947 resultados para lowland forests
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Ecological processes in tropical forests are being affected at unprecedented rates by human activities. Yet, the continuity of ecological functions like seed dispersal is crucial for forest regeneration. It thus becomes increasingly urgent to be able to rapidly assess the health status of these processes in order to take appropriate management measures. We tested a method to rapidly evaluate seed removal rates on two animal-dispersed tree species, Virola kwatae and V.michelii (Myristicaceae), at three sites in French Guiana with increasing levels of anthropogenic disturbance. We counted fallen fruits, fruit valves, and seeds of each focal fruiting tree in a single 1m2 quadrat, and calculated two indices: the proportion of seeds removed and the proportion of fruits opened by mammals. They both provide an indirect and rapid assessment of frugivore activity. Our results showed a significant decrease in the proportion of removed seeds (16%) and fruits opened (19%) at the most impacted site in comparison with the other two sites (79% for seeds, 60% and 35% for fruits). This testifies to an increased impoverishment of the primate and toucan communities at the disturbed sites. This standardized protocol provides fast information about the health status of the community of seed dispersers and predators and of their seed removal services. It is time- and cost-effective and is not species-specific, allowing comparisons among sites or over time. We suggest using it with the pantropical Myristicaceae and any other capsule-producing family to rapidly assess the health status of seed removal processes across the tropics.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Examined litterfall and litter standing crops in Altitudinal forest (AF and Semideciduous forest (SF) at Serra do Japi, Jundiai, Sao Paulo State. Total litterfall was 7 t ha-1 y-1 for AF: 4.9 leaves, 1.8 woody, 0.13 flower, 0.16 fruits; and the total for SF was 8.6 t ha-1 y-1; 5.5 leaves, 2.1 woody, 0.5 flower, 0.4 fruits. Litter standing crop was 5.5 t ha-1 y-1 for the two forest sites studied with a turnover coefficient (K1) of 1.3 for AF and 1.6 for SF. Litterfall occurred throughout the year but was greater during the dry season (August-September); seasonality of litter and leaf fall was greater in SF than in AF. -from Author
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Robert Mohlenbrock's guide to the national forests of the central U.S. provides the traveling naturalist with a wealth of information on the wide array of national forest lands in the heart of the country. Part of a three-volume series of field guides, this volume covers the states of Louisiana, Minnesota, Missouri, Montana, Nebraska, New Mexico, South Dakota, Texas, and Wyoming. While most of the forests are along the western and eastern borders of the Great Plains, readers will find a detailed travelog for a National Forest within a day's drive of most areas within the region. While not the focus of this volume, a brief mention of the National Grasslands of the Great Plains would have made it more comprehensive for the traveling naturalist.
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In Hawaii, invasive plants have the ability to alter litter-based food chains because they often have litter traits that differ from native species. Additionally, abundant invasive predators, especially those representing new trophic levels, can reduce prey. The relative importance of these two processes on the litter invertebrate community in Hawaii is important, because they could affect the large number of endemic and endangered invertebrates. We determined the relative importance of litter resources, represented by leaf litter of two trees, an invasive nitrogen-fixer, Falcataria moluccana, and a native tree, Metrosideros polymorpha, and predation of an invasive terrestrial frog, Eleutherodactylus coqui, on leaf litter invertebrate abundance and composition. Principle component analysis revealed that F. moluccana litter creates an invertebrate community that greatly differs from that found in M. polymorpha litter. We found that F. moluccana increased the abundance of non-native fragmenters (Amphipoda and Isopoda) by 400% and non-native predaceous ants (Hymenoptera: Formicidae) by 200%. E. coqui had less effect on the litter invertebrate community; it reduced microbivores by 40% in F. moluccana and non-native ants by 30% across litter types. E. coqui stomach contents were similar in abundance and composition in both litter treatments, despite dramatic differences in the invertebrate community. Additionally, our results suggest that invertebrate community differences between litter types did not cascade to influence E. coqui growth or survivorship. In conclusion, it appears that an invasive nitrogen-fixing tree species has a greater influence on litter invertebrate community abundance and composition than the invasive predator, E. coqui.
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Mangrove structure and distribution is conditioned by geomorphic processes. This paper describes the response of mangroves to sedimentary processes at the Cananeia-Iguape Coastal System on the south coast of Sao Paulo State (Brazil), between latitudes 24 degrees 40`S and 25 degrees 20`S. Within six study areas 41 plots were established along 14 transects. Plot size varied according to stem density from 2mx2m to 20mx20m. Here mangroves are strongly coupled to sedimentary processes, forming discrete architectural elements within particular depositional environments or topographic settings. These sedimentary structures and progradation environments are colonized by Laguncularia racemosa, associated with the smooth cordgrass Spartina alterniflora. Rhizophora mangle occurs typically near creeklets where tidal flooding is more frequent. Where tidal influence is restricted Avicennia schaueriana becomes dominant. Erosive margins are dominated by A. schaueriana or R. mangle. Single linkage cluster analysis yields three groups (A, B and C), with high levels of similarity, providing support to the classification of the data into two broad landform categories: depositional and erosive. Group A includes plots with the least structural development (nominal stem diameter d(n) between 1.05 and 4.61cm). Group B is composed of stems of intermediate diameter (4.99 cm <= d(n) <= 5.63cm). Group C plots have the largest structural development (5.50 cm <= d(n) <= 11.10cm). The structure of mangroves (dominance and structural development) reflects responses to geomorphology and habitat change.
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Lianas play a key role in forest structure, species diversity, as well as functional aspects of tropical forests. Although the study of lianas in the tropics has increased dramatically in recent years, basic information on liana communities for the Brazilian Atlantic Forest is still scarce. To understand general patterns of liana abundance and biomass along an elevational gradient (0-1,100 m asl) of coastal Atlantic Forest, we carried out a standard census for lianas a parts per thousand yen1 cm in five 1-ha plots distributed across different forest sites. On average, we found a twofold variation in liana abundance and biomass between lowland and other forest types. Large lianas (a parts per thousand yen10 cm) accounted for 26-35% of total liana biomass at lower elevations, but they were not recorded in montane forests. Although the abundance of lianas displayed strong spatial structure at short distances, the present local forest structure played a minor role structuring liana communities at the scale of 0.01 ha. Compared to similar moist and wet Neotropical forests, lianas are slightly less abundant in the Atlantic Forest, but the total biomass is similar. Our study highlights two important points: (1) despite some studies have shown the importance of small-scale canopy disturbance and support availability, the spatial scale of the relationships between lianas and forest structure can vary greatly among tropical forests; (2) our results add to the evidence that past canopy disturbance levels and minimum temperature variation exert influence on the structure of liana communities in tropical moist forests, particularly along short and steep elevational gradients.
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We describe the genetic transformation of the mycelial tissue of Diaporthe phaseolorum, an endophytic fungus isolated from the mangrove species Laguncularia racemosa, using Agrobacterium tumefaciens-mediated transformation (ATMT). ATMT uses both the hygromycin B resistant (hph) gene and green fluorescent protein as the selection agents. The T-DNA integration into the fungal genome was assessed by both PCR and Southern blotting. All transformants examined were mitotically stable. An analysis of the T-DNA flanking sequences by thermal asymmetric interlaced PCR (TAIL-PCR) demonstrated that the disrupted genes in the transformants had similarities with conserved domains in proteins involved in antibiotic biosynthesis pathways. A library of 520 transformants was generated, and 31 of these transformants had no antibiotic activity against Staphylococcus aureus, an important human pathogen. The protocol described here, using ATMT in D. phaseolorum, will be useful for the identification and analysis of fungal genes controlling pathogenicity and antibiotic pathways. Moreover, this protocol may be used as a reference for other species in the Diaporthe genus. This is the first report to describe Agrobacterium-mediated transformation of D. phaseolorum as a tool for insertional mutagenesis.