Showing papers in "Journal of Applied Ecology in 1986"
3,865 citations
1,194 citations
TL;DR: Warming would induce earlier blossoming and budburst in many temperate trees, with an increase in the risk of subsequent damaging frosts, if future C02-induced warming of 2 'C increased the incidence of warm springs.
Abstract: SUMMARY (1) If future C02-induced warming of 2 'C increased the incidence of warm springs, of the type that have occurred in Britain during this century, then warming would induce earlier blossoming and budburst in many temperate trees, with an increase in the risk of subsequent damaging frosts. There would, for example, be an increase in the already high incidence of frost damage to apple blossom (Malus pumila Mill.) cv. Cox's Orange Pippin, in Kent and to new vegetative shoots of Picea sitchensis (Bong.) Carr. in the Scottish uplands. (2) If budburst occurred after a constant thermal time (e.g. 100 day 'C > 5 0C after mid-January), then budburst would occur so much earlier in the spring that, on average, the temperature on the date of budburst would be lower than at present. Consequently, the risk of damaging frosts occurring after budburst would be much increased. (3) However, in many trees there is an increase in the thermal time to budburst with decreased chilling. This increase prevents very early budburst in warm springs, and lessens the risk of frost damage. (4) Theoretically, warming could delay or advance budburst, depending upon the extent to which a tree's chilling requirements are currently met. (5) Empirical thermal time-chilling models suggested that, on average, Cox's apple in Kent would blossom 18-24 days earlier than at present following 2 'C warming, but that P. sitchensis in the Scottish uplands would burst its buds only 5 days earlier than at present.
373 citations
TL;DR: In this paper, the authors present a wildlife conservation evaluation: attributes, criteria and values, assessing representativeness, ecological succession and the evaluation of non-climax communities.
Abstract: One Introduction.- 1 Wildlife conservation evaluation: attributes, criteria and values.- 2 Assessing representativeness.- 3 Ecological succession and the evaluation of non-climax communities.- Two Approaches in different geographical areas.- 4 Evaluation of tropical land for wildlife conservation potential.- 5 Evaluation methods in the United States.- 6 Selection of important areas for wildlife conservation in Great Britain: the Nature Conservancy Council's approach.- 7 Wildlife conservation evaluation in the Netherlands: a controversial issue in a small country.- 8 Evaluation at the local scale: a region in Scotland.- Three Specific habitats and groups of organisms.- 9 Forest and woodland evaluation.- 10 Evaluating the wildlife of agricultural environments: an aid to conservation.- 11 Ornithological evaluation for wildlife conservation.- 12 Assessments using invertebrates: posing the problem.- Four General principles.- 13 Conservation evaluation in practice.- 14 Design of nature reserves.- References.- Author index.
311 citations
TL;DR: This review of polar marine ecosystems covers both the Arctic and Antarctic, identifying the major threats and, where possible, predicting their possible state(s) in 2025.
242 citations
TL;DR: It was suggested that wheat/maize/soybean relay trip intercropping could improve rhizosphere environment, promote the crops root growth and increase their aboveground biomass, and accordingly, realize yield-increasing.
Abstract: A multi-year field experiment was conducted to study the variation features of rhizosphere environment and crop root growth under the cropping modes of wheat-soybean (A1), wheat-sweet potato (A2), maize (A3), wheat/maize/soybean (A4), and wheat/maize/sweet potato (A). Among the five modes, A4 increased the plant biomass, root activity, and root dry mass of wheat, maize, and soybean at their flowering and maturing stages, and the quantity of rhizosphere soil bacteria, fungi, and actinomycetes. The biomass and quantity of rhizosphere soil microbes were relay strip intercropping > single cropping, soybean > sweet potato, and fringe row > center row. It was suggested that wheat/maize/soybean relay trip intercropping could improve rhizosphere environment, promote the crops root growth and increase their aboveground biomass, and accordingly, realize yield-increasing.
209 citations
TL;DR: Hares preferred to feed on short crops and their preference for cereals declined as crops developed beyond the tillering stages, suggesting that hare numbers have declined on farms where the landscape has been simplified by field enlargement and block farming.
Abstract: (1) The movements of individual hares were studied by radio-tracking on a mixed arable farm, and hare numbers were compared with farming patterns at nine farmland sites in different parts of England. (2) Hares preferred to feed on short crops and their preference for cereals declined as crops developed beyond the tillering stages. Pastures were important feeding areas throughout the year. (3) Hares often fed at night in a different area from the place where they sheltered during the day. Consequently, some hares moved between habitats daily. (4) Woodlands and hedges were widely used as sheltering areas. (5) Hares shifted their activities between fields according to crop development. (6) The sizes and shapes of home ranges suggest that hares exploit those parts of the farm where there is easy access to a variety of crops. (7) Hare numbers in autumn were positively associated with landscape diversity between study areas. (8) Available data suggest that hare numbers have declined on farms where the landscape has been simplified by field enlargement and block farming.
175 citations
TL;DR: Ginger planting decreased the soil microbial biomass C, N and P contents significantly, and the soil urease and intervase activities under CS were higher, as compared with those under the other cropping modes.
Abstract: This paper studied the variations of soil microbial biomass C, N, and P contents and soil hydrolase activities under different cropping modes, i.e., corn + sweet potato intercropping (CS), soybean mono-cropping (SM), continuous cropping of ginger (CG), and rice-milk vetch rotation (RM) , after ginger planting in the purple soil area at the lower reaches of Minjiang River. Ginger planting decreased the soil microbial biomass C, N and P contents significantly. The decrement of the soil microbial biomass C and N contents after ginger planting was lesser under CS and RM than under SM and CG, but the soil microbial biomass P content was in adverse. Ginger planting also decreased the soil acid phosphatase activity significantly, and the decrement was the greatest under CS but the least under RM. The soil invertase activity decreased significantly under CG, and the soil urease activity had a significant decrease under SM, CG and RM. After ginger planting, the soil urease and intervase activities under CS were higher, as compared with those under the other cropping modes.
171 citations
TL;DR: There were consistent differences between species in the extent of immediate emergence, seed survival in disturbed soil and in the seasonal pattern of emergence, and the potential for regeneration by different species from the seed bank after disturbance of a plant community is provided.
Abstract: (1) The extent to which plants form a persistent seed bank and the time of year at which seedlings arise from it both have a bearing on the establishment of vegetation after disturbance. These attributes were determined for seventy dicotyledons from a range of habitats by mixing freshly-collected seeds with the top 7.5 cm of soil confined in cylinders sunk in the ground, cultivating three times yearly, and recording emergence for 5 years. (2) In about one-third of the species, few seeds persisted for longer than a year and most seedlings emerged in the autumn of sowing (Sherardia arvensis*, Galium mollugo) or early in the following spring (Chaerophyllum temulentum, Pimpinella saxifraga, Agrimonia eupatoria, Tragopogon pratensis). (3) The remaining species formed a persistent seed bank in cultivated soil from which seedlings arose in each year for which the experiments continued. Some exhibited a consistent pattern of emergence entirely (Odontites verna, Linum catharticum) or mainly (Brassica nigra, Silene dioica) in spring, while others (Hyoscyamus niger, Erodium cicutarium, Amaranthus retroflexus) emerged in late spring and summer. Emergence of Arenaria serpyllifolia, Cerastium glomeratum and Anthriscus caucalis was mainly in early autumn, while that of Legousia hybrid began in autumn and continued into spring. (4) Other species showed no pronounced pattern of emergence in successive years. Although there was often a tendency for most seedlings to emerge in spring or autumn, some appeared throughout the growing season with flushes following soil disturbance. Included in this group were Barbarea vulgaris, Coronopus didymus, Ballota nigra and Dipsacus sylvestris. (5) There were consistent differences between species in the extent of immediate emergence, seed survival in disturbed soil and in the seasonal pattern of emergence. Seeds of annual weeds of arable land were all relatively long-lived, but otherwise there appeared to be little relationship between seed persistence and habitat. The results provide indications of the potential for regeneration by different species from the seed bank after disturbance of a plant community and of the times of year at which it is likely to take place.
163 citations
TL;DR: A survey was made of all British colonies of Hesperia comma, which revealed that it had declined to about forty-nine populations, most of which were small, and the habitat on several former sites has improved for H. comma since the late 1970s, due to a recovery by rabbits and some sheep stocking on abandoned downs.
Abstract: (1) A survey was made of all British colonies of Hesperia comma, which revealed that it had declined to about forty-nine populations, most of which were small. (2) Adult H. comma proved to be very particular when egg-laying. They preferred small Festuca ovina plants that were largely surrounded by bare ground or scree, and which also grew in sheltered sunspots. Most F. ovina growing on most sites were rejected as unsuitable, and the adult population density of H. comma was correlated with how closely the sward approached the ideal structure for egg-laying. (3) Most sites that had lost H. comma still contained abundant F. ovina, but were too overgrown to be suitable for breeding. Most extinctions of H. comma occurred during a twenty-year period, when many unfertilized downs in Britain became overgrown after rabbits were killed by myxomatosis. (4) The habitat on several former sites has improved for H. comma since the late 1970s, due to a recovery by rabbits and some sheep stocking on abandoned downs. To date, H. comma has only spread to re-occupy sites that were within 4 km of existing colonies. The natural recolonization of other sites may take decades or centuries. (5) Conservationists could dramatically improve the status of H. comma by making artificial introductions to unoccupied sites. A high proportion of the existing colonies are already on nature reserves, but one-quarter of 'protected' populations had become extinct by 1982, due to inadequate grazing.
137 citations
TL;DR: In this article, the authors address the long-range, global effects of atmospheric pollutants on aquatic ecosystems and present an approach to the most primitive question in a second order subset of the general problem: have certain types of lakes become acidified as a result of anthropogenic emissions to the atmosphere.
Abstract: This book addresses the long-range, global effects of atmospheric pollutants on aquatic ecosystems. It is very closely focused. The specific topic is one approach to the most primitive question in a second order subset of the general problem: have certain types of lakes become acidified as a result of anthropogenic emissions to the atmosphere. The approach is reconstruction of the time course of pH levels in such lakes through inferences based on siliceous microfossils preserved in their sediments.
TL;DR: The livestock in aggregate provided a very broad, opportunistic, and temporally stable trophic niche that resulted from equitable use of all forage classes, and their mobility provided a means to exploit the entire region.
Abstract: (1) Seasonal patterns of forage selection, diet diversity, and habitat use were quantified for livestock managed by the Ngisonyoka Turkana in arid north-western Kenya by direct observation of free-ranging herds. The objective was to characterize the trophic niche segregation of livestock and their potential harvesting capacity for the heterogeneous vegetation resources of this ecosystem. (2) Cattle and cam Js were grazing and browsing specialists, respectively, while goats, sheep, and donkeys, were' generalists for both herbaceous and non-herbaceous vegetation. (3) Diet and habitat use were greatly influenced by season. Relative to brief rainy periods of resource abundance, long dry intervals of resource scarcity were times of reduced diet diversities (forage-class basis) for most species and greatly increased variation in habitat use. Livestock generally exhibited the greatest diet similarity in dry periods but were most segregated in terms of feeding habitats during these times. (4) The livestock in aggregate provided a very broad, opportunistic, and temporally stable trophic niche that resulted from equitable use of all forage classes, and their mobility provided a means to exploit the entire region. These attributes are essential for the persistence of nomads in this harsh, unpredictable environment, and are inimical to development tactics that serve to reduce livestock species diversity or restrict mobility.
TL;DR: In this article, the cucumber seedlings grafted on different salt-tolerant rootstock varieties (Sherpa, Tielizhen, Shintosa, and Figleaf gourd) were selected to study their physiological responses to NaCl stress.
Abstract: Based on the salt-tolerance identification of a series of cucumber rootstock varieties, the cucumber cultivar 'Xintaimici' grafted on different salt-tolerant rootstock varieties 'Sherpa', 'Shintosa' , 'Tielizhen' , and 'Figleaf gourd' was selected to study its seedlings physiological responses to NaCl stress, taking the self-rooted ones as the control. Under the stress of 100 mmol NaCl x L(-1), the leaf electrolyte leakage rate and malondialdehyde (MDA) content of the grafted seedlings were significantly lower than those of self-rooted seedlings, and the seedlings grafted on 'Figleaf gourd' showed the lowest electrolyte leakage rate and malondialdehyde (MDA) content, followed by the seedlings grafted on 'Tielizhen', 'Shintosa' , and 'Sherpa'. The leaf proline and soluble sugar contents and peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities of the grafted seedlings were significantly higher than those of the self-rooted seedlings, and the POD, SOD, CAT, and APX activities were the highest for the seedlings grafted on 'Figleaf gourd' and the lowest for the seedlings grafted on 'Sherpa', but had no significant differences for the seedlings grafted on 'Tielizhen' and 'Shintosa'. The leaf Na+ content of the seedlings grafted on different rootstock varieties ranked as 'Figleaf gourd' < 'Tielizhen' < 'Shintosa' < 'Sherpa', while the leaf K+ content had little difference for the seedlings grafted on 'Figleaf gourd', 'Tielizhen', and 'Shintosa' but was significantly higher than that for the seedlings grafted on 'Sherpa'. The self-rooted seedlings had the highest leaf Na+ content but the lowest leaf K+ content. The leaf Na+/K+ ratio of grafted seedlings was significantly lower than that of self-rooted ones, and the seedlings grafted on 'Figleaf gourd' had the lowest leaf Na+/K+ ratio.
TL;DR: Part I: Evolution and systematics; Part II: Ecology and behaviour; Part III: Management and conservation; Part IV: Management of health and disease.
Abstract: Part I: Evolution and systematics. Part II: Ecology and behaviour. Plates. Part III: Management and conservation. Part IV: Management of health and disease.
TL;DR: Production of predator biomass was as important as microbial and plant production in determining nutrient flow in this system, as the percentage of VAM colonization of plant roots increased markedly when nematode populations were decreased by nematicide treatment.
Abstract: (1) Perturbations were performed on organisms in a below-ground trophic food web in a semi-arid grassland, using five separate biocide treatments to observe changes in trophic structures, interactions, and nutrient cycling. Changes in N mineralization and trophic interactions as predicted on the basis of simple predator-prey microcosm studies were observed following removal of particular groups. (2) Five biocides: streptomycin (bactericide), captan and PCNB (fungicides), carbofuran (insecticide-nematicide), and cygon (acaricide) were applied in situ to soil in cylinders containing predominantly blue grama grass. The response of microbes, fungal grazers, soil inorganic N and plants were followed monthly between April and October 1982. (3) Grazing of bacteria or fungi by predators resulted in one or more of the following occurrences: (i) increased soil inorganic N, decreased predator populations following reduction of prey or increased plant growth after reduction of nematodes; (ii) reduction of one group of decomposers, e.g. bacteria, allowed a second decomposer group, e.g., fungi, to increase in numbers; (iii) compensatory responses of microbial feeders, e.g. decreases in bacterial feeders (protozoa and bacterivorous nematodes) were followed by compensatory increases in fungal feeders, which increased following the increase in their fungal food supply. (4) Continuing changes in nitrogen cycling were not observed, presumably because the function of the reduced group was compensated by increased numbers of the second group performing a similar function. Nematode-VAM interactions must be considered in food web and nutrient flows, as the percentage of VAM colonization of plant roots increased markedly when nematode populations were decreased by nematicide treatment. Production of predator biomass was as important as microbial and plant production in determining nutrient flow in this system.
TL;DR: The concentrations of nutrients in leaves and the relations between them indicate that N limits growth in non-N2- fixing species at most sites, while P is limiting in N2-fixing species.
Abstract: (1) Foliar nutrient relations of non-N2-fixing and potentially N2-fixing (species found to form root nodules elsewhere) deciduous trees at five savanna woodland sites in Tanzania were compared with data on soil nutrients. The study comprised forty-eight species-site combinations. (2) Nodulation and nitrogenase activity were confirmed in mature specimens of twelve of the fourteen potentially N2-fixing legume species studied. The twelve species belong to the genera Acacia, Dalbergia, Dichrostachys, Entada, Pericopsis, Pterocarpus and Xeroderris. (3) Non-N2-fixing species had, on average, a 0.0007 atom% higher 15N abundance in their leaves than potentially N2-fixing species, which had a N isotope composition close to the atmospheric. The result supported the 15N natural abundance method as an indicator of N2-fixation only in principle, as the method did not allow statements about single species. (4) The N concentration in leaves at the end of the rainy season was, on average, substantially higher in potentially N2-fixing species than in non-N2-fixing species at all sites (2.71% as compared to 1*63% of dry mass). There were no differences in the concentrations of K, Mg, Ca, S, Mn and B between the two groups at any of the sites. (5) Phosphorus in leaves of non-N2-fixing species increased considerably in relation to N, concurrently with a similar change in the soils at four sites with miombo (Brachystegia-Julbernardia) woodland vegetation, while there were no differences between sites in potentially N2-fixing species. (6) The concentrations of nutrients in leaves and the relations between them indicate that N limits growth in non-N2-fixing species at most sites, while P is limiting in N2-fixing species. Comparisons of the relation between P and N in non-N2-fixing and N2-fixing species is proposed as an indicator of the availability of these nutrients in the soil, provided that no other nutrient is limiting.
TL;DR: The Norfolk Broadland has suffered extreme eutrophication and Restoration of the once clear water and aquatic plant communities from the present phytoplankton dominance is sought.
Abstract: SUMMARY (1) The Norfolk Broadland has suffered extreme eutrophication. Restoration of the once clear water and aquatic plant communities from the present phytoplankton dominance is sought. (2) In the first two experiments, Alderfen Broad was isolated, by diversion of an inflow stream, without removal of its recently-deposited phosphorus-rich sediments. In the second, sediment was removed from Cockshoot Broad and dams were placed against the effluent-rich River Bure, but the Broad continued to be fed by a small stream draining an agricultural and fen catchment. (3) In four years (1979-82) after isolation of Alderfen Broad, the phytoplankton crop was greatly reduced and the water became clear. Net release of P04-P from the sediment ceased and the Broad became dominated by Ceratophyllum demersum L. Then, because of the reduction in turbulence of the water column by the plants, and the organic matter supplied to the sediment surface in their decay, the mechanism for release of P04-P from the sediment was reactivated and, in 1984, supported a large phytoplankton crop in the spring. The aquatic plant population declined. In 1985 there was both spring and summer phytoplankton growth, the latter probably supported by nitrogen-fixation, and the aquatic plant growth was negligible. (4) In Cockshoot Broad a reduction in phytoplankton growth followed soon after isolation and sediment-removal, and the water became very clear and has remained so. Part of the Broad has already recolonized with a diverse collection of aquatic plants. (5) The consequences of these results for the management of the rest of the Broadland waterway are discussed.
TL;DR: It is suggested that hedgerow characteristics are important in determining the local spacing of breeding partridges but they may not determine overall population size.
Abstract: (1) The influence of the quantity and quality of nesting habitat (field boundaries, including hedgerows) on the breeding density of grey and red-legged partridge was examined on ten arable farms in Britain. (2) The length of permanent field boundary was found to correlate closely with the breeding density of both species of partridge within study farms; between farms it did not. (3) In a multiple regression analysis the amount of dead grass present in the base of the hedge was the best predictor of grey partridge breeding density within farms after the length of the field boundary was taken into account. A similar analysis for red-legged partridges showed that the amount of nettle present at the base of field boundaries was the only variable related to breeding density after the overall length was taken into account. Between farms, the breeding density of both species was unrelated to the hedgerow characteristics. (4) The importance of hedges and hedgerow management to partridges is discussed. It is suggested that hedgerow characteristics are important in determining the local spacing of breeding partridges but they may not determine overall population size.
TL;DR: It is concluded that Nardus will spread in grazed moorland unless soils are very dry or Calluna is present and allowed to grow tall for periods of several years.
Abstract: (1) Botanical composition, grazing treatment and trends in heather (Calluna vulgaris (L.) Hull.) were recorded for periods of 4-15 years at moorland sites ranging in altitude from 70 to 700 m. Tussocks of Nardus stricta L. in permanent 1-M2 areas were monitored yearly at three sites. (2) Changes in the cover of Juncus squarrosus L., Molinia caerulea (L.) Moench and Nardus were inversely related to cover trends in Calluna, but only weakly so. Juncus squarrosus was unresponsive, with only one significant change at its twenty sites; Molinia increased significantly at four sites where Calluna declined. (3) Nardus showed many small increases in cover which were counterbalanced by large decreases at two of its twenty-three sites, giving a negligible overall trend. Increases were largest at sheep-grazed sites, but no significant general relationship could be shown with grazing type. (4) Nardus changes were more consistently related to the state of Calluna as expressed by percentage cover x height than to the trends of Calluna cover. Nardus declined once Calluna mean height exceeded 15 cm. At one site heavy cattle grazing reduced Nardus cover. (5) Many seedlings of Nardus became established, most in positions close to mature tussocks. (6) Increment in Nardus tussock diameter was little influenced by grazing, even though tussocks grazed in one summer were more likely to be grazed in the next. (7) It is concluded that Nardus will spread in grazed moorland unless soils are very dry or Calluna is present and allowed to grow tall for periods of several years.
TL;DR: Zhang et al. as discussed by the authors analyzed and evaluated the ecological frangibility of Qingping Town, Mianzhu City of Sichuan Province in 2006, using the aerial remote sensing images after May 12, 2008 (the date of catastrophic Wenchuan Earthquake) and the unmanned aircraft vehicle Remote Sensing images after August 13, 2010 (date of extraordinary debris flow), and in combining with the land use map (1:10000), topographic map ( 1:50000), and collected field investigation data, they concluded that complex terrain was the key factor of the ecological
Abstract: By using the aerial remote sensing images after May 12, 2008 (the date of catastrophic Wenchuan Earthquake) and the unmanned aircraft vehicle remote sensing images after August 13, 2010 (the date of extraordinary debris flow), and in combining with the land use map (1:10000), topographic map (1:50000), and collected field investigation data of Qingping Town, Mianzhu City of Sichuan Province in 2006, this paper analyzed and evaluated the ecological frangibility of the Town. In the Town, the slightly, lightly, moderately, heavily, and extremely fragile ecological zones after the extraordinary debris flow occupied 1.9%, 7.9%, 18.7%, 23.0%, and 48.5%, respectively, with the area of heavily and extremely fragile ecological zones accounting for 71.5% of the total, being 238.45 km2, i. e., the ecological environment was overall very fragile. Under the impact of the two natural hazards, the ecological frangibility degree of the Town increased obviously. As compared with that before the Earthquake, the area of heavily and extremely fragile ecological zones after the Earthquake increased by 12.4%, and the area of extremely fragile ecological zone was 1.67 times larger. The dynamic evolution of the ecological frangibility of the Town was mainly manifested in the conversion of heavily fragile ecological zone into extremely fragile ecological zone. Complex terrain was the key factor of the ecological frangibility of the Town.
TL;DR: Both a survey and a remedial effort, this work focuses on pollution by smelters of the surrounding aquatic ecosystems, and examines the chemical and biological effects of smelter pollutants -- particularly their impact on lake acidification.
TL;DR: The results indicate that, as a control measure, planting a weedy arable field to grass for 20 years will not eradicate the seeds of even the most rapidly declining species.
Abstract: (1) The decline of seeds of a natural population of arable weeds under a grass sward was monitored by germination in the field. Plots of 0.9 m2 were dug out of the turf in the 1st, 2nd, 3rd, 19th and 20th years of the experiment. All seedlings were counted and removed and the plots recultivated to a depth of 0.2 m at the end of each month for 24 months. (2) Twenty-one species were recorded of which Matricaria recutita L. and Papaver rhoeas L. were the most abundant. Chrysanethemum segetum L. and Raphanus raphanistrum L. seeds declined most rapidly with mean annual declines of over 30% per year (half lives of 1 5 and 2 years respectively), while Fumaria oficinalis L. and Aethusa cynapium L. declined least with means of 20 years). Other species were intermediate. (3) The monthly emergence of nine species, which occurred in sufficient numbers, are presented. All the species germinated to some extent in spring and autumn, although seedlings of Fumaria officinali L. and Trifolium repens L. emerged mainly in spring. (4) The results indicate that, as a control measure, planting a weedy arable field to grass for 20 years will not eradicate the seeds of even the most rapidly declining species.