Fraxinus Uhdei Research Articles

Surface deposits and intracellular concentration of atmospheric particles in foliage of urban forests in the Valley of Mexico

Foliage of urban vegetation can be used as a bioindicator of air pollution, including heavy metals. We measured surface and intracellular concentration of copper, zinc, lead, nickel, chromium, cobalt and cadmium in Fraxinus uhdei leaves from three urban forests of the Metropolitan Area of the Valley of Mexico (ZMVM) during the four seasons of the year and assessed its correlation with distance to nearest roads; we also compared obtained concentrations with the local atmospheric monitoring network. We performed a two-factor experimental design: factor forest with three levels (Naucalli Park, Forests and Tlalpan) and factor season with four levels, to analyze spatio-temporal differences in heavy metal concentration. Fifteen Fraxinus uhdei trees were selected per site and a foliage sample was taken. A t-test was applied for comparisons between deposits, while an analysis of variance and Tukey's test was used to compare between seasons and forest. Relationship between surface concentrations and distance to the streets surrounding the forests was obtained using the Stepwise method. The obtained results indicate that there are higher concentrations superficially than intracellular in all metals analyzed, except for nickel. Copper was highest in Parque Naucalli, lead, nickel, chromium and cadmium in Bosques Chapultepec and zinc in Bosques Tlalpan. Highest concentrations occurred in summer for copper, zinc, nickel and chromium and in winter for lead and cadmium. We found that the surface concentration of copper, zinc, lead and cadmium in the foliage is higher when trees are closer to avenues. Our research indicates that trees can be valuable bioindicators for air pollution, as they not only mirror the diverse pollution sources but also provide insights into pollutant exposure based on proximity to those sources.

Ball moss (Tillandsia recurvata L.) situation in an institutional green area

The “ball moss” or “paxtle” (Tillandsia recurvata L.) is one of the main health problems in the trees of the National Instituteof Astrophysics, Optics and Electronics (INAOE). With the present survey, host preference, level of infestation, mainphenological stages, and control options of the epiphyte were determined. From the tree inventory, the species and theirdimensions (normal diameter and total height) were identified, the level of infestation by “paxtle” was determined and themain phenological stages of the epiphyte were recorded. The effectiveness of sodium bicarbonate spraying for control wasevaluated. Of 2210 trees, 37.23% were infested. Jacaranda (Jacaranda mimosifolia), ash (Fraxinus uhdei), white cedar(Hesperocyparis lusitanica) and glossy privet (Ligustrum japonicum) showed the largest infestations. No specificity wasobserved. The normal diameter was associated with the level of infestation. Seed dispersal occurred from January to April.The application of sodium bicarbonate caused dehydration, necrosis and death of the epiphyte. T. recurvata has become aserious health problem in the green areas of the INAOE. It is recommended to implement control activities in the months ofOctober and November (prior to the dehiscence of the capsules and in the absence of foliage in deciduous tree species).

Tree Health Condition in Urban Green Areas Assessed through Crown Indicators and Vegetation Indices

The urban environment induces stress on trees and its impact can be identified by observing the condition of the crown. The aim of this study is to correlate the variables of crown density (Cdn), crown transparency (Ctr) and dieback (Cdie) with the following vegetation indices: the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), blue-normalized difference vegetation index (BNDVI), green-normalized difference vegetation index (GNDVI), green–red vegetation index (GRVI) and red–green–blue vegetation index (RGBVI) of the crowns of trees located in urban green areas, as well as chlorophyll fluorescence (Fv/Fm) as an indirect indicator of the overall tree health condition. A total of 549 trees were evaluated, represented in 24 families, 36 genera and 53 species; the variables had average values of 67.96% for Cdn, 35.19% for Ctr and 1% for Cdie. Correlations were found between Fv/Fm, NDVI and BNDVI. NDVI and BNDVI correlated with variables such as Cdn and Ctr, mainly in species such as Ligustrum lucidum, Jacaranda mimosifolia and Fraxinus uhdei. Therefore, it is possible to evaluate the tree health condition of trees in urban green environments through the identification of unfavorable conditions at the crown level by using vegetation indices for some of the species studied.

Evaluation of air pollution tolerance index and anticipated performance index of six plant species, in an urban tropical valley: Medellin, Colombia.

High atmospheric pollution levels in urban areas have become a global problem that threatens both human health and urban ecosystems. Trees that grow near areas with vehicular and industrial emissions can be highly affected, since they constitute the main barrier for emitted pollutants, with trees being either tolerant or sensitive to them. Different methodologies worldwide have been implemented to evaluate the tolerance and sensitivity of tree species to atmospheric pollutants. In this research, the air pollution tolerance index (APTI) and the anticipated performance index (API) are evaluated in order to determine both the degree of tolerance or sensitivity of trees to pollutants in the air and their performance in urban areas. To this end, six tree species found in four biomonitoring zones in the city of Medellín, Colombia, were selected: Mangifera indica, Tabebuia chrysantha-rosea, Erythrina fusca, Jacaranda mimosifolia, Fraxinus uhdei, and Spathodea campanulata. A total of 54 individual trees were evaluated by means of the APTI and API, and it was determined that the species with the highest tolerance (APTI≥16) and the best performance (81<API<90) was Mangifera indica, which highlights the importance of this species in urban areas with air quality problems. On the other hand, it was determined that the most sensitive species (APTI≤11) are Tabebuia chrysantha-rosea, Erythrina fusca, and Spathodea campanulata, while the species with poor performance (41<API<50) are Tabebuia chrysantha-rosea, Erythrina fusca, and Jacaranda mimosifolia. These values, therefore, can be used to classify which species can be planted as pollutant sinks and which as air quality bioindicators and thus highlight the importance of urban forests and trees for environmental management and planning in big cities with air quality problems.

Diversity of the ‘Candidatus Phytoplasma asteris’ and ‘Candidatus Phytoplasma fraxini’ isolates that infect urban trees in Bogotá, Colombia

Phytoplasmas have been associated with a disease that affects trees of at least 11 species from different botanic families in Bogotá, Colombia. 'Candidatus Phytoplasma asteris' and 'Candidatus Phytoplasma fraxini' are the major groups of phytoplasma in the area of Bogotá. In this study, the genetic diversity within 'Ca. P. asteris' and 'Ca. P. fraxini' was studied in five urban tree species: Croton species (Euphorbiaceae), Fraxinus uhdei (Oleaceae), Magnolia grandiflora (Magnoliaceae), Populus nigra (Salicaceae) and Quercus humboldtii (Fagaceae). Analyses of the 16S rRNA gene using nested PCR, RFLP and sequencing showed that phytoplasmas of 'Ca. P. asteris' could be assigned to: subgroup 16SrI-B; a new subgroup named 16SrI-AF, with a restriction pattern similar to that of 16SrI-B; and a new subgroup named 16SrI-AG, with a restriction pattern similar to that of 16SrI-K and 16SrI-AH with a restriction pattern similar to that of 16SrI-AC. 'Ca. P. fraxini' isolates belonged to a new subgroup named 16SrVII-G, with a restriction pattern similar to that of 16SrVII-A. To complement the identification of the phytoplasma strains, we amplified nonribosomal genes such as leuS and secA. Unexpectedly, it was observed that in 16 trees in which 16S rRNA gene analysis showed the presence of 'Ca. P. fraxini' only, the leuS or secA primers amplified sequences exclusively affiliated to 'Ca. P. asteris. In those plants, sequences belonging to 'Ca. P. fraxini' leuS or secA genes were not amplified. The present work contributes to the identification of novel strains of both species in Colombia, and supports previous suggestions that phytoplasmas in South America are highly variable.

Does Acid Rain Alter the Leaf Anatomy and Photosynthetic Pigments in Urban Trees?

Megapolis such as Mexico City, have atmospheric pollutants that interact with the humidity and solar radiation. The topography of this city promotes air stagnation, generating atmospheric pollutants and episodes of acid rain, a phenomenon well recorded since the end of the 1980s. However, little we know about how urban trees respond to acid rain in the city. Here we present how simulated acid rain causes anatomical and changes in photosynthetic pigments in two of the most abundant urban trees in Mexico City: Liquidambar styraciflua L. and Fraxinus uhdei (Wenz.) Lingelsh. We first described the leaf anatomy of both species. Then, we used one-year-old trees sprayed with sulfuric acid solutions at pH 2.5 and 3.8, and evaluated visible leaf damage, anatomical alterations, and chlorophyll contents. In both species, the pH 2.5 caused cuticle alterations and areas of total tissue destruction. L. styraciflua showed greater sensitivity, but we discuss some of the tolerance mechanisms. Finally, acid rain also reduced the chlorophyll contents. These results contribute toward a catalogue of urban tree species to describe pollution-induced damages, and the identification of tolerant species useful for short- and mid-term detection of environmental crisis, in cities with similar environmental conditions and urban tree composition.

CRECIMIENTO DE Fraxinus uhdei INOCULADO CON DOS CEPAS ECTOMICORRÍZICAS EN DOS SUSTRATOS, UNO CONTAMINADO CON MERCURIO

Mining is one of the most important industrial activities in many countries; however, environmental damages associated with this activity are severely detrimental. These effects are a consequence, among other things, of heavy metals originated by mineral extraction methods. To reduce the environmental impact of this activity, it is important to develop remediation technologies, including the symbiotic relationships between species that allow high survival and proper development of plants. Therefore, a mesocosm assay was carried out to document the response of Fraxinus uhdei (Wenz.) Lingelsh (ash) inoculated with ectomycorrhizal fungi on two different substrates: a mine-derived substrate from the municipality of Tlalpujahua de Rayón, Michoacán, and an organic one. The study consisted in the inoculation of F. uhdei plants with two fungi strains, Laccaria laccata and Lactarius deliciosus, on two doses: 2.5 × 105 and 1 × 106 spores per plant. Ectomycorrhizal fungi favored the development and survival in both substrates; however, the performance of the plants was higher with the organic substrate. Height, cover, and fresh weight of plants inoculated with Laccaria laccata were the highest (66 cm, 1186 cm2, and 92 g, respectively). Mercury was lower in plants inoculated with Lactarius deliciosus (F(1, 28) = 12.22; P = 0.002) with respect to those inoculated with Laccaria laccata. Our results indicate that inoculation has a positive effect on ash growth both in an organic rich substrate and a substrate produced by mining activities, also the potential use of the tree species for remediation of mining dumps.

Biomass and iron accumulation in plants of Pinus pseudotrobus and Fraxinus uhdei in Acrisols from Western-Mexico with endo- and ectomycorrhiza

Pedogenic iron rich soils are prevalent worldwide covering approximately 1000 million hectares. These soils are fragile and prone to severe degradation, in many cases resulting in high erosion rates and formation of gullies. Restoration and revegetation practices face many barriers in degraded Acrisols, including low nutrient availability exacerbated by high iron concentrations. The objective of this work was to evaluate the performance of two tree species, Pinus pseudotrobus, and Fraxinus uhdei, growing in Acrisol soils in the presence of endo, ecto or both types of mycorrhizic fungi, in order to assess the effect of the interaction for management of degraded lands. The largest Fraxinus plants, those inoculated with both types of mycorrhizic fungi, accumulated three times more biomass than the smallest, and for Pinus the largest plants, those growing in soil with both types of fungi, had 1.5 times more biomass. Iron content in tissues of the Fraxinua uhdei plants was within that reported for plants in general (0.014%), and for Pinus pseudostrobus our values were higher for all treatments but within the same order of magnitude. For ecological restoration and other management purposes these results strongly suggest that dual inoculation or planting species that allow for both types of mycorrhizic fungi to be present in the soil can improve tree species performance and therefore facilitate the recovery process of heavily degraded sites.

Reservorios de biomasa y carbono en el arbolado de la primera sección del Bosque de Chapultepec, Ciudad de México

Durante los últimos años ha habido un creciente interés por cuantificar los reservorios de carbono en los bosques naturales y urbanos y su potencial en la mitigación del cambio climático. En el presente estudio se estimaron los depósitos de biomasa y C aéreos del arbolado de la primera sección del Bosque de Chapultepec, en la Ciudad de México y se analizó su relación con el área basal y la composición de especies. Los resultados del inventario indican que el reservorio de C en el área verde de estudio es importante, al menos con respecto a la cantidad de CO2 que se emite de manera local. Además, para la especie dominante, Fraxinus uhdei, se compararon las estimaciones de biomasa de ecuaciones generadas en bosques naturales y urbanos con las obtenidas en siete árboles del sitio; la ecuación de ambientes urbanos generó una mejor estimación. A partir del inventario correspondiente a 27.3% de las áreas verdes de la primera sección y de la aplicación de relaciones alométricas, se estimaron reservorios totales de 24 217 Mg de biomasa y 11 226 Mg de C. La composición de especies y el área basal influyeron en los depósitos de biomasa y C. El valor medio de contenido de C es alto en comparación con los registrados en bosques urbanos de otras ciudades del mundo, por lo que Bosque de Chapultepec es un reservorio importante.

Correction to: Incidence and characterization of the presence of phytoplasmas in Fraxinus uhdei related with Ash Yellow disease in Colombia

Correction to: Incidence and characterization of the presence of phytoplasmas in Fraxinus uhdei related with Ash Yellow disease in Colombia

Tropical ash (Fraxinus udhei) invading Andean forest remnants in Northern South America

IntroductionExotic invasive species represent a major driver of the loss of biological diversity and services provided by ecosystems globally. An important cause of species becoming invasive is the development of commercial afforestation projects using fast-growing and adaptable exotic species, which may become invasive impacting natural environments. The tropical ash (Fraxinus uhdei), native to México, has been widely introduced to Colombia and other countries for timber, live fences, and urban greening. It is now common in many areas of the tropical mountains and has been observed expanding into native forests in Colombia.This study examined the invasion pattern and the demographic structure of tropical ash in remnant Andean forests in Colombia, to find out factors associated with the invasion process. The analysis took into account biotic and physical factors: distance to propagule source, vegetation cover types, and understory and canopy cover.ResultsAlthough the reproductive strategy of the tropical ash is of “r” type with low survival rates, the results show evidence for an active process of invasion characterized by an aggregated distribution pattern dominated by seedlings and juvenile plants. The study shows the existence of an interaction between the distance to propagule source and the vegetation cover, which has an additive effect on the demographic structure of the population.ConclusionsThis study suggests an active invasion process by the exotic tree tropical ash into a remnant of sub-humid forests in the Andean highlands. Our results showed an expanding population process with a decreasing average age from propagule sources and mature reproductive individuals within the native forest, which bring new individuals that are colonizing new areas and advancing into the forest. This research points to the need for urgent plant intervention on two aspects: the use of the tropical ash and the management of the invasion process in native forests.

Effects of Adult Feeding and Overwintering Conditions on Energy Reserves and Flight Performance of Emerald Ash Borer (Coleoptera: Buprestidae).

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), an invasive beetle from Asia, spreads through human-mediated movement and active flight. The effects of adult feeding and overwintering conditions on A. planipennis energy reserves (e.g., lipid, glycogen, and sugars) and flight are poorly understood. We conjectured that the potential energetic demands associated with the production of cryoprotectants might affect dispersal capacity and partially explain slower spread of A. planipennis in Minnesota than in the other states. Two studies sought to measure the effects of adult feeding on lipid content and flight capacity. Adult A. planipennis were fed shamel ash, Fraxinus uhdei Wenzig, leaves for 0-20 d after emergence, and half were flown on a custom flight mill for 24 h, before being frozen for comparative lipid analysis with a control group. The second study compared the effects of adult feeding on energy reserves and flight capacity of A. planipennis that were originally from St. Paul, Minnesota but overwintered in infested logs placed in Grand Rapids, Minnesota (low winter temperature, -34°C) or St. Paul, Minnesota (-26.3°C). Live adults consumed foliage at a constant rate, but lipid content (percentage of fresh mass) did not change with increases in feeding or flight. Adult glycogen content declined with flight and increased only slightly with feeding. Overwintering location affected survival rates but not energy reserves or flight capacity. These results suggest that the flight capacity of A. planipennis is largely determined before emergence, with no differences in energy reserves after cryoprotectant investment.

Accumulation and phytostabilization of As, Pb and Cd in plants growing inside mine tailings reforested in Zacatecas, Mexico

The aim of this research was to identify plant species with potential to accumulate and stabilize arsenic (As), lead (Pb) and cadmium (Cd) in mine tailings reforested and naturally recolonized locations in a semiarid region of Zacatecas, Mexico. Plant shoots from 44 species and their rhizospheric soils were analyzed for As, Pb and Cd concentration using atomic absorption spectroscopy. Most represented plant families were Asteraceae, Poaceae, Fabaceae and Cactaceae. The highest concentrations in shoots were As, followed by Pb and Cd. Among herbaceous species, Bouteloua gracilis showed the highest bioconcentration factor (BCF) of As, while Plantago lanceolata showed the highest bioconcentration factor of Pb. The shrub species with highest concentration of As in the rhizospheric soil were Opuntia robusta, Melilotus alba, Baccharis neglecta and Arundo donax (near BCF to 1.0). Similar results were observed in trees Casuarina equisetifolia, Prosopis laevigata, Fraxinus uhdei and Eucalyptus globulus. In addition, Tillandsia recurvata showed a suitable indicator of atmospheric deposition to As. In general, the results suggest that these species can be effective for tailings reforestation with the possibility to enclose potentially toxic elements. Specially, C. equisetifolia which is abundant, having the potential for future applications in other contaminated sites with different types of mine tailings or abandoned mines from arid and semiarid zones.

Survival and growth of nursery inoculated Fraxinus uhdei in acrisol gullies

Presence of degraded soils is increasing worldwide, but in many scenarios the knowledge to undertake restoration has not been acquired in an efficient, economical and socially acceptable manner. There are estimates placing moderate to severe degradation of agricultural land worldwide at 80%. Severely degraded substrates, such as gullies, sometimes lack the necessary microbiota for appropriate plant growth, under these conditions nursery inoculation can improve plant performance in the field. In order to explore the role of dual mycorrhization in Fraxinus growing in poor substrates, and also to contribute information on their usefulness in gully restoration, an experiment was conducted in which individuals of this species were inoculated with an endomycorrhyzal fungus, and ectomycorrhizal fungus and with both types of mycorrhizal fungi simultaneously, as well as urea fertilization. The results of this experiment show that establishment of Fraxinus uhdei is possible in severely degraded sites, it also provides information on the effects on the plant of multiple inoculation that cause some performance variables to improve as a result of the interaction, as was the case for the improved survival with the P. tinctorius, G. intraradices dual inoculation; whereas growth variables showed improved response to inoculation with only one of the fungi, height to inoculation with G. intraradices, and cover, number of leaves and diameter at base to inoculation with P. tinctorius. Given the improvements in growth and survival, our results suggest that in severely degraded soils, nursery inoculation of plants adapted to adverse conditions with mycorrhyzal fungi should be implemented.

Incidence and characterization of the presence of phytoplasmas in Fraxinus uhdei related with Ash Yellow disease in Colombia

For a long time, Urapan trees (Ash) have been a popular plant in parks and avenues in the principal cities of the Andes in Colombia, but now more than 53,000 trees are infected and many of them died. In 2004, the presence of phytoplasmas in the phloem of some trees with dieback symptoms was reported. In this study, the phytoplasma’s presence has been detected in all the tested Fraxinus uhdei (Wenz.) (common name, Urapan), using microscopy techniques like optical microscopy, transmission electron microscopy, and DAPI fluorescent microscopy, which indicated a further spread of the disease. The presence of phytoplasmas in the phloem of the leaves of Urapan trees was evident and related with the symptoms of the disease “Ash Yellows”. Here the relation phytoplasmas–disease symptoms have been confirmed by reproducing the symptoms through phytoplasmas transfection in Periwinkle (Catharanthus roseus) by using the ectoparasite Cuscuta campestris. The molecular analysis using PCR with universal primers of the region 16S-23S rDNA (P1/Timt, R16mF2/R16mR1, fB1/P7, fPD/Tint, F1/P7, Phytuf22/Phytuf24) confirmed the parasite’s presence and its identification as Ash Yellows phytoplasma or Candidatus Phytoplasma fraxini which belongs to the phytoplasma group 16SrVII and subgroup 16SrVII-A. These results permit to suggest a possible treatment with antibiotics that would avoid the species extinction throughout the Andes cities.

Frecuencia de reactividad cutánea hacia antígenos inhalables en pacientes con cuadro clínico de enfermedad alérgica

Allergic diseases diagnosis must be based on adequate allergological anamnesis and an immunological sensitization test; the most sensitive and specific is the skin prick test. To determine the frequency of skin reactivity to aeroallergens, by age groups, in patients of the Department of Allergy and Clinical Immunology of the Hospital Universitario de Puebla, in Mexico. A cross-sectional study was conducted that included patients aged 2 to 64 years with symptoms suggestive of allergic disease, in which skin prick tests with aeroallergens were performed; the diagnostic criteria were those of international guidelines. Frequencies, percentages and dispersion measures were calculated. Of 173 patients, 63 % were females. Mean age was 22.3 years. The frequency of skin reactivity for Quercus sp. was 12.72 %, for Periplaneta americana, 9.83 %, for Dermatophagoides farinae, 9.25 %, for Cynodon dactylon, 8.09 %, for Blatella germanica, 8.09 %, for Holcus halepensis, 6.94 %, for Dermatophagoides pteronyssinus, 6.36 %, for Schinus molle, 5.78 %, for Fraxinus uhdei, 5.20 %, for Lolium perenne, 5.20 %, for Ambrosia eliator, 5.20 % and for Artemisa tridentata, 4.62 %. Although Dermatophagoides are the most frequently reported aeroallergens, the most common aeroallergen in this study was pollen, probably owing to geographical and environmental factors, although this was not observed in the analysis by age groups.

Árboles del Valle Central de Costa Rica: reproducción Fresno (Fraxinus uhdei (Wenz.)

Se presenta una breve descripción del árbol de fresno (Fraxinus uhdei (Wenz.) Lingelsh.), con información sobre su fenología como base para la recolección de&lt;br /&gt;frutos, el manejo de las semillas, la viverización y el proceso de germinación.

Microclimatology and ecophysiology of the urban vegetation of a city with tropical climate modified by altitude in Mexico

Background. The urban area continues growing, and in most cases, the planning of green areas does not include in the species selection their physiological characteristics, which determine plant survival.&#x0D; Question/Hypothesis. Stomatal conductance (gS) is a key variable that provides information on how the environment affects a plant physiology. Therefore it is important to inquire how gS is affected in an urban site.&#x0D; Studied species/Data description. Data of environmental variables (photosynthetically active radiation, PAR; air temperature, T A; vapor pressure deficit, VPD ), leaf water potential, ?; and gS were collected in four species Ficus retusa , Fraxinus uhdei, Ligustrum lucidum and Quercus rugosa .&#x0D; Study site and years of study. Two sites, in the center and in the rural area, were selected in Puebla, Mexico, during the wet and dry seasons (2012-2013).&#x0D; Methods. Environmental variables, gS and ? were measured with a diffusion porometer and a pressure bomb through the day every two hours in apparently healthy leaves. Also an experiment under greenhouse conditions was performed.&#x0D; Results. Maximum values of PAR, T A and VPD were registered in the city center in the dry season, whereas maximum gS and ? were found in the rural area in the wet season. ? and gS were significantly higher in F. retusa followed by F. uhdei, whereas the lower values were observed in L. lucidum and Q. rugosa . All variables affected gS for all species.&#x0D; Conclusions. The results demonstrate that it is possible to recommend Ficus retusa and Fraxinus uhdei as suitable species to ameliorate the urban environment.

Transpiration and stomatal conductance as potential mechanisms to mitigate the heat load in Mexico City

Transpiration rates and stomatal and canopy conductances were monitored in Eucalyptus camaldulensis, Fraxinus uhdei, Liquidambar styraciflua and Ligustrum lucidum in México City, to explore the potential of trees to reduce the urban heat load. The experiment was carried out over a 2-week period between 11 and 27 April 2013. Four trees of each species were used. Total conductance was obtained from daily measurements of transpiration and vapor pressure deficit between 22 and 27 April, and canopy conductance from stomatal conductance and leaf area index measurements. L. styraciflua registered the highest average (4.35Ld−1) transpiration rate, whereas F. uhdei registered the minima (3.64Ld−1). Averaged canopy conductance registered values between 40mms−1 (E. camaldulensis) and 50mms−1 (L. lucidum). These results show that transpiration was strongly dominated by vapor pressure deficit (VPD) and controlled by stomatal conductance. According to the envelope function model, stomata was more sensitive to VPD than irradiance or air temperature. Finally, the presented transpiration rates are capable to reduce up to 20% of net radiation in Mexico City. With these results, it is possible to build tree arrangements to dissipate the greatest possible amount of heat produced in the city.

Mistletoe infection in an urban forest in Mexico City

Urban forests are important lungs for urbanized environments; therefore, their study and conservation are needed. Compared with trees in natural areas, urban trees develop in more stressful conditions, which may make them more susceptible to infections by parasites such as mistletoes. Bosque de Tlalpan (BT) is an urban forest embedded in one of the largest cities of the world, Mexico City. The aim of this study was to assess which mistletoe species were present in BT, determine the intensity of the infestation, and distinguish which host species are more susceptible to mistletoe parasitism based on 20 randomly selected plots. We found that Cladocolea loniceroides was extensively distributed on the cultivated area of BT (17 plots), whereas a second species, Phoradendron brachystachyum, was found only on four plots. Seven tree species were susceptible to infection by C. loniceroides, whereas only one was susceptible to infection by P. brachystachyum. Fraxinus uhdei, the most abundant host, was the one with higher severities and larger sizes (tree height and crown length); the latter variables positively influence the severity of infection. Reforestation of the cultivated area with low diversity and exotic species appears to be a reason for the increased infestation. Therefore, we support the reforestation of urban areas with native species to provide benefits such as a lower incidence of parasitic infection and tree mortality.