Lowland Pastures Research Articles

Diversity and Abundance of Arbuscular-Mycorrhizal Fungus Spores in Tropical Forest and Pasture1

As Neotropical forests are increasingly converted to agriculture (especially pastures), little is known about the impacts on microbial biodiversity. To assess such impacts, I compared spore abundance and diversity of arbuscular mycorrhizal fungi (AMF) in soils from lowland evergreen forests and pastures in Nicaragua and Costa Rica. Species composition, dominance–diversity curves, and Simpson's diversity indices were similar for both forest and pasture soils. Of 28 distinct fungus morphospecies, 11 produced more spores in pasture, while only 1 produced more spores in forest. According to species-accumulation curves, local AMF species richness did not significantly decline following conversion of forest to pasture. Because pastures contained a surprising abundance and diversity of AMF spores compared to native forest, a lack of mycorrhizal fungi is unlikely to limit plant succession, restoration, or reforestation in the pastures studied. At the regional scale, however, species-accumulation curves showed significantly greater gamma (G) diversity of spores in forest. In addition to these trends in diversity, species that sporulated more in pasture tended to have small spores, while the one species that sporulated more in forest had the largest spores. Similarly, only large-spored fungi (>300 µm) showed any seasonal variation in spore abundance, being more common in the wet season.

Estimation of energy expenditure in free-living red deer (Cervus elaphus) with the doubly-labelled water method

Energy expenditure was estimated using the doubly-labelled water (DLW) method in summer in five free-living adult, non-pregnant, non-lactating, red deer (Cervus elaphus) hinds (weight 107.3 (SE 0.9) kg; age 6 (SE 1) years) on lowland pasture under typical farming conditions. Climatic conditions were monitored throughout the experiment. Errors due to 2H losses in CH4 and faeces were calculated from previous estimates of stoichiometries. CH4 production, fractionated water loss, urinary N and O2 consumption were estimated using an iterative approach. The water flux (rH2O) in these animals consuming only fresh grass was 12 (SE 0.5) kg/d, the CO2 production (rCO2) was 1271 (SE 40) litres/d and the mean energy expenditure was 25 (SE 0.8) MJ/d. There were no significant differences in the isotope distribution spaces and flux rates, rH2O, rCO2 or energy expenditure using the multi-point or two-point approaches to calculation. The DLW-derived energy expenditure of 25 MJ/d is approximately 20% higher than the recommended intake of 21 MJ/d for adult hinds kept outdoors (Adam, 1986) and, at 757 kJ/kg0.75 per d, one third higher than the value of 570 kJ/kg0.75 per d for stags penned indoors (Key et al. 1984).

Association of the Opiine Parasitoid Diachasmimorpha tryoni (Hymenoptera: Braconidae) with the Lantana Gall Fly (Diptera: Tephritidae) on Kauai

Parasitization of the lantana gall fly, Eutreta xanthochaeta Aldrich, by an introduced larval fruit fly parasitoid, Diachasmimorpha tryoni (Cameron), was assessed by measuring total host and parasitoid recruitment in patches of lantana plants growing in 3 distinct ecological habitats on the island of Kauai. Over a 17-wk period, means of 87, 261, and 276 E. xanthochaeta galls were recruited per 10-m2 patches of lantana growing in a lowland pasture (elevation approximately 124 m), a midelevation sugarcane field (elevation approximately 500 m), and an upland forest (elevation approximately 1000 m), respectively. From 42 to 72% of all newly developed galls recruited were lost before reaching maturity from predation (presumably by birds and rodents), damage by the lantana tortricid moth, Crocidosema lantana Busck, or natural abortion inside the gall. Between 28 and 58% of newly recruited galls matured successfully. Percentage parasitism of E. xanthochaeta by D. tryoni varied significantly with ecological habitat: 4.1, 1.2, and 28% of mature E. xanthochaeta galls were parasitized by D. tryoni in the lowland pasture, the midelevation sugarcane field, and the upland forest, respectively. Percentage parasitism did not vary significantly with the number of galls recruited in each patch. Parasitoids emerging from field-collected E. xanthochaeta were significantly larger and had significantly more female-biased sex ratios (1.7:1) than those emerging from their normal rearing hosts, Ceratitis capitata (Wiedemann). Still, D. tryoni may not play a major role in regulating populations of E. xanthochaeta because it lacked a spatial density-dependent response to gall fly populations. Further studies are needed to determine how ecological habitat characteristics influence patterns of exploitation of E. xanthochaeta by D. tryoni.

Estimates of population density and dispersal in the blowflyLucilia sericata(Diptera: Calliphoridae)

AbstractTo investigate the population density and dispersal of the sheep blowflyLucilia sericata(Meigen) mark-release-recapture trials were carried out in lowland pastures in south west England. In three trials, 2142, 1351 and 451 fluorescent dust marked flies were released of which 4%, 14% and 10% were recaptured using a grid of sticky, odour-baited targets, placed between 8 m and 1000 m from the release point. There was no significant effect of wind direction on dispersal pattern and no apparent directional movement of the flies from the release point. Using the method described by Hawkes (1972) the mean distance travelled by all the flies on the first day of each of the three trials was calculated to be 108 m, 128 m and 137 m respectively. Using the method described by Fletcher (1974) the mean distances travelled were calculated to be 135 m (±42), 118 m (±27) and 183 m (± 61) on the first day of each of the three trials, respectively. The median distances travelled by the flies on the first day of each of the three trials were calculated to be 109 m, 130 m and 150 m, respectively. A Lincoln Index was used to estimate the population density of wild femaleL. sericata.The number of female flies was estimated to be zero in June, approximately one per hectare in July and six per hectare in August in 1994.

A review of the role of grazing management on the growth and performance of white clover cultivars in lowland New Zealand pastures

The current state of knowledge of white clover clonal growth processes and defoliation management is reviewed, and general recommendations on grazing principals made. Defoliation frequency determines herbage productivity through the manipulation of size/ density compensation between plant organ size (leaves) and numbers of growth units (growing point density). Hence large-leaved cultivars (Pitau, Kopu, Aran) are generally more productive under rotational grazing, whereas small-leaved cultivars are better suited to frequently grazed or set stocked conditions (Tahora, Prestige). The key to persistence is high growing point density, and the development of large-leaved densely branched cultivars should have superior performance over a wider range of grazing managements (Demand, Sustain). Grasses (perennial ryegrass, cocksfoot and tall fescue) grow by similar clonal processes to white clover and react in a similar manner to grazing management. Maintenance of pasture density (growing points/tillers) is crucial to persistence and is best achieved by rapid rotations or set stocking during spring/early summer. This provides protection against drought, and allows better exploitation of the genetic potential of species and cultivars through alternative grazing strategies over the remainder of the year. Keywords: clonal growth, cultivars, grazing management, morphology, populations, rotational grazing, seasonal growth patterns, set stocking, Trifolium repens L., white clover

Soil microbial biomass, C and N mineralization and enzyme activities in a hill pasture: Influence of season and slow-release P and S fertilizer

Hill pastures are widely used in New Zealand for sheep and cattle production. The influence of season and added slow-release fertilizer (rock phosphate and elemental S) on soil microbial pools and biochemical activities in a low-fertility hill pasture was investigated during 2 y. The soil was a Typic Dystrochrept. Specifically determined k ec -and k en -factors were used in the fumigation-extraction procedures for measuring microbial C and N. An appropriate factor for converting substrate-induced respiration values to microbial C was also determined. Fertilizer tended to increase dry matter production and the legume component of the sward in the second year of the trial, but variability was high and differences were generally non-significant. Fertilizer increased extractable soil inorganic P and S, but had no consistent, if any, effect on soil biochemical properties. Soil moisture content was generally high at all sampling times. Amounts of microbial biomass, and the percentages of microbial C and N in total C and N, respectively, were similar to those in more fertile lowland pastures. Temporal fluctuations in microbial C, N and P concentrations were small and mainly non-significant, and were related to variability in total C and N concentrations. Temporal fluctuations were also mainly non-significant for invertase and sulphatase activities, but were very marked for phosphodiesterase activity. CO 2C production under standardized conditions was highest in spring samples and significantly correlated with extractable C concentration. Min-N was generally immobilzed initially on incubation at 25°C, but net N mineralization increased over 14–56 d with maxima also in spring; NH 4 +N predominated throughout. Overall, potential rates of C and N mineralization were more susceptible to seasonal effects than were the microbial biomass pools.

Epidemiology of Ostertagia in the northwestern USA

The two most significant environmental factors that influence the epidemiology of Ostertagia are temperature and moisture. These factors vary more in the west and northwest than in any other part of the USA because of extreme regional differences in climate, topography, and land use. Consequently, patterns of Ostertagia transmission and inhibition also vary widely from region to region and from year to year. Recent data require revisions of previously accepted concepts of northern/southern transmission and inhibition. In particular, the flaw of liberal extrapolation of information from one region to another has now been recognized. Inhibition may not occur along the coast of the Pacific Northwest. Although not completely delineated, the transition zone between northern and southern patterns of inhibition appears to be significantly wider and more variable than previously recognized; Oregon data suggest a possible indeterminate and variable band extending north of the 45th parallel and south of the 43rd parallel. Summer inhibition has now been documented in areas of Oregon and Montana. Other than the recent Oregon and Montana studies, data on this transition zone in the Rocky Mountain region and high plains are sparse to non-existent. In contrast to previously accepted doctrine, the fall rise in egg count generally exceeds the traditionally accepted spring rise in many areas. From the Pacific Northwest to the Midwest, year-round transmission patterns have been observed. The presence of geothermal ground water sources produces microclimates that favor larval survival in many areas. The rangelands of the west appear to support more significant worm burdens than formerly believed, particularly as range livestock move from more arid rangeland to graze lush lowland pastures near streams or on sub-irrigated meadows. Concentrations of grazing animals in these areas that are more conducive to larval development and survival result in higher herbage contamination rates which increase long-term potential for infection.

Selection, management and use of cocksfoot cultivars in North Island pastoral farming

Cocksfoot (Dactylis glomerata) is the second most commonly sown grass species after ryegrass in New Zealand farming. In 1980, Grasslands Apanui was replaced by two new but very different cocksfoot cultivars characterised by improved digestibility and rust tolerance, cool-season growth and greater persistence. Grasslands Wana, semiprostrate and densely tillered, was developed for dryland pastures of low soil fertility heavily set stocked by sheep. Grasslands Kara, of low tiller density and open structure, was developed for lowland pastures of higher soil fertility as a companion to other tufted grass species to be rotationally grazed. Despite the different intended uses for the two cultivars, Wana was widely used in all environments. As a consequence, many farmers have been disappointed with the dominance of by Wana, particularly in lowland pastures of medium to high fertility where important companion grasses and clover have been suppressed, leading to poor pasture palatability. This paper describes key cultivar differences and discusses their implications for North Island farming systems, using the results of two on-farm trials to demonstrate cultivar and management effects. Guidelines on sowing rates, cultivar selection and management techniques for avoiding and reversing cocksfoot dominance are provided. Keywords: cool-season production, Dactylis glomerata, dominance, Grasslands Wana, Grasslands Kara, 'target cocksfoot percentage', lowland

Durchsetzungs- und Reproduktionsstrategien bei Trifolium pallescens Schreb. und Trifolium thalii Vill. : I. Untersuchungen zur Wuchsformmorphologie und Vergesellschaftung

Growth forms and community ecology of two closely related alpine Trifolium species have been studied. The species prefer distinct habitats and reproduce only by seeds: Trifolium pallescens grows on alpine screes, often in morainic areas; Trifolium thalii is predominantly to be found in subalpine-alpine pastures. This contrast in habitat behaviour was compared with the behaviour of the species along their altitudinal distribution. Observations were made in the Otztaler Alps (Tirol, Austria) and in the Montafon area (Vorarlberg, Austria). The different growth forms of these were found to correlate with the species-specific habitat and display highly adaptive plasticity along the altitudinal gradient. Trifolium pallescens is a rosette plant forming long lateral shoots which are annual with exception oft the shortened basis, while the lateral shoots of Trifolium thalii are perennial. Moreover regeneration capacity in both species is high. There are obvious relations to Trifolium repens, a closely related species of lowland pasture communities. A gradual change from generative (Trifolium pallescens, Trifolium thalii) to predominantly vegetative reproduction strategy (Trifolium repens) is obvious. The relationship between growth form, behaviour and species-specific community ecology is pointed out.

The importance of soil adhered to vegetation as a source of radionuclides ingested by grazing animals

Soil ingestion has been identified as a potentially important source of radionuclides to grazing animals. Seasonal patterns of soil adherence to vegetation and its implications for the radionuclide intake of grazing animals were measured at two west Cumbrian sites. Soil adhesion to vegetation was highly seasonal, being highest in autumn and winter. At Site 1 (a lowland pasture close to the British Nuclear Fuels plc Sellafield Reprocessing Plant, Cumbria, UK), vegetation samples were found to consist of up to 46% soil (by dry weight). Therefore, the importance of soil as a potential source of radionuclides to grazing animals was also seasonal; soil comprised up to 92% of the 137Cs and potentially all of the 239 240 Pu of vegetation samples at Site 1 and up to 62% of the 137Cs at Site 2 (an upland farm contaminated following the Chernobyl accident). Analyses of sheep faecal samples confirmed the seasonal importance of soil as a potential source of radionuclides. The importance of soil adhering to vegetation, as a source of contaminant 137Cs, increased with time after the Chernobly accident. Calculations of soil ingestion must be made when the intake of radionuclides by grazing animals is being studied. In some circumstances, present radioecological models may considerably underestimate the importance of soil ingestion.

The radioecological consequences for lowland pastures used to fatten upland sheep contaminated with radiocaesium

Current farming practice in upland areas of Cumbria, England, affected by Chernobyl fallout is to remove lambs to lowland pastures for fattening prior to slaughter. The radiocaesium ( 137Cs and 134Cs) burden of lambs is rapidly lost via excreta deposited on the pasture. This may increase the radiocaesium activities in vegetation of these pastures. Studies were performed to assess the radioecological consequences of this practice. Results obtained from experiments were used to calibrate a soil/vegetation model which was used to predict long-term radiocaesium behavior.

Uptake and retention of strontium, iodine and caesium in lowland pasture following continuous or short-term deposition

Data from the extensive routine environmental monitoring programme around the nuclear reprocessing plant at Sellafield, West Cumbria, are analysed for soil to plant uptake of strontium, iodine and caesium. Relative to the top 10 cm of soil, dry weight concentration ratios derived for lowland pastures for strontium, caesium and iodine are 9, 3 and 2 respectively. Long-term trends indicate a ‘spring flush’ of activity in vegetation, although this is not statistically significant. Uptake of caesium and iodine is highest generally for mosses and lichen and lowest for grass. The vegetational field loss of these elements over the first 50 days following deposition, is described by: Sr: R eff (t) = 0.7e −1.15t + 0.25e −0.049t + 0.05e −0.011tI: R eff(t) = 0.7e −1.26t + 0.25e −0.17t + 0.05e −0.092tCs: R eff(t) = 0.6e −0.87t + 0.2e −0.20t + 0.16e −0.065t + 0.04e −0.011t where t is in days. The functions are consistent with the effects of washoff and grazing. Equilibrium plant:soil concentration ratios are established for caesium within about 8 months following short-term deposition. Soil distribution profiles for caesium imply a half-time for transfer through the surface layers of about 6 years.

Cesium-137, 134Cs and 110mAg in lambs grazing pasture in NE Scotland contaminated by Chernobyl fallout.

The decline in Cs radioisotope levels has been studied in tissues from lambs grazing lowland pasture. The lambs were slaughtered 18 and 115 d after contamination with Chernobyl fallout. During this time the Cs activity decreased to 13% of the initial amount in animals that had continued to graze contaminated pasture and to 3.5% in animals consuming uncontaminated feed. The 137Cs concentration in grass from the field grazed by the lambs decreased with a half-time of 22 d over the period 11-100 d after contamination. The amounts of Cs radionuclides removed from the pasture by the grazing animals amounted to only 0.01% of the total, the rest remaining in the soil, with over 40% in the upper 10 mm. Small amounts of 110mAg, found in grass, declined with a half-time of 8.9 d, and the radionuclide was found to accumulate in liver tissue.

COBALT DEFICIENCY IN THE KAIWERA DISTRICT, EASTERN SOUTHLAND

SolIs and pastures were sampled at 96 sites in the Kaiwera district, an area having 12 soil types typical of eastern Southland and South Otago. Analyses indicated that ill-thrift in lambs could be due to low cobalt (Co) Intake. Upland (>300 m a.s.1.) topsoils had lower EDTA extractable Co than lowland topsoils and analysis of soil profile samples indicated that Co had been leached from upper horlzons of upland soils. Upland pastures contained much less Co than lowland pastures and Co concentration was much lower in February than in October. Sheep grazing on upland pasture had very low vitamin B 12 status from October to June and this coincided with low pasture Co concentration Sheep grazing on lowland pasture had adequate vitamin B l2, although pasture Co concentration fell to below 0.06 mg/kg for a short period in summer. We conclude that sheep grazed on upland pastures for long periods need supplementary Co or vitamin B 12 or need to be rotattonally grazed on lowland pasture to build up adequate reserves of vitamin 8, 2 Keywords: ill-thrift. sheep, vitamin B,2, pasture cobalt, seasonal variation

The archaeology of the Italian shepherd

Stock-keeping in the Mediterranean has to be adapted to the fundamental characteristics of the Mediterranean climate (mild wet winters and hot dry summers) and to the distinct variations in soil type and plant growth at different altitudes. The natural vegetation of the coastal regions is dominated by plants that can withstand the summer drought (when temperatures average 70–80 degrees F) such as the olive, holm oak, cork oak, and macchia scrub. The lowland pastures are green and succulent from autumn to spring, when temperatures average 45–55 degrees F and rainfall is relatively abundant, but are withered and of little nutritional value in the summer. In the interior mountains of Spain, Italy, and Greece, average January temperatures are below freezing and snow covers the highest regions through the winter months, but there is extensive grazing of excellent quality from the late spring to early autumn.

Pasture cobalt concentration and its effect on vitamin B12status of sheep grazing upland and lowland pastures in the Kaiwera district, eastern Southland, New Zealand

Abstract Cobalt (Co) concentrations in upland and lowland pastures of the Kaiwera district were monitored for a 13-month period from August 1985 to September 1986 and the effect of changes in pasture Co on the vitamin B12 status of grazing sheep was determined. Co concentration in upland pastures was adequate for stock in winter but fell rapidly to below the critical value of 0.08 ppm Co by lambing time and remained in the range 0.03 – 0.07 ppm for 9 – 10 months until it became adequate again in winter. Co concentration in lowland pastures also fell from adequate values in winter, but more slowly than in upland pastures and was below 0.08 ppm for only 3 – 4 months. The pattern of change in serum vitamin B12 of upland and lowland sheep was similar, as at each site values fell from being highest in spring to a minimum in summer and autumn and then increased again in winter. However, serum vitamin B12 of upland sheep was always at a lower value and in the marginal-deficient range from November through to Jul...

A comparison of caesium 137 and 134 activity in sheep remaining on upland areas contaminated by Chernobyl fallout with those removed to less active lowland pasture

Caesium contamination of vegetation in some upland areas of the United Kingdom after the Chernobyl accident remained persistently higher than many anticipated. Consequently, some sheep continued to graze vegetation containing sufficiently high caesium activity to maintain tissue activity above the limits adopted for slaughter in the United Kingdom (1000 Bq kg-1 fresh weight). In this study the caesium activity in lambs remaining on affected upland areas has been compared with that of lambs removed to a lowland site. The former lost very little caesium activity from the end of July to mid-September 1987 owing to the persistently high caesium activity of the pasture. The transfer coefficient to lamb muscle (0.79 day kg-1) was 6 times higher than that previously estimated from lowland field studies. Lambs removed to much less contaminated lowland pasture rapidly lost their Cs activity with an initial biological half life of 10 days.

Nutrient status of soils and pastures of the Kaiwera district, eastern Southland, New Zealand

Abstract Samples from 96 sites in the Kaiwera district were analysed for available major and trace elements to determine if ‘ill-thrift’ of lambs could be related to the nutrient status of soils or pastures. Major elements were slightly lower in upland soils (above about 300 m) than in lowland soils but there were no differences in pasture concentrations. Levels of cobalt (Co) and copper (Cu) extracted with EDTA were lower in upland than in lowland soils and pasture Co and Cu concentrations showed a similar pattern. Pasture Co declined markedly in all samples from October to February and was below the minimum requirements for satisfactory nutrition of sheep in many samples in February. Some pasture Cu concentrations were marginal for cattle. It is concluded that pasture growth in the district is not restricted by any nutrient limitation although nitrogen concentrations were below optimum. Sheep are probably affected by inadequate Co intake particularly when grazing upland pastures.

The efficacy of soluble glass boluses (cosecure) in grazing cattle

Two soluble glass boluses (COSECURE) per animal were given to 19 (+ bolus), silage fed, growing cattle (160-350 kg) on April 16th 1984 (day 0). After 29 days these and 11 untreated (control) animals, matched for weight, breed and sex, were turned out on to a copper deficient upland pasture. On day 153 (Sept. 21) all the cattle were moved to a lowland pasture until day 196, when they were housed and fed silage.Blood samples and liveweights were taken on 5 occasions over 240 days. Copper status was assessed from plasma copper (Cu) and caeruloplasmin (CP) levels, and selenium status by erythrocyte glutathione peroxidase (GSHPx) activity.

Effects of improved nutrition during lactation on the performance of hill lambs

AbstractTwo experiments compared the effects of grazing by hill ewes with single lambs on lowland pasture for varying periods of time. In Experiment 1 lambs kept with their mothers on lowland pasture for 0, 21, 42 or 70 d before being moved to hill grazing gave daily liveweight gains (g) of 243,329, 338 and 348 respectively in the 1–21 days postpartum period; 243,248,310 and 314 in the 22–42 days period; 118, 132, 157 and 229 in the 43–70 days period and 105, 100, 115 and 98 in the 71 days to weaning period. In Experiment 2, ewes with single lambs grazed lowland pasture for 0, 21, 56 and 110 days and the daily liveweight gains (g) recorded were 233, 348, 343 and 353 respectively in the 1–21 days postpartum period; 184, 229, 306 and 297 in the 22‐56 days period and 109, 115, 141 and 209 in the 57‐110 days period. At each weighing up to weaning there was a positive correlation between lamb weight and the number of days spent on lowland pasture. Carcass weight and killing out percentages were each also significantly improved. The implications of these results in developing a hill‐sheep system are discussed.