Floristic regeneration in five types of teak plantations in Thailand     

Puangpaka Kaewkrom  Jiragorn Gajaseni  Carl F. Jordan  Nantana Gajaseni 《Forest Ecology and Management》2005,210(1-3):351-361

Teak is the most important timber species in northern Thailand, and as such, large areas of teak forest have been disturbed or become highly degraded. Teak plantations have been established on this highly degraded land, where the rate of natural recovery is relatively slow. At the study site, five mixed or pure teak plantation types have been established to ameliorate limiting soil properties in order that long-term productivity is maintained. Observations within these plantations in northern Thailand have suggested that native species become established naturally under the shade of a “nurse” plantation, one that shades out early successional species. The objective of this study was to investigate the influence of the number of species in nurse plantations on the diversity and number of seedlings representative of mature native forests that become established within the plantations. Five types of plantations were investigated: (1) Tectona grandis L.f. (T); (2) T.grandis and Tamarindus indica L. (TT); (3) T.grandis and Gmelina arborea Roxb. (TG); (4) T.grandis, T. indica and G. arborea (TTG); (5) T.grandis, T.indica and Anacardium occidentale L. (TTA). These plantations were established primarily for the production of T.grandis (teak), with the other species introduced as economic trees. The plantations were surrounded by native stands of species representative of late successional and mature teak forests. In each of the plantations studies measurements were made on species density, species diversity, and evenness of plants regenerating in the understorey. Results showed that plantations consisting of several species in the overstorey had a higher diversity of native forest species in the understorey than the single-species plantation. Mixed plantation types were also found to reduce the density of the grass Imperata cylindrica (L.) P. Beauv. Consideration of the establishment of woody species found that TG and TTA had high densities of trees and shrubs. This suggested that if the goal of management was to regenerate forest with a high diversity of tree species similar to that found in native mature forests, multiple-species plantations, especially TG and TTA, would be more effective nurse communities than the single-species plantation in providing an environment into which seeds of native species could disperse and germinate. In addition, several climax species, such as Xylia xylocarpa (Roxb.) Taub. var. kerrii (Craib & Hutch) I.C. Nielsen, Pterocarpus macrocarpus Kurz, Largerstroemia sp., Afzelia xylocarpa (Kurz) Craib, Lannea coromandelica (Houtt) Merr., Spondias pinnata (L.f.) Kurz, Garuya pinnata Roxb., Terminalia mucronata Craib & Hutchison, Diospyoros mollis Griff., Irvingia malayana Oliv. ex Benn., Milletia leucantha Kurz, Dalbergia oliviri Gamble ex Prain, Chukrasia tabularis A. Juss and Schleichera oleosa (Lour.) Oken, were found in the early stages of succession, thus indicating that some may be suitable for planting in future restoration processes in order to accelerate natural succession and provide economic returns to managers.  相似文献   

Testing a depth‐based Habitat Classification System against reef fish assemblage patterns in a subtropical marine park     

Hamish A. Malcolm  Alan Jordan  Stephen D. A. Smith 《水产资源保护:海洋与淡水生态系统》2011,21(2):173-185

• 1. The Solitary Islands Marine Park (SIMP) in New South Wales (NSW), Australia, has strong cross‐shelf patterns of reef fish assemblages on shallow reefs (<25 m). While the SIMP also contains reef at depths of up to 75 m, marine communities below 25 m are poorly described. The Habitat Classification System (HCS) used for planning the arrangement of zones in this marine park included three depth categories for reef: shallow (<25 m); intermediate (25–60 m); and deep (>60 m). However, these had not been tested to determine if they adequately reflect biotic patterns.
• 2. Using baited remote underwater video (BRUV), fish assemblages were surveyed at 56 sites spread across shallow, intermediate, and deep reefs within the SIMP to examine spatial variation between depth categories. Relationships between assemblage patterns, depth, and four additional factors considered likely to affect assemblage patterns (distance from shore, reef type, dominant benthos, and latitude), were subsequently explored using multivariate statistical methods.
• 3. Reef fish assemblages differed significantly among the depth categories. Assemblage patterns for fish were strongly correlated with depth and moderately correlated with the dominant benthic assemblage. Correlations with the other factors were generally weak. Three distinct assemblages occurred on reefs <25 m, 25–50 m and >50 m. Shallow (<25 m) reefs also displayed strong cross‐shelf patterns, supporting the results from other studies. Weaker cross‐shelf patterns were evident at intermediate depths (25–50 m).
• 4. Depth‐based and cross‐shelf categories are clearly fundamental components for a HCS that will adequately represent reef fish assemblages for conservation planning in the SIMP. Further refining the depth criteria for the intermediate/deep boundary (to 50 m) improves this representation. Further research is required to determine the wider application of the refined HCS to other marine parks in NSW and to determine how well it represents other components of biodiversity. Copyright © 2011 John Wiley & Sons, Ltd.

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Social networks in complex human and natural systems: the case of rotational grazing,weak ties,and eastern US dairy landscapes     

Kristen C. Nelson  Rachel F. Brummel  Nicholas Jordan  Steven Manson 《Agriculture and Human Values》2014,31(2):245-259

Multifunctional agricultural systems seek to expand upon production-based benefits to enhance family wellbeing and animal health, reduce inputs, and improve environmental services such as biodiversity and water quality. However, in many countries a landscape-level conversion is uneven at best and stalled at worst. This is particularly true across the eastern rural landscape in the United States. We explore the role of social networks as drivers of system transformation within dairy production in the eastern United States, specifically rotational grazing as an alternative management option. We hypothesize the importance of weak ties within farmer social networks as drivers of change. In Wisconsin, Pennsylvania, and New York, we conducted 53 interviews with confinement, low-intensity, and rotational grazing dairy producers as well as 35 interviews with associated network actors. Though confinement and grazier networks had similar proportions of strong and weak ties, confinement producers had more market-based weak ties, while graziers had more weak-ties to government agencies and other graziers in the region. These agency weak ties supported rotational graziers through information exchange and cost sharing, both crucial to farmers’ transitions from confinement-based production to grazing systems. While weak ties were integral to initial innovation, farmers did not maintain these relationships beyond their transition to grazing. Of equal importance, grazier weak-tie networks did not include environmental organizations, suggesting unrealized potential for more diverse networks based on environmental services. By understanding the drivers, we can identify barriers to expanding weak tie networks and emergent properties in order to create institutions and policies necessary for change.  相似文献   

Effects of mountaintop mining on fish distributions in central Appalachia     

Robert L. Hopkins II  Jordan C. Roush 《Ecology of Freshwater Fish》2013,22(4):578-586

Mountaintop mining with valley fills (MTM/VF) is the main source of landscape change in central Appalachia. While our knowledge of the local‐scale effects of MTM/VF on stream chemistry and biotic assemblages has recently improved, the effects at the landscape scale are less well known. In this study, we explore the effects of MTM/VF on the distributions of six fish species with contrasting ecologies in the upper Kentucky River basin, an area heavily affected by MTM/VF. Using a museum‐based data set of 239 occurrence records, land use/land cover data and boosted regression tree modelling, we were able to create robust predictive models for the focal species (AUCs = 0.82–0.93). Models explained from 41.2 to 71.9% of the variation in species distributions. We detected a marked negative influence of MTM/VF in four of the six species distribution models – with relative influences ranging from 5.9–12.7%. Species typically inhabiting faster‐flowing riffle and run mesohabitats appeared to respond more strongly to MTM/VF. Interestingly, the mean patch size of MTM/VF was more influential than the overall proportion of the watershed affected by MTM/VF in our models. Thus, our data suggest the spatial pattern of mining disturbance is very important in determining the cumulative impact of MTM/VF. Considering the central Appalachian region is a continental hot spot for freshwater biodiversity, establishing a firm understanding of the effects of MTM/VF at the landscape scale is essential if we wish to protect these natural resources.  相似文献   

THE SPHERE OF BACTERIOLOGY     

Jordan EO 《Science (New York, N.Y.)》1904,20(516):657-666

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Pharmacokinetics of aditoprim in dogs after intravenous and oral administration: a preliminary study     

H.-M. Sutter  B. Ludwig  K. D. Bremer  J.-C. Jordan  W. F. Rehm  M. Wanner 《The Journal of small animal practice》1991,32(10):517-520

The pharmacokinetics of aditoprim (2,4-diam-ino-5-[4-[dimethylamino]-3,5-dimethoxybenzyl] pyrimidine), a dihydrofolate reductase inhibitor, were studied in three eight to 17-month-old beagle dogs. The drug was alternately injected intravenously and administered orally as a tablet in two separate experiments. The doses ranged from 4–27 to 7–25 mg/kg bodyweight. The mean plasma clearance (CI) was 15-3 ml/min/kg and the mean volume of distribution (V_ss) 13-1 litres/kg. The mean plasma elimination half-life times after intravenous injection and oral administration were 11-6 and 9-6 hours, respectively. Aditoprim was readily (t_max= one to four hours) and completely absorbed from the intestinal tract (f = 89 per cent).  相似文献   

COMBINED USE OF ULTRASONOGRAPHY AND CONTRAST ENHANCED COMPUTED TOMOGRAPHY TO EVALUATE ACUTE NECROTIZING PANCREATITIS IN TWO DOGS     

Jordan Q.  Jaeger  DVM  MS  John S.  Mattoon  DVM  Shane W.  Bateman  DVM  DVSc  Federica  Morandi  DVM  MS 《Veterinary radiology & ultrasound》2003,44(1):72-79

The imaging findings in two miniature schnauzers with acute necrotizing pancreatitis are described. Both dogs were treated previously for diabetes mellitus and hyperlipidemia. Vomiting, anorexia, and lethargy were observed in both dogs at presentation. Laboratory evaluations supportive of pancreatitis included left shift, abnormally high serum amylase and lipase activities, hypocalcemia, and abnormally high serum activities of liver enzymes. Sonographically, both dogs had diffusely enlarged hypoechoic pancreatic tissue with anechoic foci compatible with necrosis, abscessation, phlegmon, and pseudocysts formation. Contrast-enhanced computed tomography (CT) findings in both dogs were compatible with pancreatic necrosis. Dog 1 was managed medically for 11 days. Follow-up CT scan in this dog disclosed decreased pancreatic size and increased contrast enhancement compatible with partial resolution of pancreatitis.  相似文献   

A procedure for the rapid screening of strawberry seedlings for resistance to Verticilluum wilt     

V. W. L. Jordan 《Euphytica》1973,22(2):367-372

Summary A technique is described which promises to be of great assistance in breeding for resistance to verticillium wilt in strawberries.Strawberry seeds were sown on moist terylene wool, covered with black polyethylene beads and suspended over aerated liquid nutrient solution. Good germination of the seeds occurred, and the seedlings developed rapidly reaching the third-leaf stage with a well-established root system after 45 days. At this stage, the seedlings were inoculated with pathogenic isolates of Verticillium dahliae Kleb, by immersing the root systems in a conidial suspension (100000/ml) for 1 h, then replacing the seedlings in the liquid nutrient solution. Wilt symptoms, i.e. leaf wilting and necrosis, were first observed on the most susceptible seedlings 21 days after inoculation. All seedlings were re-inoculated 35 days after the initial inoculation, and those which were visually healthy 50 days later were graded as tolerant and subjected to further tests.  相似文献   

Temporal variation in precipitation chemistry on the shore of the Chesapeake Bay     

Thomas E. Jordan  David L. Correll  Donald E. Weller  Nancy M. Goff 《Water, air, and soil pollution》1995,83(3-4):263-284

We studied precipitation chemistry at the Rhode River on the western shore of the Chesapeake Bay. We sampled on an event basis, beginning in 1973 for some constituents in bulk precipitation. Beginning in 1981, we also sampled wet precipitation separately from bulk precipitation. In this report, we examine temporal variability of precipitation chemistry at different time scales. Several constituents showed long-term trends. In bulk precipitation, hydronium concentration increased by 27% of its mean concentration per decade, calcium by 67%, ammonium by 28%, and nitrate by 25%, while organic nitrogen decreased by 41%, organic phosphorus by 31%, and organic carbon by 16%. In wet precipitation, ammonium increased by 33% and calcium by 100%, while magnesium decreased by 78% per decade. Concentrations differed greatly among precipitation events, increasing as the volume of precipitation decreased and as the interval since the previous event increased. Most constituents also showed marked seasonal variation. We used a regression model to predict concentrations for each event from month, precipitation volume, and the time since the previous event. We evaluated how much of the interannual variability could be explained by these factors. The event-scale model accounted for almost half of the variability among annual means for ammonium, sodium, and magnesium in bulk precipitation, and for potassium in wet precipitation. This suggests that much of the interannual variability of concentrations may result from interannual variation in the temporal distribution of precipitation.  相似文献   

Characterisation of agricultural drainage ditch sediments along the phosphorus transfer continuum in two contrasting headwater catchments     

Mairead Shore  Phil Jordan  Per-Erik Mellander  Mary Kelly-Quinn  Karen Daly  James Tom Sims  David P. Wall  Alice Rowena Melland 《Journal of Soils and Sediments》2016,16(5):1643-1654

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