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61.
Species distribution models for Amazonian trees have mostly been produced at scales and resolutions that are too broad and coarse for practical use in either conservation or forestry. On the other hand, several studies have shown that elevation and the medium‐resolution remote sensing data available via Landsat imagery can be successfully used to detect differences in plant species composition in Amazonia. Therefore, it seems likely that the same data can also be used to predict geographical distributions of individual taxa. Here we use remotely sensed data and a maximum entropy algorithm (MaxEnt) to generate landscape‐scale distribution models at 30‐m‐resolution for five economically important timber tree genera (Apuleia, Amburana, Crepidospermum, Dipteryx, and Manilkara). Individual Landsat Thematic Mapper bands and normalized difference vegetation index yielded acceptable model performance, and the use of averaging filters (3 × 3 and 5 × 5 pixel low‐pass filters) improved model performance further. Including elevation as a predictor also improved model performance for all the genera. Our results suggest that it is possible to use Landsat bands and elevation as predictors for modeling the potential distribution of tree species in lowland Amazonia at a fine enough resolution to facilitate the practical management of forest resources. 相似文献
62.
63.
Nadja Lepsch-Cunha Paulo Y. Kageyama Roland Vencovsky 《Biodiversity and Conservation》1999,8(9):1205-1218
We quantified the within-population genetic variation of Couratari multiflora and C. guianensis, two tree species found in terra firme forests of central Amazonia. Both species have some ecological features in common, but they differ in population abundance across their geographic ranges. While C. multiflora has been found only in low-density populations in all sites studied to date, C. guianensis is relatively common in some sites and very scarce in others. In a 400-ha plot, we found 41 and 29 adults of C. multiflora and C. guianensis, respectively. Twenty-two saplings of C. guianensis and 103 seedlings of C. multiflora were also examined. The mean expected heterozygosities (Hem) of seedlings and adults of C. multiflora were 0.431 and 0.436, and the mean fixation indices (Fm), 0.114 and 0.176, respectively. For C. guianensis, saplings and adults presented Hem equal to 0.425 and 0.429, and the Fm were 0.393 and 0.527, respectively. These low-density populations of two congeneric species did not differ in terms of genetic diversity, but rather they differed in terms of mean observed heterozygosity (Hom), and therefore Fm. The species with variable population density had lower Hom and greater Fm relative to the species that is always found in low-density. 相似文献
64.
The alpha-diversity of trees found in the region of Manaus, Brazil is among the highest recorded for one-hectare plots in Amazonia or any tropical forest. Based on a survey of the distributions of 2541 Neotropical tree species, we analyzed the geographic distribution of 364 species of terra firme forest trees that occur in the region and that are not edaphic specialists. Fifteen distinct distribution patterns were recognized for trees occurring in Manaus. The great majority of species (84.9%) have continuous, somewhat restricted distributions, 35 (9.6%) show broad distributions and 20 species (5.5%) show disjunction between Amazonia and Eastern Brazil. A remarkable 150 (41.2%) of these species showed the region of Manaus as one of their distribution limits. Using the same pool of 2541 species distributions, the percentage of species with a distribution limit in Manaus was compared with that for other localities known to be centers of botanical collection. The null hypothesis that the difference in proportion of species with distribution limits among these localities and Manaus is insignificant was rejected. We conclude that the results are not an artifact of collecting density, that Manaus is indeed a crossroads of distinct phytogeographic regions, and that this explains part of the high species diversity of trees in the region of Manaus. A number of scenarios proposed for the Pleistocene in Amazonia postulate some degree of fragmentation of Amazonian forests or at least populations. As much as these theories may conflict with each other in some respects, they are compatible with the concept of Manaus as a region of re-convergence of isolated or disrupted floras and faunas. The significance of the vicinity of Manaus in the history of the Amazon flora and its current status as a repository for surprisingly high tree diversity highlights the need to make this region a conservation priority. 相似文献
65.
Felipe Vander Velden 《Anthrozo?s》2017,30(4):533-548
Narratives addressing the presence of European domestic dogs (Canis familiaris) in the encounters between Indians and non-Indians in the conquest of the Central and South American lowlands often portray those animals as terrible and bloodthirsty weapons. From the settlers’ perspective, dogs were formidable instruments in the subjugation of the native peoples they came across at various times over more than 500 years of American colonialization. But the indigenous narratives of these first contacts with dogs may exhibit distinct perspectives that view dogs not only as weapons, instruments, or tools of conquest but rather as agents or actors smoothing contact and establishing peaceful relations between Indians and non-Indians. This article explores the narratives of the first dogs encountered by two native populations in southwestern Brazilian Amazonia—the Puruborá and the Karitiana in the state of Rondônia—to demonstrate the canine agency behind the interethnic meetings in this region, where dogs were largely absent until the arrival of the Europeans and their descendants beginning in the sixteenth century. First contacts between Indians and non-Indians are complex inter-specific events, and may extend beyond only two participants (a group of non-Indians and a native people) to include at least three parties, since the actions and dispositions of dogs play a crucial role in the development of human interactions. Recollections of the first dogs encountered by the Puruborá and Karitiana point precisely toward recognizing the importance of the animal's presence as an actor, far beyond a mere instrument. 相似文献
66.
Using digital soil maps to infer edaphic affinities of plant species in Amazonia: Problems and prospects
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Gabriel Massaine Moulatlet Gabriela Zuquim Fernando Oliveira Gouvêa Figueiredo Samuli Lehtonen Thaise Emilio Kalle Ruokolainen Hanna Tuomisto 《Ecology and evolution》2017,7(20):8463-8477
Amazonia combines semi‐continental size with difficult access, so both current ranges of species and their ability to cope with environmental change have to be inferred from sparse field data. Although efficient techniques for modeling species distributions on the basis of a small number of species occurrences exist, their success depends on the availability of relevant environmental data layers. Soil data are important in this context, because soil properties have been found to determine plant occurrence patterns in Amazonian lowlands at all spatial scales. Here we evaluate the potential for this purpose of three digital soil maps that are freely available online: SOTERLAC, HWSD, and SoilGrids. We first tested how well they reflect local soil cation concentration as documented with 1,500 widely distributed soil samples. We found that measured soil cation concentration differed by up to two orders of magnitude between sites mapped into the same soil class. The best map‐based predictor of local soil cation concentration was obtained with a regression model combining soil classes from HWSD with cation exchange capacity (CEC) from SoilGrids. Next, we evaluated to what degree the known edaphic affinities of thirteen plant species (as documented with field data from 1,200 of the soil sample sites) can be inferred from the soil maps. The species segregated clearly along the soil cation concentration gradient in the field, but only partially along the model‐estimated cation concentration gradient, and hardly at all along the mapped CEC gradient. The main problems reducing the predictive ability of the soil maps were insufficient spatial resolution and/or georeferencing errors combined with thematic inaccuracy and absence of the most relevant edaphic variables. Addressing these problems would provide better models of the edaphic environment for ecological studies in Amazonia. 相似文献
67.
Homegardens may serve as reservoirs of agro-biodiversity on highly fertile, anthropogenic Amazonian Dark Earth (ADE) soils
of the Amazon basin. However, as these soils are used more intensively for market-oriented agriculture, we suspected a decrease
in their agro-biodiversity. We present data obtained from surveys on 16 farms where ADE was present in the region of Manaus,
Amazonas, Brazil. When farms were separated into two groups by market orientation, species richness on the farms was not significantly
influenced by market orientation, but there was less dominance (i.e., more diversity) for homegardens in the low-market orientation
group (P < 0.1). The proportion of native species was not affected by market orientation. Hence, while the most market-oriented
farms retained high species richness, homegardens located on them contained higher proportions of commercially interesting
species. 相似文献
68.
Orangel A. Aguilera Jean Bocquentin Rio Branco John G. Lundberg Andrea Maciente 《Pal?ontologische Zeitschrift》2008,82(2):231-245
A new fossil species of the living catfish genusPhractocephalus is described from fluvial Sediments of late Miocene age in Acre State, Brazil and the Madre de Dios region, Peru. †Phractocephalus acreornatus n. sp., is known from a complete neurocranium with associated Weberian complex vertebrae and posttemporal-supracleithra,
and several isolated skeletal elements. °Phractocephalus acreornatus is diagnosed by the following combination of characters: 1) anterior half of supraoccipital, frontals and sometimes mesethmoid
with coarse parallel ridges and sulci in addition to reticulating ridges and subcircular pits; 2) mesethmoid very broad and
coarsely ornamented; 3) lateral ethmoid projecting anteriorly above palatine condyle into olfactory capsule, its anterolateral
margin convex and fluted, and its orbital notch reduced; 4) supraoccipital process long, concealing Weberian vertebrae in
dorsal view; 5) opercle covered with rough, reticulating ridges and pits; 6) interopercle relatively deep, its outer side
coarsely ornamented; 7) pectoral spine shaft ornamented with reticulating ridges and pits. Variability of the form of the
much expanded supraoccipital process inPhractocephalus is evaluated for its taxonomic significance. Although °P.acreornatus is distinct from both modernP. hemloliopterus and fossil °P. nassi, like most Miocene fossil fishes from South America, this extinct species is closely similar to its relatives. Available
characters provide evidence for a close relationship between °P. acreornatus and °P. nassi from the Urumaco Formation, Venezuela. The provenance of these late Miocene catfishes in lowland western Amazonia and north-central
South America is congruent with paleogeographic modeis positing a large, north flowing “Paleo-Amazon-Orinoco” river System
in the Andean foreland basin during the Neogene.
相似文献
69.
The floodplains of Central Amazonia represent a complex system of inundated river valleys and shallow lakes along the Solimões–Amazonas river, which is subjected to an annual flood-pulse lasting up to 10 months. Such flooding reaching an amplitude of about ten meters causes dramatic changes in the bioavailability of nutrients and oxygen levels and poses extreme constraints for plant survival and reproductivity. Tree species of inundation forests in Central Amazonia had to evolve adaptive mechanisms to both desiccation of soils and partial or full submergence. To adapt to flooded conditions, some trees overcome the flood period by dormancy accompanied by defoliation and formation of annual rings in the wood. Other species maintain metabolism and retain the foliage during the flooding, representing another adaptive mechanism to low oxygen availability. This investigation focused on the root physiology and morphology of six species typical of white-water inundation areas (várzea) led to a preliminary classification of adaptive strategies of trees inhabiting forest communities in floodplains of the Amazon basin. 相似文献
70.
Aim We analysed presence/absence data for understorey bird species in rain forest fragments sampled from 1979 through 2001. Here we consider extinctions between 1992, when most fragments had been isolated for at least 8 years, and 2001. Our objectives were to determine whether high extinction rates documented soon after isolation continued through up to 20 years after isolation, and to examine fragment size and landscape effects on extinction. Location Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. Methods Through 1992, birds were surveyed with standardized mist net sampling in ten 1‐ to 100‐ha fragments. We repeated the mist net protocol in 2000–01. We also added remote taping of the dawn chorus and tape playback surveys for species captured in 1991–92 but not in 2000–01. Results Between 1992 and 2001, 37 species went extinct in at least one fragment. As expected, extinction rate decreased with increasing fragment size. Over 30% of species went extinct in 1‐ha fragments, compared to about 5% in 100‐ha fragments. Extinction followed a predictable pattern: most species lost from 100‐ha fragments between 1992 and 2001 had already gone extinct in smaller fragments before 1992. Despite extinctions, fragments gained species between 1992 and 2001, apparently due to species moving through the developing second growth matrix. Fragments surrounded by old second growth had lower extinction rates than predicted based on fragment size alone. Main conclusions Sequential extinctions occurred for at least 20 years. Some additional species previously lost from smaller fragments may continue to go extinct in 100‐ha fragments. At the same time, species assemblages in 1‐ and 10‐ha fragments mostly reflect second‐growth dynamics by 20 years after isolation. High species loss predicted from the first few years after isolation has not occurred, almost certainly because of recolonization. 相似文献