Una población relicta de Acer saccharum subsp. skutchii (Aceroideae) en el estado de Guerrero, México

Structure, composition, diversity, environmental relationships, and conservation status of a cloud forest with Acer saccharum subsp. skutchii (sugar maple) are described in a recently found locality at Coahuayutla de José María Izazaga municipality, state of Guerrero, Mexico. Woody individuals ≥1 cm dbh in 10 m/radius circular plots and seedlings and saplings heights of sugar maple in 5.6 m/radius circular plots were recorded. The relative ecological importance of each species was expressed in an importance value. Non-metric Multidimensional Scaling (NMDS) ordination technique was used to explore the species correlations with edaphic, geographic coordinates, elevation, and canopy gaps variables. 43 woody species in 0.126 ha were recorded. The families with most species were Asteraceae and Fagaceae. The diametric distribution of woody species showed an inverted “J” shape, indicating successful regeneration. Sugar maple is co-dominant with Carpinus caroliniana and Quercus uxoris. Most correlations between presence-absence of trees, including Acer saccharum subsp. skutchii, were with soil characteristics in the population of Guerrero and all maple localities in Mexico and Guatemala. 30% of the reported species are included in some risk category. The fire regime in the zone is a major threat for the persistence of the studied species.Se describe la estructura, composición, diversidad, relaciones ambientales y conservación de un bosque mesófilo con Acer saccharum subsp. skutchii (arce azucarero) recientemente encontrado en el municipio de Coahuayutla de José María Izazaga, Guerrero. Se registraron los individuos leñosos con ≥1 cm dap en parcelas circulares de 10 m de radio, y la altura de plántulas y plantas juveniles del arce azucarero en parcelas de 5.6 m de radio. Para cada especie se obtuvo su valor de importancia. Se utilizó la técnica de ordenación Escalar Multidimensional No-métrica (NMDS) para explorar sus correlaciones con variables edafológicas, coordenadas geográficas, de elevación y apertura de claros. Se registraron 43 especies de plantas leñosas en una superficie de 0.126 ha. Las familias mejor representadas fueron Asteraceae y Fagaceae. La distribución diamétrica de las plantas leñosas mostró una forma de “J” invertida, indicando regeneración exitosa. El arce azucarero fue codominante en el dosel con Carpinus caroliniana y Quercus uxoris. Tanto en la población de Guerrero, como en las otras cinco localidades donde habita el árbol en México y Guatemala, la mayoría de las correlaciones encontradas entre la presencia y ausencia de árboles, incluyendo Acer saccharum subsp. skutchii, y los factores ambientales se refirieron a las características de suelo. De las especies registradas en el estudio, 30% están incluidas en alguna categoría de riesgo. El régimen de incendios en la zona pone en peligro la persistencia de este árbol en el sitio de estudio

Large scale patterns of genetic variation and differentiation in sugar maple from tropical Central America to temperate North America

© 2015 Vargas-Rodriguez et al. Background: Geological events in the latter Cenozoic have influenced the distribution, abundance and genetic structure of tree populations in temperate and tropical North America. The biogeographical history of temperate vegetation that spans large ranges of latitude is complex, involving multiple latitudinal shifts that might have occurred via different migration routes. We determined the regional structuring of genetic variation of sugar maple (Acer saccharum subsp. saccharum) and its only subspecies in tropical America (Acer saccharum subsp. skutchii) using nuclear and chloroplast data. The studied populations span a geographic range from Maine, USA (46°N), to El Progreso, Guatemala (15°N). We examined genetic subdivisions, explored the locations of ancestral haplotypes, analyzed genetic data to explore the presence of a single or multiple glacial refugia, and tested whether genetic lineages are temporally consistent with a Pleistocene or older divergence. Results: Nuclear and chloroplast data indicated that populations in midwestern USA and western Mexico were highly differentiated from populations in the rest of the sites. The time of the most recent common ancestor of the western Mexico haplotype lineage was dated to the Pliocene (5.9 Ma, 95 % HPD: 4.3-7.3 Ma). Splits during the Pleistocene separated the rest of the phylogroups. The most frequent and widespread haplotype occurred in half of the sites (Guatemala, eastern Mexico, southeastern USA, and Ohio). Our data also suggested that multiple Pleistocene refugia (tropics-southeastern USA, midwestern, and northeastern USA), but not western Mexico (Jalisco), contributed to post-glacial northward expansion of ranges. Current southern Mexican and Guatemalan populations have reduced population sizes, genetic bottlenecks and tend toward homozygosity, as indicated using nuclear and chloroplast markers. Conclusions: The divergence of western Mexican populations from the rest of the sugar maples likely resulted from orographic and volcanic barriers to gene flow. Past connectivity among populations in the southeastern USA and eastern Mexico and Guatemala possible occurred through gene flow during the Pleistocene. The time to the most common ancestor values revealed that populations from the Midwest and Northeast USA represented different haplotype lineages, indicating major divergence of haplotypes lineages before the Last Glacial Maximum and suggesting the existence of multiple glacial refugia

Extending our scientific reach in arboreal ecosystems for research and management

The arboreal ecosystem is vitally important to global and local biogeochemical processes, the maintenance of biodiversity in natural systems, and human health in urban environments. The ability to collect samples, observations, and data to conduct meaningful scientific research is similarly vital. The primary methods and modes of access remain limited and difficult. In an online survey, canopy researchers (n = 219) reported a range of challenges in obtaining adequate samples, including ∼10% who found it impossible to procure what they needed. Currently, these samples are collected using a combination of four primary methods: (1) sampling from the ground; (2) tree climbing; (3) constructing fixed infrastructure; and (4) using mobile aerial platforms, primarily rotorcraft drones. An important distinction between instantaneous and continuous sampling was identified, allowing more targeted engineering and development strategies. The combination of methods for sampling the arboreal ecosystem provides a range of possibilities and opportunities, particularly in the context of the rapid development of robotics and other engineering advances. In this study, we aim to identify the strategies that would provide the benefits to a broad range of scientists, arborists, and professional climbers and facilitate basic discovery and applied management. Priorities for advancing these efforts are (1) to expand participation, both geographically and professionally; (2) to define 2–3 common needs across the community; (3) to form and motivate focal teams of biologists, tree professionals, and engineers in the development of solutions to these needs; and (4) to establish multidisciplinary communication platforms to share information about innovations and opportunities for studying arboreal ecosystems

Hargreaves2019SciAdv_data1 seedpredation perseedtypeXcagetreatXsiteXdate

Seed predation data used for analyses in Fig. 1 and Table 1. Seed predation data are averaged across 10 to 20 depots per seed type (sunflower or oat) per site per date

Hargreaves2019SciAdv_data2 seedpredation perseedtypeXcagetreatXsite & covariates

Mean seed predation intensity per site (for each seed type) and environmental covariates (climate, productivity, vertebrate richness) tested in structural equation models

Data from: Seed predation increases from the Arctic to the Equator and from high to low elevations

Species interactions have long been predicted to increase in intensity toward the tropics and low elevations because of gradients in climate, productivity, or biodiversity. Despite their importance for understanding global ecological and evolutionary processes, plant-animal interaction gradients are particularly difficult to test systematically across large geographic gradients, and evidence from smaller, disparate studies is inconclusive. By systematically measuring postdispersal seed predation using 6995 standardized seed depots along 18 mountains in the Pacific cordillera, we found that seed predation increases by 17% from the Arctic to the Equator and by 17% from 4000 meters above sea level to sea level. Clines in total predation, likely driven by invertebrates, were consistent across treeline ecotones and within continuous forest and were better explained by climate seasonality than by productivity, biodiversity, or latitude. These results suggest that species interactions play predictably greater ecological and evolutionary roles in tropical, lowland, and other less seasonal ecosystems