RESUMEN
Dominance of neotropical tree communities by a few species is widely documented, but dominant trees show a variety of distributional patterns still poorly understood. Here, we used 503 forest inventory plots (93,719 individuals ≥2.5 cm diameter, 2609 species) to explore the relationships between local abundance, regional frequency and spatial aggregation of dominant species in four main habitat types in western Amazonia. Although the abundance-occupancy relationship is positive for the full dataset, we found that among dominant Amazonian tree species, there is a strong negative relationship between local abundance and regional frequency and/or spatial aggregation across habitat types. Our findings suggest an ecological trade-off whereby dominant species can be locally abundant (local dominants) or regionally widespread (widespread dominants), but rarely both (oligarchs). Given the importance of dominant species as drivers of diversity and ecosystem functioning, unravelling different dominance patterns is a research priority to direct conservation efforts in Amazonian forests.
Asunto(s)
Ecosistema , Bosques , Humanos , Árboles , Brasil , BiodiversidadRESUMEN
Abstract An insect gall inventory was carried out in two reserves of the Peruvian Amazon, Allpahuayo-Mishana National Reserve and Quistococha Regional Reserve, both situated in Iquitos, northeastern Peru. Four vegetation types were surveyed between December, 2021 and December, 2022: terra firme forest, white-sand wet forest, and white-sand dry forest in Allpahuayo-Mishana National Reserve, and palm swamp forest in Quistococha Regional Reserve. Overall, we found 262 gall morphotypes, distributed across 75 host species representing 66 plant genera and 30 families. Fabaceae was the plant family with the greatest number of gall morphotypes (n = 48), followed by Calophyllaceae (n = 21) and Euphorbiaceae (n = 20). The plant genera that supported the highest diversity of galls were Caraipa (n = 17), Eschweilera (n = 16), Tapirira (n = 16), Micrandra (n = 14), and Iryanthera (n = 10). The plant species Tapirira guianensis (n = 16), Caraipa utilis (n = 14), Micrandra elata (n = 14), Eschweilera coriacea (n = 11), and Sloanea parvifructa (n = 10) exhibited the highest richness of galls. Among the host plants, C. utilis stands alone as the only species noted as both endemic to the Amazonian region and bearing a Vulnerable (VU) conservation status. The leaves were the most attacked organs (90% of all galls). Most morphotypes are glabrous (89%), green (67%), globoid (53%), and one-chambered (91%). We found galling insects belonging to the orders Diptera, Thysanoptera, Lepidoptera, and Hemiptera. The galling insects of Cecidomyiidae (Diptera) were the most common, inducing 22% of the gall morphotypes. In addition to the gallers, we also observed the presence of successors, cecidophages, and parasitoids. Among the sampled vegetation types, the terra firme forest presented the highest richness of gall morphotypes and host plant species. This is the first systematic inventory of insect galls in this part of the Peruvian Amazon.
Resumo Um inventário de galhas de insetos foi realizado em duas reservas da Amazônia peruana, Reserva Nacional Allpahuayo-Mishana e Reserva Regional Quistococha, ambas situadas em Iquitos, nordeste do Peru. Quatro tipos de vegetação foram pesquisados entre dezembro de 2021 e dezembro de 2022: floresta de terra firme, floresta úmida de areia branca e floresta seca de areia branca na Reserva Nacional Allpahuayo-Mishana, e floresta de pântano de palmeiras na Reserva Regional Quistococha. No total, encontramos 262 morfotipos de galhas, distribuídos em 75 espécies hospedeiras representando 66 gêneros de plantas e 30 famílias. Fabaceae foi a família de plantas com o maior número de morfotipos de galhas (n = 48), seguida por Calophyllaceae (n = 21) e Euphorbiaceae (n = 20). Os gêneros de plantas que apresentaram a maior diversidade de galhas foram Caraipa (n = 17), Eschweilera (n = 16), Tapirira (n = 16), Micrandra (n = 14) e Iryanthera (n = 10). As espécies de plantas Tapirira guianensis (n = 16), Caraipa utilis (n = 14), Micrandra elata (n = 14), Eschweilera coriacea (n = 11) e Sloanea parvifructa (n = 10) apresentaram a maior riqueza de galhas. Dentre as plantas hospedeiras, C. utilis destaca-se como a única espécie listada como endêmica da região amazônica e com um status de conservação Vulnerável (VU). As folhas foram os órgãos mais atacados (90% de todas as galhas). A maioria dos morfotipos é glabra (89%), verde (67%), globoide (53%) e possui apenas uma câmara interna (91%). Encontramos insetos galhadores pertencentes às ordens Diptera, Thysanoptera, Lepidoptera e Hemiptera. Os insetos galhadores da família Cecidomyiidae (Diptera) foram os mais comuns, induzindo 22% dos morfotipos de galhas. Além dos galhadores, também observamos a presença de sucessores, cecidófagos e parasitoides. Entre os tipos de vegetação amostrados, a floresta de terra firme apresentou a maior riqueza de morfotipos de galhas e espécies de plantas hospedeiras. Este é o primeiro inventário sistemático de galhas de insetos nesta região da Amazônia peruana.
RESUMEN
Durante el período 2000 - 2016, se llevaron a cabo 15 inventarios biológicos en áreas remotas en el pie de monte andino y el llano amazónico del Perú. En estos inventarios, 27 botánicos colectaron un total de 9397 especímenes de plantas vasculares fértiles. Hasta finales del 2017, más de la mitad de estos especímenes se han identificado a nivel de especie, de los cuales 64 especies y 2 géneros (Dicorynia y Monopteryx) representan nuevos registros para la flora del Perú. Si esta tasa de novedades se mantiene, el número de registros nuevos en el material de los inventarios podría aumentar, lo cual nos indica que aún queda mucho por descubrir en la flora andino-amazónica del Perú.
Between 2000 and 2016 we carried out 15 rapid biological inventories in remote areas of the Andean foothills and Amazon basin in Peru. During these inventories, 27 botanists collected 9397 fertile vascular plant specimens. By the end of 2017, more than half of these specimens had been identified to species. Of the 2303 species identified to date, 64 species and 2 genera (Dicorynia and Monopteryx) are new records for the flora of Peru. If this rate of discovery proves typical, the number of new records for Peru in the rapid inventory material could increase, which indicates that there is still much to discover in the Peruvian flora.
RESUMEN
The forests of western Amazonia are among the most diverse tree communities on Earth, yet this exceptional diversity is distributed highly unevenly within and among communities. In particular, a small number of dominant species account for the majority of individuals, whereas the large majority of species are locally and regionally extremely scarce. By definition, dominant species contribute little to local species richness (alpha diversity), yet the importance of dominant species in structuring patterns of spatial floristic turnover (beta diversity) has not been investigated. Here, using a network of 207 forest inventory plots, we explore the role of dominant species in determining regional patterns of beta diversity (community-level floristic turnover and distance-decay relationships) across a range of habitat types in northern lowland Peru. Of the 2,031 recorded species in our data set, only 99 of them accounted for 50% of individuals. Using these 99 species, it was possible to reconstruct the overall features of regional beta diversity patterns, including the location and dispersion of habitat types in multivariate space, and distance-decay relationships. In fact, our analysis demonstrated that regional patterns of beta diversity were better maintained by the 99 dominant species than by the 1,932 others, whether quantified using species-abundance data or species presence-absence data. Our results reveal that dominant species are normally common only in a single forest type. Therefore, dominant species play a key role in structuring western Amazonian tree communities, which in turn has important implications, both practically for designing effective protected areas, and more generally for understanding the determinants of beta diversity patterns.
Asunto(s)
Biodiversidad , Árboles , Ecosistema , Bosques , Perú , Clima TropicalRESUMEN
Wind-borne pollinating wasps (Agaonidae) can transport fig (Ficus sp., Moraceae) pollen over enormous distances (> 100 km). Because of their extensive breeding areas, Neotropical figs are expected to exhibit weak patterns of genetic structure at local and regional scales. We evaluated genetic structure at the regional to continental scale (Panama, Costa Rica, and Peru) for the free-standing fig species Ficus insipida. Genetic differentiation was detected only at distances > 300 km (Jost´s Dest = 0.68 ± 0.07 & FST = 0.30 ± 0.03 between Mesoamerican and Amazonian sites) and evidence for phylogeographic structure (RST>>permuted RST) was only significant in comparisons between Central and South America. Further, we assessed local scale spatial genetic structure (SGS, d ≤ 8 km) in Panama and developed an agent-based model parameterized with data from F. insipida to estimate minimum pollination distances, which determine the contribution of pollen dispersal on SGS. The local scale data for F. insipida was compared to SGS data collected for an additional free-standing fig, F. yoponensis (subgenus Pharmacosycea), and two species of strangler figs, F. citrifolia and F. obtusifolia (subgenus Urostigma) sampled in Panama. All four species displayed significant SGS (mean Sp = 0.014 ± 0.012). Model simulations indicated that most pollination events likely occur at distances > > 1 km, largely ruling out spatially limited pollen dispersal as the determinant of SGS in F. insipida and, by extension, the other fig species. Our results are consistent with the view that Ficus develops fine-scale SGS primarily as a result of localized seed dispersal and/or clumped seedling establishment despite extensive long-distance pollen dispersal. We discuss several ecological and life history factors that could have species- or subgenus-specific impacts on the genetic structure of Neotropical figs.
Asunto(s)
Ficus/genética , Estructuras Genéticas/genética , Moraceae/genética , Polen/genética , Animales , Costa Rica , Bosques , Panamá , Perú , Filogenia , Filogeografía/métodos , Polinización/genética , Plantones/genética , Semillas/genética , AvispasRESUMEN
The vast extent of the Amazon Basin has historically restricted the study of its tree communities to the local and regional scales. Here, we provide empirical data on the commonness, rarity, and richness of lowland tree species across the entire Amazon Basin and Guiana Shield (Amazonia), collected in 1170 tree plots in all major forest types. Extrapolations suggest that Amazonia harbors roughly 16,000 tree species, of which just 227 (1.4%) account for half of all trees. Most of these are habitat specialists and only dominant in one or two regions of the basin. We discuss some implications of the finding that a small group of species--less diverse than the North American tree flora--accounts for half of the world's most diverse tree community.
Asunto(s)
Biodiversidad , Ríos , Árboles/clasificación , Árboles/fisiología , Modelos Biológicos , Población , América del SurRESUMEN
Entre marzo y abril de 2006, la flora de los bosques estacionalmente secos en Tarapoto, San Martín fue estudiada en diez localidades. En cada una de estas localidades se estableció una parcela de 0,1 ha; cada tallo mayor de 2,5 cm de diámetro fue medido, contado e identificado a especie. Se encontraron 146 especies en 2814 individuos. En toda la zona de estudio, Myrtaceae fue la familia más diversa con 14 especies, seguida por Leguminosae con 12 especies. Igualmente, Annonaceae y Myrtaceae fueron las familias más abundantes en numero de tallos en toda la zona de estudio (461, y 412 tallos totales), mientras que Sapotaceae, con sólo 160 tallos totales, tuvo el valor más alto en área basal, debido a la Quinilla, Manilkara bidentata (A. DC.) A. Chev., el árbol más importante en la estructura de los bosques estacionalmente secos de Tarapoto. Dos especies estuvieron presentes en todos los sitios de estudio: Coccoloba sp. 1, (Polygonaceae) y Oxandra espintana (Spruce ex Benth.) Baill. (Annonaceae), mientras que 53 especies ocurrieron en un solo sitio. Los bosques estacionalmente secos de Tarapoto presentan una diversidad intermedia comparada con otros bosques secos del Neotrópico y similar diversidad a los bosques secos del Pacífico Peruano. La comunidad de árboles en estos bosques pertenece a especies de amplia distribución comparada con las especies de arbustos que tienen distribución restringida a los hábitats de bosques secos. En términos generales las áreas localizadas cerca de la carretera Tarapoto-Juanjui tienen el grado más alto de amenaza y perturbación debido a la extracción maderera y destrucción de hábitat para la creación de campos de cultivos agrícolas. Los bosques más representativos y mejor conservados de esta región se encuentran al Oeste y Sur de Picota, en el Área de Conservación Municipal El Quinillal, y en la cuenca del Río Bombonajillo y Ponasillo.
Between March and April 2006, I studied ten localities with seasonally dry forests located along the Tarapoto-Juanjui road, San Martin. At each site ten 50×2 m transects totalling 1000 m² (0,1 ha) were laid out along a 180 m baseline where all standing trees with diameter at breast height (DBH) greater than 2,5 cm were measured, counted and identified to species. I found a total of 146 species and 2814 individuals with DBH e¼ 2,5 cm. Within the study area, Myrtaceae was the most species rich family with 14 species followed closely by Leguminosae with 12 species. Annonaceae and Myrtaceae had the highest number of individuals (461 and 412, respectively), whereas Sapotaceae, with only 160 stems, had the highest basal area. The latter was mainly due to Manilkara bidentata (A. DC.) A. Chev. ("Quinilla"), the most important tree species in the seasonally dry forests of Tarapoto. Two species were present at all sites: Coccoloba sp. 1 (Polygonaceae) and Oxandra espintana (Spruce ex Benth.) (Annonaceae), whereas 53 species occurred only at one site. The seasonally dry forests of Tarapoto have an intermediate diversity compared to the other dry forests in the Neotropics and similar diversity compared to the Peruvian dry forests of the Pacific coast. Most of the tree community in these forests belong to geographically widespread species compared to shrubs that are mostly restricted to dry forests habitats. The areas located near the Tarapoto-Juanjui road ("carretera marginal") have the most disturbed forests. The best representations of Tarapoto's seasonally dry forests are located west and south of the locality of Picota, in the Area de Conservación Municipal "El Quinillal", and in the Bombonajillo and Ponasillo basins.