Showing papers in "Journal of Applied Ecology in 1979"
TL;DR: This paper found that wood-nesting birds moved more frequently from well-vegetated fencerows into fields to forage than from an equal length of wood border, and birds seldom flew directly across open fields between woods.
Abstract: (1) White-footed mice (Peromyscus leucopus) and chipmunks (Tamias striatus) moved between a beech-maple wood and connecting fencerows four times as often as they moved between traplines within the wood. They seldom moved between the wood and adjacent perennial grass fields or across the fields. (2) Birds seldom flew directly across open fields between woods. More species of birds moved more frequently between the wood and fencerows than between any other habitats. Wood-nesting birds moved more frequently from well-vegetated fencerows into fields to forage than from an equal length of wood border. Poorly developed fencerow vegetation restricted foraging by wood-nesters into fields. None of tree species diversity, line intercept measures, dendrograms, or foliage height diversity satisfactorily distinguished among the vegetation structure of different fencerows. (3) The results indicate that fencerows connect the wood to the surrounding agricultural mosaic and concentrate the activity of small mammals and birds into a habitat corridor that may relieve the isolating effect of farmland surrounding the wood.
258 citations
TL;DR: In this article, the authors discuss the ecology of tropical crops and tropical crops in the context of tropical agriculture, and propose a method to identify the root cause of tropical crop diseases.
Abstract: Ecophysiology of tropical crops , Ecophysiology of tropical crops , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
247 citations
TL;DR: Comparison of results from the two sites suggested that amongst the carabid beetles Agonum dorsal (Pont.) was the most important aphid predator, but there was also evidence that polyphagous predators other than carabids decreased the cereal aphid populations.
Abstract: 1. Experiments were done in fields of winter wheat at North Farm, West Sussex, and at Rothamsted in 1978 to investigate the effect of predation by carabid beetles and other polyphagous preadtors on populations of cereal aphids.
2. Predator populations were manipulated by pitfall trapping within plot surrounded by polythene barriers and by applying an insecticide (fonofos) within such plots. Plots were set up in March, April, May and June and the development of aphid populations within them compared with aphid populations in unenclosed control areas.
3. The numbers of carabid beetles caught in the enclosed and fonofos-treated plots were much less than in 'control' plots.
4. Aphid populations were all much smaller in 'control' plots than in those with depleted predator populations both at North Farm, where beetle populations were large, and at Rothamsted where populations were small. Aphid populations were much larger in plots where numbers of polyphagous predators were decreased early in the season than where this was done later.
5. There was an inverse relationship between numbers of polyphagous predators and aphids for the North farm experiment. In contrast, there were positive relationships between aphids and aphid-specific predators and between aphids and aphid parasites. This together with the virtual absence of the pathogenic fungus Entomophtora spp, indicated that the differences in aphid density between plots were caused by polyphagous predators rather than by other natural enemies.
6. Comparison of results from the two sites suggested that amongst the carabid beetles Agonum dorsale (Pont.) was the most important aphid predator, but there was also evidence that polyphagous predators other than carabids decreased the cereal aphid populations.
231 citations
TL;DR: White-tailed deer have a substantial influence on the reproduction ofHemlock, and on the potential of this species to replace itself in forests where hemlock is the dominant tree species.
Abstract: (1) The effect of heavy and light deer browsing on the composition and structure of eastern hemlock forests was investigated in Wisconsin, United States. (2) Sugar maple rapidly replaced hemlock when both were heavily browsed but reproduction in hemlock soon recovered upon removal of browsing. (3) White-tailed deer have a substantial influence on the reproduction of hemlock, and on the potential of this species to replace itself in forests where hemlock is the dominant tree species.
219 citations
TL;DR: The results suggest that high concentrations of toxic metals are the major cause of sparse vegetation cover, but comparisons of bare and adjacent vegetated areas suggests that phosphorus concentrations are the immediate determinant.
Abstract: SUMMARY (1) A survey was made of metalliferous mine wastes in Great Britain. The results suggest that high concentrations of toxic metals are the major cause of sparse vegetation cover, but comparisons of bare and adjacent vegetated areas suggests that phosphorus concentrations are the immediate determinant. (2) Field experiments, using a range of grass species at a large number of mine sites, showed that naturally occurring tolerant populations grew faster and persisted longer than normal commercial varieties. They provide an excellent stabilizing cover, provided adequate fertilizer was given, and have persisted for 9 years with little loss of vigour, even with minimal fertilizer treatment. (3) The most successful populations at each site were those with the highest tolerance to the metals occurring in that waste, provided that the species was appropriately adapted to the other soil conditions occurring there. (4) Three cultivars are now commercially available which are tolerant to: acid lead/zinc wastes (Agrostis tennis, cv. Goginan), calcareous lead/zinc wastes (Festuca rubra, cv Merlin) and copper wastes (Agrostis tennis, cv Parys). These enable stabilization of a wide variety of wastes.
213 citations
TL;DR: Susceptible biotypes of Senecio vulgaris and Amaranthus retroflexus were more competitive than resistant biotype under all treatments tested, and dry matter production of susceptible biotypes was greater than that of resistant biotypes, under both competitive and non-competitive conditions.
Abstract: (1) Biotypes of Senecio vulgaris L. and Amaranthus retroflexus L., which were either resistant or susceptible to atrazine [2-chloro-4(ethylamino)-6(isopropylamino)-s-triazine], were compared. Dry matter production, resource allocation patterns and competitive ability were measured. (2) Dry matter production of susceptible biotypes was greater than that of resistant biotypes, under both competitive and non-competitive conditions. (3) Resource allocation patterns were similar for both biotypes of each species. (4) Susceptible biotypes of Senecio vulgaris and Amaranthus retroflexus were more competitive than resistant biotypes under all treatments tested.
136 citations
132 citations
105 citations
TL;DR: In this paper, a bioassay method based on the uptake of 32P from 5 x 10-6 M phosphate solution during a 15 min period was used to detect phosphorus deficiency in plants.
Abstract: (1) A bioassay method, based on the uptake of 32P from 5 x 10-6 M phosphate solution during a 15 min period, was used to detect phosphorus deficiency in plants. (2) The method was tested using birch (Betuld verrucosa Ehrh.) and sycamore (Acerpseudoplatanus L.) seedlings grown in (a) sand culture supplied with 1-100 Pg P ml 1, (b) phosphorus deficient soils either unfertilized or fertilized (0.1 g P Kg-1 soil), and (c) a range of twenty-five soils varying from extremely deficient to adequate in available P content. (3) There was a negative exponential relationship (r =-0-95) between phosphorus uptake by birch from the test solution and the concentration of phosphorus previously supplied in sand culture solution. (4) Birch seedlings grown in fertilized soils took up less 32P from the bioassay solution than did those from unfertilized soils. Birch seedlings grown for 2 years in phosphate-deficient soils took up greater amounts of 32P from the bioassay solution than did those grown in soils with adequate phosphorus. Eighty-two per cent of the variation in phosphorous uptake by birch seedlings was accounted for by the extractable P content, the isotopically exchangeable P, the total P content and the phosphatase activity of the soils on which they were previously grown. Ninety-three per cent of the variation was accounted for if the plant phosphorus content and the mycorrhizal development on rootsystems were also included in the regression. The corresponding amounts of variation for sycamore seedlings, grown on the same soils, were 58 and 83% respectively. (5) The 32P uptake from the bioassay solution, by both sycamore and birch, was markedly inhibited by 5 x 10-3 M KCN in the bioassay solution, indicating that uptake was metabolically mediated. (6) The results are discussed in relation to the study of phosphorus deficiency in plants, and phosphorus availability in soils.
97 citations
TL;DR: The analysis suggests that, wherever feasible, the best strategy in the long run involves the adoption of resistant cattle combined with a single spelling period or limited dipping.
Abstract: (1) The performance of three control methods for cattle tick in Australiaacaricides, pasture spelling and tick resistant cattle-is assessed separately and in combination, using a population model and data obtained in the South-East Queensland region. In each case, the optimal strategy is first determined by computer search and is then assessed on the basis of its performance against low and high tick populations, its robustness, its long-term effects, its impact on the development of acaricide resistance, and its additional costs of fencing, feeding and handling. (2) For European breeds, which are susceptible to cattle tick, the analysis shows acaricide dipping is best performed at regular 3-week intervals, beginning either in spring or summer. In the short-term, a sequence of five or six dippings is found to be the most profitable, although a reduction in dipping may be desirable when the development of acaricide resistance is considered. (3) Two types of pasture spelling strategy are investigated; a single spelling period each year, and a rotational grazing system, involving frequent movement of cattle between two paddocks. Although the latter gives results comparable to dipping and is unaffected by the problem of acaricide resistance, the investment and maintenance costs involved in fencing are likely to be a deterrent. Single spelling appears more promising, especially if the cattle are dipped at each transfer, although pasture damage and/or feeding costs may prove prohibitive. (4) Finally, the analysis suggests that, wherever feasible, the best strategy in the long run involves the adoption of resistant cattle combined with a single spelling period or limited dipping.
94 citations
TL;DR: It might be possible to make badgers avoid cattle-grazed pasture by reducing worm populations chemically, or by increasing grass length by a different grazing routine, which could be effective in preventing the contamination of cattle by badgers with bovine tuberculosis.
Abstract: (1) The earthworm Lumbricus terrestris was the predominant food of the European badger, Meles metes L. (2) In the badger's habitat, Lumbricus terrestris was most abundant under pasture. (3) Badgers caught worms on the surface at night; when feeding in grassland, their foraging efficiency was related to grass length. (4) Within their ranges, badgers avoided pasture with long grass and with relatively low worm densities. (5) It might be possible to make badgers avoid cattle-grazed pasture by reducing worm populations chemically, or by increasing grass length by a different grazing routine. This could be effective in preventing the contamination of cattle by badgers with bovine tuberculosis.
TL;DR: A new method for determining the age of grasstrees (Xanthorrhoea spp and Kingia australis) is proposed, based on annual fluctuations in stem diameter, which is probably suitable for related arborescent monocotyledons, palms and cycads with seasonal growth cycles.
Abstract: SUMMARY (1) A new method for determining the age of grasstrees (Xanthorrhoea spp and Kingia australis) is proposed. It is based on annual fluctuations in stem diameter and is probably suitable for related arborescent monocotyledons, palms and cycads with seasonal growth cycles. (2) The average height increase of X. preissii was 1.42 cm yr- 1, and that of K. australis was 1-52 cm yr- 1. Individuals up to almost 300 and 500 years old respectively were examined, but extrapolation suggests that the tallest known specimens of X. preissii and K. australis were 350 and 650 years old respectively. (3) Flowering in both species is stimulated by fire but flowering may occur, to a limited extent, in the absence of fire. Some plants reached > 200 years without having flowered. (4) Leaf retention and floral remnants indicated intervals between plant ignition ranging from 2 to > 150 years. Fires at one forest site appear to have been much more frequent during the last 150 years than during the 150 years prior to European settlement.
TL;DR: Fungi mainly affected seed germination and the development of young seedlings; at later stages, herbivory became more important in plant survival.
Abstract: SUMMARY (1) An abundant mycoflora was found on the seed of Abutilon theophrasti, Datura stramonium, Ipomoea hederacea, and Polygonum pensylvanicum, which are colonizing annuals of early successional habitats. The fungal species differed among the plant species and most were specialists with respect to their hosts. (2) A more extensive mycoflora occurred within seed of Polygonum pensylvanicum and D. stramonium than within seed of I. hederacea and A. theophrasti. Ipomoea hederacea and A. theophrasti had greater resistance to fungal infection than P. pensylvanicum and D. stramonium. Fungi differed in their ability to penetrate seeds. (3) Seed germination and seedling development were affected, both quantitatively and qualitatively, by the fungal isolates. Polygonum pensylvanicum seedlings were more susceptible to fungal invasion than those of A. theophrasti or I. hederacea. (4) Extracts from all tissues of I. hederacea and from the roots of A. theophrasti had antifungal activity. Little activity was detected in extracts from P. pensylvanicum. (5) Plant densities of I. hederacea, D. stramonium and P. pensylvanicum remained fairly constant in the field, after seedling emergence, irrespective of density or species diversity. (6) Fungi mainly affected seed germination and the development of young seedlings; at later stages, herbivory became more important in plant survival.
TL;DR: There were differences both in the times of year at which seedlings emerged and in the extent to which seeds survived in cultivated soil among ten species of Umbelliferae, including Sison amomum, Conium maculatum and Torilis japonica.
Abstract: (1) Among ten species of Umbelliferae there were differences both in the times of year at which seedlings emerged and in the extent to which seeds survived in cultivated soil. (2) The main time of emergence of Smyrnium olusatrum was in the autumn of sowing, while that of Anthriscus sylvestris, Heracleum sphondylium, Angelica sylvestris, Conopodium majus and Pastinaca sativa was in the following spring. Few viable seeds of these species remained after a year. (3) Seeds of Sison amomum, Conium maculatum and Torilis japonica survived for longer. Sison amomum had autumn and spring peaks of emergence, while Conium maculatum and Torilis japonica were mainly spring-germinating. (4) Maximum emergence of the spring-germinating annual weed Aethusa cynapium occurred in the second or third year, and about one-fifth of the seeds were still viable and dormant after 5 years.
TL;DR: From early 1975 until the end of 1976, flowering and growth patterns were monitored and measurements of dry matter production were made at both sites, and fruit number per unit area was the main determinant of the partitioning of assimilates.
Abstract: (1) Young apple trees were grown at Bristol in England for 1 year then, in January 1975, half the batch were moved to Montpellier, in the south of France; in January 1976 six trees were returned to Bristol and a further six sent to Montpellier. From early 1975 until the end of 1976, flowering and growth patterns were monitored and measurements of dry matter production were made at both sites. Continuous weather measurements were also made. Over the growing period in 1975, Montpellier received 18% more radiant energy than Bristol; in 1976 it received 24% more. Spring temperatures were higher and dew points generally lower at Montpellier than Bristol. (2) Full bloom was reached about mid-April in France and early to mid-May in England. Fruit number per flower cluster was two to three times higher in England than in France. Shoot growth started about 3 weeks earlier in France and leaf area per tree was always higher there. (3) Up to the time of crop harvest in 1975, dry matter production by the trees in England, which had more fruits than the trees in France, was greater than in France but, over the whole season, dry matter production was 12% greater in France. In 1976, fruit loads were approximately the same at the two sites, and differences in dry matter production were proportional to leaf area duration and total radiant energy received; dry matter production in France was greater than in England up to crop harvest and 25% greater overall. (4) Fruit number per unit area was the main determinant of the partitioning of assimilates.
TL;DR: In this article, Valencia orange trees were subjected to water stress, under field conditions at Tacna, Arizona, inducing leaf water potentials between -1 and - 6.6 MPa before dawn.
Abstract: SUMMARY (1) Valencia orange trees were subjected to water stress, under field conditions at Tacna, Arizona, inducing leaf water potentials between -1 and - 6.6 MPa before dawn. The water status of trees was then studied after irrigation. (2) Rehydration began immediately after irrigation, and leaf water potentials reached normal values in less than a week. (3) The stomatal conductance of leaves recovered much more slowly, the time being related directly to leaf water potential prior to irrigation. The stomatal conductance of trees which had leaf water potentials of less than -5 MPa before dawn, prior to irrigation, did not fully recover in 2 months. (4) Leaves that had undergone severe water stress had lower leaf water potentials, for a given relative water content, than unstressed leaves. These differences are discussed in terms of osmotic adjustment and changes in bound water.
TL;DR: Rivers receiving effluent from urban areas contained more iodine than did rainwater, and more iodine more than did rivers and lakes in predominantly rural areas, suggesting that the atmosphere is potentially an important direct source of iodine for plants.
Abstract: (1) The iodine content of 132 surface soils (0-15 cm), obtained from a variety of parent materials within the U.K., ranged from 0-5 to 98.2 jig gel on a dry weight basis. The mean was 9-2 jug g-l. The highest content occurred in a fen peat soil and the lowest in a podsolized sand. With the exception of two peat soils, the range in content was O05-369 pg g-1. The results are consistent with evidence that the retention of iodine in soils is due mainly to aluminium and iron oxides and to organic matter. (2) The iodine content of various soil amendments, including sewage sludges, fertilizers and liming materials was also examined. Only Chilean nitrate and a fertilizer based on seaweed, both used to a very small extent in U.K. agriculture, had iodine contents appreciably greater than the average for soils. (3) Rivers receiving effluent from urban areas contained more iodine than did rainwater, and more iodine than did rivers and lakes in predominantly rural areas. (4) Lichens, obtained from the trunks and branches of trees, had much higher contents of iodine than grasses, suggesting that the atmosphere is potentially an important direct source of iodine for plants. However, it is not yet possible to assess, for different situations and crops, the relative importance of iodine taken up from the soil and iodine absorbed through the leaves.
TL;DR: In this paper, the authors attempted to assess the ecosystem health of Korean pine and broad-leaved mixed forest under various human disturbances, and the results showed that the health degree was in the order of 20% intensity selective cutting stand (0.21) < 50% intensity selective cutting stand(0.44) < middle and mature Birch stand ( 0.67) < youth birch stand( 0.72) < Korean pine plantation (0.,74) < larch plantation(0.,77).
Abstract: On the bases of samples investment and related data collected by others, and with the method of health distance assessment and the ecosystem health index system of Korean pine and broad-leaved mixed forest established in prior paper, this paper attempted to assess the ecosystem health of Korean pine and broad-leaved mixed forest under various human disturbances. The results showed that the health degree was in the order of 20% intensity selective cutting stand (0.21) < 50% intensity selective cutting stand (0.44) < middle and mature birch stand (0.67) < youth birch stand (0.72) < Korean pine plantation (0.74) < larch plantation (0.77).
TL;DR: L. arboreus is tolerant of soils with low concentrations of major plant nutrients; this, and its ability to fix atmospheric nitrogen, makes it a suitable pioneer species for reclaiming wastes of low fertility.
Abstract: (1) Lupinus arboreus rapidly colonizes micaceous china clay wastes, which are deficient in nitrogen, phosphorus, calcium and potassium. (2) Nitrogen accumulated at rates of about 180 Kg ha-1 y on areas where L. arboreus was established. The concentration of total, inorganic and mineralizable nitrogen increased in these soils. Non-legume species colonized the soil beneath L. arboreus and apparently benefited from the increased soil nitrogen status. (3) L. arboreus is tolerant of soils with low concentrations of major plant nutrients; this, and its ability to fix atmospheric nitrogen, makes it a suitable pioneer species for reclaiming wastes of low fertility. Trees and shrubs may be introduced in about the third year.
TL;DR: Qualitative patterns in Neotropical land-bridge island avifaunas are examined to show the extent to which the authors can predict the types of species that will survive in bird communities of varying size and to help design an optimal system of refuges.
Abstract: (1) Previous application of island biogeographic theory to the design of nature preserves has focused primarily on the number of species that can survive in a given area with time. (2) Here I examine qualitative patterns in Neotropical land-bridge island avifaunas to show the extent to which we can predict the types of species that will survive in bird communities of varying size. (3) Each avian family shows consistent differences in its representation in mainland regions or on islands, in accordance with the total size of the avifauna present. Regressions of these data allow us to predict the smallest community in which a family member can exist. (4) Distribution patterns within families show that species with wide ranges tend to survive on land-bridge islands in disproportionate numbers. This bias in survival ability would lead to increased convergence in preserved avifaunas. (5) With these qualitative patterns and previously described quantitative formulas for extinction rates we should be able to predict both the rate of species extinction on a preserve and the species most extinction prone. Application of this knowledge on a regional basis might allow us to design an optimal system of refuges.
TL;DR: There was wide variation between sowings of the same species in different years, as well as between species, and onopordum acanthium showed a contrasting pattern; most seedlings appeared in July-September, with small numbers in other months.
Abstract: (1) Achenes of seven species of Carduus, Cirsium and Onopordum were collected in August-September and mixed with the top 2-5 or 7-5 cm of soil which was then periodically disturbed during 3 or more years. (2) Between 0 and 40% of the achenes produced seedlings in the autumn of sowing. There was wide variation between sowings of the same species in different years, as well as between species. (3) Subsequent seedling emergence was mainly in March-April (Cirsium eriophorum, C. palustre, C. vulgare), April (Carduus acanthoides, C. nutans) or April-May (Cirsium arvense). Onopordum acanthium showed a contrasting pattern; most seedlings appeared in July-September, with small numbers in other months. (4) More than 90% of all seedlings of Cirsium and Carduus spp. that emerged did so within a year after sowing. There were few or none after the second year and very few dormant achenes remained after 5 years. (5) Only about half the achenes of 0. acanthium mixed with 7-5 cm of soil produced seedlings in the first 16 months. Seedlings continued to appear subsequently and up to 8%. of the achenes sown were still dormant and viable after 5 years.
TL;DR: A field experiment showed that digging caused heavy mortality of cockles and probably acted more severely on smaller ones of each age group, and laboratory experiments confirmed that few cockles buried at 10 cm could regain their near surface positions and that many died.
Abstract: The population of cockles Cerastoderma (= Cardium) eduke (L.) declined drastically in the late 1950s and '60s concurrent with intensification of digging for lug and rag worms. At Blakeney Point, where bait digging is slight, cockles remained common. A field experiment showed that digging caused heavy mortality of cockles and probably acted more severely on smaller ones of each age group. Laboratory experiments confirmed that few cockles buried at 10 cm could regain their near surface positions and that many died. Predator exclusion did not affect cockle numbers.
TL;DR: It is concluded that numerical methods are a useful tool in understanding the phytosociology and ecology of weed flora.
Abstract: SUMMARY crop types with respect to their weed flora. (3) The weed flora was closely related to crop types. In particular, there was a close relationship between the growth period of crops and their weed flora, especially the frequency of therophytes. The results are discussed in relation to the growth period of the crop, the life form of the weed species and agricultural practice. (4) It is concluded that numerical methods are a useful tool in understanding the phytosociology and ecology of weed flora.