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Screening of chilli pepper genotypes against anthracnose (Colletotrichum brevisporum)
Get PDFAnthracnose is the most important disease of chili pepper pimenta-de-cheiro (Capsicum chinense Jacq.). This species is widely cultivated in dryland areas in the Amazon, presenting high genetic diversity. Therefore, it presents a high potential for use in breeding. The objective of this study was to select pepper genotypes with potential resistance to anthracnose (Colletotrichum brevisporum). For this purpose, ripe fruits of pepper were acquired from the producing farms in the municipalities of Iranduba, Manacapuru, Rio Preto da Eva and Presidente Figueiredo. The experiments were conducted in seedlings (Phase I) and in mature and immature fruits (Phase II). The evaluation of the disease severity was performed using a scale of scores. The morphoagronomic characterization of the genotypes considered the fruits in the immature and mature stages and plant growth habit. The injured areas in the immature fruits ranged from 0.3 to 9.7 cm2 and in the mature areas, it ranged from 0.2 to 9.9 cm2. The genotypes RPE41 and MPU29 indicated resistance to anthracnose in both stages. The morphoagronomic characterization of the fruits revealed variability for mass (5.58 to 13.74 g), length [C] (4.08 to 8.16 cm), diameter [D] (1.74 to 2.54 cm), L/D ratio (1.88 to 4.70) and color of the fruit. © 2019 United Arab Emirates University
Wet and dry tropical forests show opposite successional pathways in wood density but converge over time
No full textTropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking. Here, we analyse forest recovery using 1,403 plots that differ in age since agricultural abandonment from 50 sites across the Neotropics. We analyse changes in community composition using species-specific stem wood density (WD), which is a key trait for plant growth, survival and forest carbon storage. In wet forest, succession proceeds from low towards high community WD (acquisitive towards conservative trait values), in line with standard successional theory. However, in dry forest, succession proceeds from high towards low community WD (conservative towards acquisitive trait values), probably because high WD reflects drought tolerance in harsh early successional environments. Dry season intensity drives WD recovery by influencing the start and trajectory of succession, resulting in convergence of the community WD over time as vegetation cover builds up. These ecological insights can be used to improve species selection for reforestation. Reforestation species selected to establish a first protective canopy layer should, among other criteria, ideally have a similar WD to the early successional communities that dominate under the prevailing macroclimatic conditions. © 2019, The Author(s), under exclusive licence to Springer Nature Limited
Extremely loud mating songs at close range in white bellbirds
No full textHolzner et al. show that macaques provide a net benefit to oil palm harvest by reducing losses due to rodent pests on oil palm plantations. © 2019 Elsevier LtdSexual selection in many animal species favors the evolution of elaborate courtship traits. Such traits might help signalers convey, and receivers discern, information about signaler quality; or they might be favored by perceptual or aesthetic preferences for elaborateness or beauty [1–3]. Under either scenario we expect sexual trait elaboration to be countered by proximate constraints rooted in animals’ morphology, physiology and phylogenetic history [3,4]. During expeditions to a montane rainforest in the Brazilian Amazon, we obtained amplitude-calibrated measures of mating songs in two species of cotingas, the white bellbird (Procnias albus) and the screaming piha (Lipaugus vociferans). The screaming piha sings the loudest songs of any passerine bird previously documented [5]. However, we find that white bellbirds are >9 dB louder, and thus achieve roughly triple the sound pressure levels of pihas. Mechanical constraints on amplitude, and thus limits on the reach of sexual selection, are revealed by trade-offs between maximal sound pressure and song duration. We find that song amplitude in bellbirds is context-dependent: when a female was on the display perch, a male bellbird sang only his louder song type, swiveling his body mid-song to face the female head on. We know of no other species in which such high-amplitude vocal signals are directed to receivers in such close proximity. We propose that bellbird females balance an interest in sampling males at close range with a need to protect themselves from hearing damage. © 2019 Elsevier Lt
Blowdown disturbance effect on the density, richness and species composition of the seed bank in Central Amazonia
No full textWindstorms, known as blowdowns, create large canopy gaps in the tropical rainforest. Despite the occurrence of blowdowns in Central Amazonia, no studies have yet investigated the seed bank in areas altered by blowdown in the Amazon rainforest. The seed bank plays an important role in the regeneration of larger natural gaps, and changes in, or partial loss of, seed bank can modify the successional dynamics locally. In the present study, we compared the density, richness and floristic composition of a seed bank in a post-blowdown secondary forest with approximately six years old and a continuous forest. The seed bank was characterized by collecting 160 soil samples systematically distributed in each forest type at two different times. Samples were collected at a minimum distance of 30 m from each other, sampling the superficial soil 5 cm in depth and 20 cm in diameter. At each sampling point, the slope and canopy openness was also measured. The density and floristic composition of the seed bank was estimated using counts of seedlings that had emerged in a nursery of the collected soil samples. The post-blowdown secondary forest exhibited seed banks 30% denser and 20% richer, on average, than continuous forest. The floristic composition also differed between forest types, with a predominance of Melastomataceae, Urticaceae, and Araceae in the secondary forest, followed by Cyperaceae and Moraceae; however, these did not differ between forest types. In contrast, for other families, greater richness and density were observed in the continuous forest. Higher density and richness of trees, shrubs, epiphytes, and hemiepiphytes were observed in the secondary forest, except for the richness of epiphytes. In general, terrain slope was unrelated to density, richness and floristic composition of the seed bank. Under a disturbance of great magnitude, such as a blowdown, the density and richness of the seed bank were not reduced; on the contrary, its potential for local regeneration was maintained. Despite the limited contribution of the seed bank to the regeneration of climax species, the seed bank was shown to be diverse in species, including different life forms, and may contribute to the regeneration of forest strata, even after severe disturbances. © 2019 Elsevier B.V
Amazonian fisheries
No full textThis chapter argues that riparian Amerindian groups in the central part of the Amazon Basin ever suffered for lack of animal protein, and it is highly unlikely that native groups were capable of overexploiting the fisheries in and along the larger rivers. The illustrious Brazilian historian and naturalist, Jose Verissimo, noted almost a century ago that fish was the principal animal protein source in the European and caboclo conquest of the Amazon region. The pt_BR apparently took control of the fisheries because they were the first to make significant commercial use of seines in the Amazon region. Belem is situated at the south-eastern corner of the Amazon estuary, and thus is in close proximity to freshwater, brackish water, and saltwater fishing habitats. Amazon food fishes are netted, seined, gigged, gaffed, hooked, bombed, and poisoned, and each of the methods can touch the individual psyches of authorities in different ways. © 1983 Taylor & Francis
Fire, fragmentation, and windstorms: A recipe for tropical forest degradation
No full textWidespread degradation of tropical forests is caused by a variety of disturbances that interact in ways that are not well understood. To explore potential synergies between edge effects, fire and windstorm damage as causes of Amazonian forest degradation, we quantified vegetation responses to a 30-min, high-intensity windstorm that in 2012, swept through a large-scale fire experiment that borders an agricultural field. Our pre- and postwindstorm measurements include tree mortality rates and modes of death, above-ground biomass, and airborne LiDAR-based estimates of tree heights and canopy disturbance (i.e., number and size of gaps). The experimental area in the southeastern Amazonia includes three 50-ha plots established in 2004 that were unburned (Control), burned annually (B1yr), or burned at 3-year intervals (B3yr). The windstorm caused greater damage to trees (>10 cm DBH) in the burned plots (B1yr: 13 ± 9% of 785 trees; B3yr: 17 ± 13% of 433) than in the Control plot (8 ± 4% of 2,300; ± CI). It substantially reduced vegetation height by 14% in B1yr, 20% in B3yr and 12% in the Control plots, while it reduced above-ground biomass by 18% of 77.7 Mg/ha (B1yr), 31% of 56.6 (B3yr), and 15% of 120 (Control). Tree damage was greatest near the agricultural field edge in all three plots, especially among large trees and in B3yr. Trunk snapping (70%) and uprooting (20%) were the most common modes of tree damage and mortality, with the height of trunk failure on the burned plots often corresponding with the height of historical fire scars. Of the windstorm-damaged trees, 80% (B1yr), 90% (B3yr), and 57% (Control) were dead 4 years later. Trees that had crown damage experienced the least mortality (22%–60%), followed by those that were snapped (55%–94%) and uprooted (88%–94%). Synthesis. We demonstrate the synergistic effects of three kinds of disturbances on a tropical forest. Our results show that the effects of windstorms are exacerbated by prior degradation by fire and fragmentation. We highlight that understorey fires can produce long-lasting effects on tropical forests not only by directly killing trees but also by increasing tree vulnerability to wind damage due to fire scars and a more open canopy. © 2018 The Authors. Journal of Ecology © 2018 British Ecological Societ
Decline of large-diameter trees in a bamboo-dominated forest following anthropogenic disturbances in southwestern Amazonia
No full textKey message: Reduction in the aboveground biomass of larger trees is the main consequence of disturbances in open forests dominated by bamboo. Because these trees are of central importance both for ecosystem function and for the economic value of the forest for management, the impact on these trees due to the increase of bamboo abundance following anthropogenic disturbances is both an environmental and a commercial concern. Context: Bamboo-dominated forests in southwestern Amazonia are increasingly exposed to the combined impacts of fire and selective logging. Although the climbing bamboos (Guadua spp.) are considered native species of these forests, disturbances contribute to a discontinuous canopy, which is an ideal scenario for an increase in abundance of these opportunistic plants. The regeneration of tree biomass is limited in these cases, decreasing the carbon stock of the forest. Aims: This study compares changes in bamboo abundance and forest structure in the face of forest fire and post-burn logging in the municipality (county) of Rio Branco, Acre state, Brazil. Methods: The study was conducted on the Transacreana Highway (AC 090) in the eastern portion of Acre state, Brazil. We compared changes in bamboo abundance and aboveground biomass (AGB) of an area of forest with no known recent disturbances to areas in the same forest that had been disturbed by fire and post-burn logging, which are frequent sources of disturbance in this region. The live and dead AGB values were estimated by field inventory in 2016, which was 11 years after a fire and 9 years after selective logging. The AGB values for trees and palms were estimated by allometric equations in three 2-ha areas. Bamboo abundance was expressed both by bamboo biomass (Mg ha−1) and culm density (culms ha−1), sampled by direct measurements in three 200-m2 areas. Results: Bamboo abundance was over 20% higher in forest that had been burned but not logged, as compared to undisturbed forest. Compared to undisturbed plots, aboveground forest biomass (live + dead) was 34% lower in plots exposed to fire but not logging, and 36% lower if exposed to both. Live trees and palms represented 77% of the total forest biomass (live + dead), and almost a half of this contribution (41%) was in individuals in the largest diameter class (diameter at breast height > 50 cm). Conclusion: Increase in the level of impact led to a reduction in aboveground carbon stock of the forest. One of the main consequences of disturbances in open forests dominated by bamboo is reduction of live trees and palms, especially in the diameter at breast height (DBH) class over 50 cm. © 2019, INRA and Springer-Verlag France SAS, part of Springer Nature
