bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon sequestration in a high‐elevation, subalpine forest
Authors: Monson R. K. , Turnipseed A. A. , Sparks J. P. , Harley P. C. , Scott‐Denton L. E. , Sparks K. , Huxman T. E.
Published: March 2003

We studied net ecosystem CO2 exchange (NEE) dynamics in a high‐elevation, subalpine forest in Colorado, USA, over a two‐year period. Annual carbon sequestration for the forest was 6.71 mol C m−2 (80.5 g C m−2) for the year between November 1, 1998 and October 31, 1999, and 4.80 mol C m−2 (57.6 g C m−2) for the year between November 1, 1999 and October 31, 2000. Despite its evergreen nature, the forest did not exhibit net CO2 uptake during the winter, even during periods of favourable weather. The largest fraction of annual carbon sequestration occurred in the early growing‐season; during the first 30 days of both years. Reductions in the rate of carbon sequestration after the first 30 days were due to higher ecosystem respiration rates when mid‐summer moisture was adequate (as in the first year of the study) or lower mid‐day photosynthesis rates when mid‐summer moisture was not adequate (as in the second year of the study). The lower annual rate of carbon sequestration during the second year of the study was due to lower rates of CO2 uptake during both the first 30 days of the growing season and the mid‐summer months. The reduction in CO2 uptake during the first 30 days of the second year was due to an earlier‐than‐normal spring warm‐up, which caused snow melt during a period when air temperatures were lower and atmospheric vapour pressure deficits were higher, compared to the first 30 days of the first year. The reduction in CO2 uptake during the mid‐summer of the second year was due to an extended drought, which was accompanied by reduced latent heat exchange and increased sensible heat exchange. Day‐to‐day variation in the daily integrated NEE during the summers of both years was high, and was correlated with frequent convective storm clouds and concomitant variation in the photosynthetic photon flux density (PPFD). Carbon sequestration rates were highest when some cloud cover was present, which tended to diffuse the photosynthetic photon flux, compared to periods with completely clear weather.

The results of this study are in contrast to those of other studies that have reported increased annual NEE during years with earlier‐than‐normal spring warming. In the current study, the lower annual NEE during 2000, the year with the earlier spring warm‐up, was due to (1) coupling of the highest seasonal rates of carbon sequestration to the spring climate, rather than the summer climate as in other forest ecosystems that have been studied, and (2) delivery of snow melt water to the soil when the spring climate was cooler and the atmosphere drier than in years with a later spring warm‐up. Furthermore, the strong influence of mid‐summer precipitation on CO2 uptake rates make it clear that water supplied by the spring snow melt is a seasonally limited resource, and summer rains are critical for sustaining high rates of annual carbon sequestration.
Satellite estimates of productivity and light use efficiency in United States agriculture, 1982–98
Authors: Lobell D. B. , Hicke J. A. , Asner G. P. , Field C. B. , Tucker C. J. , Los S. O.
Published: March 2003

Remote sensing of net primary production (NPP) is a critical tool for assessing spatial and temporal patterns of carbon exchange between the atmosphere and biosphere. However, satellite estimates suffer from a lack of large‐scale field data needed for validation, as well as the need to parameterize plant light‐use efficiencies (LUEs). In this study, we estimated cropland NPP with the Carnegie‐Ames‐Stanford‐Approach (CASA), a biogeochemical model driven by satellite observations, and then compared these results with field estimates based on harvest data from United States Department of Agriculture National Agriculture Statistics Service (NASS) county statistics. Observed interannual variations in NPP over a 17‐year period were well modelled by CASA, with exceptions mainly due to occasional difficulties in estimating NPP from harvest yields. The role of environmental stressors in agriculture was investigated by running CASA with and without temperature and moisture down‐regulators, which are used in the model to simulate climate impacts on plant LUE. In most cases, correlations with NASS data were highest with modelled stresses, while the opposite was true for irrigated and temperature resistant crops. Analysis of the spatial variability in computed LUE revealed significantly higher values for corn than for other crops, suggesting a simple parameterization of LUE for future studies based on the fraction of area with corn. Absolute values of LUE were much lower than those reported in field trials, due to uncommonly high yields in most field trials, as well as overestimates of absorbed radiation in CASA attributed to bias from temporal compositing of satellite data. Total NPP for US croplands, excluding Alaska and Hawaii, was estimated as 0.62 Pg C year−1, representing ∼20% of total US NPP, and exhibited a positive trend of 3.7 Tg C year−2. These results have several implications for large‐scale carbon cycle research that are discussed, and are especially relevant for studies of the role of agriculture in the global carbon balance.
Effects of elevated temperature and carbon dioxide on seed‐set and yield of kidney bean (Phaseolus vulgaris L.)
Authors: Prasad P. V. Vara , Boote Kenneth J. , Allen L. Hartwell , Thomas Jean M. G.
Published: March 2003

It is important to quantify and understand the consequences of elevated temperature and carbon dioxide (CO2) on reproductive processes and yield to develop suitable agronomic or genetic management for future climates. The objectives of this research work were (a) to quantify the effects of elevated temperature and CO2 on photosynthesis, pollen production, pollen viability, seed‐set, seed number, seeds per pod, seed size, seed yield and dry matter production of kidney bean and (b) to determine if deleterious effects of high temperature on reproductive processes and yield could be compensated by enhanced photosynthesis at elevated CO2 levels. Red kidney bean cv. Montcalm was grown in controlled environments at day/night temperatures ranging from 28/18 to 40/30 °C under ambient (350 µmol mol−1) or elevated (700 µmol mol−1) CO2 levels. There were strong negative relations between temperature over a range of 28/18–40/30 °C and seed‐set (slope, − 6.5% °C−1) and seed number per pod (− 0.34 °C−1) under both ambient and elevated CO2 levels. Exposure to temperature > 28/18 °C also reduced photosynthesis (− 0.3 and − 0.9 µmol m−2 s−1 °C−1), seed number (− 2.3 and − 3.3 °C−1) and seed yield (− 1.1 and − 1.5 g plant−1 °C−1), at both the CO2 levels (ambient and elevated, respectively). Reduced seed‐set and seed number at high temperatures was primarily owing to decreased pollen production and pollen viability. Elevated CO2 did not affect seed size but temperature > 31/21 °C linearly reduced seed size by 0.07 g °C−1. Elevated CO2 increased photosynthesis and seed yield by approximately 50 and 24%, respectively. There was no beneficial interaction of CO2 and temperature, and CO2 enrichment did not offset the negative effects of high temperatures on reproductive processes and yield. In conclusion, even with beneficial effects of CO2 enrichment, yield losses owing to high temperature (> 34/24 °C) are likely to occur, particularly if high temperatures coincide with sensitive stages of reproductive development.
Estimating net primary productivity from grassland biomass dynamics measurements
Authors: Scurlock J. M. O. , Johnson K. , Olson R. J.
Published: March 2003

To address the need for a high quality data set based upon field observations suitable for parameterization, calibration, and validation of terrestrial biosphere models, we have developed a comprehensive global database on net primary productivity (NPP). We have compiled field measurements of biomass and associated environmental data for multiple study sites in major grassland types worldwide. Where sufficient data were available, we compared aboveground and total NPP estimated by six computational methods (algorithms) for 31 grassland sites. As has been found previously, NPP estimates were 2–5 times higher using methods which accounted for the dynamics of dead matter, compared with what is still the most commonly applied estimate of NPP (maximum peak live biomass). It is suggested that assumptions such as the use of peak biomass as an indicator of NPP in grasslands may apply only within certain subbiomes, e.g. temperate steppe grasslands. Additional data on belowground dynamics, or other reliable estimates of belowground productivity, are required if grasslands are to be fully appreciated for their role in the global carbon cycle.
Growth, photosynthetic properties and Rubisco activities and amounts of marine macroalgae grown under current and elevated seawater CO2 concentrations
Authors: Israel Alvaro , Hophy Mazal
Published: March 2003

Growth rates, photosynthetic responses and the activity, amount and CO2 affinity of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) were determined for common marine macroalgae grown in seawater (containing 14.5 ± 2.1 µM CO2) or CO2‐enriched seawater (averaging 52.8 ± 19.2 µM CO2). The algae were grown in 40 L fiberglass tanks (outdoor) for 4–15 weeks and in a field experimental setup for 5 days. Growth rates of the species studied (representing the three major divisions, i.e. Chlorophyta, Rhodophyta and Phaeophyta) were generally not significantly affected by the increased CO2 concentrations in the seawater medium. Rubisco characteristics of algae cultivated in CO2‐enriched seawater were similar to those of algae grown in nonenriched seawater. The lack of response of photosynthetic traits in these aquatic plants is likely to be because of the presence of CO2 concentrating mechanisms (CCMs) which rely on HCO3– utilization, the inorganic carbon (Ci) form that dominates the total Ci pool available in seawater. Significant changes on the productivity of these particular marine algae species would not be anticipated when facing future increasing atmospheric CO2 levels.
Maximum impacts of future reforestation or deforestation on atmospheric CO2
Authors: HOUSE JOANNA I. , COLIN PRENTICE I. , LE QUÉRÉ CORINNE
Published: March 2003

There is scope for land‐use changes to increase or decrease CO2 concentrations in the atmosphere over the next century. Here we make simple but robust calculations of the maximum impact of such changes. Historical land‐use changes (mostly deforestation) and fossil fuel emissions have caused an increase in atmospheric concentration of CO2 of 90 ppm between the pre‐industrial era and year 2000. The projected range of CO2 concentrations in 2100, under a range of emissions scenarios developed for the IPCC, is 170–600 ppm above 2000 levels. This range is mostly due to different assumptions regarding fossil fuel emissions. If all of the carbon so far released by land‐use changes could be restored to the terrestrial biosphere, atmospheric CO2 concentration at the end of the century would be about 40–70 ppm less than it would be if no such intervention had occurred. Conversely, complete global deforestation over the same time frame would increase atmospheric concentrations by about 130–290 ppm. These are extreme assumptions; the maximum feasible reforestation and afforestation activities over the next 50 years would result in a reduction in CO2 concentration of about 15–30 ppm by the end of the century. Thus the time course of fossil fuel emissions will be the major factor in determining atmospheric CO2 concentrations for the foreseeable future.
Temporal evolution of the European forest sector carbon sink from 1950 to 1999
Authors: Nabuurs Gert‐Jan , Schelhaas Mart‐Jan , Mohren Godefridus (frits) M. J. , Field Christopher B.
Published: March 2003

Estimates of the role of the European terrestrial biosphere in the global carbon cycle still vary by a factor 10. This is due to differences in methods and assumptions employed, but also due to difference in reference periods of the studies. The magnitude of the sink varies between years because of inter‐annual variation of short‐term climate, but also due to long‐term trends in development of the vegetation and its management. For this purpose, we present the results of an application of a carbon bookkeeping model to the forest sector of the European forests from 1950 to 1999. The analysis includes the compartments trees, soils, and wood products. The model uses statistics on European (30 countries excl. CIS) stemwood volume increment, forest area change, fellings, wood products and their international trade, and natural disturbances, supplemented with conversion coefficients, soil parameters and information on management.

An (almost uninterrupted) increasing sink (Net Biome Production) in the European forest sector was found, increasing from 0.03 Pg C year−1 in the 1950s to 0.14 Pg C year−1 in the 1990s (for resp. 132 million hectares and 140 million hectares of forest). The sink in the tree and the soil compartment were approximately of the same size until 1970. After the 1970s the size of the sink in the tree biomass increases quickly, causing the tree biomass to account for some two thirds of the total sink in the 1990s. The results as presented here have to be regarded with caution especially with regard to the early decades of the analysis and with regard to the soil compartment.
Mycorrhizal fungal abundance is affected by long‐term climatic manipulations in the field
Authors: Staddon Philip L. , Thompson Ken , Jakobsen Iver , Grime J. Philip , Askew Andrew P. , Fitter Alastair H.
Published: March 2003

Climate change treatments – winter warming, summer drought and increased summer precipitation – have been imposed on an upland grassland continuously for 7 years. The vegetation was surveyed yearly. In the seventh year, soil samples were collected on four occasions through the growing season in order to assess mycorrhizal fungal abundance. Mycorrhizal fungal colonisation of roots and extraradical mycorrhizal hyphal (EMH) density in the soil were both affected by the climatic manipulations, especially by summer drought. Both winter warming and summer drought increased the proportion of root length colonised (RLC) and decreased the density of external mycorrhizal hyphal. Much of the response of mycorrhizal fungi to climate change could be attributed to climate‐induced changes in the vegetation, especially plant species relative abundance. However, it is possible that some of the mycorrhizal response to the climatic manipulations was direct – for example, the response of the EMH density to the drought treatment. Future work should address the likely change in mycorrhizal functioning under warmer and drier conditions.
The effect of grazing by cattle on animal performance and floristic composition in Nardus‐dominated swards
Authors: Common  , Wright  , Grant
Published: March 2003

Four groups of six spring‐calving beef cows and their calves were allocated to two replicated grazing treatments on a Nardus stricta‐dominated hill pasture in the UK during six consecutive summer grazing seasons. Treatments were applied by continuous variable stocking to maintain a sward height of either 4–5 cm (short) or 6–7 cm (tall) between tussocks of N. stricta.

Cows on both treatments ingested a greater proportion of N. stricta than was present in the sward. The short treatment reduced the herbage intake of cows proportionally by 0·35 (P < 0·001) and reduced herbage digestibility by 0·03 (P < 0·01) compared with the tall treatment. Cows lost 0·02 kg d−1 live weight on the short treatment but gained 0·27 kg d−1 live weight on the tall treatment (s.e.d. 0·077; P < 0·001). Calf liveweight gains were 0·60 and 0·86 (s.e.d. 0·034; P < 0·001) kg d−1 for the short and tall treatments respectively. The greatest liveweight gains for both cows and calves occurred during the first 5–6 weeks of the grazing season and differences between treatments increased over the season. Cattle on the short treatment consistently grazed a higher proportion of N. stricta tillers more closely than those on the tall treatment, and the percentage cover of N. stricta declined more rapidly on the short treatment. After 6 years of grazing there was a considerably greater (P < 0·001) proportion of very small tussocks, i.e. less than 140 cm2 basal area, on the short treatment than on the tall treatment. The percentage cover of broad‐ and fine‐leaved grasses also declined, in contrast to previous studies. This may have been due to lower soil fertility on the site of the current experiment.

It is concluded that high levels of utilization of N. stricta are incompatible with high levels of individual animal performance in lactating cows, although short periods in early summer may give acceptable performance. Lower levels of utilization such as that achieved on the 6–7 cm treatment resulted in moderate levels of animal performance and also gradually reduced the cover of N. stricta, although it took longer for the effect to be established.
Salinity effects on the early development stages of Panicum coloratum: cultivar differences
Authors: Taleisnik  , Pérez  , Córdoba  , Moreno  , Seffino L. García , Arias  , Grunberg  , Bravo  , Zenoff
Published: March 2003

The Argentinean semiarid Chaco region is climatically suitable for cattle raising and has an average annual rainfall of 550 mm, concentrated from November to February. There, large areas are affected by high salinity; thus, perennial forages suitable for this region must combine adequate salt and drought tolerance. Panicum coloratum is a C4 perennial grass adapted over a wide range of soil and rainfall conditions, and the purpose of this study was to evaluate the response of two cultivars (Klein Verde and Bambatsi) to salinity. Under controlled conditions, 100 and 200 mmol l−1 NaCl delayed germination and significantly reduced germination percentages and seedling survival in both cultivars. However, in the field, factors other than salinity (possibly drought) had a large impact on plant survival. In short‐term experiments under controlled environmental conditions, the vegetative growth of cultivar Klein Verde was less affected by salinity than Bambatsi. The cumulative growth over one year in a saline plot was also higher in cultivar Klein Verde. This cultivar also had higher shoot K+/Na+ ratios under salinity, as a result of higher K+ concentrations, and accumulated more triglycerides in roots. These features have been associated with salt tolerance in other species.
The extent of semi‐natural grassland communities in lowland England and Wales: a review of conservation surveys 1978–96
Authors: Blackstock  , Rimes  , Stevens  , Jefferson  , Robertson  , Mackintosh  , Hopkins
Published: March 2003

The extent of semi‐natural grassland has diminished considerably across lowland landscapes of England and Wales during the second half of the twentieth century. Locating, describing and evaluating the dwindling cover has been a major challenge for conservationists. A concentrated vegetation survey effort at grassland sites has been mounted within different parts of Britain since the late 1970s. Plant community recognition has benefited considerably from the development of the contemporary National Vegetation Classification, and its widespread adoption permits national inventory of comparable vegetation data.

Findings of a range of surveys (ninety‐eight in total), undertaken between 1978 and 1996 in England and Wales covering different forms of unimproved lowland grassland, are collated and reviewed. Vegetation data were abstracted from internally published survey reports. Calcicolous and neutral grasslands have been covered more thoroughly than acidic and wet or marshy grasslands. Cover data are summarized at community level. Overall estimates from survey results indicate that there are some 27 500–40 000 ha of calcicolous grassland, 7500–15 000 ha of unimproved neutral pasture and hay meadow, 8000–15 000 ha of acidic grassland and 9000–17 500 ha of wet grassland in lowland England and Wales; these represent only 1–2% of the cover of permanent lowland grassland. Some communities have additional representation in heathlands, mires and upland environments.

Although they require further refinement, the cover data for individual communities provide a context for assessing priorities in site‐based and agri‐environment conservation programmes. It is concluded that, as well as arresting further depletion, it will be necessary to restore and expand lowland grassland habitats to counteract the negative impacts of fragmentation and isolation of various community types, such as the Centaureo–Cynosuretum, which is widely but thinly distributed. Habitat rehabilitation schemes also need to assimilate local patterns of community diversity characteristic of both wet and dry grasslands. It is suggested that reversal of the recent successional trends that followed relaxation of grazing at certain sites might produce a more appropriate balance in the relative cover of coarse tall grasslands and fine short turf. Vegetation surveys provide a source of spatial data for identifying local aggregations of semi‐natural grassland remnants.
Changes in the population of germinated seed in a hill pasture during and after a pastoral fallow
Authors: Nie  , Barker  , Valentine  , Mackay  , Hodgson
Published: March 2003

A pastoral fallow, which involves no defoliation of pasture for a period, generally from spring to autumn, is a management tool that can be used either to reduce plant population density through self‐thinning prior to oversowing improved plant germplasm or to encourage natural reseeding in order to increase sward persistence and productivity. Two field experiments were carried out in a hill pasture in New Zealand to quantify the response of the seed population, germinated from soil plugs under glasshouse conditions for over 7 months, to pastoral fallow, as influenced by the timing and duration of the fallow, fertilizer application and aspect, and to identify the germination patterns of different plant species in fallowed and grazed swards. A spring–autumn pastoral fallow increased the germinated seed population of grasses, legumes and weeds by 161%, 51% and 59%, respectively, compared with the grazed control. The variation in germinated seed population during the pastoral fallow showed that seed quantity can be controlled by manipulating the timing and duration of a pastoral fallow. Short duration (2–3 month) pastoral fallows resulted in a significantly lower germinated grass seed population than the full (spring–autumn) fallows. Fertilizer application reduced the germinated grass seed population by 26%. The germinated legume seed population was higher with a shady than a sunny aspect. Regression analysis revealed that the germination patterns of all plant species followed a negative exponential function. Partial differentiation of this function derived a germination rate curve on which a two‐pool (ephemeral pool and base pool) model was developed to describe quantitatively the dynamics of germinable seed reserves in the soil.
Photosynthetic characteristics of perennial ryegrass and red fescue turf‐grass cultivars
Authors: Van Huylenbroeck  , Lootens  , Van Bockstaele
Published: March 2003

The photosynthetic characteristics of eleven commercial perennial ryegrass (Lolium perenne L.) and nine red fescue (Festuca rubra L.) turf‐grass cultivars were evaluated. In general, perennial ryegrass had a faster growth, with higher net photosynthesis and quantum efficiency and lower dark respiration (Rd) than red fescue. Among the perennial ryegrass cultivars two major groups were observed: the first one with slow growth, high light compensation point (Ic) and low Rd and the second one with fast growth, low Ic and high Rd. A similar ranking was evident for the red fescue cultivars tested. The chewings fescue (F. rubra ssp. commutata) cultivars belonged to the first group, whereas the strong creeping red fescue (F. rubra ssp. rubra) cultivars were classified into the second group. Slender creeping red fescues (F. rubra ssp. trichophylla) had intermediate features. These variations make it possible to use some of these characteristics in breeding programmes for turf‐grasses.
The response of a perennial ryegrass (Lolium perenne L.) seed crop to nitrogen fertilizer application in the absence of moisture stress
Authors: Cookson W. R. , Rowarth J. S. , Cameron K. C.
Published: March 2003

Responses of perennial ryegrass (Lolium perenne L.) to nitrogen (N) fertilizer application rates and timings vary widely, because water is often limiting. Yield response to N fertilizer application during autumn, late‐winter and spring, and the associated efficiency of use of these inputs, was assessed under conditions of non‐limiting soil moisture during two, one‐year lysimeter studies in Canterbury, New Zealand. There were significant (P < 0·05) increases in seed and herbage yields with increasing N fertilizer application. Seed yields differed with year; greatest yields were 300 g m−2 in 1996 and 450 g m−2 in 1997. Seed head numbers (r2=0·77), seeds head−1 (r2=0·92) and herbage yield (r2=0·92) were the major determinants of seed yield in both years. Irrigation required to maintain the soil between 70% and 90% of field capacity was directly related (r2=0·94 and 0·99 in 1996 and 1997 respectively) to increases in herbage yield.

Seed yield, seed quality (thousand seed weight and percentage of seed > 1·85 mg), efficiency of water use, efficiency of N fertilizer use and apparent N fertilizer recovery were greatest when N fertilizer was applied at a rate of 50 kg N ha−1, 50 or 100 kg N ha−1 and 150 kg N ha−1 in autumn, late‐winter and spring respectively; further increases in spring N fertilizer stimulated vegetative growth, but not seed yield.

As a management strategy, applying N fertilizer to match the N requirements of the crop during the reproductive stage of growth will result in high yields of high quality seed while minimizing environmental impact.
Quantifying the influence of sward height, concentrate level and initial milk yield on the milk production and grazing behaviour of continuously stocked dairy cows
Authors: Pulido R. G. , Leaver J. D.
Published: March 2003

Two factorial design experiments were carried out in the spring of 1994 and 1995, each of 6 weeks, to quantify the effects of sward height (SH), concentrate level (CL) and initial milk yield (IMY) on milk production and grazing behaviour of continuously stocked dairy cows. In Experiment 1, forty‐five Holstein Friesian cows were in five groups with initial milk yields of 16·9, 21·1, 28·0, 31·5 and 35·5 kg d–1, grazed sward heights were 3–5, 5–7 and 7–9 cm (LSH, MSH and HSH respectively), and concentrates were fed at rates of 0, 3 and 6 kg d–1. In Experiment 2, 48 cows were in two groups with IMY of 21·3 and 35·5 kg d–1, grazed sward heights were 3–5 and 7–9 cm (LSH and HSH), and concentrates were fed at 0 and 6 kg d–1 and ad libitum. Multiple regression models were used to quantify the effects of the three variables on milk yield persistency (MYP), estimated herbage dry‐matter (DM) intake (HDMI), grazing time (GT) and rate of DM intake (RI). The partial regression coefficients showed that increased SH led to increased MYP (Experiment 1 P < 0·001, Experiment 2 P < 0·05), increased HDMI (P < 0·01, P < 0·01), increased GT (P < 0·001, P < 0·05) and increased RI (P < 0·001, P < 0·05). Increasing CL led to increased MYP (NS, P < 0·001), decreased HDMI (P < 0·001, P < 0·001), decreased GT (NS, P < 0·001) and decreased RI (P < 0·001, P < 0·001). Higher IMY level of cows decreased MYP (P < 0·001, P < 0·001), increased HDMI (P < 0·001, P < 0·001), increased GT (P < 0·001, P < 0·05) and increased RI (P < 0·05, P < 0·01). The models were highly significant (P < 0·001), and accounted for 0·48–0·87 of the total variance. The partial regression coefficients quantified the extent to which GT and RI by cows respond positively to higher IMY, and negatively to increased CL, but respond differently (GT declines in response to a higher RI) with increasing SH.
Influence of species, cutting date and cutting interval on the fatty acid composition of grasses
Authors: Dewhurst R. J. , Scollan N. D. , Youell S. J. , Tweed J. K. S. , Humphreys M. O.
Published: March 2003

Two experiments were conducted to evaluate the effects of species, cutting date and cutting interval on the concentration of fatty acids in temperate grasses. The first experiment compared eight species, harvested in late autumn and summer. Levels of individual fatty acids were distinctive for some species, with low levels of C18:1 in Dactylis glomerata L. and high levels of C18:2 in Phleum pratense L. Differences in individual fatty acids could not be used to differentiate fescues and ryegrasses. However, fatty acid profiles could be used to differentiate species when material was managed similarly (i.e. at the same cut). There were large species × cut interaction effects, showing that management factors will be as important as plant breeding in manipulating fatty acid levels. Cultivars belonging to one Lolium perenne L. gene pool were identified as having significantly higher α‐linolenic acid and total fatty acids in late‐season (November) material.

The second experiment compared three ryegrass species over a growing season, with three or five cuts. All species had high concentrations of fatty acids and a high proportion of α‐linolenic acid during vegetative growth (late April). Fatty acid levels declined markedly in all species after this date, recovering by autumn. Kunth Lolium multiflorum Lam. and Lolium × boucheanum had higher levels of total fatty acids and α‐linolenic acid in the early and late season when compared with perennial ryegrass. Fatty acid levels (particularly C18:2 and C18:3) declined when the regrowth interval was extended from 20 to 38 d.

These studies demonstrate opportunities to change the composition of ruminant products through breeding and management of grasses for altered levels of fatty acids.
Effect of temperature on germination and early growth of subterranean clover, capeweed and Wimmera ryegrass
Authors: Turner N. C. , Thomson C. J. , Rawson H. M.
Published: March 2003

Germination of annual pasture species was studied under controlled‐environment conditions in south‐western Australia at temperatures in the range from 4°C to 35°C. Subterranean clover (Trifolium subterraneum) and Wimmera ryegrass (Lolium rigidum) had a germination of 90% between 12°C and 29°C, whereas capeweed (Arctotheca calendula) had a high germination percentage in a much narrower temperature range with an optimum of 25°C. Growth of subterranean clover, capeweed and Wimmera ryegrass between 28 and 49 days after sowing (DAS) was also studied at two photon flux densities, 13 and 30 mol m−2 d−1, and at diel temperatures in the range from 15/10°C to 33/28°C. Pasture species grown at a density of 1000 plants m−2 accumulated at least twice the amount of shoot dry matter when subjected to temperatures of 21/16°C and 27/22°C, compared with a lower temperature of 15/10°C and a higher temperature of 33/28°C. Except at the highest temperature and at high photon flux density, capeweed had lower green area indices (GAI) than the other two species at 28 DAS. Crop growth rates between 28 and 49 DAS were higher in Wimmera ryegrass than in the other two species, whereas subterranean clover had a lower relative growth rate than the other two species at all temperatures and both photon flux densities. Subterranean clover and capeweed intercepted a greater proportion of the incident radiation compared with Wimmera ryegrass. The values of radiation interception and GAI were used to estimate the number of DAS to reach 75% radiation interception [f(0·75)]. The number of days to reach f(0·75) decreased with increasing temperature from 15/10°C to reach a minimum at 27/22°C. The time taken to achieve f(0·75) was always shorter by about 10 d when the photon flux density was 30 mol m−2 d−1 in the autumn compared with 13 mol m−2 d−1 in the winter. These results are discussed in relation to the early growth of annual pasture in the field.
Effect of season and cutting frequency on root and shoot competition between Festuca pratensis and Dactylis glomerata
Authors: Carlen C. , Kölliker R. , Reidy B. , Lüscher A. , Nösberger J.
Published: March 2003

Abstract Plant competition strongly affects the species composition of managed grassland. To identify relevant processes, Festuca pratensis (Huds.) and Dactylis glomerata (L.) were grown as monocultures or mixtures in boxes placed in the field for two seasons and subjected to two cutting frequencies. Root and shoot competition effects were separated using soil and aerial partitions. Shoot competition was analysed by measuring the vertical distribution of the leaf area and root competition by analysing the absorption of tracers. Values of relative yield indicated that the two grasses fully competed for the same limiting resources under the experimental conditions. The competitive ability of F. pratensis was lower during both years relative to D. glomerata. This was mainly related to its consistently lower shoot competitive ability, which was associated with less leaf area in the upper layers of the canopy and shorter leaves. Root competitive ability of F. pratensis changed with season. It was similar to that of D. glomerata during spring and autumn, but less during summer. The lower root competitive ability in summer might be due to the lower root activity of F. pratensis, measured as rubidium (Rb) and strontium (Sr) absorption in July, 0·1 and 0·2 m below the ground. Cutting frequency did not greatly influence the relative importance of root and shoot competition during the first growing season. However, under infrequent defoliation, the competitive ability of F. pratensis decreased markedly in full competition during the second growing season. These results suggest that distinct differences in the canopy structure and root activity of different plant species can affect the relative importance of root and shoot competition during the season.
Yield response of long‐term mixed grassland swards and nutrient cycling under different nutrient sources and management regimes
Authors: Griffin T. , Giberson E. , Wiedenhoeft M.
Published: March 2003

Abstract The response of a long‐term, mixed‐species hayfield in Maine, USA, to commercial fertilizers and liquid dairy manure was evaluated over a 6‐year period, including the effects on yield, nutrient concentration and cycling, forage species composition and soil nutrient levels. Nutrient treatments included an unamended control, N fertilizer, NPK fertilizer and liquid dairy manure (LDM). The application rates of plant‐available N, P, and K were constant across treatments. Application of nutrients in any form increased forage yield, generally by 2–4 t dry matter (DM) ha−1 year−1. Yield from NPK fertilizer was 0·05–0·25 higher than from LDM, due to differences in N availability. Yield responses to P and K were minimal and there appeared to be no difference between P and K in fertilizer and manure. The forage sward became increasingly dominated by grass species as the experiment progressed; application of P and K in fertilizer or LDM allowed Agropyron repens to increase at the expense of Poa pratensis. Forage nutrient removal accounted for all applied N and K, and nearly all applied P, throughout the study period, demonstrating the important role these forages can play in whole‐farm nutrient management.
Endometrial destruction by thermal coagulation: evaluation of a new form of treatment for menorrhagia
Authors: Friberg Britt , Persson Bertil R. R. , Willén Roger , Ahlgren Mats
Published: March 2003

Objective

To report the first clinical evaluation of a new balloon endometrial, thermal destruction system CavatermTM, for outpatient treatment of menorrhagia.

Design

To elucidate possible technical problems during treatment, to evaluate how the patients tolerated the treatment and to judge which patients were suitable for this form of treatment.

Main outcome measures

Measurements of bleeding volumes in pads and tampons before and after treatment were performed as well as subjective evaluation by bleeding charts. Patients also estimated their degree of satisfaction.

Setting

Gynaecology department at a university hospital.

Subjects

36 patients under 52 years of age with menorrhagia, without suspicion of intracavitary pathology including malignancy.

Results

No procedure‐related complications occurred. The patients tolerated the treatment well. There was a significant reduction in measured bleeding volumes in pads and tampons, collected during one menstruation, 2–7 months after treatment compared with measurements before treatment. Four patients subsequently underwent hysterectomy and should not have been included in the study (two with pedunculated myoma and one with a septum; the fourth showed premalignant endometrial changes in the curettage preceding the treatment). At 18–28‐month follow up, 29 of the suitable patients (91%) reported a significant reduction in bleeding and another three patients reported reduced but still profuse bleeding compared with pretreatment; 88% (28/32) rated the treatment results as excellent, and a further 9% (3/32) as good.

Conclusions

We found the CavatermTM system for endometrial destruction to be safe, efficient and easy to use.
Sequelae of spilled ‘pelvic’ gallstones after laparoscopic cholecystectomy in women: case report and literature review
Authors: Abidogun Kehinde A. , Olawo Ayo O. , Chui David K.
Published: March 2003

Objective

To describe a case of long‐term sequelae of gallstones spilled and unretrieved during laparoscopic cholecystectomy in a woman patient and to review the published reports of similar cases.

Setting

The gynaecology department of a district hospital.

Subject

A 46‐year‐old woman presenting with persistent chronic pelvic pain 10 months after laparoscopic cholecystectomy.

Results

This woman had over 800 gallstones of various sizes left in the peritoneal cavity following laparoscopic cholecystectomy. These had become embedded in the pelvic structures and caused an extensive peritoneal reaction and adhesions involving the ovaries, fallopian tubes and loops of large bowel. Review of the literature revealed 10 earlier reports of serious complications of spilled gallstones involving the pelvic structures in women following laparoscopic cholecystectomy, with the inflammation persisting for up to 3 years.

Conclusion

Spillage of a significant quantity of gallstones at laparoscopic cholecystectomy in women should not be considered a minor complication, and open retrieval may be justified.
Adhesions after laparoscopic myomectomy: effect of the technique used
Authors: Assaf Ayman
Published: March 2003

Objective

To evaluate the technique of laparoscopic myomectomy and to assess the effect of injection of a vasoconstrictive agent on the incidence of postoperative adhesions.

Design

Prospective randomized clinical study.

Setting

University‐based and a tertiary referral private centre.

Patients

38 patients with subserous‐interstitial myomas, 3–7 cm in diameter, who were recruited from 99 women scheduled for laparoscopic myomectomy during the period from September 1994 till March 1997.

Interventions

The patients were randomly assigned to receive an injection of Ornipressin (group I, 21 patients) or no injection (group II, 17 patients) prior to myomectomy.

Main outcome measures

The incidence, type and degree of pelvic adhesions, evaluated at follow‐up laparoscopy 1 month after the original procedure.

Results

The procedure was easier and less time‐consuming in group I, compared with group II. The incidence of pelvic adhesions was higher in group I compared with group II and the adhesions were more vascular in group I.

Conclusion

The technique of laparoscopic myomectomy is feasible and safe. The incidence of postoperative pelvic adhesions is affected mainly by the technique used. Vasoconstricting agents make laparoscopy more convenient to the surgeon, but give a false impression of suitable haemostasis; our preliminary results indicate that their use may increase the incidence of pelvic adhesions.
Laparoscopic uterosacral nerve ablation in chronic pelvic pain: an overview
Authors: Khan Khalid S. , Khan Sabina F. , Nwosu Chika R. , Dwarakanath Linga S. , Chien Patrick F. W.
Published: March 2003

Objective

To assess the efficacy of laparoscopic uterine nerve ablation (LUNA) in the treatment of chronic pelvic pain, by means of a systematic overview of the published literature.

Design

Relevant papers were identified through electronic scanning of MEDLINE (1966  1997), EMBASE (1980m 1997), the Science Citation Index and the Cochrane Library, and manual searching of the bibliography of known primary and review articles. Study selection, study quality assessment and data abstraction were performed independently in duplicate. For controlled studies data were used to generate odds ratios (OR) and their confidence intervals (CI).

Subjects

These were 555 women included in 11 case series and 250 women included in two controlled observational studies and three randomized trials.

Main outcome measure

Pain relief, measured in general terms or assessed using visual analogue or numeric pain scales.

Results

In the case of pelvic pain with no visible pathological findings at laparoscopy, randomized studies showed that LUNA had a trend towards better pain relief compared with no surgical intervention (OR 9.4, 95% CI 0.7 to 472; P = 0.9) but its effect was inferior to presacral neurectomy (OR 0.24, 95% CI 0.07 to 0.8; P = 0.01). Where there was endometriosis, controlled non‐randomized studies showed that with ablative treatment of endometriosis, the outcomes were better with than without LUNA (OR 36.7, 95% CI 3.9 to 1625; P = 0.001); however, presacral neurectomy did not show better results than LUNA (OR 0.30, 95% CI 0.03 to 1.76; P = 0.1). One randomized controlled study in patients with endometriosis showed that LUNA plus ablative treatment was better than no intervention (OR 5.7, 95% CI 1.6 to 20.3; P = 0.003), an effect that was not apparent in the subgroup with minimal endometriosis (P = 0.24).

Conclusion

On theoretical grounds, LUNA has the promise of an efficacious intervention in alleviating pelvic pain. However, the pitfalls in the published research that we have identified and evaluated make it impossible for us to conclude that this intervention is universally effective. At best there is a trend indicating effectiveness in relieving primary dysmenorrhoea and mild to moderate endometriosis. For the majority of women with chronic pelvic pain, there is not sufficient evidence to guide therapeutic decision making with regard to laparoscopic uterine nerve ablation.
A prospective randomized open study comparing goserelin (Zoladex) plus surgery and surgery alone in the management of ovarian endometriomas
Authors: Shaw Robert , Garry Ray , McMillan Lindsay , Sutton Christopher , Wood Simon , Harrison Robert , Das Rajiv
Published: March 2003

Objective

To determine whether goserelin (ZoladexTM; AstraZeneca, London, UK), plus surgery offers advantages over surgery alone in the management of ovarian endometriomas.

Design

Prospective, multicentre, randomized, open‐label, parallel‐group study.

Interventions

Following preoperative aspiration of endometriomas, they were sized by ultrasound, a diagnosis of endometriosis confirmed by laparoscopy and its severity assessed. Patients were stratified according to endometrioma size and randomly allocated to one of two groups: group 1 (G1; n = 21) received a monthly (every 28 days) subcutaneous injection of goserelin 3.6 mg for 3 months (12 weeks); group 2 (G2; n = 27) received no treatment. At 3 months, the size of endometriomas was reassessed in both groups before definitive excision. Both groups were reassessed at 6 months postsurgery.

Main outcome measures

Change in size of the largest endometrioma from entry to just prior to excision.

Results

The mean change in endometrioma size was −2.29 cm in G1 and −1.29 cm in G2. The resulting (adjusted) mean difference of −1.25 cm was statistically significant in favour of G1 (P = 0.036, 95% CI −2.42 to −0.08 cm). Very difficult surgery was reported in four (22%) patients in G1 and 10 (46%) patients in G2. Mean duration of surgery was 74.2 min in G1 and 86.4 min in G2. There was a trend towards a greater reduction in mean Additive Diameter of Implants (ADI) score at 6 months postsurgery in G1 compared with G2 (−65.9 vs. −56.6). Both groups were comparable in terms of the number of complete excisions of their endometrial cysts at surgery, blood loss at surgery, Revised American Fertility Society (R‐AFS) scores and pelvic symptoms. Goserelin was well tolerated.

Conclusions

Laparoscopic aspiration of endometriomas followed by a monthly goserelin 3.6 mg depot for 3 months compared with laparoscopic aspiration alone results in significantly smaller endometriomas at 3 months and a trend towards a greater reduction in ADI score.
Laparoscopic entry port visited: a survey of practices of consultant gynaecologists in Scotland
Authors: Lingam K. , Cole R. A.
Published: March 2003

To assess how consultant gynaecologists working in Scotland achieve a pneumoperitoneum for laparoscopic procedures.

An anonymous postal questionnaire.

All consultants working in obstetrics and gynaecology in Scotland.

Questionnaire analysis.

There was a 92% response rate to the questionnaire. Of the respondents, 94.8% performed closed laparoscopy, one (0.8%) performed only open laparoscopy, and six (4.4%) employed both open and closed techniques. The majority worked with the patient in the lithotomy with Trendelenburg position. The commonest entry point, used by 88 respondents, was subumbilical. To create the pneumoperitoneum 94 respondents used 2–2.5 L of gas. Six used pressure measurement and eight used tension to gauge the pneumoperitoneum prior to trocar insertion.

The majority of consultants working in Scotland practise a closed laparoscopy entry technique.
A randomized, double‐blind comparison of two dosage levels of recombinant factor VIIa in the treatment of joint, muscle and mucocutaneous haemorrhages in persons with haemophilia A and B, with and without inhibitors
Authors: Lusher  , Roberts  , Davignon  , Joist  , Smith  , Shapiro  , Laurian  , Kasper  , Mannucci  ,   rFVIIa Study Group
Published: March 2003

Recombinant factor VIIa (rFVIIa) was developed to provide an improved procoagulant component capable of ‘by‐passing’ inhibitor antibodies in the treatment of haemophilic patients. The primary objective of this study was to compare the efficacy of two dosage regimens of rFVIIa (given intravenously at periodic intervals) in the treatment of joint, muscle and mucocutaneous haemorrhages in persons with haemophilia A and B with and without inhibitors. The study was designed as a randomized, double‐blind, parellel group, international multicenter trial. Patients were randomly allocated to treatment A: 35 μ kg−1 or B:␣70 μ kg−1, in blocks of 2. Within each block, one patient was assigned to the 35 μ kg−1 dosing regimen and the other to 70 μ kg−1 dose. One hundred and fifty subjects from 20 sites were screened for this study and 116 had baseline assessments. Of these, 84 were treated on the protocol and 32 were not treated in the study, in most cases because they did not return to the clinic with an eligible bleeding episode. One hundred and seventy‐nine bleeding episodes were treated, of which 145 (81%) were acute haemarthroses. Both treatments were efficacious, with 71% having an excellent (59% and 60%) or effective (12% and 11%) response. Overall, the mean and median number of doses given per episode of joint bleeding were 3.1 and 2, respectively. The mean number of doses was 3.1 for the 70 μ kg−1 group and 2.7 for the 35 μ kg−1 group (P value = 0.142). The study concluded that rFVIIa in a dosage of 35 μ kg−1 or 70 μ kg−1 is both safe and reasonably effective in the treatment of joint or muscle haemorrhages in haemophilic patients with inhibitor antibodies to factor VIII or factor IX. It is concluded that the appropriate dose for the treatment of joint and peripheral muscle bleeding in haemophilic patients with inhibitors is 35–70 μ kg−1 given at 2–3 h intervals until haemostasis is achieved.