bluuebunny/crossref_metadata_2025 huggingface dataset:
The controls on net ecosystem productivity along an Arctic transect: a model comparison with flux measurements
Authors: Williams Mathew , Eugster Werner , Rastetter Edward B. , Mcfadden Joseph P. , Chapin Iii F. Stuart
Published: March 2003

Assessments of carbon (C) fluxes in the Arctic require detailed data on both how and why these fluxes vary across the landscape. Such assessments are complicated because tundra vegetation has diverse structure and function at both local and regional scales. To investigate this diversity, the Arctic Flux Study has used the eddy covariance technique to generate ecosystem CO2‐exchange data along a transect in northern Alaska. We use an extant process‐based model of the soil–plant–atmosphere continuum to make independent predictions of gross photosynthesis and foliar respiration at 9 of the sites along the transect, using data on local canopy structure and meteorology. We make two key assumptions: (i) soil respiration is constant throughout the flux measurement period, so that the diurnal cycle in CO2 exchange is driven by canopy processes only (except at two sites where a soil respiration–temperature relationship was indicated in the data); and (ii) mosses and lichens play an insignificant role in ecosystem C exchange, even though in some locations their live biomass exceeds 300 g m−2. We found that even with these assumptions the model could explain much of the dynamics of net ecosystem production (NEP) at sites with widely differing vegetation structure and moss/lichen cover. Errors were mostly associated with the predictions of maximum NEP; the likely cause of such discrepancies was (i) a mismatch between vegetation sampled for characterizing the canopy structure and that contained within the footprint of the eddy covariance flux measurements, or (ii) an increase in daytime soil and root respiration. Thus the model results tended to falsify our first assumption but not our second. We also note evidence for an actual reduction in NEP caused by water stress on warm, dry days at some sites. The model–flux comparison also suggests that photosynthesis may be less sensitive to low temperatures than leaf‐level gas‐exchange measurements have indicated.
Elevated CO2 enhances water relations and productivity and affects gas exchange in C3 and C4 grasses of the Colorado shortgrass steppe.
Authors: Morgan Jack A. , Lecain Daniel R. , Mosier Arvin R. , Milchunas Daniel G.
Published: March 2003

Six open‐top chambers were installed on the shortgrass steppe in north‐eastern Colorado, USA from late March until mid‐October in 1997 and 1998 to evaluate how this grassland will be affected by rising atmospheric CO2. Three chambers were maintained at current CO2 concentration (ambient treatment), three at twice ambient CO2, or approximately 720 μmol mol−1 (elevated treatment), and three nonchambered plots served as controls. Above‐ground phytomass was measured in summer and autumn during each growing season, soil water was monitored weekly, and leaf photosynthesis, conductance and water potential were measured periodically on important C3 and C4 grasses. Mid‐season and seasonal above‐ground productivity were enhanced from 26 to 47% at elevated CO2, with no differences in the relative responses of C3/C4 grasses or forbs. Annual above‐ground phytomass accrual was greater on plots which were defoliated once in mid‐summer compared to plots which were not defoliated during the growing season, but there was no interactive effect of defoliation and CO2 on growth. Leaf photosynthesis was often greater in Pascopyrum smithii (C3) and Bouteloua gracilis (C4) plants in the elevated chambers, due in large part to higher soil water contents and leaf water potentials. Persistent downward photosynthetic acclimation in P. smithii leaves prevented large photosynthetic enhancement for elevated CO2‐grown plants. Shoot N concentrations tended to be lower in grasses under elevated CO2, but only Stipa comata (C3) plants exhibited significant reductions in N under elevated compared to ambient CO2 chambers. Despite chamber warming of 2.6 °C and apparent drier chamber conditions compared to unchambered controls, above‐ground production in all chambers was always greater than in unchambered plots. Collectively, these results suggest increased productivity of the shortgrass steppe in future warmer, CO2 enriched environments.
Are old forests underestimated as global carbon sinks?
Authors: Carey Eileen V. , Sala Anna , Keane Robert , Callaway Ragan M.
Published: March 2003

Old forests are important carbon pools, but are thought to be insignificant as current atmospheric carbon sinks. This perception is based on the assumption that changes in productivity with age in complex, multiaged, multispecies natural forests can be modelled simply as scaled‐up versions of individual trees or even‐aged stands. This assumption was tested by measuring the net primary productivity (NPP) of natural subalpine forests in the Northern Rocky Mountains, where NPP is from 50% to 100% higher than predicted by a model of an even‐age forest composed of a single species. If process‐based terrestrial carbon models underestimate NPP by 50% in just one quarter of the temperate coniferous forests throughout the world, then global NPP is being underestimated by 145 Tg of carbon annually. This is equivalent to 4.3–7.6% of the missing atmospheric carbon sink. These results emphasize the need to account for multiple‐aged, species‐diverse, mature forests in models of terrestrial carbon dynamics to approximate the global carbon budget.
Microbial processes and temperature in Chesapeake Bay: current relationships and potential impacts of regional warming
Authors: Lomas Michael W. , Glibert Patricia M. , Shiah Fuh‐Kwo , Smith Erik M.
Published: March 2003

The importance of temperature in regulating physiological processes is without question; however, the interpretation of the relationship between temperature and ecological data is much more complicated. Consequently, it is difficult to decide how the nature of the temperature response terms should be included in models used to predict responses of microbial processes to increasing regional temperature. This analysis compiles several years of data from a research programme conducted in Chesapeake Bay, in an effort to examine how individual microbial processes − as well as the balance between autotrophy and heterotrophy − have responded to temperature, and to predict changes in microbial trophic state based on realistic increases in global temperature. The upper boundary on all of the pelagic microbial rate processes that were measured could be described remarkably well as a linear function of temperature, although there was substantial scatter in the data. Pelagic microbial rate processes (e.g. phytoplankton production, respiration, bacterial productivity) showed a remarkably constrained range of Q10 values from 1.7 to 3.4. The one notable exception to this was nitrogen uptake in the North and Mid Bay, which exhibited Q10 values < 1.0. Proxies for phytoplankton biomass (e.g. chlorophyll) were largely independent of temperature while bacterial abundance was significantly related to temperature and was found to have a Q10 of 1.88.

    Using these individual temperature responses, the balance of autotrophy and heterotrophy was assessed by calculating the community photosynthesis to respiration (P:R), NH4+ uptake to regeneration (U:R) and phytoplankton to bacterial productivity (PP:BP) ratios for current conditions (all ratios) and for a 2 and 5 °C temperature increase (NH4+ U:R excluded). The NH4+ U:R ratio stayed remarkable constant at ∼1 over the entire temperature range supporting the importance of regenerative processes to nitrogen availability even during periods of heavy allochthonous inputs. These elevated temperature calculations for P:R and PP:BP suggest that the magnitude of autotrophic production during the spring bloom may decrease with increased regional temperature and, as a consequence, the Chesapeake Bay might become net heterotrophic on an annual timescale. These calculations should be considered with caution, but nonetheless demonstrate that the impact of increasing temperature on the balance of autotrophic and heterotrophic processes needs to be researched further.
Elevated atmospheric CO2 lowers leaf litter nutritional quality for stream ecosystem food webs
Authors: Tuchman Nancy C. , Wetzel Robert G. , Rier Steven T. , Wahtera Kirk A. , Teeri James A.
Published: March 2003

Up to 99% of the carbon fuelling the food webs of temperate woodland streams is derived from inputs of terrestrial leaf litter. Aquatic bacteria, fungi, and detritivore invertebrates directly utilize these inputs, transferring this energy to other components of the food web. Increases in atmospheric CO2 could indirectly impact woodland stream food webs by chemically altering leaf litter. This study evaluated CO2‐induced chemical changes in aspen (Populus tremuloides) leaf litter, and the corresponding effects on stream bacteria, fungi and leaf‐shredding cranefly larvae (Tipula abdominalis: Diptera). Leaf litter from plants grown under elevated CO2 had decreased nutritional value to aquatic decomposers and detritivores because of higher levels of structural compounds and lower nitrogen content. Consequently, elevated CO2‐grown leaf litter supported 59% lower bacterial production in a stream than litter grown at ambient CO2 levels, while not affecting fungal biomass. Larval craneflies fed elevated CO2‐grown microbially colonized leaves consumed less, assimilated less, and grew 12 times slower than their ambient fed counterparts.
Carbon emission and sequestration by agricultural land use: a model study for Europe
Authors: Vleeshouwers L. M. , Verhagen A.
Published: March 2003

A model was developed to calculate carbon fluxes from agricultural soils. The model includes the effects of crop (species, yield and rotation), climate (temperature, rainfall and evapotranspiration) and soil (carbon content and water retention capacity) on the carbon budget of agricultural land. The changes in quality of crop residues and organic material as a result of changes in CO2 concentration and changed management were not considered in this model. The model was parameterized for several arable crops and grassland. Data from agricultural, meteorological, soil, and land use databases were input to the model, and the model was used to evaluate the effects of different carbon dioxide mitigation measures on soil organic carbon in agricultural areas in Europe. Average carbon fluxes under the business as usual scenario in the 2008–2012 commitment period were estimated at 0.52 tC ha−1 y−1 in grassland and −0.84 tC ha−1 y−1 in arable land. Conversion of arable land to grassland yielded a flux of 1.44 tC ha−1 y−1. Farm management related activities aiming at carbon sequestration ranged from 0.15 tC ha−1 y−1 for the incorporating of straw to 1.50 tC ha−1 y−1 for the application of farmyard manure. Reduced tillage yields a positive flux of 0.25 tC ha−1 y−1. The indirect effect associated with climate was an order of magnitude lower. A temperature rise of 1 °C resulted in a −0.05 tC ha−1 y−1 change whereas the rising CO2 concentrations gave a 0.01 tC ha−1 y−1 change. Estimates are rendered on a 0.5 × 0.5° grid for the commitment period 2008–2012. The study reveals considerable regional differences in the effectiveness of carbon dioxide abatement measures, resulting from the interaction between crop, soil and climate. Besides, there are substantial differences between the spatial patterns of carbon fluxes that result from different measures.
Environmental controls on net ecosystem‐level carbon exchange and productivity in a Central American tropical wet forest
Authors: LOESCHER H. W. , OBERBAUER S. F. , GHOLZ H. L. , CLARK D. B.
Published: March 2003

Difficulty in balancing the global carbon budget has lead to increased attention on tropical forests, which have been estimated to account for up to one third of global gross primary production. Whether tropical forests are sources, sinks, or neutral with respect to their carbon balance with the atmosphere remains unclear. To address this issue, estimates of net ecosystem exchange of carbon (NEE) were made for 3 years (1998–2000) using the eddy‐covariance technique in a tropical wet forest in Costa Rica. Measurements were made from a 42 m tower centred in an old‐growth forest. Under unstable conditions, the measurement height was at least twice the estimated zeroplane height from the ground. The canopy at the site is extremely rough; under unstable conditions the median aerodynamic roughness length ranged from 2.4 to 3.6 m. No relationship between NEE and friction velocity (u*) was found using all of the 30‐min averages. However, there was a linear relationship between the nighttime NEE and averaged u* (R2 = 0.98). The diurnal pattern of flux was similar to that found in other tropical forests, with mean daytime NEE ca. − 18 μmol CO2 m−2 s−1 and mean nighttime NEE 4.6 μmol CO2 m−2 s−1. However, because ∼ 80% of the nighttime data in this forest were collected during low u* conditions (< 0.2 m s−1), nighttime NEE was likely underestimated. Using an alternative analysis, mean nighttime NEE increased to 7.05 μmol CO2 m−2 s−1. There were interannual differences in NEE, but seasonal differences were not apparent. Irradiance accounted for ∼ 51% of the variation in the daytime fluxes, with temperature and vapour pressure deficit together accounting for another ∼ 20%. Light compensation points ranged from 100 to 207 μmol PPFD m−2 s−1. No was relationship was found between 30‐min nighttime NEE and tower‐top air temperature. A weak relationship was found between hourly nighttime NEE and canopy air temperature using data averaged hourly over the entire sampling period (Q10 = 1.79, R2 = 0.17). The contribution of below‐sensor storage was fairly constant from day to day. Our data indicate that this forest was a slight carbon source in 1998 (0.05 to −1.33 t C ha−1 yr−1), a moderate sink in 1999 (−1.53 to −3.14 t C ha−1 yr−1), and a strong sink in 2000 (−5.97 to −7.92 t C ha−1 yr−1). This trend is interpreted as relating to the dissipation of warm‐phase El Niño effects over the course of this study.
The influence of fertilizer nitrogen, white clover content and environmental factors on the nitrate content of perennial ryegrass and ryegrass/white clover swards
Authors: Shiel  , El Tilib  , Younger
Published: March 2003

In a field experiment carried out over 3 years, the nitrate content of herbage from perennial ryegrass (Lolium perenne) swards increased exponentially with nitrogen application rate, but herbage nitrate content appeared to reach potentially dangerous concentrations only when nitrogen application rates were greater than those needed to stimulate dry‐matter production. Thus, on average over all the harvests, maximum yield could be obtained with annual application rates of 400 kg N ha–1 (six applications of 67 kg N ha–1) for perennial ryegrass and 300 kg N ha–1 (six applications of 50 kg N ha–1) for perennial ryegrass/white clover (Trifolium repens) swards, whereas the mean nitrate concentrations were 3340 and 2929 mg NO3 kg–1 dry matter (DM) respectively. Nitrate content, however, varied considerably from harvest to harvest, reaching maxima of 9345 mg NO3 kg–1 DM at 400 kg N ha–1 for perennial ryegrass and 6255 mg NO3 kg–1 DM at 300 kg N ha–1 for perennial ryegrass/white clover. The nitrate content of herbage from perennial ryegrass/white clover swards was always greater than that of perennial ryegrass swards receiving the same rate of nitrogen application, even though in the herbage from the mixed sward the nitrate content of white clover was usually less than half that of the perennial ryegrass component. The physical environment did not have a clearly interpretable effect on nitrate content, although herbage harvested in May had a much lower nitrate content than that harvested at any other time of the season. It was not possible to find a single multiple regression equation relating herbage nitrate content to nitrogen application and to other environmental variables that explained more than 60% of the variance in herbage nitrate, but it is suggested that, by reducing the later‐season nitrogen applications from 67 to 50 and finally to 33 kg N ha–1 for perennial ryegrass and from 50 to 33 kg N ha–1 for perennial ryegrass/white clover, it would be possible to achieve over 90% of the maximum yield while reducing average nitrate content to <40% of that at maximum yield, with no samples containing more than 2300 mg NO3 kg –1 DM.
Tiller size/density compensation in perennial ryegrass miniature swards subject to differing defoliation heights and a proposed productivity index
Authors: Garay A. Hernández , Matthew  , Hodgson
Published: March 2003

The objective of this study was to investigate the effects of cutting height on tiller population density, tiller weight and herbage harvested in perennial ryegrass swards. One hundred mini‐swards of Lolium perenne were established from seed on 5 May 1993 in 150 mm × 150 mm plastic pots in a greenhouse. The experimental period lasted 6 months (May to November). On 4 June all pots were cut to 50 mm and randomly allocated to five treatments (20, 40, 80, 120 and 160 mm sward surface height) with twenty replicates (four per tray). All pots were cut twice weekly to the specified surface height from 11 June, and recording began on 14 June. Every 4 weeks from 9 July to 5 November the twenty pots contained in one tray were withdrawn for destructive measurements of tiller population density and the weights of tiller components. Tiller population density increased with reduction in defoliation height, except for the 20‐mm treatment where tiller density was initially restricted. The slope of the size/density compensation (SDC) line was close to −5/2 over the range of defoliation heights 40–120 mm, but was less than −1·0 between 120 and 160 mm. These slopes are consistent with a recent theory, which proposes that variations from a slope of −3/2 will be linked to defoliation‐induced changes in canopy leaf area and to change in tiller leaf area:volume ratio, R. At defoliation heights below 120 mm, SDC slope was increased by reduction in canopy leaf area. Above 120 mm, increase in R forced a relatively rapid tiller population decline, resulting in a reduced SDC slope and decrease in canopy leaf area. Whereas traditional measures of leafiness such as leaf:stem ratio or leaf:non‐leaf ratio decreased with increasing height of defoliation, the leaf area:volume ratio, R, increased with defoliation height. Distance from an arbitrarily positioned −3/2 SDC line was correlated with sward productivity.
Variations in the dietary cation–anion difference and the acid–base balance of dairy cows on a pasture‐based diet in south‐eastern Australia
Authors: Roche  , Dalley  , Moate  , Grainger  , Hannah  , O’Mara  , Rath
Published: March 2003

The variation in the dietary cation–anion difference (DCAD) and the urinary pH of dairy cows was examined over the year 1996–97 in Victoria, south‐eastern Australia. Mineral concentrations in the pasture and dairy cow milk production were also examined. Three farmlets (A, B and C) under different feeding and management systems were used for the purpose of the study. Feeding management was based on grazed grass with stocking rates of 1·4, 2·5 and 4·7 cows ha–1 for farmlets A, B and C respectively. Cows on farmlets B and C received more supplementary feed than those on the A farmlet.

The urine of the cows in each herd was sampled for pH twice monthly, after morning milking. A sample of the feed on offer the previous day was collected and analysed for crude protein, in vitro dry‐matter digestibility and macrominerals. Milk yields were recorded on the same day as urine sampling and weather data for the previous day were also collected.

Pasture cation–anion difference was not greatly influenced by stocking rate or associated management practices, although mineral concentrations in pasture did vary. Urine pH was unaffected by changes in climate, management strategies (e.g. stocking rate), season and stage of lactation. Moreover, urine pH was also unaffected by changes in DCAD until the DCAD declined below approximately +15 mequiv. 100 g–1 for two consecutive sampling periods.

It is concluded that when this threshold for DCAD (+15 mequiv. 100 g–1) is breached, even in late lactation, a decrease in urine pH occurs. In south‐eastern Australia, the DCAD offered to non‐lactating cows in the last 2 weeks of pregnancy, in spring‐calving herds, on a pasture‐based diet is nearly always above that regarded as optimum in other feeding systems.
Factors influencing the response in intake of silage and animal performance after wilting of grass before ensiling: a review
Authors: Wright  , Gordon  , Steen  , Patterson
Published: March 2003

This review examines the response in intake of silage and animal performance after wilting of grass before ensiling. It uses data from eighty‐five published comparisons. Initial analysis identified those variables having the greatest influence on the increase in dry‐matter (DM) intake of grass silage owing to wilting. Total water loss, drying rate of the wilted material and ammonia‐N concentration of the unwilted material were the variables most closely and positively correlated to the proportional increase in DM intake as a result of wilting, with r2 values of 0·344, 0·393 and 0·240 respectively. There was little evidence of curvilinearity in any of the relationships. Stepwise regression analysis was used to identify the best multiple linear regressions for predicting the proportional increase in intake owing to wilting. Factors associated with the extent and rate of water loss in the field (total water loss and drying rate) and the quality of the unwilted material ensiled and its subsequent fermentation pattern (DM digestibility, crude protein, ammonia‐N content of unwilted silage) were the key variables in the relationship. Subsequent analysis related the increase in output of milk energy of dairy cows and liveweight gain of beef cattle to the same independent variables. This indicated that variables shown to describe the response in DM intake in the previous analysis were among those most closely related to the increases in animal performance owing to wilting of grass. To assess whether the increase in animal performance owing to wilting could be explained as a direct response to increased metabolizable energy (ME) intake of wilted compared with unwilted silages, linear relationships were derived between the increase in milk and beef production parameters and the increase in ME intake owing to wilting. From these, it was concluded that there was no clear evidence that wilting reduced the efficiency of utilization of ME in beef or dairy cattle. The present study showed that the increase in milk energy output (measured in MJ) per increase in ME intake (measured in MJ) owing to wilting was linear, with a slope of 0·19. This response from additional ME intake owing to wilting is in line with what would be anticipated when increasing ME intake by other methods.
A comparison of three methods for measuring the vertical distribution of herbage mass in grassland
Authors: Barthram  , Elston  , Bolton
Published: March 2003

Three stratified clip methods for the estimation of herbage mass and its vertical distribution in grass swards were compared. The first method used a herbage‐gripping device, which held a sample from a 2 × 9 cm area while it was harvested and cut into layers in the field. For the other two methods, turfs of herbage were dug and brought into the laboratory where areas defined by 10 × 10 cm or 2 × 9 cm quadrats were cut into layers. For the comparisons, two operators collected independent samples from a sward shortly before it was cut for silage, a sward grazed by cattle and a sward grazed by sheep.

The total mass of herbage dry matter collected depended on the method used, with the herbage‐gripping device producing greater estimates than the turf quadrats in two of the swards. The different methods produced similar estimates of the vertical distribution of mass. The larger quadrat usually produced the least variable results, while the herbage‐gripping device collected samples most quickly. There were also small differences between the estimates produced by different operators. It was concluded that because the herbage‐gripping device was the most cost‐effective it would often be the most appropriate method to use. However, when a higher level of precision per quadrat is required the large quadrat, following turf collection, would be more appropriate.
Root and shoot competition between established grass species and newly sown seedlings during spring growth
Authors: Haugland E. , Tawfiq M.
Published: March 2003

Competition between established Dactylis glomerata or Festuca pratensis/Taraxacum officinale swards and seedlings of Trifolium pratense was studied under field conditions in Norway. Root competition from the Festuca pratensis/Taraxacum officinale sward was significantly greater than that from a Dactylis glomerata sward. The balance in root and shoot competition varied between experimental years because of variation in environmental conditions. In the first experimental year, root competition had a greater effect on seedling dry weight than shoot competition, whereas the opposite was found in the second year. However, both root and shoot competition (full competition) in comparison with no competition gave proportionally the same effects in both years, indicating that an alleviation in root competition will be followed by intensified shoot competition. An increasing effect of shoot competition with time on plant dry weight was found. In a second experiment, seedlings of Lolium perenne and Trifolium pratense produced the highest plant dry weights in competition with an established Phleum pratense sward, followed by seedlings of Poa pratensis, Phleum pratense and Trifolium repens in decreasing order. However, no interactions between seedling species and competition treatments were found, indicating no differences in sensitivity between seedling species to competition from the established grass sward. The results are discussed in the context of renovating grassland by direct drilling.
The effects of a foliar spray containing phosphorus and zinc on the development, composition and yield of forage maize
Authors: Leach K. A. , Hameleers A.
Published: March 2003

Forage maize grown in areas where spring temperatures are low and accumulated heat is limited will be restricted in terms of maturity and thus nutritional value. A stagnant growth phase is commonly caused by low temperatures between germination and the five‐leaf stage, which could be caused by reduced mineral availability. The effects on maize plant development and harvest characteristics of supplying phosphorus and zinc to young plants in a foliar spray were investigated. Three different application dates, between the four‐leaf and the seven‐leaf stage, were compared. Applying the phosphorus and zinc foliar spray at the four‐leaf stage resulted in a significant (P < 0·05) increase in starch content at harvest. Cob index [proportion of plant dry matter (DM) in the cob] was increased (P < 0·05) by applying the nutrient spray at the four‐, five‐ and seven‐leaf stages. However, there was no effect on DM yield, suggesting some alteration in partitioning within the plant.
Morphological development and forage quality changes in crimson clover (Trifolium incarnatum L.)
Authors: Lloveras J. , Iglesias I.
Published: March 2003

The development of efficient forage management and utilization is facilitated by a knowledge of the changes in nutritive value and patterns of dry matter (DM) distribution within plants. The objectives of this experiment were to determine the patterns of DM accumulation and the change in nutritive value during maturation of crimson clover (Trifolium incarnatum L.), a cool‐season annual forage legume adapted to mild winter areas and acid soils. Crimson clover was established on a Dystric Eurocrept soil with pH 5·4 in Galicia, north‐western Spain, during three consecutive years (1990–92). Shoot samples were taken at approximately biweekly intervals in the spring and summer after autumn sowing, and were separated into stems, leaves and seed pods. DM accumulation, crude protein (CP) and acid‐detergent fibre (ADF) concentrations and in vitro organic matter digestibility (IVOMD) were determined for each plant part at each stage. Average annual DM production at initial flowering was 4·2 t ha–1, whereas the CP and ADF concentrations and IVOMD values were 134 g kg–1 DM, 302 g kg–1 DM and 0·720 respectively. The nutritive value declined with age, coinciding with a reduction in leaf:stem ratio (from 0·53 at the vegetative stage to 0·13 at the ripe seed stage). This decline was more rapid than that reported for other legumes, possibly because of the low leaf:stem ratio of crimson clover. However, as it is used in the Atlantic coastal areas of north‐western Spain, where it is harvested around initial flowering, it can provide forage of good quality.
Agronomic factors affecting the yield and quality of forage maize in Ireland: effect of sowing date and plastic film treatment
Authors: Keane G. P.
Published: March 2003

The objectives of these studies were to examine the effects of sowing date and plastic film on the yield and quality of forage maize (Zea mays L.) in Ireland, a marginal maize‐growing area. In 1989–95, comparisons were made of maize sown through clear plastic film (PP treatment), and maize sown in the conventional manner without plastic (NP treatment), in terms of dry‐matter (DM) yield and quality (cob, grain and starch contents). The PP treatment significantly increased DM yields in five years, with a mean yield increase of 3·10 t ha−1. Whole‐plant DM content increased (significant in four years) by a mean of 0·15; cob content increased (significant in five years) by a mean of 0·32; grain content increased (significant in all of the three years examined) by 0·75; and starch content increased from 236 to 318 g kg−1 DM (P < 0·01) in 1995 where the plastic film treatment was used. Organic matter digestibility values were similar for both treatments in 1995. Sowing date in the April‐May period had no consistent effect on DM yields, but early sowings did increase cob (significant, except in 1994), grain (significant in one (1995) of the two years tested) and starch (P < 0·05) contents (only tested in 1995). Sowing on 11 April 1995 through perforated plastic gave lower yields than the NP treatment sown on the same date, due to severe frost damage in early May.
Endometrial sampling: does combining scraping with suction using the Accurette® device improve efficacy?
Authors: Kovacs Gabor , Hocking Glenn R. , Barnett Malcolm C. , V.T. Clark Jason
Published: March 2003

Objective

To assess the efficacy of the combination of scraping and suction (using Accurette®), compared with conventional curettage, in a pilot study.

Design

Prospective study with Accurette sampling preceding conventional curettage.

Setting

Day surgery unit of a teaching hospital.

Subjects

Women presenting for dilatation and curettage for abnormal bleeding.

Intervention

Accurette sampling carried out under anaesthetic just prior to curettage. The same pathologist reported on all specimens independently, without correlating specimen identities.

Main outcome measures

Quality of the samples for histological investigation and comparison of reporting.

Results

Accurette was adequate except in the presence of polyps.

Conclusion

Endometrial sampling is a useful investigation for abnormal vaginal bleeding.
Preoperative evaluation of myometrial invasion in endometrial carcinoma by magnetic resonance imaging (MRI) and hysteroscopy: diagnostic efficacy of MRI combined with hysteroscopy
Authors: Shen Hong , Iha Tadashi , Higashi Masahiro , Kanazawa Koji
Published: March 2003

Objective

To evaluate the preoperative diagnostic usefulness of magnetic resonance imaging (MRI) combined with hysteroscopy, for the assessment of myometrial invasion in endometrial carcinoma.

Design

Prospective observational study.

Setting

Department of Obstetrics and Gynaecology, The Ryukyu University Hospital, Okinawa, Japan.

Subjects

73 patients with untreated endometrial carcinoma.

Interventions

The findings of myometrial tumour invasion preoperatively observed by MRI and hysteroscopy were compared with the histopathological findings from surgical specimens.

Main outcome measures

The sensitivity and specificity of MRI combined with hysteroscopy in diagnosing myometrial tumour invasion.

Results

In diagnosing myometrial tumour invasion (absence or presence of myometrial invasion), the sensitivities and specificities were 82.0% and 100% in MRI, 80.0% and 95.7% in hysteroscopy, and 92.0% and 95.7% in MRI combined with hysteroscopy. The sensitivity in MRI combined with hysteroscopy was significantly higher, with a false‐negative rate of only 8.0%, than that of the other two methods (P = 0.025; P = 0.014). The differences in specificity were not statistically significant among these three methods (P > 0.05). MRI had a 87.8% accuracy in assessing the depth of myometrial invasion.

Conclusion

These results indicate that MRI combined with hysteroscopy is an excellent diagnostic approach, superior to MRI or hysteroscopy alone, for the evaluation of myometrial tumour invasion, because MRI and hysteroscopy combined can compensate for the disadvantage or defect in each diagnostic procedure.
Abdominal hysterectomy: a comparison between the use of surgical staples and conventional sutures for the major pedicles
Authors: Krins Anthony , Kovacs Gabor
Published: March 2003

Objective

To compare the progress of patients undergoing abdominal hysterectomy using either surgical staples or conventional sutures for the ovarian and uterine pedicles.

Design

A prospective randomized controlled study.

Setting

A teaching hospital gynaecology unit.

Subjects

24 women presenting for abdominal hysterectomy.

Interventions

Routine abdominal hysterectomy was undertaken. Uterine and ovarian pedicles were either ligated conventionally or secured by surgical staples.

Main outcome measures

These were: duration of operation, blood loss, length of hospital stay and recovery parameters.

Results

There were no difficulties in applying the staples in this pilot study and there was no difference in the outcomes between the two methods.

Conclusions

Although the use of surgical staples is an attractive principle, this pilot study could not demonstrate an advantage to justify the cost. Further evaluation may be indicated.
Ultrasonographic and hysteroscopic follow up after transcervical resection of the endometrium
Authors: Mints Miriam , Almström Harald , Rylander Eva , Rådestad Arne
Published: March 2003

Objective

Long‐term follow‐up of women who have undergone transcervical resection of the endometrium (TCRE), and evaluation of the uterine endometrium and cavity in these women.

Design

Transvaginal ultrasound examination (TVS) with hydrosonography and hysteroscopy, including biopsies, was carried out in 61 women, 19–67 months (mean 40 months) after transcervical endometrial resection.

Results

The age range of the women was 37–58 years (mean 48 years). Of 61 women, 67% had amenorrhoea or hypomenorrhoea, 28% had withdrawal bleeding of normal amounts and three women suffered from polymenorrhoea. Of 40 women with dysmenorrhoea before treatment, 18 still had cyclic pain afterwards. In three women, dysmenorrhoea developed postoperatively. At ultrasound examination, an echo from the uterine cavity was found in 95% of the women and an echo of 5 mm or more was seen in 22%. Crypts and occlusions were present in 19% and synechiae in 4% of the women. For technical reasons, hydrosonography could not easily be done. At hysteroscopy signs of endometrium were found in 85% of the women, and synechiae were present in all women. The uterine cavity was partly occluded and narrowed. One woman had a total occlusion of the uterine cavity. Histopathological examination of the biopsies or curettage specimens from the uterine cavity showed endometrial tissue in 67% of the women.

Conclusions

Residual endometrium was found in most women after TCRE and, therefore, if hormone replacement therapy is to be used, a combination of oestrogen with gestogen should be recommended. Intracavitary synechiae were present in most women after TCRE. The synechiae may have contributed to the cyclic pain experienced by 20 women after treatment. However, the synechiae did not seem to conceal the withdrawal bleeding or menstruation. If women who have undergone TCRE develop symptoms such as bleeding and/or pain, both vaginal ultrasound and hysteroscopy with directed biopsies should be recommended.
Laparascopic port‐site recurrence in a patient with adenocarcinoma of the cervix
Authors: Smith Trudy , Guidozzi Franco , Kadar Nicholas , Van Der Wat Izak J. , Daponte Alexandros
Published: March 2003

Laparoscopic pelvic and para‐aortic lymphadenectomy was performed in a 33‐year‐old patient who presented with stage 1B poorly differentiated adenocarcinoma of the cervix. Two 10‐mm and two 5‐mm ports were used for the lymph node dissection. Histological examination of frozen sections of the pelvic and para‐aortic lymph nodes submitted confirmed the presence of metastatic disease. As a consequence of this, the planned Schauta‐type radical vaginal hysterectomy was abandoned. The patient was given post‐operative pelvic irradiation. Unfortunately, she presented 9 months later with histologically proven metastatic disease at the 10‐mm port site.
A second‐generation laparoscopic port system: EndoTIPTM
Authors: Ternamian Artin M.
Published: March 2003

Background

Ever since conventional laparoscopic trocars and cannulas were introduced, concern has been expressed regarding their safety, especially when they are used at the primary port. Despite considerable technological innovation, little has changed in port creation methods and instruments. Numerous publications from reputable centres around the world have warned of the potential dangers associated with their application and design. An interactive new port method is described and an access device is presented with several intuitive safety features which address most of these concerns.

Method

The new port system design evolved through a process of observation, the setting of minimum safety requirements and then cycles of system design, instrument design, prototype construction, evaluation, and redesign.

Results

The main advantage of the new port system is the ability to introduce and remove laparoscopic ports in an incremental visual way, without the use of axial penetration force and without the use of a trocar. Our novel ergonomically designed access device allows the surgeon to navigate past vessels, bowel or adhesions during insertion and removal of the cannula, without compromising patient safety or port competence.

Conclusion

An interactive visual port system which incorporates intuitive safety features will offer the surgeon an opportunity to better appreciate port dynamics, preserve port competence, and probably decrease laparoscopic access complications.
Laparoscopic treatment of ovarian ectopic pregnancy
Authors: Guirguis R. S.
Published: March 2003

A case of a young nulliparous patient with slight vaginal bleeding after a short period of amenorrhoea is presented. During laparoscopy, a haemorrhagic mass was seen, bulging from the right ovary, which was thought to be an ovarian ectopic pregnancy. The mass was successfully excised laparoscopically. Subsequent histological examination confirmed the diagnosis. Laparoscopic surgery is a simple, safe and effective method of treating suitable cases of ovarian ectopic pregnancy. Minimal tissue handling during laparoscopic surgery would maximize future reproductive function.
Morcellation in the bag: the superior solution to avoid spillage
Authors: Sinha Rakesh Y. , Joshi Kavita M. , Warty Neeta R. , Frey Brinda
Published: March 2003

Objective

To evaluate the new method of morcellation in the bag to avoid spillage of contents in the case of ovarian cysts.

Setting

A study of three procedures performed at an institute exclusively carrying out operative endoscopy.

Conclusion

We found our technique of morcellation in the bag to be superior to other methods described.
Pyosalpinx presenting as an ectopic pregnancy
Authors: Bollen Bart , Lewis Victor
Published: March 2003

Objective

To report a case of a pyosalpinx presenting as an ectopic pregnancy.

Subject

A 31‐year‐old patient was admitted with severe pain in the right iliac fossa 14 days after a curettage of the uterine cavity for missed abortion following 10 weeks of amenorrhoea.

Intervention

An ultrasound scan showed a mass next to the right ovary with no evidence of retained products of conception. The β‐hCG level was 1258 IU l−1. A laparoscopy suggested an ectopic pregnancy in the distal end of the right tube. A salpingectomy was performed and the histopathological findings were of acute salpingitis.

Conclusion

We describe a pyosalpinx after curettage of the uterine cavity, with high β.‐hCG levels from an intrauterine pregnancy, which indicated the wrong diagnosis of an ectopic pregnancy.
Growth of an endometrial polyp in a postmenopausal patient using raloxifene
Authors: Maia Jr Hugo , Maltez Amelia , Oliveira Maita , Almeida Marta , Coutinho Elsimar M.
Published: March 2003

Objective

To describe the association of raloxifene use with the development of an endometrial polyp in a postmenopausal patient.

Design

Case report study.

Results

Hysterosonography and hysteroscopy showed the occurrence of an endometrial polyp in a postmenopausal patient who had been using raloxifene for 8 months. Pathological investigation showed the presence of simple hyperplasia in the polyp. Oestrogen receptors were present in both the polyp and the atrophic endometrium. Progesterone receptors, on the other hand, were detected mainly in the atrophic endometrium. There was a focal p53 overexpression in the glandular epithelium of the polyp.

Conclusion

Raloxifene stimulated the development of an endometrial polyp in this postmenopausal patient. The presence of progesterone receptors in the atrophic endometrium suggests an agonistic action of raloxifene on this tissue.
The port‐decompression effect. A causative factor in the aetiology of post‐laparoscopic port‐site herniation?
Authors: Clark James T. M. , Byrne Dominic L.
Published: March 2003

Introduction Post‐laparoscopic port‐site herniation has been variously reported to have an incidence of up to 0.2%. In 86% of instances where port sizes of 10 mm or greater have been used, and lateral port sites are 35 times more at risk than suprapubic, with the umbilical locale being the most common site, associated with 75% of all hernias.

Theory A port decompressing an abdomen insufflated to a pressure of 15 mmHg has a profound suction effect and can pick up a loop of bowel while being drawn out through the abdominal wall. We believe that, on occasion, this is the mechanism by which bowel can be drawn within the abdominal wall and rectus sheath defect, thereby contributing to port‐site herniation.

Methods We have obtained photographic evidence of bowel drawn up into a channel formed by a primary trocar. We demonstrate how bowel is caught by the suction effect of decompression through an open port and show that, despite the intraumbilical entry technique favoured by Garry, a channel can form through the abdominal wall which can trap bowel. We also examine the physics of gas flow and the relationship between port size, decompression technique and suction effect.

Conclusion We suggest the abdomen should be decompressed slowly under direct vision, through the side tap, with the telescope remaining within the port. After gas release is completed, the primary port and telescope are removed together, with a clear view at all times that the port is free of any entrapped bowel.
Adenomyosis and endometrial ablation
Authors: Neis Klaus J. , Brandner Percy
Published: March 2003

Objective To present a synopsis concerning adenomyosis uteri interna with respect to endometrial ablation. The definition of adenomyosis, different diagnostic methods and their effectiveness, as well as the influence of adenomyosis on the outcome after endometrial ablation, are discussed.

Design Review.

Setting Obstetrics and gynaecology clinic of an academic teaching university hospital.

Results Depending on which definition is used, the incidence of adenomyosis varies between 8 and 61%. The term ‘adenomyosis’ should be restricted to those cases with a deeper ingrowth of glands, as only these show clinical symptoms. Adenomyosis can not be diagnosed or excluded with certainty by either sonography, diagnostic hysteroscopy, or dilation and curettage. Needle biopsies of the myometrium show low accuracy and are difficult to obtain. Hysteroscopic resection of myometrium detects some cases of adenomyosis, but misses the majority. In patients undergoing hysterectomy after unsuccessful endometrial ablation, incidence rates of 75–100% for adenomyosis were reported. Thus adenomyosis might be a principal reason for treatment failure. As there is no safe means of excluding adenomyotic foci, adenomyosis can be assumed in patients with an enlarged uterus and marked dysmenorrhoea.

Conclusion Patients with dysmenorrhoea and uteri >10 cm show a high incidence of adenomyosis. Because of an increased risk of failure, these patients should be excluded from endometrial ablation.
The laparoscopic Deschamps needle: revival of an old concept
Authors: Brölmann Hans A. M. , Bremer Gérard L.
Published: March 2003

Background 

In laparoscopic surgery there are several appropriate ways of securing uterine or ovarian vessels. The costs of stapling are high. Bipolar coagulation is a cheap and useful technique; however, it carries a risk of inadvertent heat conduction to neighbouring organs. Ligating the uterine pedicle may be a reasonable alternative, but stitching with a sharp needle may damage large arteries and can cause uncontrollable haemorrhage.

Instrument

In view of this, a laparoscopic needle similar to the Deschamps needle (with a blunt, articulating tip and a distal eye) has been developed. The needle is loaded with any regular suturing material. The instrument is introduced through an operation port of 5 mm or more. After the tissue that is to be transsected has been perforated by the Deschamps needle, a second needle‐holder is introduced and both ends of the suture are pulled outside the abdomen. The knot is tied, using a Clarke knot‐pusher. A total of four extra‐abdominal throws strengthen the final knot. The threads are then cut.

Results 

In a 24‐month period we tested the device in 50 patients, who underwent a laparoscopically assisted vaginal hysterectomy (LAVH). In all patients the uterine vessels were ligated by Deschamps suturing; in seven the ovarian vessels were also ligated using this technique.

Conclusion 

Suturing with the Deschamps needle is easy to learn, and is fast, effective and inexpensive.
Wound dehiscence at a 7‐mm port site closed with tissue adhesive
Authors: Abbott Jason , Phillips Graham
Published: March 2003

Objective 

To describe the herniation of omentum through a 7‐mm suprapubic port site, which had been closed with tissue adhesive, following laparoscopic sterilization, requiring repair under general anaesthetic.

Setting 

Minimal access gynaecological surgery unit in a district general hospital.

Subject 

A 26‐year‐old multiparous woman who presented with abdominal pain and an omental herniation through her suprapubic port site.

Intervention 

The patient required repeat laparoscopy and digital reduction of the hernia with formal repair of the rectus sheath defect.

Conclusion 

This case of herniation through a midline 7‐mm port site may have implications for the closure of wounds at laparoscopy. Most gynaecologists do not formally close the rectus sheath at laparoscopic sterilization; however, with the possibility of visceral herniation and vascular compromise, this practice may change in the future. It is not clear whether the tissue adhesive had a role in this complication.