomonitors of different life-forms revealed that the activities of the enzymes phosphomonoesterase and nitrate reductase respond linearly to simulated nitrogen deposition for the generalist neotropical moss Braunia secunda. The present work is the field validation of B. secunda and Leptodontium pungens, a specialist of oak forests, as biomonitors of nitrogen deposition. Moss samples were collected during the 2009 dry and rainy seasons from fir and oak forests at ‘‘low-pollution’’ or ‘‘high-pollution’’ sites within the Valley of Mexico, where the megalopolis of Mexico City is located, and transported to the laboratory for colorimetric determinations of enzymatic activity. The phosphomonoesterase activity was consistently higher for both mosses from the high-pollution sites than for the low-pollution sites, while the nitrate reductase had a lower activity for the plants collected from the high-pollution sites. These results suggest that the proposed biomonitors are appropriate for the region of study.},

keywords = {atmospheric pollution, biomonitors, moss, pollution, urban ecology},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2018b,

title = {Characterization of nitrogen deposition in a megalopolis by means of atmospheric biomonitors},

author = {E. A. Díaz-Álvarez and E. de la Barrera },

url = {https://rdcu.be/6jWU},

doi = {10.1038/s41598-018-32000-5},

year  = {2018},

date = {2018-09-11},

journal = {Scientific Reports},

volume = {8},

pages = {13569},

abstract = {An increase of nitrogen deposition resulting from human activities is not only a major threat for global biodiversity, but also for human health, especially in highly populated regions. It is thus important and in some instances legally mandated to monitor reactive nitrogen species in the atmosphere. The utilization of widely distributed biological species suitable for biomonitoring may be a good alternative. We assessed the suitability of an ensemble of atmospheric biomonitors of nitrogen deposition by means of an extensive sampling of a lichen, two mosses, and a bromeliad throughout the Valley of Mexico, whose population reaches 30 million, and subsequent measurements of nitrogen metabolism parameters. In all cases we found significant responses of nitrogen content, C:N ratio and the δ15N to season and site. In turn, the δ15N for the mosses responded linearly to the wet deposition. Also, the nitrogen content (R2 = 0.7), the C:N ratio (R2 = 0.6), and δ15N (R2 = 0.5) for the bromeliad had a linear response to NOx. However, the bromeliad was not found in sites with NOx concentrations exceeding 80 ppb, apparently of as a consequence of exceeding nitrogen. These biomonitors can be utilized in tandem to determine the status of atmospheric nitrogenous pollution in regions without monitoring networks for avoiding health problems for ecosystems and humans.},

keywords = {biomonitors, epiphytes, Mexico, mosses, nitrogen, pollution, stable isotopes, Tillandsia, urban ecology},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2018,

title = {Biomonitors of atmospheric nitrogen deposition: potential uses and limitations},

author = {E. A. Díaz-Álvarez and R. Lindig-Cisneros and E. de la Barrera },

doi = {10.1093/conphys/coy011},

year  = {2018},

date = {2018-03-13},

journal = {Conservation Physiology},

volume = {6},

pages = {coy011},

abstract = {Atmospheric nitrogen deposition is the third largest cause of global biodiversity loss, with rates that have more than doubled over the past century. This is especially threatening for tropical regions where the deposition may soon exceed 25 kg of N ha–1 year–1, well above the threshold for physiological damage of 12-20 kg of N ha–1 year–1, depending on plant species and nitrogenous compound. It is thus urgent to monitor these regions where the most diverse biotas occur. However, most studies have been conducted in Europe, the USA, and recently in China. This review presents the case for the potential use of biological organisms to monitor nitrogen deposition, with emphasis on tropical plants. We first present an overview of atmospheric chemistry and the nitrogen metabolism of potential biomonitors, followed by a framework for monitoring nitrogen deposition based on the simultaneous use of various functional groups. In particular, the tissue nitrogen content responds to the rate of deposition, especially for mosses, whose nitrogen content increases by 1% per kilogram of N ha-1 year-1. The isotopic signature, δ15N, is a useful indicator of the nitrogen source, as the slightly negative values (e.g., 5‰) of plants from natural environments can become very negative (–11.2‰) in sites with agricultural and husbandry activities, but very positive (13.3‰) in urban environments with high vehicular activity. Mosses are good biomonitors for wet deposition and atmospheric epiphytes for dry deposition. In turn, the nitrogen saturation of ecosystems can be monitored with trees whose isotopic values increase with saturation. Although given ecophysiological limitations of different organisms, particular studies should be conducted in each area of interest to determine the most suitable biomonitors. Overall, biomonitors can provide an integrative approach for characterizing nitrogen deposition in regions where the deployment of automated instruments or passive monitoring is not feasible or can be complementary. 

},

keywords = {biomonitors, ecosystem saturation, epiphytes, nitrogen, pollution, stable isotopes, urban ecology},

pubstate = {published},

tppubtype = {article}

}

@article{Martínez2017,

title = {PREPRINT: Germination ecophysiology for three peri-urban ephemeral weeds},

author = {D. N. Martínez and E. de la Barrera},

url = {https://peerj.com/preprints/2950/},

doi = {10.7287/peerj.preprints.2950v1},

issn = { 2167-9843},

year  = {2017},

date = {2017-04-27},

journal = {PeerJ Preprints},

volume = {5},

pages = {e2950v1},

abstract = {We determined the environmental requirements leading to germination by three common species found during the summer rainy season in a peri-urban site where construction of a university campus was underway. In particular, we evaluated laboratory responses to low-temperature stratification, day/night air temperature, and water potential for the native Onagraceae Lopezia racemosa and Ludwigia octovalvis, and the exotic Polygonaceae Rumex crispus. Low-temperature stratification had no effect on germination by L. racemosa, for which maximum germination averaging 88% was optimal at 25/15 and 30/20 ºC. Germination at 21 d was halved at –0.5 MPa and completely inhibited at –1.0 MPa. The seeds of L. octovalvis were also insensitive to low temperature stratification and their germination never exceeded 70%, with the two highest temperatures of 30/20 and 35/25 ºC being the optimum. For this species germination was maximal at 0.0 MPa, decreasing significantly under every treatment with a minimum germination of 21% for seeds incubated at –0.1 MPa. Germination for the exotic R. crispus was delayed by low-temperature stratification, although all of its seeds germinated regardless of the temperature or water potential treatment. While the environmental requirements for germination of ephemeral species often match the typical climate of their growing season, the differential responses found for the species considered in the present study provide some insight into the mechanisms leading to changes in species composition for communities from disturbed environments, including the displacement of native species and the proliferation of exotic, potentially invasive, plants.},

note = {NOT Peer reviewed. This is an early communication for feedback before peer review},

keywords = {disturbance, invasive species, land-use change, reproductive ecophysiology, seed bank, temperature, urban ecology, water relations},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2017b,

title = {PREPRINT: Mapping pollution in a megalopolis: the case for atmospheric biomonitors of nitrogen deposition},

author = {E. A. Díaz-Álvarez and E. de la Barrera },

url = {https://doi.org/10.1101/118257

},

doi = {10.1101/118257},

year  = {2017},

date = {2017-03-19},

journal = {BioRxiv},

volume = {doi: 10.1101/118257},

abstract = {An increase of nitrogen deposition resulting from human activities is not only a major threat for global biodiversity, but also for human health, especially in highly populated regions. It is thus important and in some instances legally mandated to monitor reactive nitrogen species in the atmosphere. However, deployment of automated networks can be excessively costly for most cities so the utilization of widely distributed biological species suitable for biomonitoring may be a good alternative. The aim of this work was thus to assess the suitability of different atmospheric organisms as biomonitors of nitrogen deposition, by means of an extensive sampling of a lichen, two mosses, and one bromeliad throughout the Valley of Mexico, the basin where the megalopolis of Mexico City (population 20 million) is located, and subsequent measurements of nitrogen metabolism parameters. In all cases significant responses of nitrogen content, C:N ratio and 15N were found for the lichen Anaptychia sp. the mosses Grimmia sp. and Fabronia sp., and the bromeliad Tillandsia recurvata in response to season and collected site. In turn, 15N for the mosses responded linearly to the wet deposition (R2= 0.7 for Grimmia sp. and R2=0.2 for Fabronia sp.). Also, the nitrogen content (R2=0.7), the C:N ratio (R2=0.6), and 15N (R2=0.5) for the bromeliad had a linear response to NOx. However, latter species was not found in sites with NOx concentrations above 212 ppm. These biomonitors can be utilized in tandem to determine the status of nitrogenous pollution in regions without monitoring networks.},

note = {This article is a preprint and has not been peer reviewed. },

keywords = {biomonitoring, ecophysiology, global change, lichen, megacities, mosses, nitrogen, Tillandsia, urban ecology},

pubstate = {published},

tppubtype = {article}

}

@article{Díaz-Álvarez2016b,

title = {A δ15N assessment of nitrogen deposition for the endangered epiphytic orchid Laelia speciosa from a city and an oak forest in Mexico},

author = {E. A. Díaz-Álvarez and C. Reyes-García and E. de la Barrera },

url = {http://rdcu.be/npd1

http://agro.mx/wp-content/uploads/2016/06/039-Diaz-Alvarez-laelia-rv3.pdf

http://link.springer.com/article/10.1007/s10265-016-0843-y},

doi = {10.1007/s10265-016-0843-y},

year  = {2016},

date = {2016-06-09},

journal = {Journal of Plant Research},

volume = {129},

pages = {863–872},

abstract = {Atmospheric nitrogen deposition poses a major threat to global biodiversity. Tropical epiphytic plants are especially at risk given their reliance on atmospheric sources of nutrients. The leaf, pseudobulb, and root carbon and nitrogen content, C:N ratio, as well as the nitrogen isotopic composition were studied for individuals of Laelia speciosa from a city and from an oak forest in Mexico. The nitrogen content of leaves was similar between the city and the oak forest, reaching 1.3 ± 0.2 % (dry mass). The δ15N of leaves, pseudobulbs, and roots reached 5.6 ± 0.2 ‰ in the city, values found in sites exposed to industrial and vehicular activities. The δ15N for plant from the oak forest amounted to –3.1 ± 0.3 ‰, which is similar to values measured from sites with low industrial activities. Some orchids such as Laelia speciosa produce a single pseudobulb per year, i.e., a water and nutrient storage organ, so the interannual nitrogen deposition was studied by considering the ten most recent pseudobulbs for plants from either site formed between 2003 and 2012. The C:N ratio of the ten most recent pseudobulbs from the oak forest, as well as that of the pseudobulbs formed before 2010 for plants in the city were indistinguishable from each other, averaging 132.4 ± 6.5, while it was lower for the two most recent pseudobulbs in the city. The δ15N values of pseudobulbs from the oak forest averaged ‒4.4 ± 0.1 ‰ for the entire series. The δ15N ranged from 0.1 ± 1.6 ‰ for the oldest pseudobulb to 4.7 ± 0.2 ‰ for the pseudobulb formed in the city from 2008 onwards. Isotopic analysis and the C:N ratio for L. speciosa revealed that rates of nitrogen deposition were higher in the city than in the forest. The δ15N values of series of pseudobulbs showed that it is possible to track nitrogen deposition over multiple years.},

keywords = {conservation physiology, global change, moss, Neo-volcanic axis, nitrogen, orchid, pollution, stable isotopes, urban ecology},

pubstate = {published},

tppubtype = {article}

}