bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aboveground Biomass Accumulation in a Tropical Wet Forest in Nicaragua Following a Catastrophic Hurricane Disturbance1
Authors: Mascaro Joseph , Perfecto Ivette , Barros Oton , Boucher Douglas H. , De La Cerda Iñigo Granzow , Ruiz Javier , Vandermeer John 
Published: November 2005

ABSTRACTAmong their effects on forest structure and carbon dynamics, hurricanes frequently create large‐scale canopy gaps that promote secondary growth. To measure the accumulation of aboveground biomass (AGBM) in a hurricane damaged forest, we established permanent plots 4 mo after the landfall of Hurricane Joan on the Atlantic coast of Nicaragua in October 1988. We quantified AGBM accumulation in these plots by correlating diameter measurements to AGBM values using a published allometric regression equation for tropical wet forests. In the first measurement year following the storm, AGBM in hurricane‐affected plots was quite variable, ranging from 26 to 153 Mg/ha, with a mean of 78 (±15) Mg/ha. AGBM was substantially lower than in two control plots several kilometers outside the hurricane's path (331 ±15 Mg/ha). Biomass accumulation was slow (5.36 ± 0.74 Mg/ha/yr), relative to previous studies of forest regeneration following another hurricane (Hugo) and agricultural activity. We suggest that large‐scale, homogenous canopy damage caused by Hurricane Joan impeded the dispersal and establishment of pioneer trees and led to a secondary forest dominated by late successional species that resprouted and survived the disturbance. With the relatively slow rate of biomass accumulation, any tightening in disturbance interval could reduce the maximum capacity of the living biomass to store carbon.
Aboveground Roots in Amazonian Floodplain Trees1
Authors: Wittmann Florian , Parolin Pia 
Published: November 2005

ABSTRACTSediment‐rich rivers seasonally flood central Amazonian várzea forests, leading to periodic anoxic conditions in the rhizosphere and requiring morphological and structural adaptations, such as aboveground root systems. We investigated some possible relationships between root types and environmental factors in forest plots covering 3.1 ha of várzea in the Mamirauá Sustainable Development Reserve, Brazil. Digital elevation models of the study sites were obtained; sedimentation and soil texture were investigated to check relationship between position of trees on the flood gradient, soil conditions, and aboveground root systems. Different types of aboveground roots were closely related to flooding duration and habitat dynamics. Species subjected to higher and more prolonged floods tended to produce more aboveground roots than species subjected to lower and shorter inundations. Plank‐buttressing species increased with decreasing flood height and/or flood duration, and with increasing growth height and basal area. Habitats inundated for long periods were dominated by species with low growth heights and low basal areas, which formed stilt roots and aerial roots. Root system and sediment deposition showed a close relationship, plank buttressing being more common in sites subjected to lower sediment rates. In the disturbed sites close to the main river channel colonized by pioneer species, the occurrence of buttresses was lower than in less disturbed climax stages. No clear relationship was found between root systems and sediment grain sizes.
Tree Phenology in Adjacent Amazonian Flooded and Unflooded Forests1
Authors: Haugaasen Torbjørn , Peres Carlos A. 
Published: November 2005

ABSTRACTMost phenological studies to date have taken place in upland forest above the maximum flood level of nearby streams and rivers. In this paper, we examine the phenological patterns of tree assemblages in a large Amazonian forest landscape, including both upland (terra firme) and seasonally flooded (várzea and igapó) forest. The abundance of vegetative and reproductive phenophases was very seasonal in all forests types. Both types of flooded forest were more deciduous than terra firme, shedding most of their leaves during the inundation period. Pulses of new leaves occurred mainly during the dry season in terra firme, whereas those in the two floodplain forests were largely restricted to the end of the inundation period. Flowering was concentrated in the dry season in all forest types and was strongly correlated with the decrease in rainfall. The two floodplain forests concentrated their fruiting peaks during the inundation period, whereas trees in terra firme tended to bear fruits at the onset of the wet season. The results suggest that the phenological patterns of all forest types are largely predictable and that the regular and prolonged seasonal flood pulse is a major determinant of phenological patterns in várzea and igapó, whereas rainfall and solar irradiance appear to be important in terra firme. The three forest types provide a mosaic of food resources that has important implications for the conservation and maintenance of wide‐ranging frugivore populations in Amazonian forests.
Factors Influencing Tree Phenology in Taï National Park, Côte d'Ivoire1
Authors: Anderson Dean P. , Nordheim Erik. V. , Moermond Timothy C. , Gone Bi Zoro B. , Boesch Christophe 
Published: November 2005

ABSTRACTEntrained phenology patterns of tropical trees are expected to be sensitive to short‐term fluctuations in typical rainfall and temperature. We examined 47 mo of data on the flowering, fruiting, and new leaf phenology for 797 trees from 38 species in the Taï National Park, Côte d'Ivoire. We determined the timing of the phenology cycles in relation to seasonal rainfall, temperature, and solar radiation. Regression analysis was used to examine how variations in rainfall and temperature influenced deviations in the peaks and troughs of phenology cycles. We also investigated whether populations that fruit during periods of community‐wide fruit scarcity were those populations with relatively long‐ or short‐fruiting duration. Flower, fruit, and leaf‐flushing phenophases all exhibited 12‐mo cycles. The broad peak in flowering began with the northward zenithal passing in April and ended with the southward zenithal passing in September. Fruiting peaks occurred in the long dry season, and leaf flushing peaked in the long dry season but continued into the wet season. Deviations from phenology cycles were largely attributable to short‐term fluctuations in rainfall and/or temperature. Fruiting durations of species were related to the mean diameter at breast height. Species with long‐ and short‐fruiting durations contributed equally to fruit abundance during periods of community‐wide fruit scarcity.
Geographic Variation and Succession of Arthropod Communities in Inflorescences and Infructescences of Xanthosoma (Araceae)1
Authors: García‐Robledo Carlos , Quintero‐Marín Paulina , Mora‐Kepfer Floria 
Published: November 2005

ABSTRACTPhytotelmata, small aquatic ecosystems within different structures of terrestrial plants, occur in the inflorescescences and infructescences of Xanthosoma (Araceae). This study reports changes in composition and abundance of arthropods during the anthesis of inflorescences and in the developing infructescences of three species of Xanthosoma at three different geographic locations: (1) X. undipes in a tropical cloud forest of Costa Rica, Central America; (2) X. daguense in a tropical cloud forest in the central Andes of Colombia; and (3) X. poeppigii in the Peruvian Amazonas. All Xanthosoma species displayed similar interactions with the main pollinators, dynastine beetles. We observed a succession from terrestrial to aquatic arthropods as inflorescences aged and set fruit. However, community composition varied among different Xanthosoma species. Some arthropods recorded in Xanthosoma phytotelmata have also been reported as inflorescence visitors of the dynastine‐pollinated terrestrial genus Dieffenbachia and of vines from Philodendon and Syngonium. Further research may elucidate if phytotelmata similar to those described for Xanthosoma could occur among dynastine‐pollinated genera of Araceae, both in the understory and the canopy of Neotropical forests.
Preferences and Food Quality of Fruit‐Feeding Butterflies in Kibale Forest, Uganda1
Authors: Molleman Freerk , Van Alphen Monique E. , Brakefield Paul M. , Zwaan Bas J. 
Published: November 2005

ABSTRACTMany butterflies in tropical forests feed on fruits that have fallen to the forest floor. This substrate differs in many ways from floral nectar, and therefore fruit‐feeding butterflies are expected to possess adaptations for efficient foraging, choice, and ingestion of their food. Differences in food quality and in spatial and temporal availability are also likely to have led to life history evolution. Here we describe the sugar and nitrogen content of fruits that butterflies feed on in a tropical forest in Uganda, and measure the attractiveness of these fruits to the local butterfly fauna together with the role that decay plays in the attraction. These data are supplemented with feeding observations at fruit falls in the forest. Our results show that (1) fruits contain significant and variable concentrations of sugar and nitrogen, and constitute a nutritious food source for butterflies in tropical forests; (2) fruit‐feeding butterflies use cues from the fruits and fermentation products to locate their food; (3) different classes of fruit‐feeding butterflies may vary in their preferences for certain fruits, and differ in their ability to find preferred food; and (4) fruit choice is not strongly correlated with attractiveness or nutrient content. The results are discussed in the light of the evolution of food searching and life history strategies.
Long Tongues and Loose Niches: Evolution of Euglossine Bees and Their Nectar Flowers1
Authors: Borrell Brendan J. 
Published: November 2005

ABSTRACTI examined relationships between tongue length of orchid bees (Apidae: Euglossini) and nectar spur length of their flowers in the genera Calathea, Costus, and Dimerocostus using phylogenetically independent contrasts. Long‐tubed flowers have specialized on one or several species of long‐tongued euglossine bees, but long‐tongued bees have not specialized on long‐tubed flowers. Whereas long tongues may have evolved to provide access to a wider variety of nectar resources, long nectar spurs may be a mechanism for flowers to conserve nectar resources while remaining attractive to traplining bee visitors.
Complex Nesting Behavior by Two Neotropical Species of the Ant Genus Stenamma (Hymenoptera: Formicidae)1
Authors: Longino John T. 
Published: November 2005

ABSTRACTTwo Neotropical ant species, Stenamma expolitum Smith and S. alasnew species (described here), exhibit three unusual nesting behaviors: (1) they build architecturally sophisticated nest entrances that elevate the nest opening away from the surface; (2) they maintain multiple identical nests but occupy only one of them; and (3) they keep a round “door pebble” at the nest entrance, with which they plug the opening in response to army ants. Adaptive hypotheses for these behaviors are discussed, including the possibility that there are multiple lines of defense against army ant predation.
Habitat Preferences of Ungulates in Hunted and Nonhunted Areas in the Calakmul Forest, Campeche, Mexico1
Authors: Reyna‐Hurtado Rafael , Tanner George W. 
Published: November 2005

ABSTRACTWe investigated habitat preference in the community of ungulates in the Calakmul Forest of Southern Mexico through systematically counting the tracks of six species in randomly placed transects. Tracks were associated with one of four major forest types according to Pennington and Sarukhan (1998). Forest type availability was estimated through 393 independent points on the same transects. We surveyed 90 transects in three hunted areas and one large nonhunted area, with a total of 206 km walked. A total of 1672 tracks of the six species were found. Brocket deer (Mazama americana and Mazama pandora) preferred low‐dry forest in the nonhunted area and low‐flooded forest in the hunted areas. Collared peccary (Pecari tajacu) was a generalist species in the nonhunted area, whereas in the hunted areas, it preferred the subperennial forest. White‐lipped peccary (Tayassu pecari) was found only in subperennial forest in the nonhunted area and favored low‐flooded forest in the hunted areas. White‐tailed deer (Odocoileus virginianus) preferred low‐flooded forest in the hunted areas, while it was a generalist in the nonhunted area. Tapir (Tapirus bairdii) preferred low‐flooded forest in the hunted areas. The most evident habitat difference among hunted and nonhunted areas was a major use of low‐flooded forest in the hunted areas for the species. Conservation of ungulate species in the Calakmul region requires protection of all major habitat types in hunted and nonhunted areas.
Direct and Indirect Effects of Nectar Robbing on the Pollinating Behavior of Patagona gigas (Trochilidae)1
Authors: González‐Gómez Paulina L. , Valdivia Carlos E. 
Published: November 2005

ABSTRACTIn central Chile, nectar robbing of Puya coerulea (Bromeliaceae) flowers by the austral blackbird, Curaeus curaeus, had a direct impact on the plant via removal of floral resources and, in some cases, damage or even destruction of flowers. These robbing visits also likely had an indirect impact on plant fitness due to the decreased rate of legitimate visits by the hummingbird Patagona gigas to inflorescences with many robbed flowers. The proportion of flowers within an inflorescence visited by P. gigas was inversely proportional to the ratio of robbed flowers.
Spatial and Temporal Distribution of Northern Waterthrushes Among Nonbreeding Habitats in Southwestern Puerto Rico1
Authors: Hunt Pamela D. , Reitsma Leonard , Burson Sherman L. , Steele Benjamin B. 
Published: November 2005

ABSTRACTWe surveyed nonbreeding Northern Waterthrushes (Seiurus noveboracensis) in several coastal habitats in southwestern Puerto Rico, West Indies. Waterthrush abundance was highest (mean = 2.2/point) in well‐developed mangrove habitats characterized by large trees and standing water, and lowest (mean = 0.1/point) in dry coastal scrub and savannah. Within the latter habitats, waterthrushes were more common in moist microhabitats such as temporary ponds and dry washes. Abundance in most habitats declined between October and January, probably a result of the presence of transients during the October surveys, Between January and March, abundance in mature red mangrove (Rhizophora mangle) forests increased dramatically, suggesting that this habitat provides a refuge for birds at the end of the dry season and prior to northward migration. In conjunction with other data demonstrating the use of coastal red mangroves as nocturnal roosting sites, these results suggest that mangroves are the most important nonbreeding habitat for this species. Conservation of this globally threatened habitat may thus be important for the long‐term stability of waterthrush populations.
GCRT J1745—3009: a precessing radio pulsar?
Authors: Zhu W. W. , Xu R. X. 
Published: November 2005

Abstract
A unique transient bursting radio source, GCRT J1745—3009, has been discovered near the direction of the Galactic Centre. The explanation of this phenomenon is still an open question, although some efforts to understand its nature have been made. This Letter shows that most of the observed features can be reproduced by our proposed precessing pulsar model. It is found that the precession angle of the pulsar should be larger (≳15°) than that of previously known precessing pulsars, which have a precession angle ≲10°, if the beam width of the pulsar is larger than 10°. The pulsar could be a nulling (or even extremely nulling) radio pulsars to account for the transient nature of the source. This model can be confirmed if a pulsar is detected at the position of the source. The pulsar could hardly be a normal neutron star (but could probably be a solid quark star) if the spin period of the pulsar is detected to be ≳10 ms in the future.
Genetic diversity and population structure of boreal white spruce (Picea glauca) in pristine conifer-dominated and mixedwood forest stands
Authors: Rajora Om P. , Mann Ishminder K. , Shi Yong-Zhong 
Published: November 2005

White spruce ( Picea glauca (Moench) Voss) is a characteristic primary species of the Canadian boreal forest region, where it occurs in conifer-dominated and mixedwood forest types. Genetic diversity and population structure of white spruce may differ between the conifer-dominated and mixedwood forest types owing to the inherent differences in stand structure and dynamics. The objective of our study was to determine genetic diversity and population structure of pristine white spruce stands as they occur in conifer-dominated and mixedwood forest types at the EMEND (Ecosystem Management Emulating Natural Disturbance) study sites in northern Alberta. Nuclear microsatellite DNA markers were used to examine genetic diversity and population structure of 16 pristine natural old-growth (≥100 years) white spruce stands (subpopulations) of fire origin; 8 from conifer-dominated and 8 from neighboring mixedwood forest types. High levels of genetic diversity were observed, as expected. The genetic diversity and genetic constitution of white spruce were similar between the conifer-dominated and mixedwood forest types. Most of the genetic variation resided within subpopulations, with only about 2% genetic differentiation detected among 16 subpopulations as well as among 8 subpopulations within the same forest type. The mean genetic distances among subpopulations within and between the forest types were similar. Our study suggests that white spruce genetic resources are similar in the conifer-dominated and mixedwood forest types located in the EMEND study area in northern Alberta, and it provides the benchmarks for determining and monitoring the genetic diversity impacts of forest harvesting and forest fires.
Spatial genetic and clonal structure inMaianthemum dilatatumas defined by AFLP markers
Authors: Wilson Amy S.G. , van der Kamp Bart J. , Ritland Carol 
Published: November 2005

Amplified fragment length polymorphisms (AFLPs) were used to investigate the clonal and spatial genetic structure of Maianthemum dilatatum (A. Wood) Nels. & J.F. Macbr. (Convallariaceae), a clonal rhizomatous herb, which can form large patches of continuous cover. Within a subpopulation covering approximately 3 ha, all patches (n = 21) were mapped and sampled. Within these patches, 116 ramets were sampled and assigned to 74 putative genets. Small patches appeared to be single genets while larger patches were genetically heterogeneous and only moderately differentiated (ΦST= 0.291, p = 0.001). Less intense sampling in other populations produced similar results in that single genet populations were not found. Evidence of genet natality was present with the detection of five yearlings within a single season. Spatial autocorrelation measures detected spatial genetic structure attributable to both clonal growth and gene flow processes. It was concluded that within M. dilatatum populations, clonality is a significant factor, but the spatial structuring of genetic variation suggests that both low levels of restricted gene flow and repeated recruitment of genets occur.
Conidial morphology, virulence, molecular characterization, and host–parasite interactions of selected Alternaria panax isolates on American ginseng
Authors: Quayyum H.A. , Dobinson K.F. , Traquair J.A. 
Published: November 2005

The fungus Alternaria panax Whetzel causes leaf and stem blight of American ginseng ( Panax quinquefolius L.). Six isolates of A. panax, collected from widely separated ginseng-growing areas in North America, were characterized on the basis of their colony and conidial morphology, molecular characteristics, and virulence. Colony morphology on standard media and conidial morphology based on light microscopy showed some variation with geographic locality: Wisconsin isolates were slightly different from Ontario and British Columbia isolates. Isolates from each locality were equally virulent on American ginseng. Ginseng phytotoxin was present in the conidial germination fluid of all isolates. Sequences of the β-tubulin gene from all six isolates were identical as were the sequences of the internal transcribed spacer (ITS) region of the rDNA gene. The ITS1 and ITS2 gene sequences of the six isolates were also identical to those of American and Korean isolates of A. panax deposited in GenBank. Cellulase and pectinase were detected by agar biodiffusion assays of a representative isolate. Germination of conidia of this isolate on ginseng leaflets began within 2 h of application to leaf surfaces, and over 80% of conidia germinated within 12 h of application. Conidia produced one to several germ tubes that grew in all directions over the leaflet surface. The germ tubes formed terminal appressoria over stomatal openings, epidermal cells, and epidermal cell junctions. The frequency of direct penetration into ginseng leaflets was greater than penetration through stomata. Both retraction of plasma membrane and disruption of chloroplast membranes were observed 12 h after leaflet inoculation. At 24 h after inoculation, hyphae were present in both intercellular spaces and inside mesophyll cells. Severe disruption of plasma membrane, chloroplasts, and mitochondria was observed between 24 and 48 h after inoculation.
A field study of seed dispersal and seedling performance in the invasive exotic vine Vincetoxicum rossicum
Authors: Ladd David , Cappuccino Naomi 
Published: November 2005

The exotic vine Vincetoxicum rossicum (Kleopow) Barbar. (Asclepiadaceae) is a major natural-areas pest throughout the Great Lakes Basin. Colonization of new areas by this herbaceous perennial occurs by comose wind-dispersed seeds. Previous experiments suggested a trade-off between seed dispersability and seed quality: smaller seeds dispersed farther but were less likely to emerge and seedlings were smaller when grown in competition with turf grasses in the greenhouse. We examined dispersability by trapping seeds at distances of 0–60 m from a seed source, and we assessed seedling performance by sowing seeds of known weight in an old field. Smaller seeds travelled significantly farther than larger seeds; however, the relationship between weight and distance dispersed was weak (r2 = 0.043). Large seeds were significantly more likely to emerge, and the seedlings survive and grow taller; however, the relationships between seed size and these performance variables were also weak (r2 ≤ 0.02). The dispersability–quality tradeoff is unlikely to play an important role in V. rossicum spread at the local scale, as even large seeds are competent dispersers and even seedlings from small seeds are capable of becoming established. Seedlings from polyembryonic seeds were more likely to successfully establish than seeds from which a single seedling emerged. The high seedling emergence (50% for seeds planted above ground; 72% for those buried to a depth of 1 cm) and survivorship (71%–100%, depending on embryony) are likely to contribute to the success of this species.