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Selected AbstractsShort-Term and Long-Term Effects of Soil Ripping, Seeding, and Fertilization on the Restoration of a Tropical RangelandRESTORATION ECOLOGY, Issue 2010David Kinyua Rangeland degradation is a serious problem in semiarid Africa. Extensive areas of bare, compacted, nutrient-poor soils limit the productivity and biodiversity of many areas. We conducted a set of restoration experiments in which all eight combinations of soil tilling, fertilization, and seeding with native perennial grasses were carried out in replicated plots. After 6 months, little aboveground biomass was produced in plots without tilling, regardless of seeding or fertilization. Tilling alone tripled plant biomass, mostly of herbaceous forbs and annual grasses. Perennial grasses were essentially limited to plots that were both tilled and seeded. The addition of fertilizer had no significant additional effects. After 7 years, vegetation had declined, but there were still large differences among treatments. After 10 years, one tilled (and seeded) plot had reverted to bare ground, but the other tilled plots still had substantial vegetation. Only one seeded grass (Cenchrus ciliaris) was still a contributor to total cover after 10 years. We suggest that restoration efforts on these soils be directed first to breaking up the surface crust, and second to the addition of desirable seed. A simple ripping trial inspired by this experiment showed considerable promise as a low-cost restoration technique. [source] Relative Exposure Index: an important factor in sea turtle nesting distributionAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010J. Santana Garcon Abstract 1.The threatened status of many sea turtle populations and their vulnerability to coastal development and predicted climate change emphasize the importance of understanding the role of environmental factors in their distribution and ecological processes. The factors driving the distribution of sea turtle nesting sites at a broad spatial scale is poorly understood. 2.In light of the lack of understanding about physical factors that drive the distribution of turtle nesting, the relationship between nesting site distribution and the exposure of coastal areas to wind and wind-generated waves was analysed. To achieve this, a Relative Exposure Index (REI) was developed for an extensive area in north-eastern Australia and values of the index for nesting sites of five different sea turtle species and randomly selected non-nesting sites were compared. 3.Although there are differences between species, the results show that sea turtles nest in areas of higher REI values suggesting that wind exposure is related to the spatial distribution of sea turtle nesting sites, and it may also influence nest site selection in female turtles and/or the dispersal of hatchlings towards oceanic currents. 4.The combination of these results with further research on other driving environmental factors, like oceanic currents, has the potential to allow for the identification and prediction of future nesting sites, for which conservation and management may become essential. Copyright © 2009 John Wiley & Sons, Ltd. [source] HALF A CENTURY OF CROPLAND CHANGE,GEOGRAPHICAL REVIEW, Issue 3 2001JOHN FRASER HART ABSTRACT. The census concept of total cropland is a better measure of effective agricultural land than is total farmland, which includes extensive areas of woodland owned by farmers. The cropland area of the United States dropped from 478 million acres in 1949 to 431 million acres in 1997, for a net loss of less than 1 million acres, or roughly one-fifth of 1 percent, per year. In the midwestern agricultural heartland most counties changed less than 5 percent in the half-century, and more counties gained than lost. The West was a crazy quilt of change, and in the East most counties lost more than 10 percent. Major metropolitan counties lost a few percentage points more than did adjacent areas, but at a lower rate per capita than the nation as a whole. Most of the loss of cropland was in marginal agricultural counties with soils of low inherent fertility and topography unsuited to modern farm machinery. The loss of cropland to suburban encroachment may be cause for intense local concern, but attempts to thwart development cannot be justified on grounds of a net national loss of good cropland. [source] Climate change and grasslands through the ages: an overviewGRASS & FORAGE SCIENCE, Issue 2 2007L. 't Mannetje Summary Change from cool to warm temperatures and vice versa have occurred throughout geological time. During the Jurassic and Cretaceous periods (206,65 million years ago, Ma) the climate was more uniformly warm and moist than at present and tropical rainforests were widespread. Grasses evolved during the Jurassic period and they expanded greatly as the climate differentiated with reduced rainfall and temperatures. C4 -grasses probably arose during the Oligocene period (24,35 Ma). During the Miocene period (23·8,5·3 Ma) grasslands expanded into huge areas (e.g. prairies in the USA, steppe in Eurasia, and pampas and llanos in South America). During the Quaternary period (1·8 Ma till now) some twenty-two different ice ages with periodicities of about 100 000 years occurred. Eighteen-thousand years ago, north-western Europe had a polar climate with tundra vegetation and the Mediterranean region was covered by steppe. During that time Amazonia was so dry that it was covered in extensive areas of savanna and the Sahara expanded rapidly. Only in the last 10 000 years has a closed rainforest covered the Amazonian region again. However, 9000 years ago a brief period of global warming caused excessive rains, which caused the sea and river levels to rise in north-western Europe with tremendous loss of life. The present period of extreme dryness in the Sahara only started some 5000 years ago and then the desert expanded rapidly into the Sahel. Before that the Sahara was covered by steppe. Global warming took place between about ad 900 and about ad 1200 or 1300 just before the Little Ice Age (1550,1700 ad). The article concludes with a description of temperature and vegetation changes that are occurring in Europe at present. It is predicted that C4 -grasses, which are already present in southern Europe, will further expand but that, in the short term, land abandonment will have much more deleterious effects than temperature change due to increased wild fires, loss of biodiversity and desertification. [source] Necrobiotic xanthogranuloma with paraproteinemia; an atypical caseJOURNAL DER DEUTSCHEN DERMATOLOGISCHEN GESELLSCHAFT, Issue 1 2008Yoshiyuki Ito Summary Necrobiotic xanthogranuloma (NXG) is a rare marker for paraproteinemia. An 86-year-old woman had a one year history of large red-yellow to brown annular plaques involving all limbs. Biopsies showed a non-palisading granuloma with numerous multinucleated giant cells showing prominent elastophagocytosis and extensive areas of necrobiosis throughout the entire dermis. Complete loss of elastic fibers was observed in the central atrophic area of an annular plaque. Small vascular thromboses were also present. Laboratory findings revealed paraproteinemia of IgG-lambda type. Immunohistochemical staining detected the presence of roughly equal numbers of IgG-lambda-and IgG-kappa-staining plasma cells in the dermis. We diagnosed NXG with paraproteinemia with monoclonal gammopathy (IgG-lambda type) of unknown significance. [source] Landscape complementation and food limitation of large herbivores: habitat-related constraints on the foraging efficiency of wild pigsJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003David Choquenot Summary 1The effect that the proximity of habitats containing essential resources has on animal abundance at large spatial scales is called landscape complementation. Landscape complementation can influence interaction between large herbivores and their food resources where the proximity of habitats containing essential resources constrains their foraging or demographic efficiency. 2We tested the effect that the proximity of a thermal refuge (riverine woodlands) had on interaction between wild pigs and their food resources (pasture). The numerical response of pigs (Sus scrofa L.) (estimated as r quarter,1) to pasture biomass was contrasted between four sites that were progressively more isolated from a major floodplain containing extensive areas of riverine woodland. To test whether proximity to riverine woodlands affected the numerical response of pigs through a constraint on foraging efficiency, we contrasted the numerical response of pigs between the four areas as pasture biomass declined. To test whether pigs exploited riverine woodlands primarily as a thermal refuge, we contrasted the numerical response of pigs between the four areas in different seasons. 3We found that although pasture biomass was similar in the four areas, r was lower than expected for given pasture biomass on the two areas further away from riverine woodlands. We also found that while the effect that proximity to riverine woodlands had on the numerical response of pigs became more pronounced when pasture biomass was low, it was not significantly affected by season. 4These results suggest that the need to access riverine woodlands compromises the foraging efficiency of wild pigs when the distance to this habitat is relatively high, but that the need to access this habitat may not be purely related to thermoregulation. 5We developed a simple mechanistic model that allows the effects of landscape complementation on herbivore foraging and demographic efficiency to be estimated, and used the model to predict the effect that proximity to riverine woodlands would have on variation in pig density. The model suggests that wild pigs cannot persist in areas more then 10 km from extensive riverine woodlands, unless those areas are periodically re-colonized. This suggests that at the margin of their range around inland river systems, given locations that can be occupied by wild pigs will vary temporally between being sources, pseudosinks and sinks. [source] Peat bog restoration by floating raft formation: the effects of groundwater and peat qualityJOURNAL OF APPLIED ECOLOGY, Issue 3 2002Alfons J. P. Smolders Summary 1,A prerequisite for the restoration of desiccated bog remnants is rewetting the peat surface. Frequently in Europe, extensive areas are flooded in order to maximize water retention, and growth of peat mosses is often observed in the shallow zones. In deeper waters, regeneration appears to depend on whether residual peat will become buoyant and form floating rafts. 2,In order to study the initial stages of peat bog regeneration, conditions required for peat buoyancy were studied on peat monoliths collected from three cut-over bog remnants in the Netherlands. The effects of different peat quality and water chemistry on buoyancy of the monoliths, as well as growth of Sphagnum cuspidatum and nutrient availability, were followed in a glasshouse experiment. 3,Both groundwater and peat quality affected the buoyancy of the monoliths and the growth of S. cuspidatum. When groundwater containing bicarbonate (1 mmol l,1 HCO3,, pH 6·0) was applied, the pH of peat monoliths increased from c. 3·5 to c. 4·5 due to acid buffering. As a result, two of the peat types became more buoyant and the concentration, production and emissions of methane (CH4) increased. It was concluded that the increase in CH4 production, induced by the increased pH, was responsible for the buoyancy. 4,When groundwater contained both HCO3, (1 mmol l,1) and sulphate (1 mmol l,1), pH was further increased to approximately pH 5·0 due to alkalinity generated by the SO42, reduction process. CH4 production, however, decreased because of interference from the SO42,, as confirmed in additional incubation experiments. Phosphate concentrations, however, greatly increased in the HCO3,/SO42, addition treatment due to the interaction between sulphide and iron phosphate precipitates. 5,In one of the peat types, treatments did not influence CH4 production and buoyancy, most probably because of its low decomposability. The chemical characteristics of the peat, notably the concentrations of lignin and soluble phenolics as well as C:N, C:P and C:K ratios, were all higher than in the other two peat types. 6,The increase of S. cuspidatum biomass during the experiment appeared to be strongly related to the N:P ratios of the capitula, which differed considerably among the three peat types. 7,We conclude that when bog remnants are inundated the prospects for bog regeneration are largely determined by peat quality and water chemistry. Peat mats with low concentration of lignin and phenolics and low C:N ratios are most likely to become buoyant in water with a higher pH, so providing suitable environments for Sphagnum species. When peat quality is inadequate, either shallow inundation or the addition of suitable peat from elsewhere is indicated. [source] Spatial synchrony in field vole Microtus agrestis abundance in a coniferous forest in northern England: the role of vole-eating raptorsJOURNAL OF APPLIED ECOLOGY, Issue 2000S.J. Petty 1.,The regional synchrony hypothesis (RSH) states that synchrony in microtine abundance over large geographical areas is caused by nomadic avian predators that specialize on small mammals for food. This has proved a difficult hypothesis to test because experiments at an appropriate scale are almost impossible. 2.,We used the decline of the most abundant, nomadic vole-eating raptors in an extensive conifer forest in northern England (Kielder Forest) as a natural experiment to evaluate their influence on synchronizing voles at different spatial scales. Field vole populations fluctuated on a 3,4-year cycle of abundance, similar to the periodicity in central Fennoscandia. 3.,Over a 23-year period, the combined numbers and density of kestrels and short-eared owls significantly declined. If these raptors were responsible for synchronizing vole abundance, the decline should have been associated with a decrease in synchrony. We could find no change in synchrony during the period of the greatest decline in kestrel and short-eared owl numbers (1980,97). 4.,In Kielder, vole abundance has been shown to change in a wave-like manner, with synchrony in the direction of the wave being 5,10-fold smaller than that reported in Fennoscandia. Tawny owls are sedentary and the most abundant vole-eating raptor in our study area, and might have an equalizing influence on vole abundance over smaller areas if they foraged in a density-dependent manner and responded functionally to increasing vole density. If this was the case, spatial variability in vole density should have been less in occupied than unoccupied owl territories, especially in years of low vole density when owls could take a larger proportion of the standing crop of voles. Even though tawny owls caught a significant proportion of the vole population, we could find no difference in variation in vole density between owl territories that were unoccupied, occupied with no breeding attempt, or occupied with a successful breeding attempt. 5.,We conclude that the small-scale synchrony in field vole abundance is unlikely to be caused by avian predators. Instead, it is more likely to be related to the pattern of clear-cutting that has developed in Kielder, which restricts vole dispersal. If this assumption is correct, we would predict more widespread synchrony in vole abundance in first-generation forests when extensive areas are planted over short periods of time, and this is supported by anecdotal evidence. These conclusions indicate that foresters may be able to manipulate the spatial dynamics of voles and vole predators by varying patch sizes within forests. [source] Beneficial effect of enalapril in spontaneously hypertensive rats cardiac remodeling with nitric oxide synthesis blockadeJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2002R. L. de Andrade Zorzi Abstract Aims. To study the efficiency of an angiotensin converting enzyme inhibitor on the blood pressure (BP) and the myocardium remodeling when spontaneously hypertensive rats (SHRs) are submitted to nitric oxide synthesis (NOs) blockade (with L-NAME) and simultaneously treated. Methods. Young adult male SHRs were separated in four groups (n = 5) and treated for 20 days: Control, L-NAME, L-NAME+Enalapril, and Enalapril. The alterations of the BP, heart mass/body mass ratio and stereological parameters for myocytes, connective tissue and intramyocardial vessels were studied among the groups. Results. The SHRs with NOs blockade showed a great modification of the myocardium with extensive areas of reparative and interstitial fibrosis and accentuated hypertrophy of the cardiac myocytes (cross sectional area 60% higher in animals taking L-NAME than in Control SHRs). Comparing the SHRs with NO deficiency (L-NAME group), the Control SHRs and the Enalapril treated SHRs significant differences were found in the BP and in all stereological parameters. The NO deficiency caused an important BP increment in SHRs that was partially attenuated by Enalapril. This Enalapril effect was more pronounced in Control SHRs. A significant increment of the intramyocardial vessels was observed in NO deficient SHRs and Control SHRs treated with Enalapril demonstrated by the stereology (greater microvascular densities in treated SHRs). Conclusion. Enalapril administration showed a beneficial effect on vascular remodeling and myocardial hypertrophy in SHRs. In SHRs with NO blockade, however, the beneficial effect of Enalapril occurred only in vascular remodeling. [source] Spatial pattern of Quercus ilex and Quercus pubescens recruitment in Pinus halepensis dominated woodlandsJOURNAL OF VEGETATION SCIENCE, Issue 4 2000T.R. Lookingbill Abstract. European Mediterranean landscapes have undergone changes in structure in recent years as a result of widespread agricultural land abandonment and cessation of silvicultural regimes. Studies concerning the regeneration dynamics of dominant forest species have become critical to the prediction of future landscape trends in these changing forest stands. Quercus ilex (holm oak) and Q. pubescens (downy oak) are considered to be the terminal point of secondary succession in extensive areas of the Mediterranean region. Recent studies, however, have suggested the existence of recruitment bottlenecks in oak genet populations as a result of current management regimes. In this study, we present evidence of the successful establishment of Q. ilex and Q. pubescens in Pinus halepensis (Aleppo pine) woodlands. We investigate the distribution patterns and spatial relationships among oak recruits and resident pines. Established P. halepensis is randomly distributed throughout the study area. Oak seedlings are positively associated with pine trees, suggesting that P. halepensis individuals provide safe sites for oak genet recruitment. We show that spatial patterns of recruitment are in agreement with the general model of spatial segregation described for other Mediterranean plant communities, with seeder species colonizing large openings after disturbance, followed by a more aggregated recruitment of resprouter species. [source] Magnetic resonance imaging as a tool to examine the neuropathology of multiple sclerosisNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 2 2004L. Bö Magnetic resonance imaging (MRI) has significantly extended the understanding of multiple sclerosis (MS), owing to its ability to sensitively depict the dynamics of the disease process in vivo. The subject of this review is the use of MRI in the post-mortem setting, with emphasis on how it may be used to improve the specimen selection process at autopsy. Lesions with active demyelination are highly interesting in the study of MS pathogenesis, but are rare in a typical autopsy material of chronic MS. The yield of MS lesions in autopsy specimen selection can be increased by the use of MRI-guided tissue sampling, as a significant proportion of abnormalities detected by post-mortem MRI are not macroscopically visible/palpable. The majority of these MRI abnormalities have been found to represent either discrete areas of microglial activation with no demyelination (so-called (p)reactive lesions), or active demyelinating MS lesions by further histopathological examination. The presence and extent of MS pathology outside of the focal demyelinated lesions is more readily appreciated by MRI-guided specimen sampling, as has been shown in the study of extensive areas of partial myelin loss in the spinal cord. A further advantage of MRI-guided specimen sampling is the ability to use three-dimensional and quantitative measures. The potential of correlating these with histopathological data may be further exploited in the future. The technical procedure for MRI-guided tissue sampling at autopsy is presented, and the limitations of the technique are discussed. [source] Patterns and Ecological Correlates of Pollination Modes Among Bromeliad Communities of Andean Forests in BoliviaPLANT BIOLOGY, Issue 6 2000M. Kessler Abstract: We studied the distribution of five pollination modes (ornithophily, chiropterophily, entomophily, mixed/unspecific, autogamy) among the bromeliad communities of 74 forest sites in the Bolivian Andes and adjacent lowlands. We recorded a total of 188 bromeliad species belonging to 16 genera, including 115 (61 %) ornithophilous, 14 (7 %) chiropterophilous, 45 (24 %) entomophilous, 8 (4 %) autogamous, and 6 (3 %) species with mixed pollination mode. Ornithophily was the dominant pollination mode at high elevations and in wet regions, while entomophily dominated in arid regions. Chiropterophily was most common in wet lowland regions, autogamy in arid sites, and mixed pollination in the lowlands. Pollination modes were rather evenly distributed among life-forms and ecophysiological types, with a few exceptions: terrestrial forest bromeliads, mostly belonging to unarmed, soft-leaved taxa, had a prevalence of entomophily and few ornithophilous species; large, spiny terrestrial bromeliads of Puya and Bromelioideae showed a prevalence of ornithophily; and autogamy was restricted to the neotenous subgenus Diaphoranthema of Tillandsia. The restriction of unspecific pollination modes to the lowlands is hypothesized to be related to the abundance of pollinators, eliminating the need for specialized co-evolution, or to the overall rarity of bromeliads in this environment, precluding the development of specialized relationships. The low representation of entomophilous species in small dry forest regions compared to extensive areas is assumed to be due to the seasonal influx of hummingbirds and/or bats. Overall, the frequency of individual pollination modes was related to the availability of pollinators as determined by temperatures and humidity. [source] Genetic structure and random amplified polymorphic DNA diversity of the rapidly declining Angelica palustris (Apiaceae) in Eastern Germany in relation to population size and seed productionPLANT SPECIES BIOLOGY, Issue 3 2005ANKE DITTBRENNER Abstract Angelica palustris (Besser) Hoffm. (Apiaceae) is a rare wetland community species that is currently rapidly declining because of changes in land use. In the present study, we analyzed patterns of random amplified polymorphic DNA (RAPD) variation among nine populations of A. palustris in Germany to assess its overall genetic condition. We aimed to examine the level of genetic diversity as well as its local differentiation in relation to population size and geographic distancing between populations. Results achieved from ,ST statistics and amova indicated that most of the variability is distributed among individuals within the populations (57.7%), whereas among-population variation accounted for 30.2% of the variation. Variation between regions was 12.1%. This corresponds to the results of a multivariate analysis based on the asymmetric Soerensen similarity, which also suggested a strong population differentiation, as would be expected from a short-lived species with limited seed dispersal capacities that had never covered extensive areas in Eastern Germany. Consistently the geographic differentiation was not reflected in the RAPD profile. Significant correlations were noted between population size and the percentage of polymorphic loci (P < 0.05) and genetic diversity (P < 0.05). An analysis of seed production showed positive relationships between average seed number and levels of genetic variation. Our results support concerns regarding the loss of genetic diversity in endangered plant populations because this process might have harmful effects on reproductive fitness. [source] | ||||||||||||||||