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1.
Fighting between two females for a male in the hoolock gibbon 总被引:1,自引:0,他引:1
Farid Ahsan 《International journal of primatology》1995,16(5):731-737
I observed fighting between two adult females for an adult male in a group of hoolock gibbons (Hylobates hoolock)during fieldwork conducted between November 1988 and December 1990 at Lawachara in the West Bhanugach Reserve Forest, Sylhet,
Bangladesh. I discuss the history of the episodes and the consequences of fighting. 相似文献
2.
Extirpation or Coexistence? Management of a Persistent Introduced Grass in a Prairie Restoration 总被引:4,自引:1,他引:3
Abstract Introduced perennial grasses are one of the greatest constraints to prairie restoration. Herbicides suppress but do not eliminate introduced grasses, so we explored the interaction of herbicide with two additional controls: heavy clipping (to simulate grazing) and competition from native species. A 50‐year‐old stand of the introduced perennial grass Agropyron cristatum (crested wheatgrass) in the northern Great Plains was seeded with native grasses and treated with herbicide annually for 7 years in a factorial experiment. Clipping was applied as a subplot treatment in the final 3 years. Both herbicide and clipping significantly reduced the cover of A. cristatum, but clipping produced an immediate and consistent decrease, whereas herbicide control varied among years. The cover of A. cristatum decreased significantly with increasing cover of a seeded native grass, Bouteloua gracilis (blue grama), suggesting that both top‐down (i.e., grazing) and bottom‐up (i.e., resource competition) strategies can contribute to A. cristatum control. No treatment had any effect on the seed bank of A. cristatum. Even in the most effective control treatments, A. cristatum persisted at low amounts (approximately 5% cover) throughout the experiment. The cover of B. gracilis increased significantly with seed addition and herbicide, and, after 7 years, was similar to that in undisturbed prairie. The total cover of native species increased significantly with clipping and herbicide, and species richness was significantly higher in plots receiving herbicide. Clipping season had no effect on any variable. In summary, no method extirpated A. cristatum, but clipping reduced its cover by 90% and doubled the cover of native species. Extirpation might not be a realistic goal, but relatively simple management allowed coexistence of native species. 相似文献
3.
SHARON BARUCH-MORDO STEWART W. BRECK KENNETH R. WILSON DAVID M. THEOBALD 《The Journal of wildlife management》2008,72(8):1853-1862
Abstract: Management and conservation of large carnivores increasingly includes conflicts with humans. Consequently, a greater understanding of spatiotemporal trends of conflicts is needed to efficiently allocate resources and apply targeted management. Therefore, we examined spatial and temporal distribution of American black bear (Ursus americanus; hereafter, bear)-human conflicts in Colorado, USA, related to 3 conflict types (agriculture operations, human development, and road kills). We used the Getis-Ord Gi* spatial clustering statistic to describe location and assess magnitude of bear-human conflicts in Colorado during 1986–2003 and investigated temporal trends of bear-human conflicts by type. Bear-human conflicts showed distinct spatial clustering by type, and areas of high clustering overlapped conflict types. Clustering for agriculture operations conflicts had the largest overall Gi* value and overlapped counties with high sheep production. Both human development and road-kill conflict clusters were high in areas of high-quality oak (Quercus spp.)—shrub habitat in the central and southern portions of Colorado's Front Range region and near the city of Durango in southwestern Colorado. Bear-human conflicts varied by year and type but overall increased during the 18 years. Summed across years, most conflicts were related to agriculture (32%), followed by road kills (27%) and human development (24%). The greatest proportion of agriculture operations-related conflicts (76%), human development-related conflicts (36%), and road kills (47%) occurred in 1988, 1999, and 2003, respectively. Considering that bear-human conflicts in Colorado increased over time and will likely continue to increase, we suggest wildlife managers improve data collection by obtaining detailed location data, categorizing conflict types uniformly, and applying conflict regulations consistently to strengthen inference of similar analyses. We also suggest that managers target efforts to mitigate damage by focusing on areas with high clustering of conflicts. 相似文献
4.
Feng H. Huang Jameel M. Al-Khayri Edward E. Gbur 《In vitro cellular & developmental biology. Plant》1994,30(1):70-74
Summary A micropropagation system was developed forAcacia mearnsii De Wild., which is the principal source of the world’s tanbark and an excellent firewood. Shoot tips 5-mm long from 3-wk-old
seedlings germinated in vitro served as explants. The seeds were germinated on hormone-free MS medium and the shoot tips were
cultured on three-fourth-strength MS medium supplemented with combinations of auxins [indole-3-butyric acid (IBA) andα-naphthaleneacetic acid (NAA)] and cytokinins [kinetin and benzylaminopurine (BAP)]. Cultures were maintained at 25° ± 5°
C and exposed to 12-h photoperiods of cool-white fluorescent light (70 μEm−2·s−1). Multiple shoot formation was promoted by BAP at 2 mg · liter−1 (8.87μM) and higher combined with or without 0.01 mg · liter−1 (0.049μM) IBA. Cytokinins at concentrations of less than 1 mg · liter−1 combined with 0.01 to 0.1 mg · liter−1 auxin inhibited multiple shoot formation and promoted rooting of the shoot tip explants. Shoot multiplication cultures were
maintained by transferring segments of multiple-shoot clusters onto a medium containing 2 mg · liter−1 BAP and 0.01 mg · liter−1 IBA. Although higher levels of BAP promoted more multiple shoot formation, this BAP level allowed shoot elongation as well
as multiplication. In-vitro-produced shoots were induced to root on a range of NAA concentrations (0.0 to 0.8 mg · liter−1[4.3μM]) supplemented to half- or full-strength MS medium. The highest frequency of root proliferation was on half-strength MS medium
supplemented with 0.6 mg · liter−1 (3.22μM) NAA. Plantlets survived in potting soil and exhibited normal growth under greenhouse conditions. 相似文献
5.
6.
Isam A. Eltoum Saud M. Suliaman Babiker M. Ismail Magdi M. Ali Mamoun M. A. Homeida 《Biotechnic & histochemistry》1993,68(3):146-149
Three stains, Hansel's stain, alkaline erythrocin B (AEB) and naphthalene black (NB), were used to demonstrate eosinophils in the urine of patients infected with Schistosoma haematobium. Hansel's stain was superior to the other two stains; it stained eosinophils bright red and their nuclei faint blue, and they were easily differentiated from neutrophils, lymphocytes, macrophages and epithelial cells. The method using AEB took longer than Hansel's stain and 10% of the specimens were lost during staining with this method. Like eosinophils, the neutrophils took up NB stain and their nuclei stained poorly with the counterstain. 相似文献
7.
8.
The density of gibbon populations may be estimated by listening for the loud duetted songs of monogamous territorial groups. This method requires a correction factor which must be estimated from the frequency of singing of an adequate number of known study groups. The correction factor and its error were estimated for pileated gibbons (Hylobates pileatus) in Khao Soi Dao Wildlife Sanctuary in southeastern Thailand. Among 30 groups studied, 47% sang per day, on average, but the variation between days and the variation in singing frequency between groups were large. Weather conditions, especially windiness, explained some variation in singing. During an area-wide survey of groups in the sanctuary, unexplained variation in singing from day to day accounted for approximately half of the sample error of group density estimated from 1-day listening samples. Error due to day-to-day variability can be reduced by listening for more than one day at each site. Correction factors based on the cumulative proportion of groups heard during longer (2–5-day) sample periods of listening were closer to 1.0, therefore leaving less room for error and bias of the correction factor. © 1993 Wiley-Liss, Inc. 相似文献
9.
10.
Eastern black nightshade (Solanum ptycanthum; EBN) is a problematic weed partly due to its tolerance or resistance to certain herbicides. We examined the effects of an invert emulsion (IE) on the host range and weed control efficacy of the fungus Colletotrichum coccodes (NRRL strain 15547) for biocontrol of EBN. Greenhouse tests demonstrated that several other solanaceous weeds were also infected and killed, and field tests revealed >90% EBN control and dry weight reduction in plants treated with the fungus-IE formulation. These results demonstrate that this IE formulation can promote the efficacy of this bioherbicidal pathogen. 相似文献