Home About us Contact
|
Home About us Contact | ||
|
|
||
M Area (m + area)
Selected AbstractsCoral-reef sounds enable nocturnal navigation by some reef-fish larvae in some places and at some timesJOURNAL OF FISH BIOLOGY, Issue 3 2003J. M. Leis At Lizard Island, Great Barrier Reef, catches of fish larvae by light traps that broadcast nocturnal reef sounds (noisy traps) were compared with catches by quiet traps over two 2·5 week new-moon periods in November (XI) 2000 and January (I) 2001. Three areas were sampled: near-reef (NR, 500 m from the shore) in I, middle (M, 650 m) in I and XI and offshore (O, >1000 m) in XI. The most abundant taxa captured were Apogonidae, Blenniidae, Chaetodontidae, Lethrinidae, Mullidae and Pomacentridae. Significant differences in catch were found between areas, and a position effect was found at the O and M areas. At the NR and M areas, no taxa had significantly greater catches in quiet traps, but larvae of five taxa had significantly greater catches in noisy traps. These were (areas and times of greater catches): Apogonidae (NR; M XI), Mullidae (M I & XI), Pomacentridae (NR; M I & XI), Serranidae (M I) and Sphyraenidae (NR). At the offshore area, five taxa (Apogonidae, Blenniidae, Chaetodontidae, Mullidae and Pomacentridae) had significantly greater catches in quiet traps and only Lethrinidae had significantly greater catches in noisy traps. Thus some taxa (particularly apogonids and pomacentrids which had catches up to 155% greater in noisy traps, but also lethrinids and mullids, and perhaps others), were attracted to reef sounds at night, but this apparently varied with location and time. The sound-enhanced catches imply a radius of attraction of the sound 1·02,1·6 times that of the light. More than 65 m from the speaker,the broadcast sound levels at frequencies typical of fish hearing were equivalent to background levels, providing a maximum radius of sound attraction in this experiment. [source] Spatial analysis of an invasion front of Acer platanoides: dynamic inferences from static dataECOGRAPHY, Issue 3 2005Wei Fang It is an open question whether the invading tree species Acer platanoides is invading and displacing native trees within pre-existing forest stands, or merely preferentially occupying new stands of secondary forest growth at the edges of existing forests. Several threads of spatial pattern analyses were used to assess the invasibility of A. platanoides, and to link the invasion to the structure of a plant community in the deciduous forest of the northeastern United States. The analyses were based on maps of a contiguous 100×50 m area along an A. platanoides infestation gradient. The distribution of A. platanoides was highly aggregated and the population importance value increased from 28.1 to 38.5% according to mortality estimated from standing dead trees, while the distribution of native tree species was close to random and importance value of Quercus spp. decreased from 33.4 to 26.9% over time. The size distributions of each tree species across distance indicated that A. platanoides was progressively invading the interior of the forest while the native species (including A. rubrum) were not spreading back towards the A. platanoides monospecific patch. The null hypothesis of no invasibility was rejected based on quantile regressions. There were negative correlations between A. platanoides density and the densities of native species in different functional groups, and negative correlation of A. platanoides density and the species diversity in forest understory. The null hypothesis that A. platanoides invasion did not suppress native trees or understory was rejected based on Dutilleul's modified t-test for correlation, consistent with experimental results in the same study site. The combination of multiple spatial analyses of static data can be used to infer historical dynamical processes that shape a plant community structure. The concept of "envelop effects" was discussed and further developed. [source] Measurement sampling and scaling for deep montane snow depth dataHYDROLOGICAL PROCESSES, Issue 4 2006S. R. Fassnacht Abstract The resolution of snow depth measurements was scaled from a nominal horizontal resolution of approximately 1·5 m to 3, 5, 10, 20, and 30 m using averaging (AVG) and resampling with a uniform random stratified sampling (RSS) scheme. The raw snow depth values were computed from airborne light detection and ranging data by differencing summer elevation measurements from winter snow surface elevations. Three montane study sites from the NASA Cold Lands Processes Experiment, each covering an 1100 m × 1100 m area, were used. To examine scaling, log,log semi-variograms with 50 log-width bins were created for both of the different subsetting methods, i.e. RSS and AVG. From the raw data, a scale break, going from a structured to a nearly spatially random system, was observed in each of the log,log variograms. For each site, the scale break was still detectable at slightly greater than the resampling resolution for the RSS scheme, but at approximately twice the subsetting resolution for the AVG scheme. The resolution required to identify the scale break was still from 5 to 10 m, depending upon the location and sampling method. Copyright © 2006 John Wiley & Sons, Ltd. [source] MOVPE of InN films on GaN templates grown on sapphire and silicon(111) substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2008Muhammad Jamil Abstract This paper reports the study of MOVPE of InN on GaN templates grown on sapphire and silicon(111) substrates. Thermodynamic analysis of MOVPE of InN performed using NH3 as nitrogen source and the experimental findings support the droplet-free epitaxial growth of InN under high V/III ratios of input precursors. At a growth pressure of 500 Torr, the optimum growth temperature and V/III ratio of the InN film are 575,650 °C and >3 × 105, respectively. The surface RMS roughness of InN film grown GaN/sapphire template is ,0.3 nm on 2 ,m × 2 ,m area, while the RMS roughness of the InN film grown on GaN/Si (111) templates is found as ,0.7 nm. The X-ray diffraction (XRD) measurement reveals the (0002) texture of the InN film on GaN/sapphire template with a FWHM of 281 arcsec of the InN (0002) , rocking curve. For the film grown on GaN/Si template under identical growth conditions, the XRD measurements show the presence of metallic In, in addition to the (0002) orientation of InN layer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Are tree trunks habitats or highways?AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002A comparison of oribatid mite assemblages from hoop-pine bark, litter Abstract Oribatid mites (Acari: Oribatida) are among the most diverse and abundant inhabitants of forest soil and litter, but also have species-rich assemblages on bark and in the canopies of trees. It is unclear whether the trunk of a tree acts simply as a ,highway' for movement of mites into and out of the canopy, or whether the trunk has a distinctive acarofauna. We compare oribatid assemblages from the trunk bark of hoop pine (Araucaria cunninghamii) with those from litter collected beneath the same trees. A 1.0 by 0.5 m area of bark was sampled from three trees at each of five sites using a knockdown insecticide. A 1-L sample of leaf litter was collected as close as possible to the base of each sampled tree. Mites were extracted using Tullgren funnels, identified to genus and morphospecies, and counted. Assemblages were almost 100% distinct, with only one oribatid morphospecies (Pseudotocepheus sp.) collected from both litter and bark. Litter had a higher taxon richness than bark in total and per sample, but oribatids made up a greater percentage of the acarofauna in the bark samples. We had expected that the more consistent physical substrate of bark would be reflected in greater similarity of oribatid faunas on trunks than in litter; however, the opposite proved to be the case. We conclude that hoop-pine trunks are habitats rather than highways for oribatid mites. Based on the observed higher turnover among bark faunas, tree trunks may represent habitat islands whose colonisation by particular oribatid species is more stochastic than that of the more continuous ,sea' of litter. [source] | ||||||||||