bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of tree canopy cover on soil fertility in a Nigerian savanna
Authors: Isichei Augustine Onwuegbukiwe , Muoghalu Joseph Ikechukwu
Published: July 2009

The effect of tree canopy cover on soil properties was studied over three periods: middry season (January), mid-growth period (August) and peak-growth period (October) in three 1 ha plots in savanna of north-west Nigeria. The objective was to find out whether tree canopies change the nutrient status of the soil under them relative to adjacent grasslands. Soils under tree canopies were found to have significantly higher levels of organic matter, calcium, magnesium, potassium, total exchangeable bases, cation exchange capacity and pH than those in open grasslands. Nitrogen and phosphorus were slightly higher in soils under tree canopies than those in the open grasslands. Trees 7 m and above had more influence on soil properties than smaller trees. Differences in soil properties among the study plots were due to differences in their soil texture. Seasonal trends were observed in organic matter, carbon: nitrogen ratio, cation exchange capacity, phosphorus, calcium, sodium, total exchangeable cations and percentage base saturation.
Grasses of the Precambrian Shield region in eastern lowland Bolivia. II. Life-form and C3–C4 photosynthetic types
Authors: Killeen Timothy J. , Hinz Paul N.
Published: July 2009

A life-form classification from Neotropical Gramineae is proposed for 113 native species from eastern lowland Bolivia. A factor analysis was performed on a correlation matrix of 51 vegetative attributes to identify ‘character suites,’ which were then used as the basis for the classification. The principal types are arboreal, liana, shrub-like, forb-like, bunch grass with basal foliage, bunch grass with basal and caulescent foliage, caespitose annuals, elongate rhizomes, turf grass, stoloniferous, and decumbent (the last category is further divided into subgroups: -perennial, -indefinite, -floating aquatic, and -vine-like). A key component of the life-form classification is the morphology of leaf blades, with five major patterns recognized: elongate and inrolled, elongate and conduplicate, elongate and flat with an attenuate base, short and broad with an amplexicaule base, and short and broad with a pseudopetiole.

The distribution and relative abundance of three major photosynthetic categories were compared with life-form and habitat preference. Photosynthetic type of individual species was identified based on leaf anatomy. C4-(XyMS −) species predominated in cerradao, cerrado, campo rupestre, valleyside campos, and seasonally inundated savanna, as well as on granite outcrops. C4-(XyMS + ) species were relatively rare in all habitats, but were significantly more abundant in the xeric microenvironments of granite outcrops. C3 species predominated in semi-deciduous forest and increased in relative abundance in wetland habitats. Caespitose annuals and bunch grass species were predominantly C4 type, while arboreal and liana species were uniformly C3 type. Grasses classified as decumbent or shrub-like were predominantly C3 type, while rhizomatous, stoloniferous, and forblike grasses were a mixture of C3 and C4 type.

The intent of the study was to group morphological characteristics objectively in order to derive a life-form classification specific for the Gramineae. Comparisons of the relative abundance of the various life-forms in a broad range of habitat types provide a descriptive assessment of the adaptive value of these characteristics.
Dung beetles attracted to mammalian herbivore (Alouatta palliata) and omnivore (Nasua narica) dung in the tropical rain forest of Los Tuxtlas, Mexico
Authors: Estrada Alejandro , Halffter Gonzalo , Coates-Estrada Rosamond , Meritt Dennis A.
Published: July 2009

Dung beetles attracted to howler monkey (Alouatta palliata) and coati (Nasua narica) dung were studied for an annual cycle in the tropical rain forest of Los Tuxtlas, Mexico. Pitfall traps set for 24 h month−1captured 1567 dung beetles of 21 species. The speciesCanlhidium martinto, Deltochilum pseudoparile and Canthon femoralisaccounted for 62% of all individuals captured. While species overlap was high (> 80%) between diurnal and nocturnal samples and between howler monkey and coati dung baits, coati dung attracted species such asC. martinezi, D. pseudoparileandOnthophagus rhinolophuswhile species such asC. femoralisandCopris laevicepswere numerically dominant at howler monkey dung. Thirteen non-ball rolling dung beetle species and eight ball-rolling species accounted for 43% and for 57% of all beetles captured respectively. Dung beetles were present and active in all months of the year, but occurred in higher numbers between the months of March and October, when temperatures were higher. Relative abundance of howler monkey and coati dung in the rain forest of Los Tuxtlas was estimated at 11.2 g (fresh weight) ha−1day−1and at 13.0 g ha−1day−1respectively, a seemingly low amount for the large number of scarabs attracted to the dung.
Orchid—phorophyte relationships in a forest watershed in Puerto Rico
Authors: Migenis Luis E. , Ackerman James D.
Published: July 2009

Orchid diversity, distribution and host specificity were examined in a tropical watershed in the Luquillo Experimental Forest of Puerto Rico. Eleven orchid species occur in the area. The low diversity is attributed to island isolation and large-scale hurricane disturbances. Pleurothallis ruscifolia and Maxillaria coccinea were by far the most abundant species in the area and occurred on the largest number of host species and host zones. None of the orchids were host specific or host zone specialists although preferences for hosts and vertical host zones were encountered.

Only 8.2% of the 426 trees and shrubs and 24.4% of the 45 species surveyed were orchid phorophytes (= hosts). Examination of host distribution by diameter at breast height (DBH) showed that 80.5% were greater than 16 cm DBH. Orchid species in the area tend to occur on rough bark hosts, but their preferences are not statistically significant. Guarea guidonia (Meliaceae) and Dacryodes excelsa (Burseraceae) are the two most important orchid hosts in our study site comprising 62.9% of all host trees. Careful management of these two tree species is suggested, since these species may be crucial to the maintenance of orchid abundance and diversity in the area.
A model of litterfall, litter layer losses and mass transfer in a humid tropical forest at Pernambuco, Brazil
Authors: de Sá Barretto Sampaio Everardo Valadares , Dall'Olio Attilio , Nunes Katia Smera , de Lemos Eurico Eduardo Pinto
Published: July 2009

Data on litterfall, litter layers accumulated on top of the mineral soil and layer mineralization collected for three years in a tropical rain forest at Pernambuco, Brazil, were implemented on a simulation model. Litterfall was collected biweekly using 11 collectors 1 × 1 m. Every three months, 20 litter mat samples, 0.5 × 0.5 m, were collected, divided into the L, F and H layers and the CO2 evolution from each litter layer was determined in the laboratory. Litterfall, in the three years, averaged 7.8, 8.3 and 8.2 Mg ha-1 y-1, most of it leaves. Litter mat masses varied widely from place to place (15–90 Mg ha-1) and the overall averages were 5.6, 7.6 and 26.1 Mg ha-1 for the L, F and H layers, with CO2 evolution averages of 2.27, 0.507 and 0.123 mgC g litter C-1 day-1. According to the model, the L layer had a high turnover rate, losing 4.7 Mg ha-1 y-1 through mineralization and 3.4 Mg ha-1 y-1 transferred to the F layer. Values for the F and H layers were 1.4 and 1.2 mineralized and 2.0 and 0.8 Mg ha-1 y-1 transferred. Thus, it would take 2.1, 6.7 and 39 years for newly fallen leaves to be mostly fragments, to be transformed to humus and to be incorporated to the soil organic matter, respectively. Variations of litterfall throughout the three years would have little effect on the system which was not very sensitive to litterfall changes, except for the top layer.
Ecosystem dynamics of disturbed and undisturbed sites in north Queensland wet tropical rain forest. I. Floristic composition, climate and soil chemistry
Authors: Congdon Robert A. , Herbohn John L.
Published: July 2009

This paper introduces studies of nutrient cycling in disturbed and undisturbed rain forest plots in the upper catchment of Birthday Creek, near Paluma, North Queensland. The catchment is underlain by granite and has soils of comparatively low fertility. Differences between unlogged plots and plots disturbed 25 years previously by selective logging are still apparent. Disturbed plots have soils with higher bulk densities and pH, lower CEC, kjeldahl nitrogen and available phosphorus concentrations, and changed species composition. The data suggest that recovery from selective logging is dependent on soil fertility and intensity of disturbance.
Ecological relationships between lianas and trees in lowland rain forest in Sabah, East Malaysia
Authors: Campbell E. J. F. , Newbery D. McC.
Published: July 2009

Numbers of lianas ≥2 cm gbh were recorded on trees ≥30 cm gbh in two 4 ha plots of dipterocarp forest. Associations between lianas and trees of the 12 commonest families and 16 commonest species were analysed. Liana density was 882 ha-1. Fifty-seven per cent of trees supported lianas and the mean number lianas per tree was 2.1. Lianas were highly aggregated on individual trees in most families; numbers of lianas per tree followed the negative binomial distribution for the Dipterocarpaceae but not Euphorbiaceae. Dipterocarpaceae and Euphorbiaceae differed in susceptibility, with 41 and 64% of their trees respectively supporting lianas. The proportions of trees with lianas (i.e. % trees laden) were correlated between plots at the species, but not the family, level. They were not related to tree girth; differences in proportions between families and species were maintained for trees in the 30–40 cm gbh class. At the species level, proportions of trees with lianas and the mean number of lianas per tree were significantly inversely correlated with mean branch-free bole height of trees in the 30–40 cm gbh class. Increased branch-free bole height and associated branch shedding may therefore decrease the susceptibility of trees to lianas and explain the lower susceptibility in the Dipterocarpaceae than the Euphorbiaceae.
Growth history of a Neotropical tree inferred from the spacing of leaf scars
Authors: King David A.
Published: July 2009

The Neotropical tree,Pourouma aspera(Cecropiaceae), supports large lobed leaves on an erect stem which seldom branches below a height of 5 m. The prominent leaf scars are visible on trunks of mature trees and the distance between scars is highly correlated with the height growth rate when the leaves were produced. Relationships between height growth rate, internode length and light environment were determined from markedP. asperasaplings in a tropical wet lowland forest and used to infer the past growth histories of larger saplings and trees. Inferred growth rates were quite variable, both within and between individuals. Estimated passage times to grow from 0.7 to 2.2 m tall ranged from 0.6–23 y, with a mean of 4.4 y (N = 61). The study illustrates the importance of examining the distribution of growth rate over the length of the stem in addition to the more usual distribution of numbers of individuals per growth rate class. Species such asPourouma, which respond strongly to light, complete much of their total juvenile growth during intervals of high light, even though most saplings are growing slowly in shade at any given time.
Factors influencing tree growth in tropical savanna: studies of an abrupt Eucalyptus boundary at Yapilika, Melville Island, northern Australia
Authors: Wilson B. A. , Bowman D. M. J. S.
Published: July 2009

Most of the land surface of Melville Island, Australia's second largest island, is covered in Eucalyptus savanna. One exception is an area at Yapilika where a large tract of savanna is dominated by Acacia shrubs. An ordination analysis of 122 quadrats revealed that the boundary of Eucalyptus dominance did not correspond to a major change in floristic composition. Detailed transect studies at one site on the boundary showed that Eucalyptus trees were abruptly replaced by a band of Grevillea trees which gradually gave way to Acacia shrub dominance. There was a gradual change in the floristic composition of the savanna across the boundary. The distributional limit of Eucalyptus was found to be independent of any hydrological discontinuity. There was a slight decrease (<2.5 m) in altitude from Eucalyptus to Acacia savanna. The Acacia savanna soils were sandier and their surface soil had significantly lower concentrations of Ca and Mg and significantly greater concentration of Al compared with the Eucalyptus savanna soils. Eucalyptus seedlings planted in the three savanna communities were not found to be under drought stress (pre-dawn leaf xylem potentials of > – 0.9 MPa) during the dry season. Over a 12 month period Eucalyptus tetrodonta and E. miniata seedling growth was not significantly different on the Acacia or Eucalyptus savanna, although this result may be due to the counteracting effects of greater soil fertility and tree competition in the Eucalyptus savanna and lower soil fertility in the treeless, and hence competition-free, Acacia savanna. This hypothesis is supported by the significantly greater growth of Eucalyptus seedlings on fertilized Acacia savanna soils. The limited production, dispersal and establishment of Eucalyptus seeds and the greater frequency of fires in the Acacia savanna probably explains the abrupt limit to Eucalyptus dominance along the edaphic gradient.
Growth rates and mortality patterns of tropical lowland tree species and the relation to forest structure in Amazonian Ecuador
Authors: Korning Jørgen , Balslev Henrik
Published: July 2009

Growth in diameter and the relationship between age and size are analysed for 22 tree species in Amazonian Ecuador using growth simulation by a stochastic technique that projects the diameter-age relationships of a species. Maximum diameter growth rates varied from 1.2 mm y–1 (Grias neuberthii) to 20.0 mm y–1 (Cecropia sciadophylla). Minimum growth rates ranged from almost zero in Neea divaricata to 2.4 mm y–1 in Mollia lepidota. Median growth rates ranged between c. 0.5 mm y–1 (Grias neuberthii, Neea divaricata) and 11.6 mm y–1 (Cecropia sciadophylla). The maximum simulated life-span spent between a DBH of 10 cm and the largest DBH of a species varied from 54 y (Cecropia sciadophylla) to 529 y (Neea divaricata). Fast growing species and species that potentially can grow old showed a convex survivorship curve, whereas slower growing species and species that do not grow very old showed sigmoid, linear and convex survivorship curves. The species were grouped according to their DBH-height relationship and according to their maximum age, maximum growth rate, and maximum DBH. The groups probably reflect different light requirements. A negative correlation was found between maximum age and mortality rate. Growth rates vary within species, thus the largest tree is not necessarily the oldest.
Population size structure and sex ratios in some woodlice (Crustacea: Oniscidae) from southern Africa
Authors: Dangerfield J. M. , Telford S. R.
Published: July 2009

The population size structure and adult sex ratio were recorded for four indigenous and one introduced species of terrestrial isopod from southern Africa. Interspecific variation was considerable with either discrete or continuous distributions indicative of the production of separate cohorts or continuous recruitment. Intraspecific variation was also considerable particularly in species such asAphiloscia viliswhich can be found in diverse habitats. Sex ratios were consistently female biased, a result consistent with observations made on temperate species. These observations, and a consideration of sexual dimorphism based on body mass, suggest that phenotypic plasticity may be an important tactic in the life histories of tropical woodlice and that in some populations the potential exists for strong sexual competition and complex mating systems.
Effects of soils and topography on the distribution of tree species in a tropical riverine forest in south-eastern Brazil
Authors: Oliveira-Filho Ary T. , Vilela Enivanis A. , Carvalho Douglas A. , Gavilanes Manuel L.
Published: July 2009

The relationships between soil properties, topography and tree species distribution were analysed in a tropical riverine forest at the margins of the Rio Grande, in Bom Sucesso, state of Minas Gerais, south-eastern Brazil. The forest was sampled by three 0.18 ha plots, with each plot made up of eight contiguous 15 m X 15 m quadrats, four of which were placed at the river margin and the remaining four in the forest interior. A canonical correspondence analysis indicated that the species' density distribution was significantly correlated with some soil chemical characteristics and topographical features. The soils of the three sample plots showed statistically significant differences for the levels of Ca, Mg, K and pH, with the fertility (expressed by the cation exchange capacity) increasing from Plot I to Plot III. These variations were mainly explained by the first canonical axis while the second was strongly correlated with topographical variables, separating the quadrats into two groups: those of the higher and steeper sites from those of the lower sites. The only soil property that was significantly different in lower and upper sites was the concentration of phosphorus. No significant difference in tree species distribution was found between river margin and interior quadrats, certainly because this forest sector lies on the outer side of a curve of the river where erosion is currently building high and steep river banks and forcing the forest to retreat. A tentative ecological classification of the 30 most abundant species according to their habitat preference in terms of soil fertility and topographical sites, and to their growth strategy in the forest dynamics, is presented. It is suggested that these factors play an important role in promoting the coexistence of tree species in this type of forest.
Phenological niches of coexisting serotinous plants in the Namib Desert
Authors: Günster Antje
Published: July 2009

Timing of germination and flowering under different environmental conditions was investigated in four coexisting serotinous desert plants: Blepharis grossa (annual herb), Geigeria data, Geigeria ornativa (facultative perennial herbs) and Petalidium setosum (perennial shrub). Germination patterns were similar under varying environmental conditions in the study species, except for P. setosum, which germinated later when conditions were less favourable. B. grossa always germinated early, G. alata and G. ornativa later, which could be explained by differences in their seed dispersal mode. Thus no obvious niche separation in timing of germination was indicated in the study species. Flowering periods varied between seasons rather than between species and no niche separation in flowering times existed between the study plants. This might indicate that either interspecific competition plays a minor role in a community of desert serotinous plants or that niche separation exists in other components of the plants' niche, such as seed dispersal, seedling establishment and/or microhabitat selection.
The use of a common epiphytic lichen as a bioindicator of atmospheric inputs to two Venezuelan cloud forests
Authors: Gordon Catriona A. , Herrera Rafael , Hutchinson Tom C.
Published: July 2009

The chemistry of epiphytic lichens was determined in two Venezuelan cloud forests adjacent to the Caracas Valley at Altos de Pipe and El Avila National Park. This is the second component of a two-part study examining the chemistry of fogs and their effects on sensitive biota in these forests. The widespread lichen Parmotrema madagascariaceum was chosen as an indicator of trace metal input. Background lichen collections and transplant experiments were carried out to evaluate spatial trends in atmospheric depositon of trace metals at different altitudes and exposures of the two montane locations. Elevated concentratons of metals including Pb and Zn were seen in lichen tissue and associated bark. Lead levels in lichens reached 190 μg g-1dry wt. Lichens transplanted from relatively ‘clean’ to more polluted sites showed significant increases of metals, particularly Pb. Increases of up to 6.3 μg Pb g-1mo-1after 6 and 10 months were recorded relative to background andin situlichen material. In contrast, when lichsens were reciprocally transplanted in nylon net bags from less to more exposed sites there was a significant decrease in Pb and Zn concentrations after 6 and 10 months. With long-term exposure to elevated concentrations of these trace metals epiphytic lichens, as well as other sensitive cloud forest biota, may be at risk of decline.
Plant phenology in relation to water availability: herbaceous and woody species in the savannas of northern Cameroon
Authors: Seghieri J. , Floret Ch. , Pontanier R.
Published: July 2009

Phenological patterns of herbaceous and woody plants well represented in the Sudano-Sahelian savannas of northern Cameroon were studied in relation to water availability in three contrasted soil types. Mean annual precipitation in this region is 800 mm, entirely restricted to the period May-June to September-October, but redistribution of rainwater by varying soil substrates leads to considerable heterogeneity in available water resources for plants. Results are discussed in terms of probable competition for water resources among co-occurring plants and the adaptations shown by observed patterns to prevailing environmental conditions. Water stress is seen to be a limiting factor to plant growth but does not constitute the sole trigger for the phenological phases observed, nor is it the principal factor responsible for the preponderance of annual species in the herbaceous stratum.
Daily activity patterns of small mammals in a cerrado area from central Brazil
Authors: Vieira Emerson Monteiro , Baumgarten Leandro Cláudio
Published: July 2009

We investigated the daily activity patterns of four species of small mammals in an area of cerrado habitat in central Brazil. We checked live traps at 3-hour intervals during the night.Bolomys lasiurusandCalomjis tenet(Rodentia, Muridae), two potential competitors, differed significantly in their daily activity patterns.Bolomys lasiurushad peaks during the twilight, whereasC. tenerhad a more constant activity through the night, with a peak between 2200 and 0100 h.Thalpomys cerradensis(Rodentia, Muridae) was more active immediately after sunset and in the last three hours before sunrise.Thylamys velutinus(Marsupialia, Marmosidae) was strictly nocturnal with greater activity early in the night. Other factors, such as predation pressure or diet, may be important in determining the activity patterns observed in this study.
Variation in reproductive characteristics of the stream frog Colostethus trinitatis on the island of Trinidad
Authors: Cummins Clive P. , Swan Mary J. S.
Published: July 2009

We compared reproductive characteristics of the dendrobatid frog Colostethus trinitatis at the Tamana cave in the Central Range hills and at five forest stream sites in the Northern Range hills of Trinidad. There were significant differences between sites in adult female body size, intraovarian clutch size (in absolute terms and relative to body size) and the size of tadpoles carried by male frogs. Clutch sizes ranged from 6 to 13 in the Northern Range samples and from 12 to 26 at Tamana. Adult male body size was similar at all sites. Tadpoles carried by male C. trinitatis at Tamana were significantly smaller (mean length 14.2 mm) than those carried by males at the five Northern range sites (mean length 16.4–16.7 mm). The smallest clutches and largest tadpoles were found at Mount St Benedict, where there was evidence of size-selective predation on tadpoles by fish. Tamana, where clutches were large and tadpoles small, differed from the Northern Range sites in terms of the physical environment (cave vs forest) and the abundance of invertebrates. We discuss possible ultimate and proximate causes of the differences in clutch size and tadpole size, particularly size-selective predation and availability of food.
Aspects of the population biology of the gregarious tree Cordia elaeagnoides in Mexican tropical deciduous forest
Authors: Van Groenendael Jan M. , Bullock Stephen H. , Pérez-Jiménez L. Alfredo
Published: July 2009

Cordia elaeagnoides is locally important within a large area of southern México as a highly gregarious canopy tree of dry forest and as a timber species. Its recruitment is problematic so studies of its reproduction and population dynamics were undertaken. The distylous flowers are apparently self-compatible, and pollination and seed dispersal are by wind. Pre-dispersal mortality is largely from embryo abortion, and post-dispersal predation is mostly by generalist rodents. Some seeds may survive in enforced dormancy for two or more years. Recruitment was apparently absent for more than a decade, but had previously occurred within established stands, where size classes were interspersed at random. Population size structure suggests that recruitment over the last century occurred in several pulses. Growth rates determined from ring counts and remeasurement of marked trees support a size-age relationship. The youngest reproductive trees are estimated to be about 18 years old, and about 5% of the present population is over 95 years old.
Species richness and density of ground herbs within a plot of lowland rainforest in north-west Borneo
Authors: Poulsen Axel Dalberg
Published: July 2009

In a I-ha plot all ground herb species were recorded. Within the plot selected properties were investigated in three 20 m × 20 m subplots. The number of ground herb species and individuals in the subplots were lowest near to a local hilltop and they increased towards the lowest part of the plot. There was no significant difference in canopy openness, or in thickness of leaf litter layer, between the upper and lower subplots. In the upper subplot the soil layer was thin and the weathered bedrock was close to the surface. In the lower subplot the soil was much deeper. The pH and concentrations of Mg were significantly lower and %loss-on-ignition, total P and total N concentrations were significantly higher in the upper subplot. Elevation and soil moisture were significantly correlated in the upper 10 cm of soil. It is not possible to select any one abiotic property as being the critical determinant of the gradient of ground herbs. However, it is suspected that the availability of water in the topsoil, particularly after droughts, may be more important than the soil nutrients in limiting herb distribution.
A comparison of ground-dwelling small mammal communities in primary and secondary tropical rainforests in China
Authors: Wu De-Lin , Luo Jia , Fox Barry J.
Published: July 2009

Trapping was conducted in primary and secondary forests to investigate the effects of past logging on small mammal communities. Thirteen I-ha sites were snap-trapped for three consecutive days in tropical monsoon rainforest in Xishuangbanna Nature Reserve, southern China. A total of 3900 trap-days yielded 198 captures, of which 118 were in the primary forest and 80 in the secondary forest. A total of 12 ground-dwelling species (eight Rodentia, Muridae; three Insectivora, Soricidae; one Insectivora, Erinaceidae) were caught, five (all Rodentia, Muridae) occurred in the primary forest and 11 in the secondary forest. The most abundant species wasNiviventer confucianus, accounting for 62% and 39% of the total captures in the primary and the secondary forests, respectively. In the secondary forest the mean abundances of the two dominant species,N. confucianusandMaxomys surifer, were reduced, and a non-commensal form ofRattus rattusdisappeared, butN. fulvescensshowed no change whileMus pahariincreased. The seven species which occurred only in secondary forest had very low abundance. Overall, the multivariate Mantel test showed the two communities to be significantly different. After logging, species diversity increased, and the two dominant species had increased body mass and their mean abundance decreased.
Changes in tree species abundance in a Neotropical forest: impact of climate change
Authors: Condit Richard , Hubbell Stephen P. , Foster Robin B.
Published: July 2009

The abundance of all tree and shrub species has been monitored for eight years in a 50 ha census plot in tropical moist forest in central Panama. Here we examine population trends of the 219 most numerous species in the plot, assessing the impact of a long-term drying trend. Population change was calculated as the mean rate of increase (or decrease) over eight years, considering either all stems ≥10 mm diameter at breast height (dbh) or just stems ≥100 mm dbh. For stems ≥10 mm, 40% of the species had mean growth rates <1% per year (either increasing or decreasing) and 12% had changes ≥5% per year. For stems ≥100 mm, the figures were 38% and 8%.

Species that specialize on the slopes of the plot, a moist microhabitat relative to the plateau, suffered significantly more declines in abundance than species that did not prefer slopes (stems ≥10 mm dbh). This pattern was due entirely to species of small stature: 91% of treelets and shrubs that were slope-specialists declined in abundance, but just 19% of non-slope treelets and shrubs declined. Among larger trees, slope and non-slope species fared equally. For stems ≥100 mm dbh, the slope effect vanished because there were few shrubs and treelets with stems ≥100 mm dbh. Another edaphic guild of species, those occurring preferentially in a small swamp in the centre of the plot, were no more likely to decline in abundance than non-swamp species, regardless of growth form. Species that preferentially colonize canopy gaps in the plot were slightly more likely to decrease in abundance than non-colonizing species (only for stems ≥10 mm dbh, not ≥100 mm). Despite this overall trend, however, several colonizing species had the most rapidly increasing populations in the plot.

The impact of a 25-year drying trend and an associated increase in the severity of the 4-month dry season is having an obvious impact on the BCI forest. At least 16 species of shrubs and treelets with affinities for moist microhabitats are headed for extinction in the plot. Presumably, these species invaded the forest during a wetter period prior to 1966. A severe drought of 1983 that caused unusually high tree mortality contributed to this trend, and may also have been responsible for sharp increases in abundance of a few gap-colonizers because it temporarily opened the forest canopy. The BCI forest is remarkably sensitive to a subtle climatic shift, yet we do not know whether this is typical for tropical forests because no other large-scale censuses exist for comparison.
Diet, growth and movements of juvenile crocodiles Crocodylus porosus Schneider in the Klias River, Sabah, Malaysia
Authors: Sah Shahrul Anuar Mohd , Stuebing Robert B.
Published: July 2009

A total of 14 spotlight surveys were carried out from January 1992 to February 1993 along 37 km of the Klias River in north-western Sabah, Malaysia. Surveys were at low tide between 1900 and 0600 h from a survey boat at 15 km h−1 by two observers. A total of 221 sightings were made, which varied between 2 and 29 per survey (mean 15.8). A total of 55 juvenile crocodiles were captured, with 16 recaptures. Calculated density was 0.9–1.8 individuals km−1, while the estimated crocodile population was 46.1 ± 10.2 (SD) for the survey area. Percentage sightings according to total length were: 42% ≤0.5 m; 40% >0.5-≤1.0 m; 5% > 1.0-≤3.0; and 13% eyes only. Recapture of 16 tagged juveniles suggested that hatchlings ≤0.5 m total length remained within >0.5 km of their release point for at least one month, and juveniles 0.5-≤1.0 m more than one year. Hatchlings had growth rates between 0.01 and 0.08 cm d−1 and 0.3 and 1.5 g d−1, while larger juveniles grew at least 0.11 cm d−1 and 2.7–2.9 g d−1. Stomachs of hatchlings and juveniles contained crabs (Ocypodidae), prawns (Atyidae), insects and small fish (Hemiramphidae). Relatively large numbers of juvenile Crocodylus porosus (82.4%) in the Klias River suggests that the area, though under hunting pressure, is desirable as a site for the conservation of C. porosus in the Sabah.
Relationships between herb layer and canopy composition in a tropical rain forest successional mosaic in Singapore
Authors: Turner I. M. , Tan H. T. W. , Chua K. S.
Published: July 2009

Clusters of four circular forest plots, 0.2 ha in total area, were inventoried for canopy tree (≥30 cm gbh) and terrestrial herb floristic composition at 46 sites in the Central Catchment Nature Reserve, Singapore. The Nature Reserve covers a complex mosaic of lowland tropical forest of different successional stages, with much of the area covered in secondary forest 50–100 years old developed on exhausted agricultural soils. A total of 449 species of tree and 59 species of terrestrial herb were recorded from the clusters. Facultatively-terrestrial epiphytes were excluded from the analysis. Possible reasons for the low herb diversity are discussed. There was a marked similarity between ordinations (detrended correspondence analysis) of the clusters based on tree canopy composition weighted by species relative contribution to cluster total basal area and the herb flora composition, with a highly significant correlation between first axis scores of the two ordinations. Both ordinations showed the three clusters from freshwater swamp forest to be highly distinctive from the rest. The two forest strata exhibited a parallel response to the successional gradient, though the low diversity and patchy distribution of the herb flora blurred the distinction between primary and secondary communities more clearly seen in canopy composition.
Production of metabolic gases by nests of the termiteMacrotermes jeanneliin Kenya
Authors: Darlington J. P. E. C. , Zimmerman P. R. , Greenberg J. , Westberg C. , Bakwin P.
Published: July 2009

Nests of a fungus-growing termiteMacrotermes jeannelidischarge all their metabolic gases through a single outlet to the atmosphere. This made it possible to measure the production of metabolic gases, and the rates of water loss, for intact nests in the field. Rates of production of carbon dioxide and methane from isolated nest components (different termite castes and intact fungus combs) were measured. Using previously published nest population data and fungus comb weights in relation to nest size, the expected gas production rates for intact nests were calculated. These estimates were compared with direct observations of the gaseous outflow from intact nests. The rates were in reasonable agreement, but some nests emitted excess carbon dioxide, probably produced by respiration of tree roots and non-termite soil organisms. Large nests may have a total gas outflow of 100,000 to 400,000 1 d–1including 800 to 1500 1 d–1of CO2and 0.5 to 1.3 1 d–1of CH4. Nests lose water at the rate of up, to 13 1 d–1gross, but allowing for ambient humidity the net water loss was up to about 5 1 d–1. Some of this is metabolic water, but the larger proportion comes from the soil. Area-based estimates of gas production were made for this and two other species ofMacrotermes, but they are not accurate because the field distribution and mound density are not adequately known.
Abundance and diversity of soil macrofauna in northern Botswana
Authors: Dangerfield J. M.
Published: July 2009

The abundance and diversity of soil macrofauna were assessed in a range of vegetation types in northern Botswana. Hand-sorting of soil was used to extract all fauna greater than 2 mm body length from sandy soils in both the dry season (June) and towards the end of the single rainy season (February). Abundance varied significantly between samples from within a sampling location, within a vegetation type and occasionally between seasons. Greater densities were found in wet season samples from locations within closed canopy woodland except where permanent water was a significant feature of the habitat. Overall abundance was comparable to published estimates from more moist tropical and temperate habitats suggesting an important role for soil macrofauna in semi-arid systems. Ordinal level diversity also varied significantly within vegetation types and with season.
Erratum
Authors: Green P.
Published: July 2009

Green, P. T. (1997)

Red crabs in rain forest on Christmas Island, Indian Ocean: activity patterns, density and biomass. Vol. 13 Part 1: 17–38. On page 29 the phrase: “but a significant correlation existed across sites (r=0.81, n=44, P<0.001).” should read: “but a significant correlation existed across sites (r=-0.69, n=44, P<0.001).”

On page 33 the phrase “but the same correlation accounted for 81% of total variation when all sites were analysed together.” should read: “but the same correlation accounted for 48% of total variation when all sites were analysed together.”
Persönlichkeit und Networking: Eine Analyse mittels Interpersonalem Circumplex
Authors: Wolff Hans-Georg , Muck Peter M.
Published: July 2009

Zusammenfassung. Während mehrere Studien den positiven Effekt von Networkingverhalten, d. h. Aufbau, Pflege und Nutzung von beruflichen Kontakten, auf die Karriere belegen, existieren nur wenige Studien, die interindividuelle Unterschiede als Determinanten von Networkingverhalten untersuchen. Da Networking genuin soziales Verhalten darstellt, bietet sich zur Untersuchung dieser Fragestellung der Interpersonale Circumplex von Wiggins (z. B. Wiggins, Trapnell & Phillips, 1988 ) an, der acht Facetten interpersonalen Verhaltens auf einer sozialen Dominanzdimension und einer emotionalen Affiliationsdimension abbildet. In einer Fragebogenstudie mit N = 213 Berufstätigen zeigt sich, dass Networking signifikant positive Zusammenhänge sowohl mit der Dominanzdimension als auch mit der Affiliationsdimension aufweist. Zusätzlich zeigt eine differenzierte Betrachtung von Networkingsubskalen, dass externes (vs. internes) Networking sowie der Aufbau (vs. die Pflege und Nutzung) von Kontakten stärkere Zusammenhänge mit Dominanz aufweisen. Insgesamt legen die Ergebnisse nahe, dass Networkingverhalten durch die Kombination einer dominanten mit einer affiliativen Disposition erleichtert wird.
DAI/ZBP1 recruits RIP1 and RIP3 through RIP homotypic interaction motifs to activate NF‐κB
Authors: Rebsamen Manuele , Heinz Leonhard X , Meylan Etienne , Michallet Marie‐Cécile , Schroder Kate , Hofmann Kay , Vazquez Jessica , Benedict Chris A , Tschopp Jürg
Published: July 2009

Detection of viral nucleic acids is central to antiviral immunity. Recently, DAI/ZBP1 (DNA‐dependent activator of IRFs/Z‐DNA binding protein 1) was identified as a cytoplasmic DNA sensor and shown to activate the interferon regulatory factor (IRF) and nuclear factor‐kappa B (NF‐κB) transcription factors, leading to type‐I interferon production. DAI‐induced IRF activation depends on TANK‐binding kinase 1 (TBK1), whereas signalling pathways and molecular components involved in NF‐κB activation remain elusive. Here, we report the identification of two receptor‐interacting protein (RIP) homotypic interaction motifs (RHIMs) in the DAI protein sequence, and show that these domains relay DAI‐induced NF‐κB signals through the recruitment of the RHIM‐containing kinases RIP1 and RIP3. We show that knockdown of not only RIP1, but also RIP3 affects DAI‐induced NF‐κB activation. Importantly, RIP recruitment to DAI is inhibited by the RHIM‐containing murine cytomegalovirus (MCMV) protein M45. These findings delineate the DAI signalling pathway to NF‐κB and suggest a possible new immune modulation strategy of the MCMV.
Enhanced control of diamond nanoparticle seeding using a polymer matrix
Authors: Scorsone E. , Saada S. , Arnault J. C. , Bergonzo P.
Published: July 2009

We have improved the diamond nanoparticle seeding approach for chemical vapor deposition diamond growth in a novel process that consists of embedding the nanoparticles into a polymer matrix. We used a thin film of polyvinyl alcohol (PVA) doped with nanoparticles, which burns away during the initial stages of growth, leaving a stable distribution of nanoparticles on the substrate to initiate growth. The study shows that by varying the initial concentration of nanoparticles in the polymer preparation, it is possible to control the density of nanoparticles on the surface, over a wide range of densities. In some experimental conditions, the high densities of diamond seeding values obtained compare well with the highest values reported by the state-of-the-art. Moreover, the technique also opens up the route to very large area seeding, and this onto most types of substrates. In situ x-ray photoelectron spectroscopy (XPS) analyses showed that after pyrolysis of the polymer under H2 plasma, no significant residual carbon from the polymer was observed. Also, in the case of growth on silicon substrates, no silicon carbide was observed at the surface, showing that no reaction takes place between the polymer and the silicon surface itself. Finally, XPS also demonstrated that the polymer has not modified significantly the surface of the diamond nanoparticles after its pyrolysis. This approach improves the reproducibility of diamond nanoparticle seeding on flat surfaces and is more versatile as it may be applied to complex three-dimensional structures or cavities.
Ionization of 2,5-dimethylfuran by electron impact and resulting ion-parent molecule reactions
Authors: Jiao C. Q. , Adams S. F. , Garscadden A.
Published: July 2009

2,5-dimethylfuran (C6H8O) is an important fuel additive and a possible renewable liquid fuel for the future. This paper presents a recent Fourier transfer mass spectrometry study on the formation of ions from C6H8O by electron impact ionization and by ion-molecule reactions. Cross sections of the partial electron impact ionization have been measured and the pathways of major fragmentation channels of the parent ion have been examined. The kinetics of the reactions of C6H8O with selected product ions from electron impact and Ar+ have been studied.
Magnetic tunnel contacts to silicon with low-work-function ytterbium nanolayers
Authors: Patel R. S. , Dash S. P. , de Jong M. P. , Jansen R.
Published: July 2009

Unambiguous proof of spin transport in semiconductor spintronic devices requires a control experiment to exclude spurious signals that arise from the presence of the ferromagnetic contacts. It is shown here that insertion of a low-work-function Yb nanolayer in ferromagnetic tunnel contacts to silicon allows a selective suppression of the tunnel spin polarization for 2 nm of Yb and simultaneous control of the Schottky barrier height. The insertion of a nonmagnetic nanolayer provides a versatile method to exclude artifacts and a solution for nanoscale devices or other geometries in which the frequently employed Hanle effect cannot be applied and a control experiment did not exist.
The effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels
Authors: Kim Tae Jun , Kim Joong Kyun , Jung Jae-Chul , Jung Hae-Yoon , Whang Ki-Woong
Published: July 2009

In this work, we studied the effect of self-erase discharge on the luminous efficacy of alternating current plasma display panels. Through discharge current analysis, we observed that self-erase discharge occurred mainly between the sustain cathode and the address electrode, which has an influence on the luminous efficacy. We varied the amount and timing of the self-erase discharge in order to observe the effects on the luminous efficacy. We found that the luminous efficacy could be improved by a self-erase discharge when adjusted to occur right before the main discharge in the small gap structure. In the long gap structure, on the contrary, we could increase the luminous efficacy when we suppressed the self-erase discharge. In addition, we suggest various waveforms to control self-erase discharge as a result of our panel experiments.
Atmospheric pressure plasma jet: Effect of electrode configuration, discharge behavior, and its formation mechanism
Authors: Jiang Nan , Ji Ailing , Cao Zexian
Published: July 2009

Atmospheric pressure plasma jet (APPJ) can protrude several centers into the ambient air; therefore it holds remarkable promise for many innovative applications. The mechanism underlying this nonthermal discharge, however, remains unsettled that it has been often taken as resulting from dielectric barrier discharge or vaguely referred as streamerlike. We generated APPJ by using a quartz capillary tube with three distinct electrode configurations: conventional double dielectric electrodes for making dielectric barrier discharges, single dielectric electrode, and single bare metal electrode attached to the tube orifice. The jets generated by using the double dielectric electrodes were found consisting of three distinct parts and of different origins. The plasma jet starting from the active electrodes is essentially the propagation of streamers induced by corona discharge. With one single electrode, plasma jets can be generated in both downstream and upstream directions simultaneously; and more importantly at a significantly reduced voltage (peak-to-peak value from 3.6 kV on, at 17 kHz), this is particularly the case with the bare metal electrode configuration which also helps promote the jet velocity. The typical jet velocity at 104 m/s, the occurrence of a second streamer observed in the optical emission as well as the voltage and/or gas flow dependence of jet length can be reasonably accounted for by a streamer mechanism. These results may help steer the research into the underlying physics and will also facilitate a safer and more flexible implementation of this marvelous cold plasma source.
Enhanced transport properties in LaxMnO3−δ thin films epitaxially grown on SrTiO3 substrates: The profound impact of the oxygen content
Authors: Orgiani P. , Aruta C. , Ciancio R. , Galdi A. , Maritato L.
Published: July 2009

We report on structural, magnetic, and transport properties of LaxMnO3−δ (LMO) thin films, epitaxially grown on SrTiO3 substrates by molecular beam epitaxy. Transport properties were investigated as a function of the La/Mn stoichiometry and the oxygen content. Optimal oxygenated LMO films (with stoichiometry ratio La/Mn=0.88) show a metal-insulator transitions temperature TMI∼387 K and magnetotransport similar to those found in strontium-doped La1−xSrxMnO3 manganites compounds. Also in presence of a La/Mn slight unbalance (namely, x=0.98), LMO films show a very high TMI∼370 K. However, LMO samples with La/Mn ratio larger than one, show severely depressed conducting properties, being insulating for x>1.10. All these findings clearly demonstrate that the lanthanum deficiency is a very efficient way to dope manganites, as in the case of bivalent cation-substitution.
Controlling enhanced transmission through semiconductor gratings with subwavelength slits by a magnetic field: Numerical and analytical results
Authors: Yin Haiping , Hui P. M.
Published: July 2009

We exploit the change in the permittivity tensor of a conductor by a static magnetic field as a handle to control enhanced transmission in a semiconductor grating. Numerically, results of rigorous coupled-wave analysis (RCWA) incorporating the tensorial permittivity reveal that zeroth order transmission peaks at normal incidence can be shifted by about 15% to longer wavelengths and the peak values of transmission readily doubled when a moderate magnetic field is applied. Analytically, a single-mode theory incorporating anisotropy is developed and results are in quantitative agreement with RCWA, indicating that the tunability in the transmission stems from the waveguide mode.