bluuebunny/crossref_metadata_2025 huggingface dataset:
Reproduction in an Orchid Can Be Resource‐Limited over its Lifetime1
Authors: Meléndez‐Ackerman Elvia J. , Ackerman James D. , Rodriguez‐Robles Javier A.
Published: March 2006

Most orchids studied thus far show long‐term resource adjustments to increases in fruit production within a flowering season, but none of these offers rewards to their potential pollinators. If nectar production is energetically expensive, then resources utilized to produce fruits and seeds may be even more limited in pollinator‐rewarding orchids than in non‐rewarding ones. Thus, resource adjustments may be more dramatic or entirely different in nectar producing plants. In this study, we performed artificial hand‐pollinations for two consecutive flowering seasons in die nectar producing orchid Comparettia falcata, and tested whether or not fruit set, seed set, and seed viability were limited by the quantity of pollinations or by resources. In addition, we compared mechanisms of short‐term (fruit abortion within seasons) and long‐term consequences (percent change in leaf length and change in flower number per plant between seasons, probability of shoot and inflorescence production, and mortality) between hand‐ pollinated and unmanipulated plants. The relationships among plant traits related to vegetative size and reproduction also were examined. Hand‐pollinations showed some negative effects. Fruit set was higher in hand‐pollinated plants in the first season but was similar to the controls in the second. Seed set was significantly lower and abortions were higher than in unmanipulated plants. On the other hand, some of our measurements were unaffected by die hand‐pollination treatment. Unexpectedly, there were no significant differences between groups in percent change in leaf length, change in flower number per plant between seasons, or die probability of shoot and inflorescence production. Although there was a strong correlation between leaf size and die number of flowers produced within a season, associations between leaf size and traits related to current or future reproduction were not consistent. Like other epiphytic orchids, pollination limitation occurred within a single season in C. falcata., but increases in fruit production also resulted in reduced lifetime fitness as estimated by a compounded fitness index. Contrary to all other epiphytic orchids studied, long‐term adjustments to increased fruit production in C. falcata through reduction in future growth or flower and inflorescence production were either minor or lacking. Our results suggest that the nature of plant strategies associated with resource constraints during sexual reproduction may be dependent on whether or not plants have evolved traits that are costly.
Dioecy in South American Deprea (Solanaceae)1
Authors: Sawyer Neil W. , Anderson Gregory J.
Published: March 2006

Dioecy in the Solanaceae is rare, occurring in < 1 percent of the species worldwide and known in only two species from South America. We report the occurrence of cryptic dioecy in the Neotropical genus Deprea. Studying herbarium material of the Venezuelan endemic D. paneroi revealed morphological distinctions that tentatively served to divide collections into male and female morphs. This discovery prompted investigation of population structure, crossing studies, and morphometric analyses of 95 individuals from the largest known wild population and a small sample of greenhouse‐grown plants. About 60 percent of the population was reproductive, and of these, nearly equal numbers exhibited female or male characteristics. Plants that bore fruit and small sterile anthers were characterized as female; those that lacked fruit but produced pollen in large anthers were characterized as male. The morphology, receptivity, and developmental phenology of pistils were identical in both forms. Crossing studies revealed significant enlargement of the ovaries in open‐pollinated female flowers and female X male hand‐pollinations. The ovaries in open‐pollinated male flowers and male X male hand‐pollinations never enlarged. These results suggest that the only legitimate combination is female X male. Dioecy in the family and possible mechanisms for the evolution and maintenance of dioecy in D. paneroi are discussed.
Disease of Red Mangrove (Rhizophora mangley) in Southwest Puerto Rico Caused by Cytospora rhizophorae1
Authors: Wier Andrew M. , Tattar Terry A. , Klekowski Edward J.
Published: March 2006

A high frequency of dieback and mortality was found in Rhizophora mangle (red mangrove) in coastal mangrove forests of southwest Puerto Rico. Eight plots were established in a variety of mangrove environments to assess the extent and severity of the dieback and mortality. The imperfect fungus Cytospora rhizopborae was isolated consistently from stem dieback and associated canker tissues. No other pathogenic microorganisms were isolated. Pathogenicity was demonstrated in greenhouse and field inoculation experiments with C. rhizophorae using young R. mangle seedlings. In field studies of seedlings inoculated, mortality was 33 percent, and greenhouse mortality was as high as 50 percent. Cytospora rhizophorae was isolated consistently from diseased mangrove tissue; the fungus was grown in pure culture and then inoculated into healthy red mangroves, causing cankers. Koch's postulates were fulfilled by infecting R. mangle with C. rhizophorae, producing disease symptoms, and successfully re‐isolating C. rhizophorae from the diseased tissue. This is the first documentation of the pathogenicity of C. rhizophorae associated with mortality in red mangrove. In the coastal mangrove forests of southwest Puerto Rico, C. rhizophorae may play an important role in the frequency of dieback and mortality in R. mangle, producing slow stem diameter growth and causing frequent stem and root wounds.
Difference in Intensity of Ant Defense among Three Species ofMacarangaMyrmecophytes in a Southeast Asian Dipterocarp Forest1
Authors: Itioka Takao , Nomura Masahiro , Inui Yoko , Itino Takao , Inoue Tamiji
Published: March 2006

To examine interspecific variation in the intensity of ant defense among three sympatric species of obligate myrme‐cophytes ofMacaranga(Euphorbiaceae), we measured the ratio of ant biomass to plant biomass, ant aggressiveness to artificial damage on host plants, and increase in herbivore damage on host plants when symbiont ants were removed. Increase in herbivore damage from two‐ and four‐week ant exclusion varied significantly among the three species. The decreasing order of vulnerability to herbivory wasM. winkleri, M. trachyphylla, andM. beccariana.The antip/ant biomass ratio (= rate of the dry weight of whole ant colonies to the dry weight of whole aboveground plant parts) and ant agressiveness also varied significantly among the three species; the orders of both the ant/plant biomass ratio and ant aggressiveness were the same as in the herbivory increase. These results indicated that the intensity of ant defense differs predictably among sympatric species of obligate myrmecophytes onMacaranga.In addition to the interspecific difference in the total intensity of ant defense, when symbiont ants were excluded, both patterns of within‐plant variation in the amount of herbivore damage and compositions of herbivore species that caused the damage differed among species. This suggests that the threeMacarangaspecies have different systems of ant defense with reference to what parts of plant tissue are protected and what herbivorous species are avoided by ant defense. Thus, it is important to consider the interspecific variation in ant defense amongMacarangaspecies to understand the herbivore community onMacarangaplants and the mechanisms that promote the coexistence of multipleMacarangamyrmecophytes.
Seed Dispersal of a High Quality Fruit by Specialized Frugivores: High Quality Dispersal?1
Authors: Wenny Daniel G.
Published: March 2006

Dispersal quality, as estimated by the cumulative effects of dispersal, germination, seed predation, and seedling survival, was examined for Beilschmiedia pendula (Lauraceae) in Monteverde, Costa Rica. I determined the pattern of dispersal by finding seeds deposited by birds, protected the seeds from seed predators with cages to assess germination and seedling survival, and examined seed predation rates with marked seeds. Seed predation, germination, and seedling survival were compared between seeds naturally dispersed by birds and seeds placed at randomly located sites.

Approximately 70 percent of seeds dispersed by birds (N= 244) were deposited <10 m from crown edges of fruiting B. pendula trees, although some seeds were dispersed at least 70 m away. Larger seeds were more likely to be dispersed under or close to the parent trees, and larger seeds produced larger seedlings. Seed size was not correlated directly with seedling survival, but larger seedlings at three months were most likely to survive one year. Seed predation by mammals and insects and seedling mortality due to fungal pathogens were concentrated beneath the crowns of parent trees. Seedlings and saplings were more abundant beneath fruiting B. pendula trees, but individuals farther away were taller on average. Thus, dispersal is beneficial for B. pendula, but such benefits appear most pronounced at a small spatial scale; seeds dispersed >30 m from the crown edges actually had a lower probability of survival than those dispersed 10–20 m. Only 10 percent of B. pendula. seeds received high‐quality dispersal in terms of landing in the zone with the highest per seed probability of seedling survival 10–20 m from parental crowns.
Spatial Distribution of Vascular Epiphytes (including Hemiepiphytes) in a Lowland Amazonian Rain Forest (Surumoni Crane Plot) of Southern Venezuela1
Authors: Nieder Jürgen , Engwald Stefan , Klawun Martin , Barthlott Wilhelm
Published: March 2006

The mobile crane of the Surumoni project allowed for the first time ever a complete inventory and spatial description of the epiphytic vegetation of a tropical lowland rain forest plot (1.5 ha), at La Esmeralda on the upper Orinoco River, Venezuela. A total of 778 individual vascular epiphytes of 53 species was found, dominated by 19 orchid species and 14 species of Araceae. Fifty percent of all individual plants were obligate ant‐garden epiphytes. The distribution of epiphytes was highly clumped and not random. The clumped occurrence of holoepiphytes (complete life cycle on host tree) was the consequence of the rarity of suitable phorophytes (host trees;e.g., size and age) in the plot and the preference of ants for gaps where most of the ant‐garden epiphytes were found. In comparison, hemiepiphytes were distributed more evenly because of greater independence from tree suitability. The dispersal modes of epiphytes did not explain their distribution patterns. There was no consistent difference in distribution between anemochorous and zoochorous epiphytes, presumably because availability of suitable substrate is the more important factor for epiphyte establishment and growth. Whereas the vertical distribution of epiphytes could be attributed largely to deterministic factors such as physiological adaptation and requirements, horizontal distribution appeared to be governed by suitable substrate, which in turn seemed to be governed by stochastic gap formation.
Estudio Fenológico de Cactíceas en el Enclave Seco de la Tatacoa, Colombia1
Authors: Ruiz Adriana , Santos Mery , Cavelier Jaime , Soriano Pascual J.
Published: March 2006

Durance un año se realizó el estudio fenológico de tres cactáceas columnares Stenocereus griseus (Haw.) Britton & Rose, Pilosocereus sp., Cereus hexagonus (L.) Mill., y una cactácea decumbente, Monvillea cf. smithiana (Britton & Rose) Backeberg., en el enclave seco interandino de La Tatacoa, Colombia. Los polinizadores y/o dispersores de las cactáceas fueron capturados mensualmente y se recolectaron las muestras fecales para la identificatión de los granos de polen y las semillas de los frutos consumidos. La floración de todas las especies fue prolongada y mostraron patrones bimodales, multimodales, o irregulares. La fructificación en todas las especies también se extendió durante todo el año, con un desfase de dos meses con respecto a la floración. Aunque no se encontró una correlatión significativa entre los valores mensuales de precipitatión y la producción de flores y frutos, la floración durante la época seca fue mayor en S. griseus, mientras que Pilosocereus sp. y C. hexagonus mostraron los valores más altos durante la época de lluvias. La productión de frutos también fue estacional, con un incremento durante la época de lluvias para S. griseus y C. hexagonus. La floración y fructificatión en M. cf. smithiana no mostraron diferencias significativas entre la época seca y la lluviosa. Los murciélagos Glossophaga longirostris, Carollia perspicillata, Sturnira lilium y algunas aves como Melanerpes rubricapillus (Picidae) y Mimus gilvus (Mimidae), y una mariposa nocturna (Sphingidae), fueron algunos de los polinizadores y/o consumidores de estas especies de cactáceas.
Quetzal Abundance in Relation to Fruit Availability in a Cloud Forest in Southeastern Mexico1
Authors: Solórzano Sofía , Castillo Silvia , Valverde Teresa , Ívila Lourdes
Published: March 2006

The Resplendent Quetzal(Pharomachrus mocinno)is an altitudinal migrant that nests in high elevation cloud forests and migrates toward lower areas during the summer rainy season. It has been suggested that its migratory movements are related to the abundance of ripe Lauraceae fruits. We studied the quetzal diet during two consecutive years, as well as changes in fruit abundance of the plant species on which the bird feeds at El Triunfo Biosphere Reserve, southeastern Mexico. The quetzal was observed feeding on 32 plant species; of these, 24 are new records in its diet. We chose 20 of these 32 species and studied their fruit phenology for two years in order to describe the relationship between fruit and quetzal abundance. Our results showed that quetzal abundance in the breeding area was correlated with the total number of fruiting species, whereas the correlation between quetzal abundance and the number of fruiting Lauraceae species was only marginal. Additionally, a correlation test showed that quetzal abundance was marginally correlated with total fruit availability (total no. of fruits per month); however, the correlation between quetzal abundance and the number of fruits in the Lauraceae was not significant. Our results suggest that the dynamics of food resources may be playing a major role in the quetzal's migratory behavior. Knowing the bird's diet may aid in characterizing the type of habitat adequate for its conservation. Our observations in this respect suggest that conservation efforts to preserve this bird species should concentrate on the protection of its habitat, including both breeding and nonbreeding (migration) locations.
Patterns of Floristic Differentiation among Atlantic Forests in Southeastern Brazil and the Influence of Climate1
Authors: Oliveira‐Filho Ary T. , Fontes Marco Aurélio L.
Published: March 2006

The tree flora of southeastern Brazilian Atlantic forests was investigated according to two main aspects: (a) the variations in floristic composition of bodi rain and semi‐deciduous forests were analyzed in terms of geographic and climatic variables by performing multivariate analyses on 125 existing floristic checklists; and (b) the links of both rain and semi‐deciduous forests to Amazonian forests and Cerrados (woody savanna) were assessed. All analyses were performed at the species, genus, and family levels. The information obtained for the 125 forest areas was organized into an environmental database containing geographic and climatic records, and a floristic database containing binary presence records for 2532 species, 520 genera, and 106 families. Canonical correspondence analyses (CCA) were utilized to assess the relationship between geographic and climatic variables, and tree flora composition. Venn diagrams and cluster analyses were used to assess the floristic links to Amazonian forests and Cerrados. The following patterns were detected at all three taxonomic levels: (a) the differentiation between rain and semi‐deciduous forests is floristically consistent and strongly correlated with rainfall regime, although transitions may be abrupt to gradual; (b) a north–south differentiation exists for both rain and semi‐deciduous forests, probably caused by variations in both temperature and rainfall regime; (c) The flora of semi‐deciduous forests also changes with increasing distance from the ocean and the associated increasing rainfall seasonality; and (d) elevation and associated temperatures are strongly correlated with the internal differentiation of both rain and semi‐deciduous forests. To a considerable extent, the tree flora of semi‐deciduous forests is a subset of the rain forest flora, probably extracting species that are able to cope with a longer dry season. There is greater floristic similarity at the species level between Atlantic rain and semi‐deciduous forests than between any of these and either Amazonian rain forests or Cerrados. Nevertheless, semi‐deciduous forests and Cerrados show stronger links, particularly at the generic and familial levels. Therefore, rhere is little floristic ground for viewing Atlantic rain forests as being closer to their Amazonian counterparts than to the adjacent semi‐deciduous forests. The most appropriate view of rain and semi‐deciduous forests in southeastern Brazil is that of a continuum in tree species distribution. We suggest that the definition of Atlantic forests should be as comprehensive as that of Amazonian forests.
Hummingbird‐Pollinated Floras at Three Atlantic Forest Sites1
Authors: Buzato Silvana , Sazima Marlies , Sazima Ivan
Published: March 2006

We studied 86 species of hummingbird‐pollinated flowers and their pollinators at a coastal lowland site and two highland rain forest sites in southeastern Brazil. The Jaccard index for hummingbird‐pollinated floras showed greater floristic similarity between the two highland communities than between floras of high altitudes and that of near sea level. The lowland site had slightly greater richness than either of the two highland sites. Bromeliaceae was the most important family, accounting for ca. 36 percent of the bird‐pollinated species and comprising 33 percent of the richest flowers. The plant populations bloomed annually for the most part. Both the wet lowland and the dry highland floras showed flowering seasonality, whereas the cloud highland flora had aseasonal flowering. A hermit hummingbird was the major pollinator in the lowland community. A hermit and a non‐hermit hummingbird shared most of the floral resources in the two highland communities. Hermit hummingbirds are the major pollinators of hummingbird‐pollinated floras in the Atlantic rain forests of southeastern Brazil. These areas may be as rich as Central and other South American areas in hummingbird‐pollinated flowers, and altogether present an older development history when compared to the North American flora.
Reproductive Modes of Atlantic Forest Hylid Frogs: A General Overview and the Description of a New Mode1
Authors: Haddad Célio F. B. , Sawaya Ricardo J.
Published: March 2006

This paper reports a new reproductive mode in anurans, observed for the green treefrog, Hyla leucopygia, a species from the Atlantic Forest of Brazil and a member of the H. albosignata group. The reproductive mode of H. leucopygia is defined as follows: aquatic eggs and embryos in subterranean constructed nests; subsequent to flooding, feeding tadpoles in ponds or streams. We suggest that the new reproductive mode is widespread among the species in the H. albosignata group. The specialized courtship behaviors of H. leucopygia, characterized by vocalizations and a stereotyped sequence of mutual touches between male and female, are described. A review of the reproductive modes of hylid frogs is provided, with 11 modes recognized for the Atlantic Forest hylids and 12 modes for hylids around the world.
Biogeography of South American Forest Mammals: Endemism and Diversity in the Atlantic Forest1
Authors: Costa Leonora Pires , Leite Yuri L. R. , da Fonseca Gustavo A. B. , da Fonseca Mónica Tavares
Published: March 2006

We used parsimony analysis of endemicity (PAE) to investigate the distribution patterns of South American lowland forest mammals, focusing on centers of endemism and diversity. We utilized distribution data available for species of marsupials, rodents, and primates that occur in South America. Two grids were superimposed on the distribution maps: a larger one encompassing tropical and subtropical South America, and a smaller and more precise grid covering the Atlantic Forest only. Also, the number of species per quadrat was estimated. The results support the idea that the distribution of this fauna is structured in the form of centers of endemism. In addition, there is good congruence between the areas identified here and those proposed by other authors, reinforcing the value of PAE in this kind of analysis. The hierarchical relationships among areas, however, are not clear and sometimes discordant with other biogeographic analyses.
The Avifauna of Rio Doce Valley, Southeastern Brazil, a Highly Fragmented Area1
Authors: Machado Ricardo Botnfim , Da Fonseca Gustavo Alberto Bouchardet
Published: March 2006

We analyzed the avifauna from four areas of the Rio Doce basin (the municipal districts of Nova Era [NE], António Dias [AD], Caratinga [BSC], and Marliéria [RDSP]) located in eastern Minas Gerais state. Based on captures with mist nets, 75 bird species belonging to 15 families were inventoried; however, the species composition varied gready among the study areas. Fifty species and 231 of the 466 individuals recorded during this study were captured at NE. In the AD area, 33 species and 132 individuals were captured. The other two areas, BSC and RDSP, contributed only 103 captures and 22 species. By analyzing species composition as a function of altitude of the study areas, it was verified that a variation of 500 m altitude was sufficient in determining the difference in existing bird communities. Formicariidae species, such as Drymophila squamata, Thamnophilus punctatus, and Conopophaga melanops, were captured exclusively in the BSC and RDSP areas, located below the 500 m altitude limit while their congeners (D. ochropyga, T. caerulescens, and C. lineata) were found exclusively in the highest areas (NE and AD). Significant seasonal variations in die species composition were observed (Green's test: Q = 12.79 in NE, 12.84 in AD, 12.4 in BSC, and 20.68 in RDSP; P < 0.05), and we believe that such variations could be associated with seasonal movements between die highest and lowest areas of the Rio Doce basin. As such, the impacts of fragmentation to the Atlantic Forest along this stretch of the Rio Doce basin may have affected the natural dynamics of avian movements. The destruction of > 90 percent of the original Atlantic Forest vegetation cover already may have seriously compromised the population viabilities of birds endemic to this area.
Patch Structure within Brazilian Atlantic Forest Fragments and Implications for Conservation1
Authors: Augusto André , Tabanez Jacinto , Viana Virgilio Maurício
Published: March 2006

Forest structure and tree species composition were studied in four Atlantic seasonal forest fragments ranging from 0.7 to 220 ha, isolated for more than a century in southeastern Brazil. Four physiognomic units were recognized within these fragments: (1) low forest, (2) bamboo forest, (3) high forest, and (4) mature forest. Tree density, basal area, and species diversity (Shannon‐Wiener index) increased from low forest to bamboo forest to high forest to mature forest. Liana cover was highest in low forest. Gap‐opportunistic species were the dominant ecological group in low forest, bamboo forest, and high forest, while shade tolerant canopy species formed the dominant group in mature forest. These structural and compositional features formed a gradient of forest development from the least developed low and bamboo forests to the most developed mature forest. Low forest is hypothesized to be in a stage of arrested succession and high forest a stage of degraded forest. A conceptual model is suggested to explain how these physiognomic units may be related to one another. Although these fragments were covered mainly by high and low forests and thus had a degraded structure, species diversity remained high in all of them. Fragments thus may undergo degradation long after isolation, even when they have been protected from human disturbance for a considerable period. Nonetheless, they also preserve important samples of local and regional floristic diversity for a long time after isolation.
Tanzanian Forest Edge Microclimatic Gradients: Dynamic Patterns1
Authors: Newmark William D.
Published: March 2006

Air temperature, vapor pressure deficit, and light intensity microclimatic gradients were examined along four forest edge and four paired forest interior transects in the East and West Usambara Mountains, Tanzania. Between 14 August 1995 and 11 August 1998, 287, 282, and 196 air temperature, vapor pressure deficit, and light intensity gradients, respectively, were measured along the four forest edge and four interior transects. The relationship between microclimate and distance from the forest edge was examined using piecewise linear regression. All microclimatic gradients were classified into one of nine shapes based on the sign and the size of the two estimated slopes. The relative frequency in the shapes of 65 percent of air temperature gradients, 52 percent of vapor pressure deficit gradients, and 62 percent of light intensity gradients along forest edge transects exceeded the relative frequency of these same shapes along forest interior transects, indicating that a majority of the forest edge microclimatic gradients measured were influenced by edge effects. Yet this result also indicated that approximately one‐third of all air temperature and light intensity gradients and nearly one‐half of all vapor pressure deficit gradients recorded during this study were affected by factors independent of edge effects per se, and that forest edge microclimatic gradients were temporally nonconstant. For air temperature and vapor pressure deficit gradients, low spatial but high temporal variation existed in estimated edge width and the relative change in microclimate between the forest edge and interior. For light intensity gradients, both high spatial and temporal variability characterized estimated edge width and relative change in microclimate between the forest edge and interior. The pooled mean edge width and relative change in microclimate between die forest edge and interior across the four forest edge transects for air temperature, vapor pressure deficit, and light intensity gradients were 94.1 m and 2.00°C, 82.6 m and 0.29 kPa, and 60.5 m and 10.6 joules/sec/m2, respectively. These results suggest that forest edge microclimatic gradients in general may be inherently dynamic and nonconstant.
The Macrofauna of Water‐filled Tree Holes on Barro Colorado Island, Panama1
Authors: Yanovlak Stephen P.
Published: March 2006

The fauna of water‐filled tree holes in Neotropical forests is not well documented. Cumulatively, 54 macroinvertebrate and 5 vertebrate taxa were found in artificial and natural tree holes censused over four wet seasons on Barro Colorado Island, Panama. Most of the species were in the insect order Diptera, occurred as aquatic larvae in tree holes, and were detritivore/omnivores. Half (49%) of the collected species are considered specialists in this and similar container habitats, and three invertebrate taxa were previously unknown from tree holes. Successional patterns were weak in tree holes, but some taxa predictably colonized holes shortly after they were filled. The mosquito Culex urichii was more common and abundant in artificial than in natural tree holes; occurrence frequencies and densities of most other taxa were similar between hole types.

RESUMES

La macrofauna de reservorios de agua en los huecos de los árboles de bosques neotropicales no ha sido bien documentada. En total, 54 grupos de macroinvertebrados y 5 grupos de vertebrados fueron encontrados en huecos artificiales y naturales examinados durante cuatro estaciones lluviosas en la Isla Barro Colorado, Panamá. De las especies encontradas, la mayoría pertenecen al orden Diptera. También, la mayoría ocurren como larvas acuáticas y son detrívoros/omnívoros. Cerca de la mitad (49%) de las especies son consideradas como especialistas en este tipo de háabitat y reservorios similares, y tres grupos de invertebrados no han sido reportados en los huecos de los árboles. No existen patrones de sucesión fuertes en los huecos de los árboles, pero algunos grupos colonizan los reservorios poco tiempo después que están llenos. El mosquito Culex urichii file la especie más común y más abundance en los huecos artificiales que en los huecos naturales; las frequencias y densidades de otras especies fueron similares entre los dos tipos de huecos.
Terrestrial Small Mammal Richness and Habitat Associations in an Amazon Forest–Cerrado Contact Zone1
Authors: Lacher Thomas E. , Alho Cleber J. R.
Published: March 2006

The Amazon Forest and the Cerrado of central Brazil share an extensive zone of integration. Each of these major ecosystems remains poorly studied; however, the composition of communities at the contact zone is even less well described. Small mammals were sampled during a ten–week period in a zone of contact between Amazonian forest and Cerrado. The vegetation in the area was a complex mixture of tropical and semi–deciduous forest, and grassland and savanna woodland formations. Mammals were marked and recaptured on 0.25– to 0.5–km transects and vouchers were collected. A total of 19 species was caught (13 rodents and 6 marsupials) in 4621 trap nights. Transitions from one vegetation type to another were abrupt with ecotones frequently < 5 m in width. The highest a–diversity was 7 species in cerrado. Ten of the 19 species were restricted to one habitat and 6 were restricted to two habitats. Three generalist grassland species occurred in more than two habitats, all variations of savanna. These data support other research indicating high habitat specificity of vertebrates and plants in the Brazilian savannas. The diversity of habitats within reserves in tropical grasslands must be given consideration in the design of protected areas in order to maximize the conservation of mammalian biodiversity.

RESUMES

A floresta Amazônica e o Cerrado do Brasil Central compartilham uma zona extensa de integração. Estes ecossistemas são pouco estudados, e a composição das comunidades que ocorrem na zona de contato é ainda menos conhecida. Pequenos mamiferos foram capturados durance um período de 10 semanas em uma zona de contato entre a floresta Amazônica e o Cerrado. A vegetação desta área é um complexo de florestas semidecíduas e tropicais, campos e cerrados. Mamiferos foram capturados e marcados em transetos variando de 250 a 500 m; uma coleção de referênda também foi feita. Capturamos um total de 19 espécies (13 roedores e 6 marsupiais) em 4621 noitesarmadilhas. As transições entre tipos de vegetação foram abruptas com ecótonos frequentemente menores que 5 m de largura. O cerrado teve a a‐diversidade mais alta: sete espécies. Dez das 19 espécies estavam restritas a um habitat e seis a dois habitats. Três espécies generalistas de savana ocorreram em mais de dois habitats, mas sempre em algum tipo de campo ou cerrado aberto. Estes dados corroboram com outras pesquisas indicando um alto nivel de especificidade de habitat para vertebrados e plantas no Cerrado. Consequentemente, para melhor preservar a diversidade de mamíferos no Brasil Central deve‐se dar mais atenção à diversidade de habitats em áreas de proteção no Cerrado.
Dietary Choices of the Pouched Mouse (Saccostomus mearnsi) in Central Kenya1
Authors: Metz M. R. , Keesing F.
Published: March 2006

Although there is growing recognition of the importance of small mammals in savanna ecosystems of east Africa, the ecology and behavior of these organisms are not well known. We conducted studies on the dietary preferences of one rodent, the pouched mouse (<Saccostomus mearnsi), which is the dominant small mammal in a widespread habitat in central Kenya. To establish the food preferences of this species, we: (1) conducted cafeteria trials in the laboratory whereby individual mice were offered seeds and a selection of herbaceous vegetation from the habitat; (2) surveyed the habitat for piles of vegetation clipped by these mice and identified these clippings to species; and (3) estimated the abundance of plant species in the habitat to determine if the mice were clipping species in proportion to their availability. Our results indicated that 5. mearnsi prefers green vegetation to seeds, at least during wet seasons, and that it has a strong preference for forbs. In cafeteria trials, 5. mearnsi chose 93 percent green vegetation and only 7 percent seeds. The forb Commelina africana was highly preferred over other food items offered. In the habitat, two forbs, C. africana and Monsonia angustifolia, constituted > 40 percent of the piles of clippings, although these two species together made up < 4 percent of the available vegetation. Grasses also were clipped frequently, although in lower proportions than their availability in the habitat. The herbivorous habits of 5. mearnsi establish the potential of this species to compete for resources with ungulates, which are abundant in this habitat.
Vegetative Identification of Tropical Woody Plants: State of the Art and Annotated Bibliography1
Authors: Rejmánek Marcel , Brewer Steven W.
Published: March 2006

This annotated bibliography is provided in order to assess the achievements and gaps in the literature on vegetative identification of woody plants in the tropics. The bibliography includes 258 references divided into general references (48), pantropical and multi‐continental keys (4), Africa (46), Asia (53), Australia and New Guinea (21), and the Neotropics (86). Vegetative keys are not easy shortcuts to the identification of woody tropical plants to species. Identification of sterile material requires as much, if not more, training as that required for using keys that emphasize floral and fruit characters. Nevertheless, the literature surveyed in this bibliography may be helpful to biologists seeking references for the geographic region in which they work, models for the construction of vegetative keys and field guides, and/or the types of characters that should be observed in the field.
Nitrogen and Phosphorus Release from Decomposing Leaves under Sub‐Humid Tropical Conditions1
Authors: Kwabiah A. B. , Stoskopf N. C. , Voroney R. P. , Palm C. A.
Published: March 2006

For many soils of the tropics, inputs of organic materials are essential to sustain soil fertility and crop production. Research in the quality of organic inputs, a key factor controlling rates of decomposition and nutrient release, continues to guide selection and use of organic materials as nutrient sources. The relationship between decomposition patterns and the quality parameters of the fresh leaves of six agroforestry species:Sesbania sesban, Croton megalocarpus, Calliandra calothyrsus, Tithonia diversifolia, Lantana camara, andSenna spectabilis, was investigated in a litterbag study over a period of 77 days in the highlands of western Kenya. The litterbags were buried 1 cm below the soil surface and covered with soil ofca1 cm thickness. Percent leaf mass and total N and P that remained with time strongly correlated with total P and C/P ratio (R2= 0.60‐0.90) during the first 35 days of study; but afterwards, correlation was stronger with the initial soluble polyphenolics (Pp)/P ratio (R2=0.69‐0.92) than with total P and C/P ratio. Loss of leaf mass and release of N and P followed the exponential function, yt= y0* e‐kt, from which the specific decay rate constants (k) were calculated for loss of leaf mass (kB) and release of N (kN) and P (Kp). Among the plant species, thekvalues were lowest inCalliandrawithkB=0.012/d,kN=0.017/d andkp= 0.044/d.Lantanahad the highest K values withkg=0.067/d andkp=0.119/d, but the highestkNvalue of 0.109/d occurred inTithonia.ThekBvalues for all organic materials were lower than their correspondingkNandkpvalues, suggesting that leaching of N and P from litters may have augmented the microbial mineralization of N and P. There was a strong correlation between thekB, kN, andkpvalues and total P (r = 0.82‐0.96;P0.01), but not total N, lignin (LIG), or Pp. Rates of N and P release followed the general trend:Tithonia > Senna > Lantana > Sesbania > Croton > Calliandra.The results indicated that, among the quality parameters studied, total P is the most important factor controlling rate of decomposition and N and P release from organic inputs in the area of study.
Brazilian Päramos. III. Patterns and Rates of Postfire Regeneration in the Campos de Altitude1
Authors: Safford Hugh DeForest
Published: March 2006

Postfire vegetation development was studied at two recent mountaintop burns in the Serra do Caparaó, Espírito Santo/ Minas Gerais, and the Serra dos órgãos, Rio de Janeiro, Brazil. Both fires occurred within the páramo‐like “campos de altitude”, a system of orographic grass‐ and scrublands restricted to the highest peaks of southeast Brazil. Data collected included pre‐ and postfire heights and densities of shrubs and trees, and cover of all taxa. Slopes of different aspect and altitude were sampled at each site to evaluate the effects of varying physical environment on regeneration. Rapid vegetative regeneration was common among shrubs and bamboo, with most taxa surviving fire. Regeneration and postfire colonization rates varied among species, and appeared to depend both on physical variables associated with different slopes, aspects and altitudes, and biotic variables. Most plant species in the campos de altitude show some form of evolutionary adaptation to fire. The distribution of species and plant populations across the landscapes of the campos de altitude appears to be largely the result of fire and its interactions with the biota, local topography, and climate. Results suggest that fire is an integral part of the ecology in these humid, seasonally dry ecosystems. Successful management of these unique and highly threatened systems requires a detailed understanding of the fire regime and its role in structuring biotic communities.

RESUMES

A regeneração da vegetação pós‐incêndio foi estudada em dois locais recentemente queimados nos campos de altitude da Serra do Caparaó, Espírito Santo/Minas Gerais e da Serra dos órgãos, Rio de Janeiro, Brasil. Foram amostradas as alturas e a densidade de plantas lenhosas pré‐ e pós‐incêndio, tal como a cobertura vegetal do estrato herbáceo. Em cada local foram amostradas encostas com orientações diferentes e também diferentes altitudes para avaliar os efeitos de variações do ambiente fisico na regeneração. A regeração da vegetação, especialmente de arbustos e bambu, se mostrou rápida, com a maioria das espécies sobrevivendo ao incêndio. As taxas de regeneração e colonização pósincéndio variaram entre espécies e entre locais e aparentemente dependem tanto de variáveis fisicas ligadas a rumos, declividades e altitudes diferentes, como também de variáveis bióticas. A maioria das espécies de plantas nos campos de altitude a prestam adaptações ao fogo. A distribuição das espécies e populações de plantas na paisagem dos campos de altitude parece ser o resultado da ação do fogo e de sua interação com a biota, a topografia local e o clima. Os resultados sugerem que fogo é um fator fundamental da ecologia desses ecosistemas úmidos porém sazonalmente secos. é impossível estabelecer um manejo adequado desses ecossistemas únicos e ameaçãdos sem uma compreensão detalhada do regime de fogo e do papel que incéndios desempenham na estructuração de comunidades bióticas.
Seedling Mortality in Hawaiian Rain Forest: The Role of Small‐Scale Physical Disturbance1
Authors: Drake Donald R. , Pratt Linda W.
Published: March 2006

Most montane rain forests on the island of Hawaii consist of a closed canopy formed by Cibotium spp. tree ferns beneath an open canopy of emergent Metrosideros polymorpha trees. We used artificial seedlings to assess the extent to which physical disturbance caused by the senescing fronds of tree ferns and the activities of feral pigs might limit tree regeneration. Artificial seedlings were established terrestrially (N= 300) or epiphytically (N = 300) on tree fern stems. Half of the seedlings on each substrate were in an exclosure lacking feral pigs and half were in forest with pigs present. After one year, the percentage of seedlings damaged was significantly greater among terrestrial seedlings (25.7%) than epiphytic seedlings (11.3%). Significantly more terrestrial seedlings were damaged in the presence of pigs (31.3%) than in the absence of pigs (20.0%). Senescing fronds of tree ferns were responsible for 60.3 percent of the damaged seedlings. Physical disturbance is potentially a major cause of seedling mortality and may reduce the expected half‐life of a seedling cohort to less than two years.
Deforestation in Costa Rica: A Quantitative Analysis Using Remote Sensing Imagery1
Authors: Sánchez‐Azofeifa G. Arturo , Harriss Robert C. , Skole David L.
Published: March 2006

Accurate estimates of forest cover and forest fragmentation are critical for developing countries such as Costa Rica, which holds four to five percent of the world's plant and bird species. We estimated forest cover for Costa Rica using Landsat 5 Thematic Mapper satellite scenes acquired between 1986 and 1991. In 1991, 29 percent (ca 14,000 km2) of the land cover of Costa Rica was closed forest cover; of that forested area, ca 30 percent is protected by national conservation policies. Forest loss in a study area representing ca 50 percent of Costa Rica's territory during a five‐year period (1986–1991) was 2250 km2, and the estimated deforestation rate was ca 450 km2/yr, or ca 4.2 percent/yr, of remaining forest cover. Forests are almost completely eliminated from the Tropical Moist Forest and Premontane Moist Forest life zones, and the level of fragmentation of remaining forests may be more advanced than previously thought.

RESUMES

La obtención de estimaciones precisas de la cobertura forestal y su nivel de fragmentación es crítica para la conservatión de la biodiversidad. Costa Rica contiene en su territorio nacional entre el cuatro y cinco por ciento de todas las especies de plantas y aves del mundo. Este estudio provee una estimatión precisa de la cobertura nacional forestal del país y su distribution a nivel ecológico basada en imágenes de satélite adquiridas entre 1986 y 1991 por el Trazador Temático Landsat 5. Para 1991, el país tenía una cobertura forestal de bosque perennifolio del 29 por ciento (ca 14,000 km2); el 71 por ciento de este bosque carecía de protectión mientras que el 29 por ciento restante está protegido por el Sistema Nacional de áreas de Conservación. La pérdida total de bosque en el area de estudio, durante un periodo de cinco años (1986‐1991) y la cual representa ca 50 por ciento del territorio nacional, rue de 2250 km2. La tasa de deforestatión estimada es de ca 450 km2 por año, o ca 4.2 por ciento anual. El proceso de deforestatión tropical ha eliminado casi completamente los bosques húmedo tropical y húmedo premontano del país. Los resultados de este trabajo sugieren que el nivel de fragmentación de los bosques costarricenses puede ser mas grande de lo que se habiá pensado.
Age of A2 Horizon Charcoal and Forest Structure near Porto Trombetas, Pará, Brazil1
Authors: Francis John K. , Knowles Oliver Henry
Published: March 2006

To study the structure and composition of old‐growth forest in the Saracá‐Taquera National Forest near Porto Trombetas, Brazil, we established 36 0.25 ha plots and described the vegetation. We collected charcoal from the A2 soil horizon of each plot for radiocarbon dating. Although fires have been very rare in this forest during historic times, the presence of charcoal in these soils indicates fire at some earlier period. The ages (conventional radiocarbon age adjusted to 1997) of the charcoal ranged from 177 to 1547 years. These ages, however, did not correlate significantly with any of several measures of biodiversity or stand characteristics. The relative uniformity of the current old‐growth forest indicates that either the prehistoric fires were of such low intensity that they had little long‐term effect on the vegetation or that the present stands have progressed to near steady state.
Morphology and Biology of Napoleonaea vogelii (Lecythidaceae) Flowers in Relation to the Natural History of Insect Visitors1
Authors: Frame Dawn , Durou Sébastien
Published: March 2006

In Gabon, we investigated the floral morphology and biology of Napoleonaea vogelii (Lecythidaceae), a cauliflorous understory tree of lowland humid rain forest, and made observations on the behavior of insect visitors. The major insects visiting flowers were: a thrips (Ceratothripoides brunneus), a small moth (Glyphipterix sp.), four species of leaf beetles (Gabonia colae, Gabonia sp. undescribed, Macrocoma sp., and Monolepta sp.), three species of weevils (Endaeus sp. 1–3), and two species of ants (Technomyrmex sp. and Monomorium sp.). In TV. vogelii, the flower is quite complex, and we propose a floral morphological definition for complexity. Insect visitors are spatially segregated on the flower. The evolution of the morphology and biology of the flower of N. vogelii is influenced by insect visitors, both pollinating and non–pollinating. The thrips are the likely pollinators of the flower.

RESUMES

Au Gabon, nous avons étudié Napoleonaea vogelii (Lecythidaceae), un arbre cauliflore du sous bois de la for○t humide de plaine. Nos recherches ont porté sur la morphologic et la biologic florales. Nous avons observé le comportement des insectes visiteurs, dont les principals espèces sont: un thysanoptère (Ceratothripoides brunneus), un lépidoptère (Glyphipterix sp.), quatre espèces de coléoptères chrysomélides (Gabonia colae, Gabonia sp. non décrite, Macrocoma sp., et Monolepta sp.), trois espèces de coléoptères curculionides (Endaeus sp. 1‐3), et deux espèces de fourmis (Technomyrmex sp. et Monomorium sp.). La fleur de N. vogelii est trés complexe et nous proposons une définition mor‐phologique de la complexityé florale. II existe une ségrégation spatiale des insectes visiteurs dans la fleur. L'évolution de la morphologic et de la biologic de la fleur de N. vogelii est liée aux insectes visiteurs, aussi bien les pollinisateurs que les autres. II est fort probable que les thysanoptères pollinisent la fleur.