Caracterização de uma floresta estacional semidecidual em Varginha, MG. E comparação com remanescentes da região.

Foi realizado o levantamento florístico e fitossociológico na porção mais extensa de mata no Parque Florestal Municipal São Francisco de Assis, na cidade de Varginha, sul de Minas Gerais. A área tem cerca de 10 ha e é cortada por um pequeno córrego. Foram lançadas 25 parcelas de 20m x 20m e medidos e cadastrados todos os indivíduos arbóreos com DAP > 5cm. Foram encontrados 1568 indivíduos que, juntos, somaram área basal de 23,65 m2, sendo registrados 102 espécies, 72 gêneros e 42 famílias no levantamento fitossociológico e 111 espécies, 77 gêneros e 43 famílias no levantamento florístico. As famílias com maior número de espécies foram Myrtaceae, Fabaceae e Melastomataceae. As espécies de maior valor de importância foram Casearia arborea, Copaifera langsdorffii, Tachigali rugosa e Myrcia splendens. Os resultados encontrados são os esperados para as Florestas Estacionais Semideciduais da região.

Parasitóides (Braconidae) associados à Anastrepha (Tephritidae) em frutos hospedeiros do litoral sul da Bahia

Dentre os organismos que atuam no controle biológico natural dos tefritídeos, os representantes da família Braconidae constituem-se no mecanismo de parasitismo natural mais atuante, e na região Neotropical, representantes de Opiinae são os principais agentes de controle de Anastrepha. Este trabalho teve por objetivo conhecer a percentagem de parasitismo e as espécies de braconídeos associados às fruteiras cultivadas em municípios da região Litoral Sul da Bahia. No período de agosto de 2005 a março de 2008, coletaram-se frutos hospedeiros de moscas-das-frutas de diversas espécies botânicas, e dos frutos foram obtidas as seguintes espécies de Anastrepha: A. fraterculus, A. obliqua, A. bahiensis, A serpentina, A. sororcula e A. zenildae. Do total de 838 exemplares de braconídeos, 21,36% foram da espécie Utetes anastrephae (Viereck), provenientes de cajá, carambola, goiaba, manga e pitanga; 4,42% da espécie Asobara anastrephae (Muesebeck) obtidos dos frutos de cajá, carambola e goiaba, e apenas um exemplar da espécie Opius bellus Gahan (0,12%) que emergiu da amostra de goiaba. A espécie Doryctobracon areolatus (Szépligeti) (74,10%) foi predominante e emergiu dos pupários provenientes de todos os frutos hospedeiros coletados, provavelmente pela maior eficiência desta espécie em localizar as larvas dos tefritídeos. A percentagem média de parasitismo de Anastrepha spp. foi de 4,45%.

Quaternary and Paleogene calcareous nannofossils of ODP Leg 115

The occurrences of ten datum events for the Quaternary and top Pliocene nannofossils are identified at nine Leg 115 sites. A quantitative investigation of Paleogene nannofossils in 470 samples selected from 11 holes at 9 sites yielded 197 taxa, including one new species and 10 unidentified taxa that are likely to be new species. Regional differences in the timing of some biostratigraphically important events are recognized, and a set of datum events useful for biostratigra- phy in the tropical Indian Ocean is presented. Biogeographical differences are minor for Paleogene cores from the tropical sites (Sites 707-716); however, the Quaternary and late early Oligocene floras observed at the two subtropical sites (Sites 705 and 706) differ significantly from the corresponding floras of the tropical sites. Bathymetrically controlled dissolution is recognized by the reduction of species diversity in the Paleogene flora. Selective dissolution of nannofossils is also evidenced by the percentage reduction of three holococcolith taxa, Lanternithus minutus, Zygrhablithus bijugatus, and Holococcolith type A as well as by the increase of Coccolithus pelagicusand Cribrocentrum reticulatumin the deeper sites.

Eocene-Oligocene nannofossils from the Labrador Sea

During Ocean Drilling Program (ODP) Leg 105, a thick sequence of lower Eocene to lower Oligocene sediments was recovered from Hole 647A in the southern Labrador Sea. These sediments contain diverse, well-preserved, high-latitude calcareous nannofossil flora. The nannofossil biostratigraphy of the hole indicates the presence of a minor hiatus between Zones NP 16 and NP 17 in the upper middle Eocene and a barren interval separating Zones NP 13 and NP 15. Species abundance is highest within the lower to middle Eocene and starts to decline near the base of the upper Eocene. No major change in the nannoflora was observed across the Eocene/Oligocene boundary, although a slight decrease in species abundance was recorded. The Paleogene calcareous nannofossils of nearby DSDP Site 112 were reexamined and compared with those of Site 647. Several cores were reassigned to different nannofossil zones. The calcareous nannoflora are dominated by high-latitude indicative species and also exhibit a high diversity, which suggests the influence of more temperate water masses in this region during Eocene and Oligocene time. One new subspecies from the middle Eocene, Sphenolithus furcatolithoides labradorensis, is described.

Cretaceous and Paleogene calcareous nannofossils from ODP Leg 123

Two of five holes drilled at two separate sites during Leg 123 of the Ocean Drilling Program intersected thick and relatively complete sections of Upper Cretaceous-Paleogene nannofossiliferous sediments. Although dominated by turbidite deposition in the upper part, Hole 765C contains a thick and relatively complete Albian-Oligocene section, including a particularly thick Aptian interval, with abundant and fairly well-preserved nannofossils. Several unconformities are confidently interpreted in this section that span much of the Santonian, late Campanian, Maestrichtian, late Eocene, and early Oligocene. Hole 766A contains a thick and relatively complete Albian-lower Eocene section having generally abundant and well-preserved nannofossils. Several unconformities also have been identified in this section that span much of the Coniacian, early Campanian, Maestrichtian, and late Eocene through early Pliocene. The chronostratigraphic position and length of all these unconformities may have considerable significance for reconstructing the sedimentary history and for interpreting the paleoceanography of this region. A particularly thick section of upper Paleocene-lower Eocene sediments, including a complete record across the Paleocene/Eocene boundary, also was cored in Hole 766A that contains abundant and diverse nannofossil assemblages. Although assemblages from this section were correlated successfully using a standard low-latitude zonation, difficulties were encountered that reduced biostratigraphic resolution. Several lines of evidence suggest a mid-latitude position for Site 766 during this time, including (1) high assemblage diversity characteristic of mid-latitude zones of upwelling and (2) absence of certain ecologically controlled markers found only in low latitudes.

Benthic foraminiferal composition at the inner wall of the Middle America Trench, Costa Rica

The sediments of Deep Sea Drilling Project Site 565 and University of Texas Marine Science Institute Cores IG-24-7-38 to -42 taken on the landward slope of the Middle America Trench exhibit characteristics of material subject to reworking during downslope mass flow. These characteristics include a generally homogeneous texture, lack of sedimentary structures, pervasive presence of a penetrative scaly fabric, and presence of transported benthic foraminifers. Although these features occur throughout the sediments examined, trends in bulk density, porosity, and water content, and abrupt shifts in these index physical properties and in sediment magnetic properties at Site 565 indicate that downslope sediment creep is presently most active in the upper 45 to 50 m of sediment. It cannot be determined whether progressive dewatering of sediment has brought the material at this depth to a plastic limit at which sediment can no longer flow (thus resulting in its accretion to the underlying sediments) or whether this depth represents a surface along which slumping has occurred. We suspect both are true in part, that is, that mass movements and downslope reworking accumulate sediments in a mobile layer of material that is self-limiting in thickness.

Abundances and contents of major silicoflagellates from IODP Holes of Exp302

The silicoflagellate taxa obtained in IODP Expedition 302 (ACEX) were identified and counted in order to establish the silicoflagellate biostratigraphy in the central Arctic Ocean. These microfossils in the ACEX samples were preserved in the Lithology Units 1/6 and 2, which are dark silty clay and biosiliceous ooze, respectively. The silicoflagellate skeletons in the ACEX samples are assigned to 56 taxa. Seven taxa were described as new species, which were abundant in Lithology Unit 2. Comparison with several study cases outside the Eocene Arctic Ocean suggested that the silicoflagellate assemblages in ACEX were unique in Lithology Unit 2. The dominance of silicoflagellate taxa varied throughout the lithological section. Based on the cluster analysis by Morishita similarity index C(Lambda), the silicoflagellate assemblageswere divided into nine assemblage groups. The silicoflagellate datum event of the first occurrence of Corbisema hexacantha in the lower part of Lithology Unit 1/6 is regarded. Based on the datum events for silicoflagellate and palynomorphs, the assigned epoch of Lithology Units 1/6 and 2 is the middle Eocene.

Calcareous nannofossils from the Sumisu Rift and Izu-Bonin Forearc Basin

During Ocean Drilling Program Leg 126, we recovered three expanded Pleistocene sections from the active backarc rift (Sumisu Rift) and three expanded Oligocene-Miocene sections from the forearc basin of the Izu-Bonin volcanic island arc. Quantitative analysis of the Pleistocene nannofossils revealed five major assemblages between 0 and LO Ma: Assemblage 1 (Holocene-0.085 Ma) contains dominant Emiliania huxleyi; Assemblage 2 (ca. 0.085-0.275 Ma) contains dominant small Gephyrocapsa and common E. huxleyi and Gephyrocapsa oceanica; Assemblage 3 (ca. 0.275-0.6 Ma) contains dominant Gephyrocapsa caribbeanica; Assemblage 4 (ca. 0.6-0.9 Ma) contains a peak abundance of small Gephyrocapsa in the middle part, and dominant occurrences of two types of G. caribbeanica in the lower and upper parts; and Assemblage 5 (ca. 0.9-1.0 Ma) contains dominant small Gephyrocapsa and common G. caribbeanica and Reticulofenestra asanoi. These assemblages are largely synchronous with similar assemblages recognized from tropical and subtropical regions, and can be used for finer subdivision of the Pleistocene than that based on standard Pleistocene nannofossil datums. The Oligocene-Miocene sections contain several hiatuses: up to 3 m.y. may be missing from the uppermost Oligocene (Zone CP19) at Sites 792 and 793; all of Zone CN2 is missing at Sites 792 and 793; part of Zone CN3 and all of Zone CN4 are missing at Site 792. Biochronology of several nannofossil datums at Leg 126 sites indicate that Sphenolithus distentus, Sphenolithus ciperoensis, Cyclicargolithus floridanus, and Discoaster kugleri have diachronous occurrences compared with other sites in the western Pacific Ocean and Philippine Sea.

Silicoflagellate abundances in sediments of ODP Leg 207 sites

The Ocean Drilling Program (ODP) drilled at five sites in the western Atlantic Ocean during Leg 207. The objective of the drilling was to recover samples from the shallow buried Cretaceous and Paleocene sediments on the Demerara Rise off Suriname, South America. These sediments are being studied for a number of paleoceanographic studies of the low-latitude Atlantic off the coast of Suriname (this volume). For this report two sites, Sites 1257 and 1258, were selected for silicoflagellate study because shipboard results suggested these two sites as the only ones with siliceous microfossils of Paleocene-Eocene age. The Demarara Rise is a predominant submarine plateau located off the coast of Suriname and French Guyana. This plateau stretches 380 km along the coast and is 220 km wide. The depth to seafloor along the depth transect drilled during ODP Leg 207 ranges from 1000 to 4500 m, but most of the remainder of the plateau lies in shallow water of 700 m. Much of this area is covered with 2-3 km of sediments. The Demerara Rise is built on rifted Precambrian continental crust. The plateau was one of the last places to be in contact with West Africa during the opening of the Atlantic Ocean (see Shipboard Scientific Party, 2004). Site 1257 (9°27'N, 54°20'W; water depth = 2951 m) is located on a terrace on the northwestern Demerara Rise ~400 km from Suriname. This is the second deepest water depth location drilled during Leg 207. Sediments from this area range in age from Miocene to Albian. This area is part of the transform fault that separated from Central America and western Africa. Three holes were drilled at Site 1257. Site 1258 (9°26'N, 54°43'W; water depth = 3192 m) is located on the western slope of the Demerara Rise ~380 km north of Suriname. This site is the distal and deepest site of the paleoceanographic depth transect drilled across Demerara Rise during Leg 207. The area is located on a ridge of Paleocene sediments cropping out on the seafloor. Three holes were drilled at Site 1258, but only one is studied.

Contribution of woody habitat islands to the conservation of birds and their potential ecosystem services in an extensive Colombian rangeland

The conservation of birds and their habitats is essential to maintain well-functioning ecosystems including human-dominated habitats. In simplified or homogenized landscapes, patches of natural and semi-natural habitat are essential for the survival of plant and animal populations. We compared species composition and diversity of trees and birds between gallery forests, tree islands and hedges in a Colombian savanna landscape to assess how fragmented woody plant communities affect forest bird communities and how differences in habitat characteristics influenced bird species traits and their potential ecosystem function. Bird and tree diversity was higher in forests than in tree islands and hedges. Soil depth influenced woody species distribution, and canopy cover and tree height determined bird species distribution, resulting in plant and bird communities that mainly differed between forest and non-forest habitat. Bird and tree species and traits widely co-varied. Bird species in tree islands and hedges were on average smaller, less specialized to habitat and more tolerant to disturbance than in forest, but dietary differences did not emerge. Despite being less complex and diverse than forests, hedges and tree islands significantly contribute to the conservation of forest biodiversity in the savanna matrix. Forest fragments remain essential for the conservation of forest specialists, but hedges and tree islands facilitate spillover of more tolerant forest birds and their ecological functions such as seed dispersal from forest to the savanna matrix.

Pollen and spores record, and paleotemperature reconstructions for mid-Holocene sediments of the Northwest Pacific

Sannai-Maruyama is one of the most famous and best-researched mid-Holocene (mid-Jomon) archaeological sites in Japan, because of a large community of people for a long period. Archaeological studies have shown that the Jomon people inhabited the Sannai-Maruyama site from 5.9-4.2 +/- 0.1 cal. kyr B.P. However, a continuous record of the terrestrial and marine environments around the site has not been available. Core KT05-7 PC-02, was recovered from Mutsu Bay, only 20 km from the site, for the reconstruction of high-resolution time series of environmental records, including sea surface temperature (SST). C37 alkenone SSTs showed clear fluctuations, with four periods of high (8.4-7.9, 7.0-5.9, 5.1-4.1, and 2.3-1.4 cal. kyr B.P.) and four of low (-8.4, 7.9-7.0, 5.9-5.1, and 4.1-2.3 cal. kyr B.P.) SST. Thus, each SST cycle lasted 1.0-2.0 kyr, and the amplitude of fluctuation was about 1.5-2.0 °C. Total organic carbon (TOC) and C37 alkenone contents, and the TOC/total nitrogen ratio indicate that marine biogenic production was low before 7.0 cal. kyr B.P., but was clearly increased between 5.9 and 4.0 cal. kyr B.P., because of stronger vertical mixing. During the period when the community at the site prospered (between 5.9 and 4.2 +/- 0.1 cal. kyr B.P.), the terrestrial climate was relatively warm. The high relative abundance of pollen of both Castanea and Quercus subgen. Cyclobalanopsis supports the interpretation that the local climate was optimal for human habitation. Between 5.9 and 5.1 cal. kyr B.P., in spite of warm terrestrial climates, the C37 alkenone SST was low; this apparent discrepancy may be attributed to the water column structure in the Tsugaru Strait, which differed from the modern condition. The evidence suggests that at about 5.9 cal. kyr B.P, high productivity of marine resources such as fish and shellfish and a warm terrestrial climate led to the establishment of a human community at the Sannai-Maruyama site. Then, at about 4.1 +/- 0.1 cal. kyr B.P., abrupt marine and terrestrial cooling, indicated by a decrease of about 2 °C in the C37 alkenone SST and an increase in pollen of taxa of cooler climates, led to a reduced terrestrial food supply, causing the people to abandon the site. The timing of the abandonment is consistent with the timing (around 4.0-4.3 cal. kyr B.P.) of the decline of civilizations in north Mesopotamia and along the Yangtze River. These findings suggest that a temperature rise of ~2 °C in this century as a result of global warming could have a great impact on the human community and especially on agriculture, despite the advances of contemporary society.

Distribution of diatoms in surface sediments and some limnological characteristics of studied lakes in the Siberian arctic

The investigation of the species composition and ecology of diatoms of modern bottom sediments in water bodies of arctic polygonal tundra in three subregions of North Yakutiya has been carried out. As a result, 161 taxons of diatoms were determined; the determinant role of the depth, conductivity, pH of the water, and geographic latitude in their distribution was confirmed, and two complexes of species with respect to the leading abiotic factors were distinguished. The diatoms of the first complex prefer shallow water bodies of high latitudes with neutral and slightly alkaline water and relatively high conductivity. The second complex is confined to the water bodies of lower latitudes with small conductivity, as well as neutral and slightly acidic water.

Oligocene-Miocene calcareous nannofossils in ODP Leg 149 holes

During Ocean Drilling Program (ODP) Leg 149, five sites were drilled on the Iberia Abyssal Plain in the northeastern Atlantic Ocean. Both Mesozoic and Cenozoic sediments were recovered. Oligocene to Miocene sediments were cored at deepwater Sites 897, 898, 899, and 900. Except for a few intervals, occurrences of generally abundant and well-preserved calcareous nannofossils suggest that the deposition of the turbidite-type sediments occurred above the calcite compensation depth (CCD). One major unconformity in the middle late Miocene is present. Detailed quantitative analyses of calcareous nannofossils are used to determine the changes occurring among the nannoflora in relation to sea-level variation. A succession of 89 biohorizons from the early Oligocene to the late Miocene are defined by combining the biostratigraphic results of the four sites studied in the Iberia Abyssal Plain. One new genus and eight new species are described: Camuralithus, Camuralithus pelliculatus, Ericsonia detecta, Helicosphaera limasera, Sphenolithus akropodus, Sphenolithus aubryae, Sphenolithus cometa, Reticulofenestra circus, and Syracosphaera lamina. Two new variations and seven new combinations are also introduced.

Middle Eocene to Miocene calcareous nannofossil of ODP Leg 125

During Ocean Drilling Program Leg 125, a thick sequence of middle Eocene to Pleistocene pelagic sediments, volcanogenic sediments, and predominantly extrusive volcanic rocks was recovered. Calcareous nannofossils were examined from 15 holes at nine sites, but Eocene to Miocene calcareous nannofossils were found only from Holes 782A, 784A, 786A, and 786B. In portions of Holes 786A and 786B, datable nannofossil oozes were found intercalated among volcanic flows. The nannofossil biostratigraphy of these holes indicates the presence of three well-defined hiatuses: within the lower Oligocene, between the upper Oligocene and middle Miocene, and between the middle and upper Miocene. An attempt was made to correlate the magnetochronological data with the first or last occurrences of the following species: Sphenolithus distentus, Reticulofenestra bisecta, Reticulofenestra reticulata, and Cyclicargolithus floridanus abisectus n. comb. The results indicate that the FO of Sphenolithus distentus can extend down to Zone CP16 (34.7 Ma), the LO of Reticulofenestra bisecta best defines the boundary between CP19a and CP19b (23.5 Ma), and the LO of Cyclicargolithus f. abisectus n. comb, can extend up to Subzone CN5a (12.5 Ma). No latest Oligocene Cyclicargolithus f. abisectus n. comb, acme was observed. Cyclicargolithus abisectus is considered a subspecies or variant of Cyclicargolithus floridanus because their LOs coincide. As a consequence of these observations, we have modified the definitions of Bukry's Subzones CP14a, CP14b, and CNla. Analyses of sediment-accumulation rates indicate that the rates increased gradually from the Eocene to Miocene. This is especially evident since the late Miocene in Hole 782A. In different parts of the Izu-Bonin forearc basin, however, the rate is not everywhere the same and appears to vary according to the import of volcanogenic materials.