¿Es Oncidium poikilostalix una especie invasora? Ecología poblacional y comportamiento reproductivo de esta orquídea epífita en Chiapas, México

Background and Aims: Biological invasions are considered as second to habitat loss as a cause of the extinction of species. The study of population dynamics is particularly relevant for species with expansive behavior. The aims of this study were to: (1) evaluate the population ecology of Oncidium poikilostalix in shaded coffee plantations in Mexico, (2) evaluate the reproductive behavior of O. poikilostalix in this habitat, and (3) determine whether this orchid should be considered as an invasive species. Methods: During 2013-2015, most of the individuals of the Mexican population of O. poikilostalix (located south of the state Chiapas) were marked and measured. Additionally, the flower and fruit production (first flowering and repeated flowering), mortality and recruitment of new individuals were registered annually, and its potential distribution was modeled. Key results: Within this period a population increase of 1.11% was observed, with a proportional increase in the number of flowers and fruits. There was a strong correlation between the leaf area of individuals and the production of flower spikes (R=0.690, p<0.001) and flowers (R=0.775, p<0.001). The number of mature individuals that had repeated flowering varied from 47.1% in 2013 to 22.5% in 2015. There was also correlation between the leaf area of individuals with the fact that they do not flower, flower once and repeated flowering (X2=277.65, p<0.001). The Mexican population of O. poikilostalix is located on the northern limit of the potential distribution of this species. Conclusions: It is unlikely that O. poikilostalix behaves as an invasive species. Despite being a locally abundant taxon, with an apparently healthy population established in traditional shaded coffee plantations, its distribution in Mexico is limited, which may represent a serious risk to its survival in the country.Antecedentes y Objetivos: Las invasiones biológicas se consideran la segunda causa de extinción de especies después de la destrucción del hábitat. Cuando se trabaja con especies con una tendencia expansiva, los estudios de dinámica poblacional son particularmente relevantes. Los objetivos de este estudio fueron: (1) evaluar la ecología poblacional de Oncidium poikilostalix en cafetales de sombra en México, (2) evaluar el comportamiento reproductivo de O. poikilostalix en este hábitat, y (3) determinar si esta orquídea se debe considerar como una especie invasora. Métodos: Durante 2013-2015 se marcaron y midieron la mayoría de los individuos de la población mexicana de O. poikilostalix (localizada al sur del estado de Chiapas). Además, se registraron anualmente la producción de flores y frutos (primera floración y floración repetida), la mortalidad y el reclutamiento de nuevos individuos, y se modeló su distribución potencial. Resultados clave: Dentro de este periodo se observó un incremento poblacional de 1.11%, con un aumento proporcional en el número de flores y frutos. Existe una fuerte correlación entre el área foliar de los individuos, y la producción de espigas (R=0.690, p<0.001) y flores (R=0.775, p<0.001). El número de individuos adultos que tuvieron floración repetida varió de 47.1% en 2013 a 22.5% en 2015. También se encontró correlación entre el área foliar de los individuos y el hecho de que no florezcan, florezcan una vez, o presenten floración repetida (X2=277.65, p<0.001). La población mexicana de O. poikilostalix se localiza en el límite norte de la distribución potencial de esta especie. Conclusiones: Es poco probable que O. poikilostalix sea una especie invasora. A pesar de ser un taxon localmente abundante, con una población aparentemente sana establecida en cafetales tradicionales de sombra, su área de distribución en México aún es restringida, lo que puede representar un grave riesgo para su supervivencia en el país.This work was funded by the National Council for Science and Technology (CONACYT), Mexico, and El Colegio de la Frontera Sur (ECOSUR)

Organización espacIal y estructura de una poblacIón de Ionopsis utricularioides (OrchIdaceae) en un área suburbana de Pinar del río, Cuba

Se determinó la estructura poblacional y hábitos de crecimiento de una población de Ionopsis utricularioides (Orchidaceae), en un huerto de naranjos (citrus sinensis; Rutaceae), localizado en la finca “La Juanita”, Pinar del Río, Cuba. Se tuvieron en cuenta todos los árboles de naranjo del huerto y la población total de I. utricularioides. Se midieron las siguientes variables: altura y diámetro de los naranjos y ramas donde crecían las orquídeas, distribución de las orquídeas en los forófitos (tronco, ramas o ramillas), estadio de vida de las orquídeas (inmaduras o adultas), orientación de las orquídeas en el forófito, si las plantas estaban solitarias o agregadas y especie de los vecinos en el caso de las agregadas. Se estudiaron un total de 10 árboles de c. sinensis, ocho de ellos forófitos de la orquídea. Se contabilizaron 217 plantas de I. utricularioides. En el tronco de los árboles no se encontraron plantas de I. utricularioides y en las ramillas creciá 98.61% de la población. El número de plantas es relativamente abundante en los dos estadios de vida. Gran parte de las plantas de I. utricularioides se encontraron creciendo en agregación con otros individuos de su misma especie o con otras especies de epífitas vasculares. Esta es una población establecida y madura. Crecer en agregación le puede brindar ventajas competitivas a I. utricularioides.We determined the population structure and some habitat conditions of a Ionopsis utricularioides (Orchidaceae) population in an orange orchard (citrus sinensis, Rutaceae), located in the “La Juanita” farm, Pinar del Río, Cuba. We took into account all the orange trees of the orchard, and located all the individuals of I. utricularioides. The following variables were analyzed: height and diameter of branches in growing orchids, orchid distribution on phorophytes (trunk, branches or twigs), life stage of the orchids (immature or adults), orientation of orchids in the phorophyte, if the plants were solitary or aggregated, and kind of neighbours in the case of the aggregate. Of the 10 trees of c. sinensis, eight trees had orchids of I. utricularioides, with 217 plants. Almost all orchids were observed on the twigs (98.61 %) and none were observed on the trunk of the tree. The number of plants is relatively high in the two stage of life. Most plants of I. utricularioides were found growing aggregate with individuals of the same species, or with other species of vascular epiphytes. This is a stable and mature population. Growing up in aggregation can give competitive advantages to I. utricularioides

Comparison of transient and asymptotic perturbation analyses of three epiphytic orchid species growing in coffee plantations in Mexico: effect on conservation decisions

Background: Epiphyte removal forms part of routine management in shade coffee plantations. Aims: Assess the current status of three population orchids growing in Mexican shaded coffee plantations and evaluate the effect of perturbing the transient behaviour of different life stages. Methods: We modelled the short-term response of eliminating I) non-reproductive juveniles, or II) reproductive adult plants from coffee bushes, on populations of Oncidium poikilostalix, Lepanthes acuminata and Telipogon helleri (Orchidaceae). First, we calculated the transient dynamics per se and second, we made a perturbation analysis on population inertia. Finally, we made a comparison with a traditional sensitivity analysis. Results: All three species showed different positive asymptotic growth rate: O. poikilostalix (λmax = 1.106), L. acuminata (λmax = 1.209), and T. helleri (λmax = 1.012). The effect of eliminating the major part of the juvenile or adult orchids gave population inertia in relation to steady state, respectively, (+19%, -24%) for O. poikilostalix, (+17%, -28%) for T. helleri and (+57%, -35%) for L. acuminata. Conclusions: Eliminating juveniles or adults affects in different ways the short-term dynamics due to differential impact on size stages that have the non-linear effects associated with important disturbances that currently affect orchids growing in coffee plantations.The work was supported in part by the National Council for Science and Technology (CONACYT), Mexico

Spatio-temporal dynamics of the invasive orchid Oeceoclades maculata (Orchidaceae), in four different habitats in southeast Chiapas, Mexico

The expansion of invasive species is a global concern. Within the Orchidaceae there are a number of invasive species. One of the most widely distributed invasive orchids in Mexico is Oeceoclades maculata (Lindl.) Lindl. By examining the population dynamic variations of an invasive species in its range of expansion, we can identify the factors that have contributed to that variation. Life Table Response Experiments (LTRE) were used to describe the dynamic of four populations of O. maculata in different ecosystems in south Chiapas, Mexico. Our goals were to quantify the contributions of differences between years and sites, and their interactions, to overall differences in population growth rate (λ), and to underlying vital rates. Fertility, survival and growth made the largest contributions, both positive and negative, to annual differences in λ. Spatial variations in λ were also found. The largest plants (S3 and S4) made the contributions of greatest magnitude each year and in each site. In seven of eight cases, the inclusion of the interaction term gave a better estimate of the population growth rate. This investigation highlights the need for taking into account life-history variations at different scales when the research goal is to study expansion of an invasive species in a heterogeneous landscape. The usefulness of LTRE studies was also demonstrated to better understand the natural history of the species and thus lay the groundwork for planning efficient management strategies, either for the conservation of rare, endangered species, or for the control of invasive species.This work was partially funded by The National Council for Science and Technology (CONACYT)

Ecología y estructura poblacional del endemismo cubano Tetramicra malpighiarum (Orchidaceae), en el Parque Nacional Desembarco del Granma, Cuba

In Cuba, there are 315 species of Orchidaceae family, approximately 32 % of these species are endemic. During 2012 and 2013 an endemic population of Tetramicra malpighiarum (Orchidaceae) was studied at the Desembarco del Granma National Park, Cuba. We determined the abundance of this species, life classes (immature and adult), phorophytes inhabited, vertical distribution (trunk, branches or twigs), solitary or aggregated growing, and its cardinal orientation on phorophytes. We found 254 individuals of T. malpighiarum distributed in 20 phorophytes. For the first time, were found individuals of T. malpighiarum grew on other five species of phorophytes, besides of Malpighia incana (Malpighiaceae) and Erythroxylum havanense (Erythroxylaceae). Of the total of individuals recorded, 69.3 % were adult and 93.7 % were growing on the twigs. The number of solitary individual and aggregated individuals was similar. The population shows a slight tendency to grow toward south and northwest orientations. This is the first study to describe the population ecology of T. malpighiarum, but it is recommended to conduct long-term genetic and demographic studies. These future studies should be explored the reproductive system (e.g., level of endogamy) and population genetic of this species endemic of Cuba in order to evaluate its permanency in the future. En Cuba se reconocen aproximadamente 315 especies para la familia Orchidaceae, de las cuales son endémicas alrededor de 32 %. Durante 2012 y 2013, se estudió una población del endemismo cubano Tetramicra malpighiarum (Orchidaceae), en el Parque Nacional Desembarco del Granma, Cuba. Se estudió la abundancia de la especie, clases de vida de los individuos (inmaduros y adultos), forófitos sobre los que crecían, micrositios que ocupaban en los mismos (tronco, ramas o ramillas), si los individuos estaban solitarios o agregados y orientación cardinal que tenían sobre los forófitos. Se encontraron 254 individuos de T. malpighiarum, distribuidos en 20 forófitos. Por primera vez se localizaron individuos de T. malpighiarum ocupando otras cinco especies de forófitos, además de Malpighia incana (Malpighiaceae) y Erythroxylum havanense (Erythroxylaceae). Fueron adultos 69.3 % de los individuos y en las ramillas crecía 93.7 % de la población. Es similar el número de individuos de T. malpighiarum creciendo agregados y creciendo solitarios. La población muestra una pequeña tendencia a crecer preferentemente con orientaciones sur y noroeste. Este trabajo es una primera aproximación a la ecología poblacional de T. malpighiarum, pero es fundamental realizar estudios genéticos y demográficos a largo plazo, que permitan monitorear el comportamiento poblacional y reproductivo de este endémico cubano, y averiguar los niveles de endogamia y variabilidad genética de los individuos, para conocer su posible comportamiento y permanencia en el futuro

Impact of different shade coffee management scenarios, on a population of <i>Oncidium poikilostalix</i> (Orchidaceae), in Soconusco, Chiapas, Mexico

<p><b><i>Background</i></b>: Understanding the effect of perturbation, be it natural or anthropogenic, on the demography and dynamics of the plant populations can help conservation management planning.</p> <p><b><i>Aims</i></b>: We assessed the impacts of management of a shade coffee plantation on a population of <i>Oncidium poikilostalix</i> (Orchidaceae).</p> <p><b><i>Methods</i></b>: We studied in a coffee (<i>Coffea arabica</i>) agroecosystem the impact of the current traditional management [T] and two hypothetical epiphyte control management scenarios (intense ‘desmusgue’ [ID] and moderate ‘desmusgue’ [MD]), on the only known Mexican population of <i>O</i>. <i>poikilostalix</i>. Based on 3 years of field demographics data, the population dynamics of the orchid were projected using T, ID and MD scenarios for 20 years into the future.</p> <p><b><i>Results</i></b>: Under the current management T, the population of <i>O. poikilostalix</i> was projected to grow continuously (λ = 1.102). Conversely, under management ID, the loss of individuals would lead to a sustained population decline (λ = 0.843); in the case of MD, the population would decline more slowly with the population growth rate tending towards equilibrium (λ = 0.966).</p> <p><b><i>Conclusions</i></b>: The changes in the management of coffee plantations that have become common throughout the south-east of Mexico represent a threat to the survival of the only population of <i>O. poikilostalix</i> in Mexico, and likely threaten other epiphytic species.</p