Abstract Semi-arid environments are dominated by extreme environmental conditions that directly influence seed dispersal and germination, as well as the establishment, development and maintenance of plant cover. This cycle depends directly on the availability of the water resource. However, in semi-arid areas water is limited. Therefore, the species that grow there develop adaptations for their dispersal, such as structures and mobility strategies to ensure their survival. The stages of dispersal until the seeds establishment follow different strategies or mechanisms to pass from one phase to another. This strategy in addition to humidity, water availability and substrates ensure dispersion. The interaction of seed banks and seed structures are a determining factor for species to adapt to arid and semi-arid zones. Additionally, the seminal microstructures play a particular role in each species by providing advantages in the face of inclement weather that they must overcome, as is the case with the prominent thread and the thin integuments of seeds, as well as the singular forms that facilitate not only water absorption but also dispersal towards safe places that accomplish the beginning of the establishment process.

Resumen Los ambientes semiáridos son dominados por condiciones extremas que influyen de manera directa en la dispersión y germinación de semillas, así como el establecimiento, desarrollo y mantenimiento de la cubierta vegetal. Este ciclo depende directamente de la disponibilidad del recurso hídrico. Sin embargo, en las zonas semiáridas el agua es limitada, por lo que las especies que ahí habitan presentan adaptaciones para su dispersión como el desarrollo de estructuras y estrategias de movilidad para asegurar su supervivencia. Las etapas de la dispersión hasta el establecimiento de las semillas se manifiestan mediante distintas estrategias o mecanismos para pasar de una fase a otra. Lo anterior aunado a la humedad, la disponibilidad de agua y los sustratos favorecen la dispersión. La interacción de los bancos de semillas y sus estructuras constituyen un factor decisivo para que las especies se adapten a las zonas áridas y semiáridas. Adicionalmente, las microestructuras seminales juegan un papel particular en cada especie al proporcionar ventajas ante las inclemencias que deben sortear, como sucede con el hilo prominente y los tegumentos delgados de las semillas, así como las formas singulares que facilitan no sólo la absorción de agua, sino la dispersión hacia sitios seguros que hagan posible iniciar el proceso de establecimiento.

RESUMEN Se avaluó el efecto sobre cobertura vegetal (CV) por medio de Índices de Vegetación Ajustado de Suelo (SAVI). Los resultados indican tendencias de cambio de 2016 a 2020 bajo distinto manejo en seis predios del APFF, en Ocampo, Coahuila. El índice promedio para 348 832 datos, no mostró normalidad, ni la H Kruskal Wallis indicó diferencias significativas entre valores estimados de predios. Terrenos particulares con manejo de conservación tuvieron valores SAVI altos indicando mayor CV, los comunitarios con manejo ganadero tuvieron valores SAVI bajos y menor CV. De 2016 y 2017 hubo diferencias significativas (H, P < 0.01) y estadísticamente similares de 2018 a 2020 mientras que en el 2019 se registraron los mayores valores SAVI. El índice mostró utilidades para cubrir grandes extensiones de terreno en regiones áridas y semiáridas, posibilitando detección de cambios en CV para análisis y planeación del manejo de recursos.

ABSTRAC Effects on vegetation cover (VC) are evaluated calculated Soil Adjusted Vegetation Index (SAVI), showing change trends between 2016 and 2020 under differentmanagement in six properties of the PFF, Ocampo, Coahuila. Index values and the average generated n = 348 832 data, showing no normality. Kruskal Wallis H test did not indicate significant differences between the estimated values of terrains. Private lands with conservation management had high SAVI values indicating higher CV, community lands with livestock management had low SAVI values and lower CV. From 2016 and 2017 there were significant differences (H, P < 0.01) they were statistically similar, for 2018 to 2020 different, in 2019 the highest SAVI values were recorded. The Index was useful for covering large areas of land in arid and semiarid regions, making it possible to detect changes in CV for analysis and resource management planning.

Abstract Alkaline phosphatase is a membrane enzyme that is widely spread all over the human body. Its physiological role is still under study and it intervenes in the hydrolytic catalysis of monoesters of orthophosphoric acid in an alkaline environment, in the presence of divalent cations. Its total activity is represented by its multiple present forms, which include isoenzymes, isoforms and macro enzymes. Isoenzymes are the product of different ancestral genes from different chromosomes, while isoforms are the product of several genes located in different loci of a chromosome, which show a different posttranslational glycosylation pattern. Isoenzymes originated from chromosome 1 are more abundant in liver, bones, white blood cells and kidney. Chromosome 2-derived isoenzymes (intestinal, placental, and placental-like forms) show differences among themselves in both syntheses from tissues and chemical structures. Macroenzymes are enzyme associations to non-enzymatic components (immunoglobulin, lipoprotein, plasmatic membrane segments), such as bile macroenzyme. Hyperphosphatasemia is a disorder that features elevated alkaline phosphatase (ALP) total activity blood levels, either due to physiological causes such as pregnancy and growth or due to pathological circumstances in response to hepatobiliary, bone, neoplastic or idiopathic disease. Several clinical situations show hyperphosphatasemia, due to the increase of some of the isoenzymes, isoforms or macroenzymes. The study of these fractions of ALP facilitates the determination of its origin in case of an increase in the total activity of the ubiquitous enzyme, which contributes to a more precise diagnosis.

Resumen La fosfatasa alcalina (ALP) es una enzima de membrana ampliamente distribuida en el organismo humano. Su papel fisiológico está aún en estudio e interviene en la catálisis hidrolítica de los monoésteres del ácido ortofosfórico en medio alcalino en presencia de cationes divalentes. Su actividad total está representada por formas múltiples que incluyen isoenzimas, isoformas y macroenzimas. Las isoenzimas son producto de diferentes genes ancestrales provenientes de cromosomas diferentes, mientras que las isoformas son el producto de varios genes ubicados en distintos loci de un cromosoma, que presentan un diferente patrón de glicosilación postraduccional. Las originadas a partir del cromosoma 1 son más abundantes en hígado, hueso, glóbulos blancos y riñón. Las provenientes del cromosoma 2 (intestinal, placentaria y símil placentaria), presentan síntesis tisular y estructura química diferenciales entre ellas. Las macroenzimas son asociaciones de la enzima con componentes no enzimáticos como inmunoglobulinas, lipoproteínas o con fracciones de membrana plasmática, en el caso de la macroenzima biliar. La hiperfosfatasemia es la elevación de la actividad total de la ALP en suero, ya sea por causas fisiológicas como en el embarazo y durante el crecimiento; o en circunstancias patológicas en respuesta a enfermedades hepatobiliares, óseas, neoplásicas e idiopáticas. Numerosas situaciones clínicas cursan con hiperfosfatasemia a causa del aumento de alguna/s de las isoenzimas, isoformas o macroenzima. El estudio de estas fracciones de la ALP facilita la determinación de su origen ante un incremento de la actividad total de la enzima ubicua, lo que contribuye a un diagnóstico más preciso.

Resumo A fosfatase alcalina (ALP) é uma enzima de membrana amplamente distribuída no organismo humano. Seu papel fisiológico ainda está em estudo e intervém na catálise hidrolítica de monoésteres do ácido ortofosfórico em meio alcalino na presença de cátions bivalentes. Sua atividade total é representada por múltiplas formas, incluindo isoenzimas, isoformas e macroenzimas. As isoenzimas são o produto de diferentes genes ancestrais que provêm de diferentes cromossomos, enquanto as isoformas são o produto de vários genes localizados em diferentes loci de um cromossomo, que apresentam um padrão de glicosilação pós-traducional diferente. Os originários do cromossomo 1 são mais abundantes no fígado, ossos, glóbulos brancos e rins. As do cromossomo 2 (intestinal, placentária e símile placentária) apresentam síntese tecidual e estrutura química diferenciais entre si. Macroenzimas são associações da enzima com componentes não enzimáticos como imunoglobulinas, lipoproteínas ou com frações de membrana plasmática no caso da macroenzima biliar. A hiperfosfatasemia é a elevação total da atividade da ALP em soro, seja por causas fisiológicas como gravidez e crescimento; ou em circunstâncias patológicas em resposta a doenças hepatobiliares, ósseas, neoplásicas e idiopáticas. Inúmeras situações clínicas ocorrem com a hiperfosfatasemia, devido ao aumento de algumas das isoenzimas, isoformas ou macroenzimas. O estudo dessas frações da ALP facilita a determinação de sua origem diante de um aumento na atividade total da enzima ubíqua, o que contribui para um diagnóstico mais exato.

Abstract Evidences of vegetation coverage management were analyzed according to Soil Adjusted Vegetation Index (SAVI) values in private and communal lands of the Maderas del Carmen and Ocampo Natural Protected Areas; the index values were generated from three Landsat satellite images of 1985, 2001 and 2019. The data index values were acquired from forests, scrublands, and grasslands from supervised classified maps generated with training areas, from Inegi vegetation and land use map series II, IV and VI, adding resources management intensity as a factor derived from property maps. A shapefile point network of the study area, with 500 m of separation, was created in order to capture the values of presence of forest, scrubland, or grassland ecosystems; the management intensity (Private lands with conservation, private lands with management, and communal lands with management) and the SAVI values from the three dates generated a database used to analyze the index values (vegetation coverage) through time. Normality tests were made in the database; no normal distribution was detected on them. The variance of the index was calculated by ecosystem and management factor (intensive, moderate and conservation). The results of the non-parametric H Kruskal Wallis tests indicated significant differences (α>0.95, Z = 2.394 critical value) on the three dates for all the ecosystems and management intensities. In the forests and grasslands, the private lands under conservation management exhibited the highest vegetation index values, while in the scrublands, the highest values corresponded to lands with a moderate management.

Resumen Se analizaron evidencias de manejo en la cobertura vegetal, a partir de valores del Índice de Vegetación Normalizado de Suelo (SAVI) en terrenos privados y comunales de las áreas naturales protegidas Maderas del Carmen y Ocampo; los índices se generaron de tres imágenes de satélite Landsat de 1985, 2001 y 2019; los valores del índice se capturaron en áreas de bosque, matorral y pastizal de clasificaciones supervisadas obtenidas con áreas de entrenamiento usando las series II, IV y VI de Uso de Suelo y Vegetación de Inegi; y se agregó el factor manejo del recurso procedente de mapas prediales. En una red de puntos espaciada a 500 m dentro del área, se capturó la presencia de bosque, matorral y pastizal; la intensidad de manejo en terrenos privados (conservación y con manejo), así como terrenos comunales con manejo, además del valor del índice SAVI de tres fechas; con ello, se generó una base de datos para el análisis del comportamiento del índice (cobertura vegetal). Las pruebas de Chi cuadrada no detectaron una distribución normal. La varianza del índice se realizó por ecosistema y el factor de manejo (intensivo, moderado y de conservación). Los resultados indicaron diferencias significativas en la prueba H no paramétrica de Kruskal Wallis (α>0.95, Z = 2.394 valor crítico) en las tres fechas para todos los ecosistemas e intensidades de manejo. En bosques y pastizales los terrenos bajo manejo de conservación registraron los valores más altos de Índice de Vegetación; y en matorrales correspondió a los sitios de manejo moderado.

Abstract Carbon monoxide (CO) is a gas produced mainly by incomplete combustion of hydrocarbons. Poisoning from environmental exposure can present with nonspecific symptoms and is the most important cause of increased carboxyhemoglobin (COHb). Its blood level depends on the duration of exposure, minute ventilation, and the concentrations of CO and oxygen in the environment. The high toxicity lies in the tissue hypoxia that is generated. The case of a male patient, 73 years old, under follow-up in the hospital for non-specific interstitial pneumonia as the underlying pathology was presented. In a laboratory control, COHb 11,9% was found. There was no exposure to tobacco and there was no use of gas heating but of an electric ceramic panel, recently painted with synthetic enamel type paint. The suspension of the use of the panel normalised the COHb. The CO product of thermal decomposition of synthetic enamel explains the cause of poisoning.

Resumen El monóxido de carbono (CO) es un gas producido principalmente por combustión incompleta de hidrocarburos. La intoxicación por exposición ambiental puede presentarse con síntomas inespecíficos y constituye la causa más importante de aumento de carboxihemoglobina (COHb). Su nivel en sangre depende de la duración de la exposición, la ventilación minuto y las concentraciones de CO y oxígeno en el ambiente. La elevada toxicidad radica en la hipoxia tisular que se genera. Se presenta el caso de un paciente masculino, 73 años, en seguimiento en el hospital por neumonía intersticial no específica como patología de base. En un control de laboratorio se encontró 11,9% de COHb, sin exposición a tabaco. No utilizaba calefacción a gas sino un panel cerámico eléctrico, recientemente pintado con esmalte sintético. La suspensión del uso del panel normalizó la COHb. El CO, producto de descomposición térmica del esmalte sintético, explica la causa de la intoxicación.

Resumo O monóxido de carbono (CO) é um gás produzido principalmente pela combustão incompleta de hidrocarbonetos. A intoxicação por exposição ambiental pode se apresentar com sintomas inespecíficos e é a causa mais importante de aumento da carboxihemoglobina (COHb). Seu nível em sangue depende do tempo de exposição, da ventilação minuto e das concentrações de CO e oxigênio no ambiente. A alta toxicidade está na hipóxia tecidual gerada. Apresentamos o caso de um paciente do sexo masculino, 73 anos, em acompanhamento hospitalar por pneumonia intersticial inespecífica como patologia de bas. Em um controle laboratorial, achou-se 11,9% de COHb, sem exposição ao tabaco. Não utilizava aquecimento a gás e sim um painel elétrico cerâmico, recentemente pintado com esmalte sintético. A suspensão do uso do painel normalizou o COHb. O CO produto da decomposição térmica do esmalte sintético explica a causa da intoxicação.

ABSTRACT A rapid, sensitive, precise and accurate liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for levo 3,4-dihydroxyphenylalanine (L-DOPA) determination in Vicia faba during different growth stages. The method applied a simple sample preparation step followed by a chromatographic separation on a Kinetex XB Core-Shell C18 (100 mm x 4.6 mm, 2.6 µm) column, using a mixture of ultrapure pure water (A) with 0.5 % (v/v) formic acid and methanol (B) as mobile phase. Analysis of L-DOPA was carried out by MS/MS applying a Multiple Reaction Monitoring (MRM) method using the transition m/z 198 → m/z 152. This LC-MS/MS method allowed a well-resolved detection of L-DOPA in ca. 2 min within 6 min run. Method was validated showing a linear range from 0.05 to 10 mg L-1 (R2 = 0.99); repeatability showed RSD value of 1.40%. Recoveries ranged from 94.14 to 116.62% with RSD values ≤ 5.66% and detection and quantification limits were 0.01 and 0.05 mg L-1, respectively. Applying this validated method, L-DOPA was determined in Vicia faba samples to determined its tissue distribution. As expected, a broad range of L-DOPA content finding the lowest content in seeds (4.72±2.12 mg g-1) and the highest in sprouts (133.60±5.65 mg g-1).

ABSTRACT Capsaicinoids are organic compounds present in several foods like chili peppers. This group of molecules are responsible of fruit pungency, as well as, of several healthy properties. The present work reports an optimized and validated liquid chromatography method coupled to fluorescence and mass spectrometry detectors for a selective determination of capsaicin in Chili peppers (Capsicum annum and C. pendulum). To the best our knowledge this is the first report about capsaicin determination in chili peppers commercialized in Chile. Chromatographic conditions were optimized giving the following optimal conditions: 76% organic phase (MeOH: ACN: acetic acid (50:50:0.1 v/v/v) at 9 min of gradient program and column temperature of 35°C. With these conditions capsaicin, dihydrocapsaicin and nordihydrocapsaicin were separated in 15 min. Data calibration curve (0.01-2.00 mg L-1) fitted a linear regression model with a determination coefficient (R2) of 0.9986. Repeatability (relative standard deviation, RSD) and intermediate precision (RSD) showed values of 1.51% (n=6) and 1.04% (n=3), respectively. Recovery (n=3) at three levels ranged from 94.80 to 109.40%, (RDS <2.39%). The method was applied to analyze 10 chili peppers varieties commercialized in Chile. A broad range of capsaicin and dihydrocapsaicin contents were observed, finding values from 0.1 up to 127.3 µg g-1.

ABSTRACT To evaluate the anti-Helicobacter pylori activity of the major polyphenol compounds of propolis and their cellular damage, both as single molecule or in combination. Honey bees propolis were fractionated by using CPC and preparative HPLC. Four major polyphenols (chrysin, pinocembrin, galangin and caffeic acid phenethyl ester) were identified by thin layer chromatography–mass spectroscopy and liquid chromatography–mass spectroscopy. These compounds inhibited both ATCC and clinical H. pylori strains, with caffeic acid phenethyl ester being the most active. The four compounds presented minimum inhibitory concentration in the range 256–1024 µg ml−1 and a fractional inhibitory concentration of 64–512 µg ml−1. In mixtures all compounds showed an indifference effect (FIC < 0.15) but chrysin + galangin which was synergistic (FIC = 2.0). Killing curves show a similar behavior as the antibiotic amoxycillin. On the other hand, analyses by transmission electron microscopy at sub inhibitory concentration show vesicle formation and cell lysis after exposition to both individual polyphenol compounds and in mixture. The major compounds of propolis show anti-H. pylori activity both as individual compounds and in mixture. When combined they present mainly indifference but exert a lytic activity upon H. pylori, suggesting a potential bactericidal activity of propolis.

ABSTRACT Acetazolamide (ACZ) is a carbonic anhydrase inhibitor that exhibits diuretic activity. In medicine, it is principally used in open-angle glaucoma, for prevention or amelioration of symptoms associated with acute high-altitude sickness and as an adjunct to other anticonvulsants in centrencephalic epilepsies. Furthermore, ACZ is sometimes used by athletes to mask the presence of doping substances, so its use has been banned in competitions. The aim of this work was the development of a sensor to determine ACZ in pharmaceuticals, as quality control way, and serum, for clinical and doping analyzes. The sensor has been developed modifying a glassy carbon electrode with carbon nanofibers. The electrochemical characterization of the sensor was performed by cyclic voltammetry using the redox mediator potassium ferrocyanide. ACZ electrochemical behavior was studied as well. Measurements were performed in a conventional three electrodes cell using differential pulse voltammetry. The influence of some experimental variables involved in the preparation and performance of the sensor –amount of modifier, supporting electrolyte, pH, scan rate and pulse amplitude– were optimized. This methodology provided a linear calibration plot for ACZ in the 1 – 17 µM concentration range. Furthermore, the proposed sensor exhibited suitable analytical properties, with detection and quantification limits of 0.06 µM and 0.2 µM respectively; analytical sensitivity of 1.142 µA/µM, repeatability of 0.72 %, and it was applied to determine ACZ in pharmaceuticals (tablets) and spiked human serum, being an excellent tool to perform quality control and antidoping control.

ABSTRACT Avocado peels were used to extract proanthocyanidins (PACs) as starting material to prepare semi-synthetic derivatives of epicatechin by nucleophilic attack with pyrogallol and resorcinol. One-step isolation of both semi-synthetic derivatives was successfully performed through centrifugal partition chromatography (CPC), and identified by TLC and LC-MS/MS. The effect upon adherence of Helicobacter pylori ATCC 43504 to AGS cells and the subsequent induction of pro-inflammatory IL-8 release was tested for these two semi-synthetic derivatives. Bacterial adherence and IL-8 synthesis was evaluated using AGS cells con-infected with FITC-labeled H. pylori. Concentration of 700 μg/mL of epicatechin-pyrogallol and epicatechin-resorcinol decreased H. pylori adherence to AGS cells to less than 20% and reduced IL-8 production to less than 10%. In conclusion, semi-synthetic adducts prepared from avocado PACs reduce significantly the adherence and IL-8 production in H. pylori-infected AGS cells.

ABSTRACT The effect of different variables in the electrochemical removal of estriol (E3) in aqueous solution was studied and it was compared with the removal of 17 α- Ethinylestradiol. The photoelectroxidations were carried out with DSA electrode (Ti/RuO2), varying the pH, substrate concentration and supporting electrolyte, potential configuration of saline bridge, reactor volume, and light source. Results for both Estriol and 17 α- Ethinylestradiol are similar, showing to be the best removals at concentrations of 500 ug/L of substrate, volumes to be treated of 90 ml of solution, saline bridge of 30 cm in length, voltages between 0.8 and 3, concentration of Na2SO4 of 0.1 M, pH between 6 and10, and UV lamp of 125 W.

Abstract This study documents the first register of Boletus luridellus (family Boletaceae) in the states of Nuevo León and Tamaulipas. Pure cultures were obtained in vitro; synthesis of mycorrhizae was achieved with Quercus fusiformis, and fruiting bodies were produced under greenhouse conditions for the first time. This species forms mycorrhizae with Quercus fusiformis, Q. polymorpha and Q. canbyi, in its natural environment. This species has a good potential for inoculation of oak seedlings in order to obtain better seedling growth under greenhouse conditions in northeastern Mexico, where oaks are currently planted in urban gardens, parks and new urban developments. This symbiosis is interesting because it occurs in a dry geographic zone where temperatures are high during the summer. Boletus luridellus is reported to be an edible species that grows well and produces sporocarps on a yearly basis (another experiment) in the gardens of the School of Forest Science in Linares, Nuevo León.

Resumen Se presenta el primer registro de Boletus luridellus (Boletaceae, Boletineae) para los estados de Nuevo León y Tamaulipas, México. Se identificó la especie y se obtuvieron cultivos puros in vitro, se midió el crecimiento en dos medios de cultivo, se obtuvo la síntesis de micorrizas en plántulas de Quercus fusiformis y se regristra por primera vez la producción de esporomas de esta especie en condiciones de invernadero. En las entidades citadas, B. luridellus forma ectomicorrizas con Quercus fusiformis, Q. polymorpha y Q. canbyi, porque tiene potencial para producción de plántulas inoculadas de encino en vivero o invernadero, en el noreste de México, donde se utilizan frecuentemente para arborizar áreas urbanas, parques y nuevos fraccionamientos. Dicha simbiosis es de interés porque ocurre en una zona geográfica donde las temperaturas son altas durante el verano y el hongo puede inducir resistencia a sequía y mejorar crecimiento de las plantas. Se ha comprobado que Boletus luridellus crece bien en campo y produce esporomas cada año en los jardines del campus de la Facultad de Ciencias Forestales en Linares, Nuevo León, además se cita como comestible en la literatura especializada.

Abstract Conifer species largely depend on climatic variables, but their distribution is modified by climate change. The objectives in this study were to model the potential distribution of 20 Pinus species in Mexico, determine which climatic variables influence their distribution and establish their bioclimatic profile. Our hypothesis was that bioclimatic variables predict the potential distribution of coniferous species. A total of 10 222 presence records paired with 19 bioclimatic and three topographic variables were analyzed with the MaxEnt algorithm to generate potential distribution model of each species. Model validation was determined assessing their response curves (omission /commission analysis) and the sensitivity of their Receiver Operated Curve (ROC), area under the curve (AUC), and Jackknife tests to measure each variable effect. The ROC test showed that species with few records either overestimate or underestimate the prediction. The bioclimatic and topographic variables with the greatest contribution in the models were altitude, average temperature of the warmest quarter (Bio10) and annual average temperature (Bio1), both in °C; the variables related to low temperature, low precipitation and terrain aspect did not explain the species distribution. The species with the greatest potential surface area, with a 0.70 probability were: P. montezumae, P. devoniana and P. pseudostrobus with 14 744.8, 14 436.1 and 11 594.8 potential km2. The generated prediction models are reliable, since their AUC values were higher than 0.90. The model´s adjustment dependent on the number of records of the bioclimatic variables that constitute it.

Resumen Las especies de coníferas dependen en gran medida de las variables climáticas, pero su distribución se modifica por el cambio climático. Los objetivos de este estudio fueron modelar la distribución potencial de 20 especies del género Pinus en México, determinar qué variables climáticas que influyen en su distribución y establecer su perfil bioclimático. La hipótesis fue que las variables bioclimáticas predicen la distribución potencial de especies de coníferas. Un total de 10 222 registros, 19 variables bioclimáticas y tres topográficas se analizaron con el algoritmo de MaxEnt para generar el modelo de distribución potencial de cada especie. La validación del modelo se determinó acorde a curvas de respuesta (análisis de omisión/comisión) y sensibilidad Curva Operada por el Receptor (ROC) - área bajo la curva (AUC) y pruebas Jackknife para medir el efecto de cada variable. La prueba ROC mostró que las especies con pocos registros sobrestiman y subestiman la predicción. Las variables bioclimáticas y topográficas con mayor contribución en los modelos fueron altitud, Bio10 y Bio1 (Temperatura promedio del trimestre más cálido y Temperatura media anual, ambas en °C); pero las variables relacionadas con bajas temperatura, poca precipitación y exposición no explicaron la distribución de las especies. Las especies con superficie potencial mayor con probabilidad de 0.70 fueron P. montezumae, P. devoniana y P. pseudostrobus con 14 744.8, 14 436.1 y 11 594.8 km2. Los modelos de predicción generados son confiables pues los valores de AUC fueron superiores a 0.90. El ajuste de un modelo es dependiente del número de registros de las variables bioclimáticas que lo constituyen.

Abstract: The distribution of forest pests in Mexico is uncertain. Information on forest areas potentially affected by a type of pest and their climatic and ecological preferences is scarce. The objective of this study was to model the potential distribution of insect borers (B), defoliators (d), bark beetles (D) and mistletoes (M), using climate and mensuration variables and the software Maximum Entropy (MaxEnt). Records of forest pests were obtained during the National Forest and Soil Inventory (2009-2014) provided by the National Forestry Commission. The training and validation of the models was performed with k-fold partitioning through the dismo package of R. The analyses of results indicate that the generated models had acceptable fit (AUC > 0.85). The potential area estimated by the model, in accord with the lower threshold of known presence (> 0.1), was around 270 (B), 307 (D), 315 (d) and 308 mil km2 (M). The largest potential area is predicted for the states of Chihuahua, Durango and Oaxaca, as well as the highest probability of occurrence (> 0.90). Climate variables had the highest percentage of contribution for D and d (75.1 and 71.9 %), whereas the mensuration variables were the highest for B and M (73.6 and 59.8 %). Analysis of the mensuration parameters indicate that, for the records of presence used, the four types of pest tend to prefer forests with small diameter trees and sites with fewer host species. The forests with the greatest susceptibility are found in Chihuahua (M) and Michoacán, Estado de México, Chihuahua, Nuevo León, Jalisco and Chihuahua (D).

Resumen: La distribución de plagas forestales en México es incierta, pues existe información escasa sobre áreas potenciales de bosques por ser afectados mediante algún tipo de plaga, o información sobre sus preferencias climáticas y ecológicas. El objetivo del presente estudio consistió en modelar la distribución potencial de insectos barrenadores (B), defoliadores (d), descortezadores (D) y muérdagos (M) mediante variables climáticas y dasométricas a través de MaxEnt (Máxima Entropía). Los registros de plagas forestales se obtuvieron durante el desarrollo del Inventario Nacional Forestal y de Suelos (2009-2014) y fueron proporcionados por la Comisión Nacional Forestal. Los modelos se probaron y validaron con el paquete dismo de R. Los generados mostraron ajustes aceptables (AUC > 0.85). La superficie potencial estimada por modelo, acorde al umbral mínimo de presencia conocida (> 0.1), fue alrededor de 270 (B), 307 (D), 315 (d) y 308 mil km2 (M). La mayor área potencial para los cuatro tipos de plaga se predijo en Chihuahua, Durango y Oaxaca, así como la probabilidad de ocurrencia más alta (> 0.90). Las variables climáticas contribuyeron con el mayor porcentaje para D y d (75.1 y 71.9 %); mientras que, para B y M, las dasométricas (73.6 y 59.8 %). El análisis de parámetros dasométricos indica que los cuatro tipos de plaga tienen preferencia por bosques con árboles de diámetros pequeños y sitios con pocas especies hospederas. Los bosques con mayor susceptibilidad se ubican en Chihuahua (M) y Michoacán, Estado de México, Nuevo León, Jalisco y Chihuahua (D).

ABSTRACT. The world’s climate has changed significantly in recent years and with it the distribution of species. The aim of the study was to generate potential distribution models of three pinyon pine species, Pinus cembroides, P. culminicola and P. nelsonii, of northwestern Mexico. To establish the most accurate model, two scenarios were used: a) with 19 Worldclim bioclimatic variables, and b) with the same variables plus the topographic variables of elevation, slope and exposure. It was modeled with REMIB CONABIO records, a total of 208, 89 and 67 records for each species with logistic adjustment and 500 iterations. The Jacknife test was performed to establish the participation percentage of the variables in the model. The results show that both scenarios adequately predict the potential distribution of the species studied. According to the AUC value, the model fits are better for restricted-distribution species with 0.999 for P. nelsonii and P. culminicola and 0.998 for P. cembroides, the model integrating elevation, minimum temperature and slope, with an average contribution of 18.6, 16.6 and 32.8% for each variable. The potential distribution of P. cembroides can be extended in northeastern Mexico, because the model significantly integrated maximum temperature variables and discriminated those derived from precipitation.

RESUMEN. El clima del mundo está cambiando de forma significativa en los últimos años y con ello la distribución de las especies. El objetivo del estudio fue generar modelos de distribución potencial de las especies de pinos piñoneros Pinus cembroides, P. culminicola y P. nelsonii del noroeste de México. Para establecer el modelo más preciso, se usaron dos escenarios: a) con 19 variables bioclimáticas Worldclim, y b) con las mismas variables más las variables topográficas de altitud, pendiente y exposición. Se modeló con registros REMIB CONABIO, un total de 208, 89 y 67 registros para cada especie con ajuste logístico y 500 iteraciones. Se realizó la prueba de Jacknife para establecer el porcentaje de participación de las variables en el modelo. Los resultados muestran que ambos escenarios predicen de forma adecuada la distribución potencial de las especies estudiadas. De acuerdo al valor AUC, los ajustes del modelo son mejores para las especies de distribución restringida con 0.999 para P. nelsonii y P. culminicola y de 0.998 para P. cembroides, integrando el modelo la altitud, la temperatura mínima y la pendiente, con contribución promedio de 18.6, 16.6 y 32.8% cada variable. La distribución potencial de P. cembroides puede ampliarse en el noreste de México, debido a que el modelo integró de forma significativa variables de temperatura máxima y discriminó aquellas derivadas de la precipitación.