Showing papers in "Journal of Applied Ecology in 1990"

Conservation for the twenty-first century

Abstract: K.O. Wilson: Conservation: the next hundred years David Western: Population, resources and environment in the 21st century Tarzie Vittachi: Demographics and socioeconomics: the people factor David Western: Conservation biology Jared Diamond: Overview of recent extinctions Norman Myers: A major extinction spasm: predictable and inevitable? Storrs Olson: Extinction on islands: man as a catastrophe Ian Atkinson: Introduced animals and extinctions David Woodruff: The problems of conserving genes and species Robert C. Vrijenhoek: Population genetics and conservation John Eisenberg & Larry Harris: Conservation: a consideration of evolution, population and life history Sam McNaughton: Ecosystems and conservation in 2100 Brian Walker: Diversity and stability in ecosystems conservation David Western: Why manage nature? David Hales: Changing concepts of national parks Alvaro Ugalde: An optimal parks system Jeffrey McNeely: Protected areas and human ecology: how national parks can contribute to sustaining societies of the 21st century David Western: Conservation without parks: wildlife in the rural landscape Larry Harris & John Eisenberg: Enhanced linkage: necessary stops for success in conservation of faunal diversity Bryn Green: Conservation in man-made landscapes William G. Conway: The prospects for sustaining species and their evolution Mark Stanley Price: Reconstructing ecosystems Mary Pearl: the human side of conservation Eugene Hargrove: Conservation and human values Holmes Rolston: Biology without conservation: an environmental misfit and contradiction in terms Bryan Norton: The cultural approach to conservation biology David Ehrenfeld: Hard times for diversity Perez Olindo: A planner's perspective Arturo Tarak: A national perspective Reuben Olembo: International perspectives in conservation planning Michael Bean: Conservation legislation in the century ahead Mary Pearl: How the developed world can promote conservation in emerging nations James Lee: Conservation in a world in search of a future Lester Crystal: American broadcast journalism: its coverage of conservation crises Michael Soule: Conservation biology in the 21st century.

Changing landscapes: an ecological perspective.

Abstract: "Landscape Ecology" is an emerging science of gaining momentum over the past few decades in the scientific as well as in the planning-management worlds. Although the field is rooted in biology and geography, the approaches to understanding the ecology of a landscape are highly divers. This hybrid vigor provides power to the field. One can no longer view a local ecosystem or land use in isolation from global areas and time frames. The surrounding landscape mosaic and the flows and movements in a landscape must be considered, especially the linkage between humans requiring resources provided by nature, the constraints on their use as well as the responding landscape.

Chemical Mediation of Coevolution

Abstract: When writing can change your life, when writing can enrich you by offering much money, why don't you try it? Are you still very confused of where getting the ideas? Do you still have no idea with what you are going to write? Now, you will need reading. A good writer is a good reader at once. You can define how you write depending on what books to read. This chemical mediation of coevolution can help you to solve the problem. It can be one of the right sources to develop your writing skill.

Treating cattle with ivermectin : effects on the fauna and decomposition of dung pats

Abstract: The old-growth, multiple ages, multispecies natural forest has played an important role in terrestrial ecosystem dynamics model and the global carbon budget. However, carbon fluxes of old forests in subtropical regions are rarely reported in China. In the present study, the CO₂ flux of an old-growth subtropical evergreen and deciduous broad-leaved mixed forest was observed using eddy covariance technique in Tianmu Mountain of Zhejiang Province. Based on the data sets which were observed from July 2013 to June 2014, the variations of net ecosystem exchange (NEE), eco-system respiration (Re), and gross ecosystem exchange (GEE) were analyzed. The results showed that during the study period, the monthly NEE all had a negative value (acted as a carbon sink) except for December and February (acted as a carbon source). The average monthly NEE was -61.52 g C · m⁻², the monthly carbon sequestration showed a double-peak curve and the maximum carbon sink was -149.40 g C · m⁻², which occurred in June while the maximum carbon source was 23.45 g C · m⁻², which occurred in February. The maximum of monthly mean CO₂ flux occurred in June with a value of -0.98 mg · m⁻² · s⁻¹, while the minimum value occurred in December with a value of -0.35 mg · m⁻² · s⁻¹. The NEE at the time point of positive and negative conversion had typical seasonal characteristics. The yearly NEE, Re, and GEE were -738.18, 931.05 and -1669.23 g C · m⁻², respectively. Compared with other forest ecosystems located at the similar latitude, the carbon fixation of the old-growth forest was larger, likely due to its complicated structure within the canopy and the presence of young-growth regeneration and successional stands. This showed that other than in carbon neutral, old-growth forests of Tianmu Mountain in subtropical China had a strong capability in carbon sequestration.

The influence of flooding regimes on forest distribution and composition in the Tana River floodplain, Kenya

Abstract: (...) The results suggest that floodplain forest growth can only be sustained at or above elevations which receive floods of a critical maximum frequency and duration. Tolerance to flooding thus seems to be a major determinant of forest distribution. A series of dams have been constructed in the Tana headwaters. The probable changes to the floodplain forest resulting from a new hydrological regime are discussed. Low regeneration levels in the Tana floodplain forest may reflect dependence on periodic favourable hydrological conditions for regeneration (...)

Destruction of wetland habitats by lesser snow geese: a keystone species on the west coast of Hudson Bay.

Abstract: SUMMARY (1) Large numbers of lesser snow geese breed in colonies in coastal brackish and freshwater marshes in the lowlands along the west coast of Hudson Bay. Where colonies are present, the geese determine the structure and species composition of the coastal plant communities. (2) During recent decades, substantial increases in the number of birds have occurred, resulting in the outward spread of the colonies into new areas which are used for nesting, feeding and moulting. (3) Patterns of foraging vary in space and time. In spring at the nesting sites, before the onset of above-ground growth of vegetation, adult geese grub for roots and rhizomes of graminoid plants in relatively dry areas, and in wet habitats they eat the swollen bases of shoots of sedges, particularly Carex aquatilis. In summer, adults and goslings graze intensively on leaves of grasses and sedges over wide areas. Swards dominated by Carex subspathacea are produced in brackish marshes, but the leaves of graminoids of the freshwater sedge meadows are also clipped extensively. (4) Grubbing of vegetation by geese each spring creates bare areas (1-5 mi2) of peat and sediment. The increased numbers of birds have increased the scale of disturbance, with large areas now stripped of vegetation, particularly by the McConnell River. At some sites, erosion of peat has exposed the underlying glacial gravels. There is little likelihood that the vegetation which re-establishes will closely resemble the original. Further expansion of goose colonies in this region may be limited by available food resources.

Shrub layer dynamics under different herbivore densities in an arid savanna, Botswana.

Abstract: (1) A grazing experiment in an arid savanna in Botswana examined heavy and moderate grazing by cattle. The dynamics of the shrub layer were followed for 5 years. (2) In the areas with no and moderate grazing, shrub densities fluctuated but showed no consistent change, while density increased with heavy grazing. At the end of the experiment, density, cover, total mass, shoot and leaf mass and leaf area of shrubs were higher in the area under heavy grazing than in those under no or moderate grazing. There were no differences in shrub abundance between ungrazed and moderately grazed areas. (3) The increase in shrub abundance with heavy grazing was accounted for by two of the five recorded species, Acacia mellifera and Grewia flava. Both are shallow rooted suggesting that they were favoured by an increase in water availability in the surface soil following overgrazing of the grass layer.

Stomatal and boundary-layer conductances in an Amazonian terra firme rain forest.

Abstract: (1) Diurnal measurements of stomatal conductance (gs) and boundary layer conductance (ga) were made through the canopy at a primary rain forest site in the Amazon Basin, Brazil, in three experimental seasons and over a range of soil water conditions. (2) Maximum values of g, were observed near the top of the 40 m deep canopy and they declined towards the forest floor. Observed values of ga also decreased through the canopy, but a slight maximum occurred 20 m from the ground. (3) In the upper part of the tree canopy the diurnal maximum in gs occurred in the midmorning and the value declined for the remainder of the day. This peak was less marked lower in the canopy, and was not present near the forest floor. (4) g, was correlated negatively with specific humidity deficit (D) and positively with solar radiation (S). The response of gs to D increased with increasing S at all but the highest values of S. (5) The lowest values of gs occurred at the same time as the lowest soil water potentials, although these corresponded to only moderate soil water deficits.

An Introduction to the Physiology of Crop Yield.

Abstract: Preface Acknowledgements Introduction Part 1 Fundamental principles of crop physiology Interception of solar radiation by the crop canopy Photosynthetic efficiency - photosynthesis and photorespiration Photosynthetic efficiency - respiration Dry-matter partitioning Part 2 Crop case histories Temperate cereals Potatoes Grassland Part 3 Crop Simulation Mathematical models and crop physiology References Index

Illegal exploitation of black rhinoceros and elephant populations : patterns of decline, law enforcement and patrol effort in Luangwa Valley, Zambia

Abstract: (1) At the start of the 1980s, conservationists in Africa gave a high priority to protecting the largest remaining populations of black rhinos and elephants from illegal exploitation. This study documents the demise of both species in the Luangwa Valley, Zambia. (2) Sightings and captures by law enforcement patrols were used to monitor (i) changes in rhino and elephant numbers during 1947-69 and 1979-85; (ii) their motivation and success at capturing offenders involved in illegal activity during 1979-85; and (iii) the distribution of illegal activity in relation to patrol effort and the abundance of rhinos and elephants during 1979-85. Sightings were analysed with log-linear models and population trends for elephants and rhinos so derived compared favourably with accurate methods of counting both species. (3) Elephants increased at an instantaneous annual rate of +0 06 from 1947 to 1969, causing the 'elephant problem' of the 1960s and 1970s. Sightings of rhinos and elephants were negatively correlated in different areas of Luangwa Valley during this period. (4) The overall rates of decline of rhinos and elephants were-0 63 and -0 12 during 1979-85, following rapid increases in the price of rhino horn and ivory on world markets. These declines arose from illegal activity as most skulls had their trophies removed. (5) Sightings of rhinos and elephants changed at different rates in each area of Luangwa Valley. Rhinos declined in all areas at rates ranging from -0 99 to -0 24, but elephants increased in some areas due to local immigration. By 1985 there was a positive correlation between sighting rates of rhinos and elephants. (6) Despite these large declines in rhino and elephant numbers, law enforcement units were motivated and successful at capturing offenders involved in illegal activity in Luangwa Valley during 1979-85. (7) Most staff in law enforcement units spent about half each month patrolling on foot under remote and difficult conditions. Offenders caught on foot patrols provided information for making arrests more successfully on vehicle patrols. Arrests were made cost-effectively and about 40% of operating costs were recovered from found and seized ivory. (8) Offenders involved in less serious illegal activity originated from most areas of Luangwa Valley. In contrast, well-organized armed gangs exploited rhinos and elephants and originated from areas outside Luangwa Valley. Offenders who exploited rhinos and elephants were delivered sentences that did not uphold wildlife laws. (9) Signs of illegal activity, such as poachers, their camps and fresh carcasses, were encountered throughout the year. Encounters of illegal activity generally showed consistent trends across years within different areas, but most trends in illegal activity were complex rather than exponential across time. (10) Increased patrol effort affected levels of illegal activity. Poachers and camps tended to be seen less often in more heavily patrolled areas even though these held a relative abundance of quarry. Finds of fresh carcasses declined with rhino and elephant numbers, but also were found less frequently in areas of heavier patrol effort. (11) Differences in patrol effort were related directly to rates of change in rhino and elephant abundance, and were sufficient to create areas of relative safety which

Animals in primary succession : the role of fauna in reclaimed lands

Abstract: Part 1 General introduction to topic: fauna studies and land reclamation technology, a review of the history and need for such studies, J.D.Majer. Part 2 Functional aspects of fauna in reclaimed land: the influence of fauna on soil structure, Ian Abbot the role of fauna in nutrient turnover, B.R.Hutson the influence of fauna on plant productivity, Richard P.Urbanek the influence of fauna on plant species composition, R.J.Whelan long-term colonization of fauna in reclaimed land, J.D.Majer. Part 3 Practical aspects of fauna in reclaimed land: a methodology for collecting standardized biological data for planning and monitoring reclamation and rehabilitation programmes, N.T.Allen design of reclamation to encourage fauna, S.R.Viert the influence of substrate toxicity on soil macrofauna return in reclaimed land, Wei-Chun Ma and H.Eijsackers the reclamation of lands for agricultural grazing, W.A.Laycock wetland habitat development on mined lands, J.R.Newrot the reclamation of lands for outdoor recreation, David E.Samuel. Part 4 Case studies: the return of soil fauna to coal-mined areas in the German Democratic Republic, W.Dunger sixteen years of fauna invasion and succession in the Lauwerzeepolder, Jan Meijer the return of vertebrate fauna to surface coal-mined areas in Tennessee, Dale K. Fowler the return of the vertebrate and invertebrate fauna to bauxite-mined areas in south-western Australia, D.Nichols et al soil biota and plants in the rehabilitation of degraded agricultural soils, C.A.Parker. Part 5 Synthesis: colonization of rehabilitation land by animals - an ecologist's overview, H.Recher. Part 6 Bibliography: bibliography of fauna studies in reclaimed lands, J.Butcher et al.

The social badger : ecology and behaviour of a group-living carnivore (Meles meles)

Abstract: List of plates Introduction The badgers of Wytham Aims and methods of the study in Scotland Food and available resources Foraging behaviour Territories and numbers in the clans Badgers in captivity Social organization Observations on communication Some conclusions References Index

Bacterial genetics in natural environments.

Abstract: Section I: General Aspects of Studying Genetics in Nature.- 1 Genetic approaches to the study of gene transfer in microbial communities.- 2 Factors influencing the dissemination of DNA by bacterial conjugation.- 3 Factors limiting gene transfer in bacteria.- 4 Phage genetics and ecology.- Section II: Aquatic Habitats.- 5 Plasmid transfer in the epilithon.- 6 Laboratory standardised biofilms as a tool to investigate genetic transfers in water systems.- 7 Survival of laboratory and freshwater bacteria carrying an extrachromosomal xylE gene in freshwater microcosms.- 8 Gene transfer in marine environments.- 9 Gene transfer in activated sludge.- Section III: Terrestial Habitats.- 10 Plasmid transfer between soil bacteria.- 11 Gene transfer in polluted soils.- 12 The potential for gene exchange between rhizosphere bacteria.- 13 The use of a Sesbania rostrata microcosm for studying gene transfer among microorganisms.- 14 Plasmid transfer to indigenous bacteria in soil and rhizosphere: problems and perspectives.- 15 Use of wide host range promoters to monitor the fate of recombinant DNA in soil.- 16 The role of soil bacteria in risk assessment analysis.- 17 Gene transfer between streptomycetes in soil.- 18 The survival of genetically engineered microorganisms and bacteria on inanimate surfaces and in animals.- Section IV: Conclusions.- 19 Plasmid transfer and the release of genetically engineered bacteria in nature: a discussion and summary.

Species-Specific Differences in the Net Assimilation of Zinc, Cadmium, Lead, Copper and Iron by the Terrestrial Isopods Oniscus asellus and Porcellio scaber

Abstract: SUMMARY (1) Specimens of the woodlice Oniscus asellus L. and Porcellio scaber Latreille (Crustacea: Isopoda) were collected from a contaminated deciduous woodland (Haw Wood) 3 km downwind of a primary zinc, lead and cadmium smelting works, and from a similar but uncontaminated site (Wetmoor Wood). They were maintained for 20 weeks in factorial combination on leaves of field maple (Acer campestre L.) collected from the litter layer at the two sites. (2) Twelve isopods were removed from each of the eight experimental tanks every 4 weeks and dissected into three 'tissue compartments' (hepatopancreas, gut and rest) in which the concentrations of zinc, cadmium, lead, copper and iron were determined by flame and flameless atomic absorption spectrometry. (3) There were considerable differences in the extent to which the two species accumulated or lost zinc, cadmium and lead during the experiment. For example, zinc was retained by contaminated P. scaber fed on uncontaminated leaf litter but was lost rapidly from the hepatopancreas of 0. asellus fed on the same diet. In contrast, cadmium and lead were accumulated to a much greater extent in 0. asellus than in P. scaber. By the end of the experiment, mean concentrations of cadmium and lead in the hepatopancreas of 0. asellus were at least five times higher than in the hepatopancreas of P. scaber in every case. (4) Copper was accumulated by the hepatopancreas of both species in all experimental situations. (5) Concentrations of iron increased in all the woodlice during the experiment but the metal was stored predominantly in the gut, not in the hepatopancreas. (6) The possible reasons for the differences in the net assimilation of zinc, cadmium and lead between the two species, and for the substantial increase in the concentration of copper in the hepatopancreas of isopods fed on leaf litter from their 'own' site are discussed. (7) Comparisons between the concentrations of metals in the tissues of healthy and moribund isopods suggested that death of individual woodlice in the laboratory was due to zinc poisoning. Critical concentrations of zinc in the hepatopancreas (on a dry weight

Egg cold hardiness and topoclimatic limitations to outbreaks of Epirrita autumnata in Northern Fennoscandia.

Abstract: Egg cold hardiness and topoclimatic limitations to outbreaks of Epirrita autumnata in Northern Fennoscandia.

Rabbit grazing, plant competition and seedling recruitment in acid grassland

Abstract: (1) Two experiments were done to determine the effect of grazing by rabbits on plant recruitment in mature grassland and on cultivated soil. The first was a factorial experiment, with and without rabbit fencing, and with and without soil cultivation, carried out between 1986 and 1989 in acid grassland with a long history of rabbit grazing. In the second, carried out between 1982 and 1985 in two contrasting arable fields, rabbits grazed crops of winter wheat, with fencing enclosures erected at different times and for different durations. (2) Rabbit grazing affected the stature and composition of the grassland throughout the year. Species that increased in cover in rabbit-grazed grassland included the grass Anthoxanthum odoratum and the forb Rumex acetosella. Species that decreased included the grasses Festuca rubra and Agrostis capillaris and the forbs Vicia sativa and Trifolium repens. There was negligible change in the total number of plant species with grazing. (3) The cultivated treatments showed that the seed bank under the acid grassland was extremely heterogeneous. (4) Eight of the twenty-three commonest ruderal species beneath acid grassland decreased in cover significantly (e.g. Capsella bursa-pastoris and Papaver dubium), and none increased significantly. In contrast, most of the ruderal species in the seed bank of nearby arable soils increased under grazing. (5) Most plant species on cultivated grassland soils regenerated from vegetative fragments (e.g. Holcus mollis, Stellaria graminea, Rumex acetosa and R. acetosella), rather than by germination of seed. Regrowth shoots outnumbered seedlings by a factor of between 3 and 23 3. (6) The extent of spatial heterogeneity within and between plots in both the composition of the buried seed bank, and in recruitment by vegetative regrowth, highlights the need for large sample sizes in this kind of study. (7) The mechanisms that determine whether a plant species increases or decreases under grazing are discussed.

Root dynamics, production and distribution in agroecosystems on the Georgia piedmont using minirhizotrons

Abstract: Growth rates, death rates and distribution of grain sorghum and weed roots in conventional tillage (CT) and no-tillage (NT) plots were measured using the minirhizotron technique. Total root production in the two systems was estimated by combining minirhizotron and soil coring methods (...)

Elemental and fibre contents of savanna grasses : variation with grazing, soil type, season and species

Abstract: The contents of water, crude protein, cell contents, cell wall, lignocellulose, hemicellulose, cellulose, lignin, silica, ash and nineteen elements, and their variation with season, soil type and grazing intensity, were examined in East African savanna grasses (...)