Background : In central Amazonia, previous low intensity land use engenders succession dominated by Cecropia spp. which proceeds at high rates; however, at higher intensity of use succession is ...arrested and dominated by Vismia spp. over the long-term. Factors driving these two successional pathways are unknown. Aims : We aimed to elucidate seedling growth under the two alternative successional pathways. Methods : We experimentally determined the effects of successional age and photosynthetically active radiation (PAR) on relative height growth (RHG) of nine species of shade-tolerant tree seedlings in secondary forests dominated by Cecropia and Vismia , varying in age from 1–20 years. Results : In Cecropia -dominated successions, seedling RHG decreased with increasing successional age and with associated decreasing PAR. In Vismia -dominated successions, RHG was independent of successional age and PAR, and PAR did not change with successional age, being always higher than in Cecropia stands. The RHG of seedlings was lower in Vismia - than in Cecropia -dominated stands for similar PAR levels . Conclusions : Successional age and light availability affect seedlings growth differently in the two successional pathways. Unlike in Cecropia -dominated successions, in Vismia -dominated secondary forests seedling growth is limited by factors other than light. In a scenario of increasing land use intensity, constraints to seedling development in secondary forests can reduce species diversity in human-altered landscapes.
Little is known about factors that cause spatial variability in edge effects, the diverse physical and biotic changes associated with the abrupt boundaries of fragmented forests. We examined the ...influence of three types of surrounding vegetation (cattle pastures,
Cecropia-dominated regrowth, and
Vismia-dominated regrowth), on edge-related tree mortality in Amazonian rainforest fragments. An ANCOVA revealed that the type of surrounding vegetation and distance to edge both had significant effects on tree mortality. Differences among vegetation types were greatest within 0–20 m of fragment edges, with edges bordered by cattle pastures having higher mortality than those bordered by
Cecropia- and
Vismia-dominated regrowth. Edge effects appeared to penetrate further into pasture-bordered edges (ca. 60–100 m) than those bordered by regrowth forest (ca. 40–60 m), but this difference was nonsignificant because of considerable patchiness in tree mortality. Overall, our results suggest that edge effects in forest fragments are significantly influenced by the structure of surrounding vegetation, and that the capacity of different regrowth forests to buffer edge effects can be predicted from the growth form and stand features of the dominant tree species. Management of surrounding vegetation can ameliorate the negative effects of edge creation on small forest fragments.
The Amazon Basin is at the center of an intensifying discourse about deforestation, land-use, and global change. To date, climate research in the Basin has overwhelmingly focused on the cycling and ...storage of carbon (C) and its implications for global climate. Missing, however, is a more comprehensive consideration of other significant biophysical climate feedbacks i.e., CH
4
, N
2
O, black carbon, biogenic volatile organic compounds (BVOCs), aerosols, evapotranspiration, and albedo and their dynamic responses to both localized (fire, land-use change, infrastructure development, and storms) and global (warming, drying, and some related to El Niño or to warming in the tropical Atlantic) changes. Here, we synthesize the current understanding of (1) sources and fluxes of all major forcing agents, (2) the demonstrated or expected impact of global and local changes on each agent, and (3) the nature, extent, and drivers of anthropogenic change in the Basin. We highlight the large uncertainty in flux magnitude and responses, and their corresponding direct and indirect effects on the regional and global climate system. Despite uncertainty in their responses to change, we conclude that current warming from non-CO
2
agents (especially CH
4
and N
2
O) in the Amazon Basin largely offsets—and most likely exceeds—the climate service provided by atmospheric CO
2
uptake. We also find that the majority of anthropogenic impacts act to increase the radiative forcing potential of the Basin. Given the large contribution of less-recognized agents (e.g., Amazonian trees alone emit ~3.5% of all global CH
4
), a continuing focus on a single metric (i.e., C uptake and storage) is incompatible with genuine efforts to understand and manage the biogeochemistry of climate in a rapidly changing Amazon Basin.
Methicillin-Resistant Staphylococcus aureus (MRSA) represents one of the major causes of nosocomial infections, leading to high mortality. Surfaces in clinics, as well as the attending uniform and ...the hands of the dental doctor can be MRSA reservoirs. Having this in mind, the purpose of this study was to evaluate the presence of Methicillin-Sensitive Staphylococcus aureus (MSSA) and MRSA on dental medicine equipment surfaces. 354 Samples were collected from six equipment surfaces in six attendance areas before and after patient consultation and cultured in a selective medium. Polymerase Chain Reaction (PCR) was used to confirm the identity of bacterial strains as MRSA or MSSA. Data analysis was performed with chi-square tests with Bonferroni correction. It was observed 55.6% of uncontaminated samples. Contamination was: 17.5% MRSA (5.9% of samples collected before patient attendance and 11.6% after); 39.3% MSSA (14.1% collected before and 25.2% after). The prevalence of MRSA and MSSA was significantly higher after patient care. Integrated Clinic represented the most contaminated attendance area (MRSA − 41.7%, MSSA − 51.2%), the chair arm rest was the most contaminated surface for MRSA (29.7%) and the dental spittoon the most contaminated surface for MSSA (23.5%). Although a low level of contamination was observed, dental clinics, through patients possibly carrying bacteria, may be reservoirs for MRSA and MSSA transmission, and might contribute to potential nosocomial infections.
In fragmented tropical landscapes, among the most pervasive causes of ecological change are edge effects – diverse ecological alterations associated with the abrupt, artificial boundaries of forest ...fragments (Laurance & Bierregaard 1997, Lovejoy et al. 1986, Turner 1996). A striking edge effect in fragmented Amazonian forests is chronically elevated tree mortality (Ferreira & Laurance 1997, Laurance et al. 1998a). Large (> 60 cm diameter) trees are especially vulnerable to fragmentation, dying three times faster within 300 m of edges than in forest interiors (Laurance et al. 2000). Elevated tree mortality alters canopy-gap dynamics, promotes a proliferation of disturbance-adapted successional species (Laurance et al. 1998b), reduces above-ground biomass (Laurance et al. 1997), and accelerates litter production (Didham & Lawton 1999, Sizer et al. 2000) and carbon cycling (Nascimento & Laurance, in press).
Abstract
Metaplastic breast cancer (MBC) comprises less than 1% of all breast cancers, and it is defined by a mixture of adenocarcinoma plus mesenchymal and epithelial components. It is more common ...in older and black female patients. It has a larger size and faster growth, and it is frequently node-negative and triple-negative when compared with invasive ductal carcinoma. The authors report the case of a 72-year-old female patient, presenting with a breast lump, whose biopsy revealed a probable MBC with chondroid differentiation. She underwent a breast conservative surgery (BCS) and axillary sentinel lymph node dissection (SLND). The pathological report was concordant with the biopsy, and the patient was proposed to chemoradiotherapy. Despite its rarity and more severe features at diagnosis, BCS plus SLND plus radiotherapy should be offered to these patients, associated with chemotherapy. Chondroid differentiation is the rarest of all histological subtypes.
Background: The tradeoff between seed mass and seed number per plant is widely established for different taxa, guilds, and communities. Relative to primary forest species, pioneer species generally ...produce large numbers of small seeds. Aims: We tested if the relationship between seed mass and seed number was connected to the fruit variables – namely, fruit mass and fruit number per tree – in order to evaluate tradeoffs in seed packaging. Methods: Seed mass and seed number per tree as well as fruit mass and fruit number per tree were measured for 12 pioneer species common to secondary forests in the central Amazon. Results: Seed mass, seed number, fruit mass, and fruit number varied by several orders of magnitude among species. Seed number was explained only partially by seed mass alone (R ² = 0.55), but nearly completely by the combination of seed mass, fruit mass and fruit number (R ² = 0.94). The number of seeds per fruit was positively correlated with fruit mass and total seed number per tree and negatively with seed mass and fruit number. Seedling and adult abundances were most dependent on fruit number and fruit mass, not seed number and seed mass. Conclusions: Biomass tradeoffs between seed mass and seed number are partially dependent on seed packaging, specifically seeds per fruit, fruit mass and fruit number per tree for pioneer trees in the central Amazon.
Succession in the Brazilian Amazon depends on prior land-use history. Abandoned clearcuts become dominated by Cecropia trees and exhibit species replacements characteristic of natural succession in ...forest lightgaps. In contrast, abandoned pastures are dominated by Vismia trees that inhibit natural succession for a decade or more. Here we explore how advance regeneration and limited seed dispersal may contribute to the arrested succession in Vismia-dominated stands. Vegetation surveys showed that every Vismia stem in 3–8 year old Vismia stands originated as a re-sprout. In Cecropia stands, all tree species, including Vismia, originated mostly from seeds, after deforestation and abandonment. The 100% re-sprouts of Vismia in the abandoned pastures confirms that Vismia dominance results from re-sprouting following pasture fires. Seed rain in both Vismia and Cecropia dominated stands was limited almost exclusively to second growth species already reproducing in those stands, suggesting that the bats and birds foraging there were not bringing mature forest seeds into the second growth, but simply feeding and depositing local second growth species. As dispersal was similar in both stand types, dispersal differences cannot account for the ongoing dominance of Vismia relative to the ongoing successional transitions in Cecropia stands. Overall, advance regeneration in the form of Vismia re-sprouts is much more likely to be the driver of Vismia dominated succession than differential dispersal of mature forest seeds. In order to avoid extensive forest conversion into unproductive Vismia wastelands in the Amazon Basin, forestry permits for harvesting timber should include restrictions on subsequent anthropogenic degradation, such as conversion to pasture and prescribed burning.
The harvesting of non-timber forest products has been proposed as an alternative to timber harvesting that can increase rural income while having a reduced impact on forest structure. However, ...surprisingly little is known about the biological consequences of harvesting these products. We conducted a 3-year experiment in which we simulated the stem harvesting of the Amazonian plant
Ischnosiphon polyphyllus, which is used by traditional and indigenous populations in the Amazon for the construction of baskets, mats, and other handicrafts used in manioc cultivation. We found that plant mortality is limited in all except the most extreme harvesting treatments. However, we also found that plants recuperate extremely slowly from experimental harvesting. These results suggest that current harvesting strategies may not be conservative enough to ensure long-term population survival.
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