Browsing by Autor "A C."

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Alkaloid Profile Characterisation and Bioactivity Evaluation of Bolivian Hippeastrum Species (Amaryllidaceae) as Cholinesterase Inhibitors
(Multidisciplinary Digital Publishing Institute, 2025) María Lenny Rodríguez-Escobar; Rogéria Inês Rosa Lara; Margoth Atahuachi Burgos; A C.; Carla Maldonado; Jaume Bastida; Luciana R. Tallini; Laura Torras‐Claveria
Amaryllidaceae alkaloids from the Amaryllidoideae subfamily exhibit broad pharmacological activities, including neuroprotection and anticancer effects. Galanthamine is a key compound for Alzheimer's therapy. The Hippeastrum genus, particularly in Bolivia, offers significant potential for novel drug discovery, emphasising the need for conservation and further phytochemical research. Twenty-seven samples from Bolivian Hippeastrum species were investigated in terms of their alkaloid profile and anticholinesterase activity. The phytochemical analysis of Bolivian Hippeastrum species via GC-MS identified 48 Amaryllidaceae alkaloids, displaying diverse structural groups with potential pharmacological significance. Lycorine- and Homolycorine-type alkaloids were predominant, particularly in H. chionedyanthum and H. haywardii, with high concentrations of lycorine, a promising anticancer compound. The species H. evansiarum and H. mollevillquense contained notable quantities of Galanthamine type alkaloids, relevant for Alzheimer's treatment. This study also highlights variability in acetylcholinesterase and butyrylcholinesterase inhibitory activities, with H. lara-ricoi and H. haywardii demonstrating strong inhibition. These findings suggest that Hippeastrum species are a valuable source of bioactive compounds, warranting further research into their therapeutic applications.
Chusquea sect. Tenellae (Bambuseae, Bambusoideae, Poaceae), a taxonomic revision of a new section from South America
(Q15088586, 2017) Lakshmi Attigala; A C.; Lynn G. Clark
The Chusquea ramosissima informal group, including four named species, is classified within Chusquea subg. Chusquea based on morphological characters, but has not been rigorously studied in its entirety. The putative synapomorphies distinguishing the C. ramosissima informal group from the remainder of Chusquea subg. Chusquea are the presence of a pseudopetiolate culm leaf blade that remains green and synflorescences borne on a mix of longer leafy and shorter non-leafy subsidiary branches per node, features unknown in the rest of the subgenus or the genus as a whole. In addition, the species of the C. ramosissima informal group share a bud complement with a set of 1–4 laterally compressed, + falcate subsidiary buds on each side positioned facing each other, a central bud with parallel sides and a broadly triangular apex, and thin-textured spikelets. Because of this unique combination of characters, including two that are unique within Chusquea, and molecular support, we here formally describe Chusquea sect. Tenellae within Chusquea subg. Chusquea to accommodate this group. Five species, distributed in Argentina, Brazil, Bolivia, Paraguay and Uruguay, are included in the newly recognized Chusquea sect. Tenellae: C. fasciculata, C. ramosissima, C. tenella, C. tenuiglumis, and the newly described C. ovatifolia. This revision includes a comparison of sect. Tenellae with the five previously recognized sections of subg. Chusquea, detailed descriptions for the five species of sect. Tenellae, line illustrations or images for all species, maps of their distributions, and morphological keys for their identification. The names Chusquea fasciculata, C. tenuiglumis, C. tenuiglumis var. laxiuscula and C. tenuiglumis var. subcylindrica are lectotypified.
Disentangling environmental and spatial processes of community assembly in tropical forests from local to regional scales
(Wiley, 2015) Gabriel Arellano; J. Sebastián Tello; Peter M. Jørgensen; A C.; M. Isabel Loza; Vania Torrez; Manuel J. Macía
Understanding patterns and mechanisms of variation in the compositional structure of communities across spatial scales is one of the fundamental challenges in ecology and biogeography. In this study, we evaluated the effects of spatial extent (i.e. size of study region) on: 1) whether community composition can be better explained by environmental (i.e. niche‐based) or spatial (e.g. dispersal‐based) processes ; and 2) how climate and soils contribute to the influence of environment on plant community composition. We surveyed community composition across a network of 398 forest plots spanning a ∼4000 m elevational gradient in the Madidi region in northwestern Bolivia. Using redundancy analyses and hierarchical variation partitioning, we disentangled the effects of environmental and spatial predictors on species composition, further decomposing the environmental effect between its climatic and soil components. We repeated analyses for 200 sub‐regions ranging in spatial extent from ∼250 to ∼17 500 km 2 . Our analyses show a high degree of idiosyncrasy in results that come from different sub‐regions. Despite this variability, we were able to identify various important patterns in the structure of tropical plant communities in our study system. First, even though sub‐regions varied in size by nearly two orders of magnitude, the total amount of explained variation in community composition was scale independent; at all spatial scales, environment and space accounted for about 25% of the differences in community composition among plots. Second, the measured environmental effect was higher than the spatial effect on average and in the vast majority of sub‐regions. This was true regardless of the spatial extent of analysis. Finally, we found that both climatic and soil variables accounted for significant fractions of variation, but climate was always more important than soils.
Disentangling the roles of bracken fronds and litter on natural seedling recruitment in fire-disturbed tropical montane habitats
(Elsevier BV, 2024) Cecilia L. López; César Mayta; A C.; Mariana Villegas; Emili Antonia Jiménez; Víctor Vásquez; Isabell Hensen; Silvia C. Gallegos
Tropical montane forests are diverse ecosystems often affected by uncontrolled human-induced fires causing tree mortality and creating large deforested areas. After fires, Pteridium spp. ferns (bracken) often dominate, and forest regeneration in these areas is slow. In this study, we evaluated the effects of bracken fronds and litter, as well as the micro-environmental conditions created by the fern, on the density and species diversity of naturally recruiting seedlings. At eight sites, 120 experimental plots were established among forest and bracken-dominated areas with the following treatments: (a) fronds and litter intact (F+L+); (b) fronds intact and litter removed (F+L-); (c) fronds removed and litter intact (F-L+); and (d) fronds and litter removed (F-L-). After one year, all seedlings were registered, identified and classified according to their life-form (tree, shrub, herb, vine), dispersal vector (wind- or animal-dispersed) and successional status (early-, mid-, and late-successional). For all treatments we assessed 12 micro-environmental variables. We identified 3649 naturally-recruiting seedlings corresponding to 278 species from 70 families. We found positive effects of bracken fronds particularly on tree seedling recruitment: treatments with fronds had greater densities of both animal- and wind-dispersed tree seedlings, 1.8 and 1.4 fold higher, respectively, compared to treatments without fronds. Similarly, the density of early-, mid- and late-successional tree species was 1.3, 1.7 and 1.9 times higher in treatments with than without fronds. Furthermore, species diversity of early-, mid- and late-successional tree species was higher in the treatments with fronds. The environmental conditions generated by bracken presence, such as photosynthetically active radiation, soil temperature, live bracken biomass and litter depth, had positive effects on seedling density of all, animal-dispersed and early-successional tree species, and negative effects on seedling recruitment of other life-forms, notably from early successional stages. To promote forest regeneration in bracken-dominated areas, active restoration measures such as direct seed addition and transplants of nursery-raised seedlings of mid- and late-successional species should be considered. Since bracken can hinder the establishment of some life forms and species but favor others, it is recommended to include a trait-based approach to understand species responses to environmental factors and select species that are optimally adapted to bracken-dominated habitat conditions to promote forest regeneration. • Bracken facilitates seedling recruitment of mid- and late-successional tree species. • Bracken fronds’ shade increases species diversity of tree seedlings. • Bracken litter decreases natural recruitment of herbs. • Animal-dispersed species have higher recruitment under bracken fronds and litter.
Ecological metabolomics of tropical tree communities across an elevational gradient: Implications for chemically-mediated biotic interactions and species diversity
(2023) D. Henderson; Brian E. Sedio; J. Sebastián Tello; Leslie Cayola; A C.; Belen Alvestegui; Nathan Muchhala; Jonathan A. Myers
Abstract Seminal hypotheses in ecology and evolution postulate that stronger and more specialized biotic interactions contribute to higher species diversity at lower elevations and latitudes. Plant-chemical defenses mediate biotic interactions between plants and their natural enemies and provide a highly dimensional trait space in which chemically mediated niches may facilitate plant species coexistence. However, the role of chemically mediated biotic interactions in shaping plant communities remains largely untested across large-scale ecological gradients. To test this hypothesis, we used ecological metabolomics to quantify the chemical dissimilarity of foliar metabolomes among 473 tree species (906 unique species-plot combinations) in 16 tropical tree communities along an elevational gradient in Madidi National Park, Bolivia. We predicted that chemical dissimilarity among co-occurring tree species would be greater, and chemical phylogenetic signal lower, in communities with greater tree species richness and warmer, wetter, and less-seasonal climates, as pressure from natural enemies is likely to be greater in these locales. Further, we predicted that these relationships should be especially pronounced for secondary metabolites derived from biosynthetic pathways known to include anti-herbivore and antimicrobial defenses than for primary metabolites. We found that median chemical dissimilarity among tree species with respect to all metabolites and secondary metabolites increased with tree species richness, decreased with elevation, and increased along a principal component of climatic variation that reflected increasing temperature and precipitation and decreasing seasonality. In contrast, median chemical dissimilarity among tree species with respect to primary metabolites was unrelated to tree species richness, elevation, or the principal component of climatic variation. Furthermore, phylogenetic signal of secondary and primary metabolites decreased with tree species richness. Among tree communities in moist forests, phylogenetic signal of secondary metabolites also increased with elevation and decreased with the temperature and precipitation. Our results support the hypothesis that chemically mediated biotic interactions shape elevational diversity gradients by imposing stronger selection for interspecific divergence in plant chemical defenses in warmer, wetter, and more stable climates. Our study also illustrates the promise of ecological metabolomics in the study of biogeography, community ecology, and complex species interactions in high-diversity ecosystems.
El Incienso de Bolivia: Una Especie Nueva de Clusia (Clusiaceae) de los Bosques Montanos del Norte de La Paz, Bolivia
(Missouri Botanical Garden Press, 2008) Freddy S. Zenteno-Ruíz; A C.
A Clusia L. incense tree, Clusia pachamamae Zenteno-Ruíz & A. Fuentes (Clusiaceae), is described and illustrated. This new species from the montane Yungas forests of northwestern Bolivia differs clearly from other species of section Anandrogyne Planchon & Triana in having spicate short-pedunculate inflorescences with six to 16 sessile and decussate flowers. The species differs from various others to which it is morphologically close (and which also have sessile flowers) in the following ways: from C. tarmensis Engler by having 5- or rarely 6- (vs. always 6-)locular fruits and leaves with winged petioles 1.5–2.6 × 0.6–1.8 cm (vs. 0.4–0.8 × 0.2–0.3 cm); from C. peruviana Szyszylowicz by having obovate to rarely elliptic leaves more than 9 cm long (vs. elliptic and less than 9 cm), and a male inflorescence with six to 16 (vs. three to five) flowers; from C. cajamarcensis Engler by having flowers with five (vs. six) petals and a 5- or rarely 6- (vs. always 6-)locular ovary. This species exudes from its bark and branches a yellow resin that is collected and marketed by local villagers northwest of Bolivia where it is used traditionally for incense in Andean and Catholic rituals.
Elevational Gradients in β-Diversity Reflect Variation in the Strength of Local Community Assembly Mechanisms across Spatial Scales
(Public Library of Science, 2015) J. Sebastián Tello; Jonathan A. Myers; Manuel J. Macía; A C.; Leslie Cayola; Gabriel Arellano; M. Isabel Loza; Vania Torrez; Maritza Cornejo; Tatiana B. Miranda
Despite long-standing interest in elevational-diversity gradients, little is known about the processes that cause changes in the compositional variation of communities (β-diversity) across elevations. Recent studies have suggested that β-diversity gradients are driven by variation in species pools, rather than by variation in the strength of local community assembly mechanisms such as dispersal limitation, environmental filtering, or local biotic interactions. However, tests of this hypothesis have been limited to very small spatial scales that limit inferences about how the relative importance of assembly mechanisms may change across spatial scales. Here, we test the hypothesis that scale-dependent community assembly mechanisms shape biogeographic β-diversity gradients using one of the most well-characterized elevational gradients of tropical plant diversity. Using an extensive dataset on woody plant distributions along a 4,000-m elevational gradient in the Bolivian Andes, we compared observed patterns of β-diversity to null-model expectations. β-deviations (standardized differences from null values) were used to measure the relative effects of local community assembly mechanisms after removing sampling effects caused by variation in species pools. To test for scale-dependency, we compared elevational gradients at two contrasting spatial scales that differed in the size of local assemblages and regions by at least an order of magnitude. Elevational gradients in β-diversity persisted after accounting for regional variation in species pools. Moreover, the elevational gradient in β-deviations changed with spatial scale. At small scales, local assembly mechanisms were detectable, but variation in species pools accounted for most of the elevational gradient in β-diversity. At large spatial scales, in contrast, local assembly mechanisms were a dominant force driving changes in β-diversity. In contrast to the hypothesis that variation in species pools alone drives β-diversity gradients, we show that local community assembly mechanisms contribute strongly to systematic changes in β-diversity across elevations. We conclude that scale-dependent variation in community assembly mechanisms underlies these iconic gradients in global biodiversity.
Elevational range sizes of woody plants increase with climate variability in the Tropical Andes
(Wiley, 2023) Flavia Montaño‐Centellas; A C.; Leslie Cayola; Manuel J. Macía; Gabriel Arellano; M. Isabel Loza; Beatriz Nieto‐Ariza; J. Sebastián Tello
Abstract Aim The climate variability hypothesis proposes that species subjected to wide variation in climatic conditions will evolve wider niches, resulting in larger distributions. We test this hypothesis in tropical plants across a broad elevational gradient; specifically, we use a species‐level approach to evaluate whether elevational range sizes are explained by the levels of thermal variability experienced by species. Location Central Andes. Time Period Present day. Taxon Woody plants. Methods Combining data from 479 forest plots, we determined the elevational distributions of nearly 2300 species along an elevational gradient (~209–3800 m). For each species, we calculated the maximum annual variation in temperature experienced across its elevational distribution. We used phylogenetic generalized least square models to evaluate the effect of thermal variability on range size. Our models included additional covariates that might affect range size: body size, local abundance, mean temperature and total precipitation. We also considered interactions between thermal variability and mean temperature or precipitation. To account for geometric constraints, we repeated our analyses with a standardized measure of range size, calculated by comparing observed range sizes with values obtained from a null model. Results Our results supported the main prediction of the climate variability hypothesis. Thermal variability had a strong positive effect on the range size, with species exposed to higher thermal variability having broader elevational distributions. Body size and local abundance also had positive, yet weak effects, on elevational range size. Furthermore, there was a strong positive interaction between thermal variability and mean annual temperature. Main Conclusions Thermal variability had an overriding importance in driving elevational range sizes of woody plants in the Central Andes. Moreover, the relationship between thermal variability and range size might be even stronger in warmer regions, underlining the potential vulnerability of tropical montane floras to the effects of global warming.
Especie nueva de Weinmannia (Cunoniaceae) de los Bosques andinos altimontanos de La Paz, Bolivia
(Museo Botánico Córdoba, 2021) A C.
Weinmannia epicae is described and illustrated. It grows in Andean high-montane forests of the Yungas region in the department of La Paz, northwestern Bolivia, between 2900 and 3300 m. It differs from other morphologically similar species as W. cundinamarcensis, W. haenkeana and W. pubescens by having the maximum number of leaflets pairs usually between 10 to 14, medial leaflets of 1.3 to 2.3 cm, with more or less rough surface and undersurfaces with hirsute to hirsute-villous indument, and mature capsules villous-pubescent of 5-7 × 1.8-2.7 mm, conspicuously pedicellated. The differences with morphological similar species are pointed out, and information on their geographical distribution, ecology, phenology and the assessment of conservation status according to IUCN criteria are provided.
Expelled by the Antarctic ice: Evolutionary history of the tribe Cunonieae (Cunoniaceae)
(Wiley, 2025) Francisco Fajardo‐Gutiérrez; Mariasole Calbi; Markus S. Dillenberger; J. Sebastián Tello; A C.; Nora H. Oleas; Ricardo A. Segovia; Christine E. Edwards; Yohan Pillon; James Richardson
Abstract The tribe Cunonieae comprises five genera and 214 species of shrubs and trees currently distributed in the Southern Hemisphere and the tropics, exhibiting an amphi‐Pacific disjunct distribution shared with Araucariaceae, Myrtaceae, Nothofagaceae, Podocarpaceae, and Proteaceae, among others. To address the central question of how historical geological forces have shaped the distribution of plant diversity in the southern hemisphere, we aimed to provide evidence from the biogeographical history of Cunonieae. We generated the most densely sampled phylogenetic trees of Cunonieae available to date, with 121 samples and 81 species, based on 404 new sequences of plastid and nuclear DNA regions with high hierarchical phylogenetic signal ( matK , trnL‐F , rpl16 , and internal transcribed spacer (ITS)). We included 184 samples of Rosids to estimate divergence times using fossil calibration points. For biogeographic inference, we employed a time‐stratified model including fossils as tips. Cunonia and Pterophylla were paraphyletic in the ITS tree, and Cunonia was paraphyletic in the plastid tree. Pancheria , Vesselowskya , and Weinmannia were monophyletic, the latter with conflicting nuclear and plastid phylogenies. The crown group Cunonieae was dated at ~56 Ma, and its ancestral areas were Antarctica and Patagonia. Antarctica acted as a bridge between Australia and South America before the consolidation of the Antarctic Ice Sheet and the extinction of the lineage in Antarctica from the Oligocene to the Miocene. Following that, Cunonieae spread to lower latitudes via Zealandia/Oceania and Patagonia/South America. Geological changes during the Pliocene facilitated a further burst in diversification along the Andes, in Madagascar, and in New Caledonia, where at least three colonization events occurred.
Hydrocotyle apolobambensis (Apiaceae), una Especie Nueva Andina del Noroeste de Bolivia
(Missouri Botanical Garden Press, 2010) J. Moises Mendoza F.; A C.
Se describe e ilustra Hydrocotyle apolobambensis M. Mend. & A. Fuentes (Apiaceae), una nueva especie de hojas trifolioladas, restringida a la cordillera de Apolobamba, en la cuesta oriental del noroeste de Bolivia. La especie es similar a H. palmata Mathias con la que comparte su área distribución natural, pero difiere de ella por tener un menor número de flores, pedicelos pubescentes, lóbulos de las hojas redondeados a obtusos y el indumento piloso. Se adiciona una clave y una tabla comparativa para distinguirla de otras especies trifolioladas de Hydrocotyle L. de América del Sur.
Bauhinia tuichiensis(Fabaceae, Cercideae), una Especie Nueva del Bosque Seco de la Región Madidi, Bolivia
(Missouri Botanical Garden Press, 2012) Leslie Cayola Pérez; A C.
Bauhinia tuichiensis Cayola & A. Fuentes es una especie nueva de Fabaceae coleccionada en bosque seco durante las expediciones de campo del Proyecto Inventario Florístico de la Región Madidi en Bolivia. Además de B. cookii Rose, B. tuichiensis es la segunda de 15 especies dentro de la serie Decandrae Wunderlin, K. Larsen & S. S. Larsen (tribu Cercideae Bronn, sección Amaria (S. Mutis ex Caldas) Endl.) que presenta flores amarillas. Bauhinia tuichiensis se diferencia de B. cookii, la especie morfológicamente más emparentada, por tener inflorescencias densas (vs. laxas), con raquis corto de ca. 3 mm (vs. 10–15 mm); gineceo más grande 7–10 × 1.5 mm (vs. 4–5 × ca. 0.2 mm), ovario ovoide (vs. linear) y estigma capitado (vs. linear) más ancho 1.5–2 mm (vs. ca. 0.2 mm).Bauhinia tuichiensis Cayola & A. Fuentes is a new species of Fabaceae that was collected in dry forest during fieldwork for the Madidi Project in Bolivia. In addition to B. cookii Rose, B. tuichienis is the second species of 15 within the series Decandrae Wunderlin, K. Larsen & S. S. Larsen (tribu Cercideae Bronn, sección Amaria (S. Mutis ex Caldas) Endl.) that has yellow flowers. Bauhinia tuichiensis differs from B. cookii, a morphologically more closely related species, having dense inflorescences (vs. lax) with short rachis ca. 3 mm (vs. 10–15 mm), larger gynoecium 7–10 × 1.5 mm (vs. 4–5 × ca. 0.2 mm), ovoid ovary (vs. linear), and stigma capitate (vs. linear), wider at 1.5–2 mm (vs. ca. 0.2 mm).
Additions, Combinations, and Synonyms for the Bolivian Moss Flora
(2005) Steven P. Churchill; A C.
Fifty-five mosses are newly recorded for Bolivia. Additional collection data are given for twelve mosses considered little known or rare in the country. Six new synonyms are recognized, five from Bolivia, one from Brazil: Hookeria scabripes Müll. Hal. [Callicostella scabripes (Müll. Hal.) Broth.] = Callicostella pallida (Hornsch.) Ångstr.; Leucobryum fragile Herzog = Leucobryum subobtusifolium (Broth.) B.H. Allen; Macromitrium pinnulatum Herzog = Macromitrium microstomum (Hook. & Grev.) Schwägr.; Schlotheimia vesiculata Herzog [Macromitrium vesiculatum (Herzog) Herzog] = Macromitrium stellulatum (Hornsch.) Brid.; Cyclodictyon breve Herzog = Cyclodictyon albicans (Hedw.) Kuntze; and from Brazil: Callicostella paludicola Broth. = Callicostella merkelii (Hornsch.) A. Jaeger. Three new combinations are proposed: Entosthodon subaloma (Herzog) S.P. Churchill (Goniobryum subaloma Herzog), Syntrichia xerophila (Herzog) S.P. Churchill (Tortula xerophila Herzog), Thamniopsis lepidopiloides (Herzog) S.P. Churchill (Hookeriopsis lepidopiloides Herzog).
Additions to the Bolivian Bryophyte Flora
(2008) Steven P. Churchill; Ninel N. Sanjines A.; A C.; Reinaldo Lozano
Eleven hepatics and seven mosses are newly recorded for Bolivia. New generic records include Cronisia, Nowellia, Pleurozia (hepatics), and Meiothecium (mosses). Additional records for 21 bryophytes that were previously little known in Bolivia, including several from the isolated Chiquitano low mountain ranges, are given. Papillaria tenella Herzog and the name Papillaria diversifolia Herzog nom. nud. are identical to Toloxis imponderosa (Taylor) W.R. Buck
Matching Dendrochronological Dates with the Southern Hemisphere 14C Bomb Curve to Confirm Annual Tree Rings in Pseudolmedia rigida from Bolivia
(Cambridge University Press, 2015) Laia Andreu‐Hayles; Guaciara M. Santos; David Herrera‐Ramírez; Javier Martin-Fernández; Daniel Ruíz; Tatiana Erika Boza Espinoza; A C.; Peter M J⊘rgensen
This study used high-precision radiocarbon bomb-pulse dating of selected wood rings to provide an independent validation of the tree growth periodicity of Pseudolmedia rigida (Klotzsch & H. Karst) Cuatrec. from the Moraceae family, collected in the Madidi National Park in Bolivia. 14 C content was measured by accelerator mass spectrometry (AMS) in 10 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar dates were determined by dendrochronological techniques and were also used to select the samples for 14 C AMS. In order to validate these preliminary dates using the established Southern Hemisphere (SH) 14 C atmospheric concentration data set, the targeted rings were selected to be formed during periods before and after the 14 C bomb spike nuclear tests (i.e. 1950s–1960s). The excellent agreement of the dendrochronological dates and the 14 C signatures in tree rings associated with the same dates provided by the bomb-pulse 14 C atmospheric values for the SH (SHCal zone 1–2) confirms the annual periodicity of the observed growth layers, and thus the high potential of this species for tree-ring analysis. The lack of discrepancies between both data sets also suggests that there are no significant latitudinal differences between the 14 C SHCal zone 1–2 curve and the 14 C values obtained from the selected tree rings at this geographic location (14°33′S, 68°49′W) in South America. The annual resolution of P. rigida tree rings opens the possibility of broader applications of dendrochronological analysis for ecological and paleoclimatic studies in the Bolivian tropics, as well as the possibility of using wood samples from some tree species from this region to improve the quality of the bomb-pulse 14 C SHCal curve at this latitude.
Oligarchic patterns in tropical forests: role of the spatial extent, environmental heterogeneity and diversity
(Wiley, 2015) Gabriel Arellano; Peter M. Jørgensen; A C.; M. Isabel Loza; Vania Torrez; Manuel J. Macía
Abstract Aim Oligarchic patterns can vary from weak (i.e. little difference between rare and common species) to strong (i.e. a set of dominant species is immediately evident). Our aim was to understand the relationships between the strength of the oligarchic patterns, diversities (alpha, beta and gamma), and five potential causes (elevational variability, soil heterogeneity, elevation, soil conditions and geographical extent). Location The Amazon–Andes transition in the Madidi region (Bolivia). Methods We established 398 plots of 0.1 ha each, containing 121,183 individual woody plants belonging to 2390 species. Then we defined 500 sub‐regions (= unique overlapping subsets of 50 plots from the pool of 398 plots) so they varied in extent from 220 to 17,700 km 2 within the study area. We employed two independent path analyses to relate environmental characteristics and geographical extent of sub‐regions to (1) oligarchic strength and (2) alpha, beta and gamma diversities. We used generalized linear models to relate diversities to different measures of oligarchic strength. Results Oligarchies at larger extents were weaker, a trend strongly driven by the pure effect of area and, secondarily, by environmental heterogeneity. Oligarchies at higher elevations were weaker than expected, and oligarchies in acidic and nutrients‐poor soils were not stronger than those in less stressful soils. Trends in oligarchic strength were inversely correlated with those of gamma and beta diversity: weaker oligarchies were found in species‐rich and heterogeneous communities. Main conclusions Environmental heterogeneity and low landscape connectivity limit the strength of the oligarchic pattern. Although diversities (particularly beta diversity) and oligarchic strength are closely related, they are somewhat differently driven by external factors. In particular, oligarchic strength is more sensitive to spatial extent and less sensitive to environmental heterogeneity than beta diversity. Finally, the study of oligarchic patterns should consider a priori expectations based on species richness and turnover.
Phylogeny of Weinmannia (Cunoniaceae) reveals the contribution of the southern extratropics to tropical Andean biodiversity
(Elsevier BV, 2025) Ricardo A. Segovia; Eduardo Aguirre-Mazzi; Christine E. Edwards; Alexander G. Linan; A C.; Andrea Chaspuengal; Kyle G. Dexter; Francisco Fajardo‐Gutiérrez; William Farfán-Ríos; Nora H. Oleas
Prestonia leco, una Especie Nueva de Apocynaceae de los Bosques Montanos Húmedos de Bolivia
(Missouri Botanical Garden Press, 2010) A C.; J. Francisco Morales
Se describe e ilustra a Prestonia leco A. Fuentes & J. F. Morales (Apocynaceae), una especie nueva de los bosques montanos húmedos del noroeste de Bolivia. Esta especie parece estar cercanamente relacionada con P. denticulata (Vell.) Woodson, de la que difiere por sus inflorescencias conspicuamente ramificadas (vs. no ramificadas) y corola con el tubo floral más largo (18–22 mm vs. 11–13 mm).Prestonia leco A. Fuentes & J. F. Morales (Apocynaceae), a new species from the wet montane forest of northwestern Bolivia, is described and illustrated. It appears to be closely related to P. denticulata (Vell.) Woodson, but differs by its conspicuously branched inflorescences (vs. unbranched) and longer corolla tube (18–22 mm vs. 11–13 mm).
Radial growth decline in a tropical Andean treeline in Bolivia
(2025) Rose Oelkers; Laia Andreu‐Hayles; Rosanne D’Arrigo; Arturo Pacheco-Solana; Milagros Rodríguez‐Catón; M. Eugenia Ferrero; Ernesto Tejedor; A C.; Carla Maldonado; Daniel Ruíz
Abstract. Relative to research efforts in higher latitiudes, the impact of climate shifts in the tropical treeline remains understudied. Little is known about the tree growth dynamics and climate response at this treeline over the past few centuries, and at present under a rapidly changing environment. Here we provide information on recent changes in tree-ring patterns of Polylepis pepei BB.Simpson, a tropical tree species that grows in a monospecific forest at the elevational treeline in the Andes-Amazon ecotone of Bolivia and identify factors that limit its radial growth. We first developed a ring width (RW) chronology spanning 1867–2018 C.E. using dendrochronological methods and independently verified annual periodicity with radiocarbon dating. The RW chronology indicates a significant (p < 0.01) radial growth decline in P. pepei since 1997, a trend that mirrors a decrease reported in other Polylepis species from the drier central Andes of South America. P. pepei tree-ring width (RW) was mostly limited by mean, minimum, and maximum temperature and precipitation during austral summer (November–January). Over the instrumental period (1981–2019) prior-year temperatures negatively affected current-year tree growth (p < 0.05), while prior-year wet conditions were associated with higher growth (p < 0.05). Gridded temperature records (1901–2019) showed a significant increase in minimum temperatures and a decline in the diurnal temperature range since 1967, which may reduce orographic convection and water availability at higher elevations where our forest is located. In situ daily measurements from dataloggers in the forest recorded higher temperatures and lower relative humidity values when data was available. Our results suggest less moisture availability associated with warming conditions was related to the observed tree-growth decline. If temperature continues to rise at current rates, one of the highest-elevation tree species on the globe, P. pepei, could face severe consequences. This work provides insights into the past and historical trends of a tropical Andean treeline, which shows a recent decline also observed in other high-elevation forests (4657–4800 m.a.s.l.) of tropical South America (>17° S).
Relative effects of edaphic conditions and climate on palm communities in the Central Andes
(2021) Fabiola Montoya; Moraes R. Mónica; A C.; Leslie Cayola; Ana Antezana; Tatiana Lopes de Miranda; Esther Mosqueira-Meneses; M. Isabel Loza; J. Sebastián Tello
ABSTRACT Palms (family Arecaceae) are conspicuous and structural elements in forests ecosystems of tropical regions and mountain forests in South America. Additionally, many species of palms are culturally and economically important to human populations. Because of their ecological and ethnobotanical significance, understanding the drivers of palm distribution and diversity is critical. However, most past research has focused in tropical lowland palm communities, while our understanding of montane tropical palm ecology and biogeography is comparatively lacking. We investigate the environmental factors that influence patterns of richness, composition, and abundance of palms in the Central Andes. In particular, we are interested in the relative effects that soil edaphic conditions and climate have on palm community structure. For these analyses, we used a network of 88 forest plots distributed along a broad elevational gradient (1,000 – 3,200 meters), which are part of the Madidi Project in north-western Bolivia. We carried out palm community-level analysis, as well as species-specific analyses for each of the 16 most common species. We found that soils and climate contribute differentially to shaping Andean palm diversity and distributions. We found that soils explain more variation in species composition (14.4%) than climate (3.45%), but that climate explains more variation in species richness (13%) than soils (6.1%). Moreover, species-specific analyses reveal that there is great variation in how different common species respond to their abiotic environment. Our results contribute to understanding the drivers of biodiversity for a highly important group of plants in one of the most important hotspots for biodiversity. RESUMEN En el neotrópico, las palmeras (Arecaceae) son un grupo diverso y abundante de plantas que constituyen elementos estructurales en bosques tropicales tanto de tierras bajas como de montaña. Además, muchas especies de palmeras son culturalmente y economicamente importantes para muchas poblaciones humanas. Debido a su importancia ecológica y etnobotánica, entender los mecanismos que controlan la diversidad y la distribución de las palmeras es extremadamente importante. Sin embargo, la mayoría de la investigación hasta el momento se ha enfocado en comunidades de palmeras de tierras bajas, mientras que la ecología y biogeografía de las palmeras de montañas es relativamente poco entendida. En este estudio, nosotros investigamos los factores ambientales que influencian la riqueza, composición y abundancia de palmeras en los Andes Centrales. En particular, estamos interesados en entender los efectos relativos de las condiciones edáficas del suelo y el clima en la estructura de comunidades de palmeras. Para nuestros análisis, usamos una red de 88 parcelas de árboles distribuidas a lo largo de un gradiente elevacional (1,000 – 3,200 metros), la misma que es parte del Proyecto Madidi en Bolivia. Encontramos que el suelo y el clima tienen efectos diferentes. El suelo explica más variación en la composición de especies (14.4%) que el clima (3.45%), pero el clima explica más variación en la riqueza de especies (13%) que los suelos (6.1%). Además, análisis independientes para las 16 especies más comunes demuestran gran variación en como cada especie responde a las condiciones ambientales. Nuestros resultados contribuyen a entender los factores que controlan la diversidad de un grupo importante de plantas en una de las regiones más diversas del planeta.