Los hongos micorrízicos arbusculares (HMA) son importantes para el desarrollo y supervivencia de las plantas. Esto ha motivado el análisis del uso de algunas especies de HMA de uso comercial como biofertilizantes de cultivos a nivel nacional. En Tamaulipas, el conocimiento acerca de la diversidad de HMA es escaso. El objetivo del presente trabajo fue determinar la presencia e identidad taxonómica de hongos micorrízicos arbusculares asociados a la familia Euphorbiaceae (sensu lato) en el Área Natural Protegida Altas Cumbres. Las esporas fueron obtenidas a través de propágulos extraídos de plantas trampa de diferentes especies, cultivadas en suelo y raíces de la zona de estudio. El estatus micorrízico se determinó mediante la técnica de tinción de Phillips y Hayman y la identificación de HMA, a través de la extracción de esporas por el método de tamizado húmedo con centrifugación con sacarosa, y su caracterización morfológica. Todas las raíces mostraron estructuras típicas de los HMA, evidenciando la presencia de esta asociación en los 74 taxones de euforbiáceas. Se registró una riqueza de 9 especies de HMA ubicadas dentro de 6 géneros, 4 familias y 3 órdenes, siendo Glomus (Familia Glomeraceae) el género con mayor riqueza específica. Se detectó la presencia de los géneros Entrophospora, Funneliformis y Rhizophagus por primera vez en Tamaulipas. Los resultados denotan lo ampliamente distribuidos que se encuentran los HMA en las plantas de la familia Euphorbiaceae en el Área Natural Protegida Altas Cumbres y la necesidad e importancia de continuar con investigaciones sobre las micorrizas arbusculares.

<p><strong>Background: </strong>The edge effect differentially affects the species in their life stages. We analyzed the environmental conditions associated with the abundance by life stage of four species of timber trees on the edge of a subdeciduous tropical forest.<strong></strong></p><p><strong>Hypothesis:</strong> The edges have higher light incidence and temperature, favorable conditions for the seedlings, so it is expected that the edge will have more abundance of seedlings with respect to the forest interior.</p><p><strong>Species under study:</strong> <em>Bursera simaruba</em> (L.) Sarg.<em>, Cedrela odorata</em> L.<em>, Guazuma ulmifolia </em>Lam.<em>, Lysiloma divaricatum </em>(Jacq.) J.F. Macbr.</p><p><strong>Study site and dates:</strong> Reserva de la Biosfera "El Cielo" (Tamaulipas), Mexico. January-December 2016.</p><p><strong>Methods: </strong>The abundance by life stages and environmental conditions were quantified within the gradient. These variables were correlated, in addition the requirements between stages were contrasted and they were associated with the identified environments.</p><p><strong>Results:</strong> <em>Guazuma ulmifolia</em> showed a negative response to the edge effect, while <em>Cedrela</em> <em>odorata</em> responded positively. The environmental requirements differed between the first life stages and adults. The abundance of the seedlings was associated to conditions of higher light incidence.</p><strong>Conclusions:</strong> Environmental requirements differentially affect each life stage. The abundance of seedlings increases in conditions of higher light incidence, but not in the rest of the stages, except in <em>C. odorata</em>. The loss of cover and the consequent formation of borders can lead to a reduction in the abundance of these species, with economic implications.

Background: The plant community in southern Texas and the adjacent region in Mexico is Tamaulipan thornscrub (MET). However, the recently published proposals for quantitative hierarchical classification have evidenced the presence of more communities and the need for quantitative descriptions of these associations to determine their conservation status. Question: What is the structure and floristic composition of a semi-thorn shrubland in Reynosa’s northwestern region? Studied species: Tamaulipan low semi-thorn scrubland. Study site and dates: Hills in Reynosa’s northwestern region (Tamaulipas), Mexico. August 2018-July 2019. Methods: Abundance, height and coverage of each plant species were measured on 33 plots of 10 × 10 m. Horizontal structure was analyzed by Importance Value Index, vertical structure was estimated through a modification of the Pretzsch Index and in addition alpha diversity indices were calculated. Results: Richness was 55 species, within 54 genera and 25 families. The importance values were centered mainly in small, spineless shrub species (Lippia graveolens, Calliandra conferta, Turnera diffusa and Krameria ramosissima). The vertical structure presented four defined strata with 50 % of species equally represented in all strata and the remaining 50 % restricted to a single stratum (A = 2.86, Amax = 5.39, Arel = 52.98 %). The species with the highest proportional density were distributed only in stratum IV (0-1.12 m). Conclusions: The community is a clearly defined low semi-thorn scrubland. The structural characteristics indicate that it can be a possible transition plant association between MET and piedmont scrub. This reinforces the proposals of the recently published classification systems. Translate stop   Translate stop  

Background The cultural importance assigned to biodiversity is a complex subject, its study has been developed from ethnobotany and ethnomicology, mainly. A new proposal to address cultural importance is from the biocultural key species. Therefore, integrating information on the knowledge and use of various biological groups, the species with the greatest cultural relevance were selected. Methods An index (BKSI: Biocultural Key Species Index) was integrated, which assesses the relevance based on general attributes associated with fauna, flora and funga. The study was carried out in the Náhuatl community called El Barco, Lolotla; in the Huastec Hidalguense region. Field work was carried out for two years (2018–2019) with 24 field trips. Percentage ethnographic method combined with snowball (10% of the population) were applied; and as the ethnographic tool multiple free listings (n = 50) were used. Results In total of 335 species associated to 537 traditional names in Spanish and indigenous language (Náhuatl) are reported, that belongs to different biological groups (fungi and plants; fish, amphibians, reptiles, birds and mammals). The biocultural relevance degree was categorized respect to the obtained value in the index (BKSI); a representative set of each biological group was selected, being those with the highest biocultural relevance. Conclusions It is proposed that these species constitute a useful tool in the application of programs that promote the conservation of diversity from a biocultural approach; they may even promote the proper use of resources or biological restoration.