María del Rosario Pineda-López

Comparative demographic analysis in contrasting environments of Magnolia dealbata: an endangered species from Mexico

The study of population regulation and demography in natural habitats is critical for the conservation of rare and endangered species. We address the impact of cattle exclusion on the demographics of Magnolia dealbata (Magnoliaceae), an endangered species according to IUCN and Federal Mexican laws. Sixteen permanent plots were established, eight of which were enclosed to livestock, in the mountain cloud forest in Coyopolan, Mexico, which has the largest population of M. deadlbata. Censuses of the plots were undertaken annually during three annual cycles to record seed number, recruitment, mortality, and growth (defined as length and diameter at breast height). The effects of two treatments (with and without livestock exclusion) on the dynamics of M. dealbata were investigated using transition matrix models and life table response experiment (LTRE) analysis. Contrary to expectations, there was no significant effect of cattle exclusion on population growth rates (λ). Furthermore, the λ, estimated from the mean transition matrix for both treatments was greater than one. The transitions with the highest elasticity values were similar between the two treatments, while reproductive stage contributed more to differences in population growth rate and were less variable than the non-reproductive stage. LTRE analysis showed that treatment differences had little effect on λ. Livestock exclusion appears to lead more to differences in the arrangement of the values of the transition matrix than to the rate of population growth for M. dealbata.

Can Pinus plantations facilitate reintroduction of endangered cloud forest species

Coniferous plantations have been widely used by reforestation programs seeking to mitigate the effects of deforestation in mountainous areas in different parts of the world. However, some studies show that pine plantations can simulate natural mechanisms of succession, thereby facilitating the incorporation of other native species of mid- and late-successional stages. Existing pine plantations could function as a substitute habitat and facilitate the establishment of native and endangered cloud forest species. To test this hypothesis, we planted two endangered species from the family Juglandaceae (Juglans pyriformis and Oreomunnea mexicana) under twelve-year-old canopy plantations of Pinus patula and compared them to individuals planted in open (control) sites and recorded their survival and growth. The results show that the survival of J. pyriformis and O. mexicana was significantly higher below the canopy of P. patula plantations than in the open site. However, growth rates varied significantly among species and sites. Although pine plantations may favor the survival of seedlings, they cannot ensure the growth of plants without additional forest management.

Present and future potential distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) under different climate change scenarios

Abstract The current distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) and its future potential response to climate change have not been addressed. Thus, in this work, we focus on both aspects of this species by means of ecological niche modeling, using different general circulation models and Intergovernmental Panel on Climate Change emission scenarios. Because the species’ life history includes a hibernation period, we performed two different sets of analysis: one considering the whole annual cycle and another considering only the species’ active season. According to our results, the current potential distribution of X. perotensis extends further out of the Oriental Basin, to which the species is endemic. Future projections vary among different climatic scenarios and data sets used in the modeling process, but virtually all of them project a substantial encroachment of the species’ potential distribution area by 2050. Our models suggest that, compared with species that are active throughout the year, X. perotensis, being a seasonal species, could be affected by climate change, increasing the risk of extinction. This may pose a serious threat to the Perote ground squirrel’s persistence throughout the following decades.

Does Baccharis conferta Shrub Act as a Nurse Plant to the Abies religiosa Seedling

The role played by nurse plants represents a common ecological process in nature; this being an interaction where a particular species benefits from the presence of another species. Nurse plant species offer an efficient aid for the survival and growth of other species, including some which are of economic importance or interest for conservation. Baccharis conferta Kunth (shrub) and Abies religiosa (tree) are two common species which cohabit in the mountains of Mexico. It is general a practice, when establishing plantations to clear the mountainside, which involves cutting down and removing all shrubs. In order to discover whether B. conferta acts as a nurse plant when Abies religiosa seedlings are becoming established, this research evaluated the effect of this plant on the survival and growth of Abies religiosa seedlings. After taking records for two years, we found that the survival of A. religiosa did not vary significantly under the two contrasting conditions (65% with B. conferta and 55 % without B. conferta, nor was there significant interaction among years, contrasting conditions and experimental plots (G 2 = 0.01, P> 0.91). However, height and coverage were significantly greater under the B. conferta canopy ((t = 3614, P 0.49). We concluded that B. conferta promotes the seedling growth of A. religiosa, reducing costs for commercial plantations or plantations aimed towards restoration.

Altitudinal Record of Dendroctonus approximatus Dietz (Coleoptera: Curculionidae) in Veracruz, Mexico

Among bark beetles, the genus Dendroctonus Erichson causes the most damage to trees in forests around the world (Six and Bracewell 2015), attacking trees of the genera Pinus L., Picea A. Dietr., Pseudotsuga Carrière, and Larix (Mill.) (all Pinaceae) (Wood 1963; Six and Bracewell 2015). The group comprises 20 species (ArmendárizToledano et al. 2015), of which 13 are found in the forests of Mexico. In Mexico, 40.5% of pest control reports are attributed to damage by Dendroctonus species (Pérez-Camacho et al. 2013). Species in this genus have been classified into two groups according to the order of colonization of the host, with six species (D. mexicanus Hopkins, D. frontalis Zimmermann, D. adjunctus Blandford, D. rhizophagus Thomas and Bright (Salinas-Moreno et al. 2010), D. pseudotsugae Hopkins, and D. ponderosae Hopkins) considered as primary pests and the remaining seven as secondary pests, including D. approximatus Dietz (Ruiz et al. 2009; Salinas-Moreno et al. 2010; Vı́ctor and Zúniga 2016). Dendroctonus approximatus attacks 17 species of Pinus, of which the following species are known to occur in Veracruz: P. ayacahuite C. Ehrenb. ex Schltdl., P. hartwegii Lindl., P. montezumae Lamb., P. patula Schltdl. and Cham., P. pseudostrobus Lindl., and P. teocote Schltdl. and Cham. (Salinas-Moreno et al. 2010), practically all of which are economically important species in Mexico. Dendroctonus approximatus usually has one generation per year but can have two generations in years with warmer conditions. The species’ pheromone system is unknown (Six and Bracewell 2015). This report offers the first geo-referenced data on the altitudinal distribution of D. approximatus in the northwestern region of the volcano Cofre de Perote, Veracruz, Mexico. The specimens were collected by means of eight-cone Lindgren traps baited with generalist bait composed of frontalin, alphaand beta-pinene, and endo-brevicomine (Sistema Injecthor De Mexico) from June 2014 to July 2016 in coniferous ecosystems of the communities of El Conejo and Los Pescados (Perote), El Rosario (Xico), and El Zapotal (Acajete) in Veracruz (Table 1). Four traps (three baited and one unbaited) were placed at intervals of 100 m per site. The sites occurred at altitude intervals of 250 m from 2,000 to 3,500 m elevation (Table 1). Beetles caught in traps were collected and transferred to 70% ethyl alcohol every 15 days. Specimens were identified to genus using Wood (1982), and species identification was made by Thomas Atkinson (University of Texas, Austin, TX). Genitalia of collected insects were compared to those of D. approximatus specimens from the Entomological Collection of the Institute of Plant Health of the Colegio de Postgraduados (CEAM) in Texcoco, Mexico, following Vı́ctor and Zúniga (2016). Genitalia were dissected by separating the abdomen from the rest of the body and immersing it in 10% potassium hydroxide at 80° C for 20 minutes to macerate the tissue. Once extracted, the genitalia were immersed in 70%