bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate change effects on net carbon exchange of a boreal aspen–hazelnut forest: estimates from the ecosystem model ecosys
Authors: Grant R. F. , Nalder I. A.
Published: March 2003

Although boreal forests are currently sinks for atmospheric C, there is some concern that they may not remain so under hypothesized warming of the boreal climate. The ecosystem model ecosys was used to evaluate possible changes in ecosystem C exchange and accumulation under changes in atmospheric CO2 concentration (Ca) proposed in emissions scenario IS92a, and accompanying changes in air temperature and precipitation proposed by general circulation models running under IS92a. Ecosys was first tested under current climate by comparing modelled rates of C exchange and accumulation with those measured in a mixed aspen–hazelnut stand in central Saskatchewan. The model was then run with daily increments of Ca, temperature and precipitation, and differences in C exchange and accumulation between current and changing climates were evaluated. Model results indicated that over a 120‐y period, a mixed aspen–hazelnut stand currently accumulates about 14 kg C m−2. Under the hypothesized changes in climate this stand would accumulate an additional 8.5 kg C m−2, largely through higher rates of CO2 fixation and longer growing seasons under higher Ca and temperature. This additional accumulation would be entirely as aspen wood, while soil organic matter would change little. This accumulation would therefore be vulnerable to losses from fire and insects.
Seasonal soil‐surface carbon fluxes from the root systems of young Pinus radiata trees growing at ambient and elevated CO2 concentration
Authors: Thomas Stephen M. , Cook Freeman J. , Whitehead David , Adams John A.
Published: March 2003

Elevated atmospheric CO2 concentration may result in increased below‐ground carbon allocation by trees, thereby altering soil carbon cycling. Seasonal estimates of soil surface carbon flux were made to determine whether carbon losses from Pinus radiata trees growing at elevated CO2 concentration were higher than those at ambient CO2 concentration, and whether this was related to increased fine root growth.

Monthly soil surface carbon flux density (f) measurements were made on plots with trees growing at ambient (350) and elevated (650 μmol mol−1) CO2 concentration in large open‐top chambers. Prior to planting the soil carbon concentration (0.1%) and f (0.28 μmol m−2 s−1 at 15 °C) were low. A function describing the radial pattern of f with distance from tree stems was used to estimate the annual carbon flux from tree plots. Seasonal estimates of fine root production were made from minirhizotrons and the radial distribution of roots compared with radial measurements of f. A one‐dimensional gas diffusion model was used to estimate f from soil CO2 concentrations at four depths.

For the second year of growth, the annual carbon flux from the plots was 1671 g y−1 and 1895 g y−1 at ambient and elevated CO2 concentrations, respectively, although this was not a significant difference. Higher f at elevated CO2 concentration was largely explained by increased fine root biomass. Fine root biomass and stem production were both positively related to f. Both root length density and f declined exponentially with distance from the stem, and had similar length scales. Diurnal changes in f were largely explained by changes in soil temperature at a depth of 0.05 m.

Ignoring the change of f with increasing distance from tree stems when scaling to a unit ground area basis from measurements with individual trees could result in under‐ or overestimates of soil‐surface carbon fluxes, especially in young stands when fine roots are unevenly distributed.
Temperature responses of carbon mineralization in conifer forest soils from different regional climates incubated under standard laboratory conditions
Authors: Dalias Panagiotis , Anderson Jonathan M. , Bottner Pierre , Coûteaux Marie‐Madeleine
Published: March 2003

14C‐labelled straw was mixed with soils collected from seven coniferous forests located on a climatic gradient in Western Europe ranging from boreal to Mediterranean conditions. The soils were incubated in the laboratory at 4°, 10°, 16°, 23° and 30 °C with constant moisture over 550 days. The temperature coefficient (Q10) for straw carbon mineralization decreased with increasing incubation temperatures. This was a characteristic of all the soils with a difference of two Q10 units between the 4–10° and the 23− 30 °C temperature ranges. It was also found that the magnitude of the temperature response function was related to the period of soil incubation. Initial temperature responses of microbial communities were different to those shown after a long period of laboratory incubation and may have reflected shifts in microbial species composition in response to changes in the temperature regime. The rapid exhaustion of the labile fractions of the decomposing material at higher temperatures could also lead to underestimation of the temperature sensitivity of soils unless estimated for carbon pools of similar qualities. Finally, the thermal optima for the organic soil horizons (Of and Oh) were lower than 30 °C even after 550 days of incubation. It was concluded that these responses could not be attributed to microbial physiological adaptations, but rather to the rates at which recalcitrant microbial secondary products were formed at higher temperatures. The implication of these variable temperature responses of soil materials is discussed in relation to modelling potential effects of global warming.
Organic carbon cycling in Taylor Valley, Antarctica: quantifying soil reservoirs and soil respiration
Authors: Burkins Melody B. , Virginia Ross A. , Wall Diana H.
Published: March 2003

Organic carbon reservoirs and respiration rates in soils have been calculated for most major biomes on Earth revealing patterns related to temperature, precipitation, and location. Yet data from one of the Earth's coldest, driest, and most southerly soil ecosystems, that of the McMurdo Dry Valleys of Antarctica, are currently not a part of this global database. In this paper, we present the first regional calculations of the soil organic carbon reservoirs in a dry valley ecosystem (Taylor Valley) and report measurements of CO2 efflux from Antarctic soils. Our analyses indicate that, despite the absence of visible accumulations of organic matter in most of Taylor Valley's arid soils, this soil environment contained a significant percentage (up to 72%) of the seasonally unfrozen organic carbon reservoir in the terrestrial ecosystem. Field measurements of soil CO2‐efflux in Taylor Valley soils were used to evaluate biotic respiration and averaged 0.10 ± 0.08 μmol CO2 m−2 s−1. Laboratory soil microcosms suggested that this respiration rate was sensitive to increases in temperature, moisture, and carbon addition. Finally, a steady‐state calculation of the mean residence time for organic carbon in Taylor Valley soils was 23 years. Because this value contradicts all that is currently known about carbon cycling rates in the dry valleys, we suggest that the dry valley soil carbon dynamics is not steady state. Instead, we suggest that the dynamic is complex, with at least two (short‐ and long‐term) organic carbon reservoirs. We also suggest that organic carbon in the dry valley soil environment may be more important, and play a more active role in long‐term ecosystem processes, than previously believed.
Interannual variability in global soil respiration, 1980–94
Authors: Raich James W. , Potter Christopher S. , Bhagawati Dwipen
Published: March 2003

We used a climate‐driven regression model to develop spatially resolved estimates of soil‐CO2emissions from the terrestrial land surface for each month from January 1980 to December 1994, to evaluate the effects of interannual variations in climate on global soil‐to‐atmosphere CO2fluxes. The mean annual global soil‐CO2flux over this 15‐y period was estimated to be 80.4 (range 79.3–81.8) Pg C. Monthly variations in global soil‐CO2emissions followed closely the mean temperature cycle of the Northern Hemisphere. Globally, soil‐CO2emissions reached their minima in February and peaked in July and August. Tropical and subtropical evergreen broad‐leaved forests contributed more soil‐derived CO2to the atmosphere than did any other vegetation type (∼30% of the total) and exhibited a biannual cycle in their emissions. Soil‐CO2emissions in other biomes exhibited a single annual cycle that paralleled the seasonal temperature cycle. Interannual variability in estimated global soil‐CO2production is substantially less than is variability in net carbon uptake by plants (i.e., net primary productivity). Thus, soils appear to buffer atmospheric CO2concentrations against far more dramatic seasonal and interannual differences in plant growth. Within seasonally dry biomes (savannas, bushlands and deserts), interannual variability in soil‐CO2emissions correlated significantly with interannual differences in precipitation. At the global scale, however, annual soil‐CO2fluxes correlated with mean annual temperature, with a slope of 3.3 Pg C y−1per °C. Although the distribution of precipitation influences seasonal and spatial patterns of soil‐CO2emissions, global warming is likely to stimulate CO2emissions from soils.
Estimation of the carbon sequestration by a heterogeneous forest: night flux corrections, heterogeneity of the site and inter‐annual variability
Authors: AUBINET MARC , HEINESCH BERNAD , LONGDOZ BERNAD
Published: March 2003

Continuous measurements of the net CO2 flux exchanged in a mixed forest with the atmosphere were performed over 5 years at the Vielsalm experimental site. The carbon sequestration at the site was deduced by a summation of the measurements. Problems associated with this summation procedure were discussed. The carbon sequestration in the ecosystem was presented and its interannual variability was discussed.

An estimation of the night flux correction was given. The correction was applied by replacing measurements made during quiet nights by a parameterization. The impact of the correction was shown to vary between 10 and 20% of the uncorrected flux, according to the year. The need to include the storage flux during turbulent periods was emphasized: its neglect leads to an error which will be greater than the one it tries to correct.

It was also shown that the heterogeneity of the site made it necessary to split the data into separate series corresponding to the different vegetation patches and to fill the data gaps by using an algorithm that takes account of the weather conditions. Two series were defined, one corresponding to a beech subplot, the other to a conifer subplot. The uncertainty owing to the data split and the data gap‐filling was about 15–20% annually.

The carbon sequestration was then analysed in both the subplots. The length of the growing season was about 210 days in the beech and 240 days in the conifer. The carbon sequestration over 5 years was 2.28 kg C m2−2 in the beech and 3.58 kg C m2−2 in the conifer. The main difference between the species appeared in spring, between March and May, when the beeches were leafless.

Significant interannual variations were observed in both the subplots. They appeared mainly in summer and were primarily because of the variations in the radiation and air humidity regimes. In addition, an impact of the interannual variation of the vegetation area index (VAI) and of the leaf initiation date was observed in the beech. Finally, a decline of the carbon sequestration efficiency of the ecosystem during the season was observed in both the subplots. It was because of neither the variation in any climatic variables nor VAI variation.
Does elevated atmospheric carbon dioxide affect internal nitrogen allocation in the temperate trees Alnus glutinosa and Pinus sylvestris?
Authors: Temperton Victoria M. , Millard Peter , Jarvis Paul G.
Published: March 2003

Nitrogen‐fixing plant species growing in elevated atmospheric carbon dioxide concentration ([CO2]) should be able to maintain a high nutrient supply and thus grow better than other species. This could in turn engender changes in internal storage of nitrogen (N) and remobilisation during periods of growth. In order to investigate this one‐year‐old‐seedlings of Alnus glutinosa (L.) Gaertn and Pinus sylvestris (L.) were exposed to ambient [CO2] (350 µmol mol−1) and elevated [CO2] (700 µmol mol−1) in open top chambers (OTCs). This constituted a main comparison between a nitrogen‐fixing tree and a nonfixer, but also between an evergreen and a deciduous species. The trees were supplied with a full nutrient solution and in July 1994, the trees were given a pulse of 15N‐labelled fertiliser. The allocation of labelled N to different tissues (root, leaves, shoots) was followed from September 1994 to June 1995. While N allocation in P. sylvestris (Scots pine) showed no response to elevated [CO2], A. glutinosa (common alder) responded in several ways. During the main nutrient uptake period of June–August, trees grown in elevated [CO2] had a higher percentage of N derived from labelled fertiliser than trees grown in ambient [CO2]. Remobilisation of labelled N for spring growth was significantly higher in A. glutinosa grown in elevated [CO2] (9.09% contribution in ambient vs. 29.93% in elevated [CO2] leaves). Exposure to elevated [CO2] increased N allocation to shoots in the winter of 1994–1995 (12.66 mg in ambient vs. 43.42 mg in elevated 1993 shoots; 4.81 mg in ambient vs. 40.00 mg in elevated 1994 shoots). Subsequently significantly more labelled N was found in new leaves in April 1995. These significant increases in movement of labelled N between tissues could not be explained by associated increases in tissue biomass, and there was a significant shift in C‐biomass allocation away from the leaves towards the shoots (all above‐ground material except leaves) in A. glutinosa. This experiment provides the first evidence that not only are shifts in C allocation affected by elevated [CO2], but also internal N resource utilisation in an N2‐fixing tree.
The use of n‐alkanes to estimate herbage intake and diet composition by dairy cows offered a perennial ryegrass/white clover mixture
Authors: Hameleers A. , Mayes R. W.
Published: March 2003

The n‐alkane technique for estimating herbage intake and diet selection in dairy cows fed perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) herbages was evaluated. Pairs of animals were offered either 8, 10, 12 or 14 kg dry matter (DM) d−1 of herbage alone or with 2 kg DM d−1 of barley. Fresh herbage was cut daily from a perennial ryegrass/white clover sward and the appropriate amount was fed in four feeds during the day. Individual intakes and the white clover proportion of the diet were estimated during a 12‐d period using the n‐alkane technique. Animals were dosed twice daily with paper pellets containing dotriacontane (C32‐alkane). Faecal grab samples were collected after the morning and afternoon milking. Three least‐squares optimization methods were compared in calculating the white clover proportion in the diet; then, total DM intake was calculated. The different least‐squares optimization methods gave similar predictions of the white clover content of the forage consumed. No significant (P < 0.05) effects of sampling routine, concentrate (barley) fed or interactions between the two were detected with respect to the difference between calculated and actual intake, the difference as a proportion of the total intake and estimated white clover content of the diet. The difference between the calculated and actual intake ranged from 139 to 366 g DM d −1, which resulted in a proportional difference ranging from 0.004 to 0.02 depending on sampling routine. The actual white clover content of the herbage mixture fed was 0.42 ± 0.008, whereas the estimated white clover content ranged from 0.41 ± 0.006 to 0.43 ± 0.008. The results suggest that accurate herbage intake estimates can be achieved in dairy cows grazing perennial ryegrass/white clover swards if representative samples from herbage consumed can be collected.
The establishment of alfalfa into different maize residues by conservation‐tillage and its effect on insect infestation
Authors: Byers  , Bahler  , Stout  , Leath  , Hoffman
Published: March 2003

The effect of management of maize residues on the population of insects inimical to the establishment of alfalfa, Medicago sativa L., was examined 1 month after sowing. Alfalfa was sown in early and late April, and late May for 3 consecutive years in Centre County, Pennsylvania, USA. The sowings were made by conservation tillage (direct drilled into maize residue with minimal disturbance of soil) into three different maize residues after (1) silage, (2) silage‐plus‐winter rye cover and (3) grain. A fourth sowing was by conventional tillage (spring ploughing and harrowing maize residue) after grain. A pesticide, carbofuran (granular formulation) was applied at sowing to half of the plots. Methiocarb bait, a molluscicide, was applied as a split application to the same plots, one‐half at sowing and the remainder 2 weeks later. Alfalfa plots in the silage‐plus‐rye maize residues were colonized with fewer insects than the other residue treatments. Excessive growth of rye in early spring that was not successfully suppressed by herbicide treatment produced vigorous rye plants and fewer alfalfa seedlings. Consequently, silage plus rye had the lowest yield of alfalfa in early April sowings in 2 out of 3 years. Insects known to feed on alfalfa, such as tarnished plant bugs, Lygus lineolaris (Palsot de Beauvois), the plant bug, Plagiognathus politus Uhler, pea aphids, Acyrthosiphon pisum (Harris), and meadow spittlebugs, Philaenus leucophthalmus spumarius (L.), were collected by sweep net 1 month after sowing and less often in the silage‐plus‐rye treatment. These species were present in greater numbers in the other maize residues that had significantly more alfalfa forage.

The insidious flower bug, Orius insidious (Say), and a damsel bug, Nabis americoferus Carayon, were collected in significantly greater numbers in the early April sowings, which corresponded with the peak populations of pea aphid. The potato leafhopper, Empoasca fabae (Harris), was most abundant in plots sowed in late April or late May.

Pesticide treatment applied at the time of sowing had very little effect on numbers of insects collected by sweep net 1 month later in 1986 and 1988. However, pesticide treatment significantly increased yield by 280 kg ha−1 in 1987, even though sweep net collections of insects were not reduced by the pesticide treatment. Therefore, the beneficial effect of the pesticide could not be explained on the basis of the insects collected.

The highest yields of alfalfa were obtained from the early April sowing into maize residues. This coincided with the time when the majority of alfalfa pests were less abundant than in later sowings; fewer pests were found on the sowings into silage‐plus‐rye residue. Also, when the rye forage yield was combined with the alfalfa yield, this became the most productive system.
A comparison of two grassland‐based systems for autumn‐calving dairy cows of high genetic merit
Authors: Gordon  , Ferris  , Patterson  , Mayne
Published: March 2003

A full lactation study compared the performance of autumn‐calving dairy cows of high genetic merit under two contrasting systems of milk production: high forage (HF) and high concentrate (HC). During the winter, animals on system HF were offered a silage with a high feeding value characteristics, supplemented with 5·5 kg of concentrate [crude protein content of 280 g kg−1 dry matter (DM)] through an out‐of‐parlour feeding system. From 14 March, these animals were given increasing access to grazing, achieving 24‐h turnout on 15 April. Thereafter, until day 305 of lactation, these animals were offered a large daily herbage allowance (23·0 kg grass DM cow−1, measured above a height of 4·0 cm), supplemented with 0·5 kg d−1 of a ‘high‐magnesium’ concentrate. During the winter, animals on system HC were offered a silage of medium feeding value, mixed with ≈14·0 kg of concentrate d−1 (crude protein content of 202 g kg−1 DM) in the form of a complete diet. These animals commenced grazing on 9 April, achieving 24‐h turnout on 18 April. From 18 April until 9 June, daily herbage allowances and concentrate feed levels were 17·0 kg DM and 5·0 kg respectively; thereafter, and until day 305 of lactation, these daily allowances were reduced to 15·0 kg of herbage DM and 4·0 kg of concentrate. Animal performance during the first 305 days of lactation for systems HF and HC, respectively, were as follows: total concentrate DM inputs, 842 and 2456 kg; total silage DM intakes, 2205 and 1527 kg; total grass DM intakes, 3019 and 2044 kg; total feed DM intake, 6061 and 6032 kg and total milk output, 7854 and 8640 kg. Total milk output per cow with system HF was 786 kg lower than for system HC, despite similar total DM intakes, suggesting a greater total nutrient requirement with the former to support a given milk production. However, the study confirms that relatively similar levels of animal performance can be achieved from systems based on very different sources of nutrient supply.
Water sorption isotherms of leaves and stems of Trifolium pratense L.
Authors: Stencl  , Homola
Published: March 2003

Moisture sorption isotherms of red clover, Trifolium pratense L., leaves and stems from the first cut of the season were determined using a gravimetric dynamic method with continuous recording of changes in sample weight. Equilibrium data for adsorption and desorption of water from red clover were investigated at ambient temperatures in the range of 20–50°C and with water activity in the range of 0·20–0·99. Sorption capacity decreased as temperature increased. Rehydration of the dried material resulted in hysteresis. Four models available in the literature (Chung‐Pfost, Halsey, Henderson and Oswin) were evaluated by determining the best fit to the experimental data. The Henderson equation was found to be a good model for moisture adsorption and desorption of leaves, and the Oswin equation was a good model for moisture adsorption and desorption of stems.
The effect of harvest date and inoculation on the yield, fermentation characteristics and feeding value of forage pea and field bean silages
Authors: Fraser M. D. , Fychan R. , Jones R.
Published: March 2003

Two experiments describe the ensiling potential of whole‐crop forage peas (Pisum sativum) and field beans (Vicia faba). In Experiment 1, forage peas (cv. Magnus) and field beans (cv. Mayo) were harvested at 10, 12 and 14 weeks after sowing, and ensiled in 10 kg mini‐silos either untreated or treated with an inoculant (Lactobacillus plantarum). In terms of yield and ensiling potential, the optimum growth stage for harvesting forage peas occurred at 12 weeks of growth. In contrast, delaying the harvest of field beans until 14 weeks gave the highest yields of dry matter (DM) and crude protein (CP). Changes in crop maturity had little effect on the chemical composition of the fresh forages, but between‐harvest date differences were observed in the DM, ammonia‐N, CP, water‐soluble carbohydrates (WSC), acid‐detergent fibre (ADF), neutral‐detergent fibre (NDF), lactic acid and volatile fatty acids (VFA) concentrations and pH of the corresponding silages. Fermentation was improved by applying an inoculant. In Experiment 2, forage peas and field beans were harvested at 14 weeks after sowing and ensiled as round‐bale silage, either untreated or treated with an inoculant. The yields of the crops were similar, and the only difference in the chemical composition of the wilted forages was a higher CP concentration in the field beans. However, after the ensiling process was complete, the forage pea silages were found to have significantly higher DM, WSC, starch and butyric acid concentrations compared with the field bean silages, and lower ammonia‐N, CP, ADF, acetic acid and lactic acid concentrations. Inoculation was found to increase the lactic acid concentration and reduce the pH and ammonia‐N and acetic acid concentrations of the silages. Each of the silages produced in Experiment 2 was offered to six Suffolk crossbred wether lambs, aged 10 months. Voluntary DM intakes were similar on all treatments, despite the apparent digestibility of the forage pea silages being significantly higher than that of the field bean silages. Nitrogen retention was higher for lambs offered forage pea silage. Application of an inoculant was found to have a negative effect on the amount of N retained, indicating the necessity for more detailed investigations into proteolytic activity within these crops during the fermentation process.
Yield profile of tall fescue (Festuca arundinacea) in comparison with meadow fescue (F. pratensis) in Finland
Authors: Niemeläinen O. , Jauhiainen L. , Miettinen E.
Published: March 2003

Yield profile characteristics of tall fescue (Festuca arundinacea Schreb.), cv. Retu, were compared with those of meadow fescue (Festuca pratensis Huds.). The study was conducted in Finland and was based on official variety trial data recorded between 1980 and 1998 at 17 trial sites between latitudes 60° and 66°N. The crops were managed according to silage‐cutting regimes. The pattern of yield formation of the tall fescue cv. Retu differed significantly from that of meadow fescue cultivars, both within a growing season as well as in sward age. Tall fescue cv. Retu established slowly, and the dry‐matter (DM) yield from the first cut, made in the first year of harvest, was significantly lower than that for meadow fescue. In the second and third years, the DM yield from the first cut did not differ between tall fescue and meadow fescue. Tall fescue produced significantly higher DM yield as regrowth (second and third cuts) than meadow fescue. The sward age significantly affected total DM production. In first‐year swards, there were no significant differences in total DM yield between tall fescue and meadow fescue but, in the second‐ and third‐year swards, tall fescue produced significantly higher DM yields than meadow fescue. The difference in yield profile between tall fescue and meadow fescue was similar in all the environments included in the study. DM yield for the first cut (kg DM ha–1) for tall fescue cv. Retu, in comparison with meadow fescue cultivars, was 2495 vs. 3099 (P < 0·001), 3735 vs. 3741 (NS, P=0·94) and 3553 vs. 3468 (NS, P=0·30) in the first‐, second‐ and third‐year swards respectively. The respective DM regrowth yields (second plus third cut) were: 6059 vs. 5416 (P < 0·001); 5445 vs. 4221 (P < 0·001); and 5580 vs. 4113 (P < 0·001) in first‐, second‐ and third‐year swards. Total DM yields per season for tall fescue vs. meadow fescue were (kg DM ha–1) 8554 vs. 8515 (NS, P=0·69), 9180 vs. 7962 (P < 0·001) and 9133 vs. 7581 (P < 0·001) in first‐, second‐ and third‐year swards respectively. Over the three‐year sward rotation period, which is common in Finland, tall fescue produced on average 12% higher DM yield than meadow fescue. Both tall fescue and meadow fescue suffered little winter damage in Finnish conditions; the differences between cultivars of the two species were small. The results indicated that tall fescue cv. Retu is a productive and persistent forage species suited to Finnish growing conditions.
OSYAQ, an organ‐specific growth model for forage grasses
Authors: Herrmann A. , Schachtel G. A.
Published: March 2003

The effects of different stem‐to‐leaf proportions on the yield and quality of forage grasses is a question of importance to plant breeders. This paper describes the growth submodule of OSYAQ, an organ‐specific yield and quality model. The model input includes daily average air temperature, precipitation, potential evapotranspiration and incoming global radiation. The major processes implemented in the growth submodule are photosynthesis, maintenance and growth respiration, recycling of senescent plant material and remobilization of reserves. The model calculates separately yield formation for stem, leaf and ear. Available assimilates are partitioned to the various plant parts according to the concept of relative sink strength. Calibration and validation were based on a 2‐year and a 1‐year field trial, respectively, carried out under long‐ and short‐day conditions withLolium multiflorumssp.gaudini. These tests indicated a good performance of the model for the long‐day growth but showed some deficiencies for regrowth after defoliation under conditions of extreme water shortage. The paper discusses these results and possible improvements. It concludes that the growth module of OSYAQ provides a suitable tool for the analysis of the effects of varied stem‐to‐leaf ratios on yield.
Divergent recurrent selection for seedling tiller number in Altai wildrye
Authors: Jefferson P. G. , Lawrence T. , Kielly G. A.
Published: March 2003

Seedling tiller number is a possible selection criterion to improve seedling establishment of Altai wildrye, Leymus angustus (Trin.) Pilger, an important grass for autumn grazing of beef cattle in semiarid environments. Forty‐two half‐sib families selected for high seedling tiller number (HTN) and eighteen half‐sib families selected for low seedling tiller number (LTN) by four cycles of divergent recurrent selection were compared with four controls, Altai wildrye cultivars Prairieland, Eejay and Pearl, and crested wheatgrass (Agropyron desertorum (Fisch. Ex Link) Schultes), cultivar Nordan, on dryland and irrigated sites at Swift Current, Saskatchewan, Canada. Seedling tiller count, seedling height, tiller weight and seedling dry‐matter yield (DMY) were determined on two plants per plot and DMY was determined for each plot for 2 years post‐establishment. HTN half‐sib families had more, lighter and shorter tillers than LTN half‐sib families. There was a negative correlation (r=–0·42, P < 0·01, n=60) between seedling DMY and tiller number. HTN half‐sib families had higher DMY in post‐establishment years at the dryland site only. Seedling tiller number in Altai wildrye may be related to DMY at sites at which resource availability delays seedling establishment, but selection for HTN will not increase seedling DMY owing to concomitant changes in carbon allocation.
Frequency of defoliation of native and naturalized species of the Flooding Pampas (Argentina)
Authors: Agnusdei M. G. , Mazzanti A.
Published: March 2003

This study describes the effect of herbage mass of species on defoliation patterns in a multispecies temperate–subhumid natural grassland of the Flooding Pampas at low, medium and high sward herbage mass [761 ± 8·7, 989 ± 137 and 1591 ± 44·0 kg green dry matter (DM) ha–1 respectively] maintained by continuous grazing of cattle at variable stocking rates. Four native and naturalized warm‐season species were studied: the grasses Cynodon dactylon, Leersia hexandra and Paspalum dilatatum and the legume Lotus tenuis. Sward state of the four species was described in terms of sward surface height, herbage biomass and the number of individual grass tillers and legume stems per unit area. The defoliation pattern was monitored twice‐weekly during an experimental period of 3 weeks on permanently marked individual plants. Proportions of individual plants defoliated and the ranking of species selected differed among sward treatments and species. The results showed that the density of the species was a major factor determining the pattern of species defoliation and suggest that, in continuously grazed mixtures, the pattern of defoliation might be more dependent on the abundance of a species in the plant community than on species preferences. The results show the importance of considering this structural characteristic of swards in understanding the process of species selection by large herbivores in multispecies vegetation.
Factors affecting digestibility of temperate forages from seminatural grasslands: a review
Authors: Bruinenberg M. H. , Valk H. , Korevaar H. , Struik P. C.
Published: March 2003

Abstract To indicate possibilities for the use of forages from seminatural grasslands in ruminant production systems, a literature study to describe the nutritive value of those forages was carried out. In species‐rich grasslands, the digestibility of forages is usually lower than the digestibility of forages produced by grasslands used for intensive production. There is also more variation within a species‐rich sward, because of different stages of maturity of the individual species and because of likely variations in digestibility among forage species independent of stage of maturity. Moreover, the presence of dicotyledonous species may have a positive or negative effect on digestibility. In forages from seminatural grasslands, the relationship between chemical composition and digestibility differs from that of Lolium perenne, which is often used as a research standard. Therefore, predictions of the digestibility of species‐rich forage can be inaccurate. The relationship between in vivo and in vitro digestibility may also be different from the relationship that is common for L. perenne. In some cases, the in vivo digestibility is higher than the in vitro value, as calibrations are based on L. perenne. Therefore, the quality of forages from seminatural grasslands might be higher than predicted, and this may increase the scope for practical use of this kind of forage in ruminant nutrition systems.
Laparoscopic management of a patient with torsion of paratubal cyst associated with defect of the omentum
Authors: Mitsunari Masahiro , Harada Tasuku , Yoshioka Hiroki , Iwabe Tomio , Onohara Yoshimasa , Tanikawa Masahiro , Terakawa Naoki
Published: March 2003

We present an unusual case of torsion of a paratubal cyst in the mesosalpinx, associated with a defect of the omentum, in which laparoscopic management proved effective. A large paratubal cyst in the left mesometrium which was twisted twice around the defect of the omentum was removed laparoscopically. The patient's postoperative course was uneventful. Early diagnosis and treatment by laparoscopy are essential in the management of adnexal torsion.
Clear cell carcinoma arising in an endometrial polyp
Authors: Maltez Amelia , Maia Hugo , Oliveira Maita C. , Marques Dilson , Coutinho Elsimar M.
Published: March 2003

This paper describes the appearance of a clear cell carcinoma in an endometrial polyp of an 80‐year‐old patient. The transition between benign and malignant tissue in the polyp was abrupt and did not involve the presence of atypical hyperplasia. Overexpression of p53 protein was detected in the tumour but not in the benign tissue. There was a lack of oestrogen receptors in the clear cell carcinoma but not in the polyp.
Ethanol exhalation as a predictor of dilution hyponatraemia during endometrial ablation
Authors: Geerinckx Koen , Vanderheyden Tina , Meulemans Wim , Verhamme Peter , Hannon Heidi , Thys Johan
Published: March 2003

This study investigated the effectiveness of ethanol as an early indicator of resorption during transcervical endometrium resection (TCRE). Ethanol was added as a marker and exhaled alcohol concentrations were measured with an Alcomed test. Ninety‐three patients underwent endometrial ablation under general anaesthesia and exhaled ethanol levels and blood sodium concentrations were monitored simultaneously every 3 minutes. In 23% of the cases the Alcomed test was the first indicator of absorption. Relevant changes in blood sodium concentrations appeared later in 9% of the cases and gives a positive Alcomed test. The predictive exhaled ethanol value for preventing the transurethral prostate resection (TUR) syndrome is 1.5 promille. A marked difference in fluid resorption during hysteroscopic myomectomy was observed (400–1000 ml during TCRE and myomectomy vs. 100–300 ml TCRE only). Of 83 TCRE patients, 23 had a positive Alcomed test. Ten patients underwent a hysteroscopic myomectomy. Sensitivity and specificity were determined for a decrease of more than 5 mmol l−1 in blood sodium and for several ethanol levels. The sensitivity was 100% for an ethanol level of at least 0.05 promille. The specificity was 90.9% and the positive predictive value 41.7%. All patients with a decrease of more than 5 mmol l−1 in blood sodium concentration were detected using a threshold of 0.05 promille exhaled ethanol and nine out of 10 patients with a blood sodium decrease of at least 5 mmol l−1 also had an ethanol level of at least 0.05 promille. Unfortunately a positive Alcomed test has a poor prognostic value.
Laparoscopic salpingectomy: electrosurgery or sutures?
Authors: Sherif Lotfy S. , Foda Ahmed I. , El Zayat Moustafa M. , Badawy Ahmed M. , Magos Adam L.
Published: March 2003

Objective

To determine the optimal haemostatic method during laparoscopic salpingectomy.

Design

Observational study.

Setting

The Royal Free Hospital, London and Mansoura University Hospital, Egypt.

Subjects

72 patients undergoing laparoscopic salpingectomy for various indications.

Design

The patients were randomly allocated to one of two groups in which bipolar electrosurgery or pre‐tied sutures were used as the primary method of haemostasis. The two groups were compared with regard to several intraoperative and postoperative variables.

Results

The times required for securing and cutting the fallopian tube and for completing the procedures were shorter in the bipolar electrosurgery group than in the suture group, but the differences were not statistically significant. There were no significant differences between the groups with regard to any of the intraoperative or postoperative follow‐up variables.

Conclusion

Bipolar electrosurgery and suturing are equally effective for laparoscopic salpingectomy. Although many prefer to use bipolar electrosurgery for this procedure, the choice between different modalities will still depend upon the surgeon's preference and the circumstances obtaining during the procedure.
Endometrial carcinoma in postmenopausal patients using hormone replacement therapy: a report on four cases
Authors: Maia Hugo , Maltez Amelia , Calmon Luis C. , Moreira Katarina , Coutinho Elsimar M.
Published: March 2003

Objective

To report the occurrence of endometrial carcinoma in polyps in postmenopausal patients using hormone replacement therapy (HRT).

Setting

A private hospital with facilities for carrying out hysteroscopy.

Subjects

Four postmenopausal patients who developed endometrial carcinoma while using HRT.

Interventions

Hysteroscopy with biopsy, immunohistochemical investigation for oestradiol, progesterone receptors and p53 overexpression.

Results

All four cases of carcinoma were associated with endometrial polyps. The cancerous cells were positive for oestrogen receptors, negative for progesterone receptors and showed p53 overexpression in all cases.

Conclusions

The lack of detectable progesterone receptors in endometrial carcinomas arising in polyps in HRT patients indicates an unopposed action of oestrogens, which may accelerate the carcinomatous changes in polyps through a p53 pathway.
Use of the SAND balloon catheter for the laparoscopic surgery of benign ovarian cysts
Authors: Yamada Takashi , Okamoto Yukiko , Kasamatsu Hajime
Published: March 2003

Objective

We studied the advantages and disadvantages of using the newly developed SAND balloon catheter for the laparoscopic treatment of benign ovarian cysts and hydrosalpinx.

Methods

The SAND balloon catheter, which has two balloons at the tip, can hold and extend the ovarian cyst, which allows suction of the cystic fluid, and irrigation of the cystic cavity. Laparoscopic surgery using this catheter was carried out in 36 cases of ovarian or uterine cysts, or hydrosalpinx (32 patients).

Results

The cystic fluid in all 36 cases was successfully aspirated without gross identification of spillage. Adhesiolysis of the cyst was easily done by pulling the ovarian cyst with the SAND balloon catheter. None of the 36 cysts ruptured during aspiration and irrigation. The balloon did not slide during the procedure in any of the 36 cases. In 16 of the 32 patients who underwent the laparoscopic procedure, a conservative cystectomy procedure, in which only the cyst was excised, was performed. In the remaining 16 patients, oöphorectomy was performed.

Conclusions

The SAND balloon catheter was extremely useful for aspirating the cystic fluid, and for the irrigation and excision of the cyst, during the laparoscopic surgery of benign ovarian cysts.
Cerebellar infarction after uncomplicated laparoscopic hysterectomy
Authors: Meltomaa Seija S. , Mäkinen Juha I. , Niskanen Riitta M. , Salonen Markku A.
Published: March 2003

Objective

To review a case of cerebellar infarction after uncomplicated laparoscopic hysterectomy.

Methods

The clinical course and radiological findings in a 45‐year‐old previously healthy woman are reviewed.

Results

The patient suffered from headache and dizziness from the first postoperative day after a surgically uncomplicated laparoscopic hysterectomy. At 1 week after the operation she was readmitted because of continuing symptoms. Computer tomographic scan results of the brain were normal, while magnetic resonance imaging revealed two small infarctions in the right cerebellar hemisphere. At 3 years after the operation she still has mild neurological symptoms and is not capable of her previous work.

Conclusion

Haemodynamic changes related to head‐down tilt position combined with pneumoperitoneum may have hazardous effects on the brain even in previously clinically healthy patients.
Uterine serous papillary carcinoma arising inside an endometrial polyp removed by hysteroscopy
Authors: Maia Hugo , Maltez Amélia , Rodrigues Maíta , Coutinho Elsimar M.
Published: March 2003

Objective 

To describe a papillary, serous carcinoma arising in an endometrial polyp.

Setting 

Endoscopy unit of a private, urban hospital.

Interventions 

The polyp was diagnosed by hysteroscopy. Polypectomy was carried out using the 27F resectoscope. Steroid receptors and over‐expression for p53 and c‐erb B2 protein were investigated in the polyp by immunohistochemical methods.

Results 

There was a focal area of papillary serous carcinoma in the endometrial polyp. The malignant neoplasm showed over‐expression for p53 and c‐erb B2 oncoprotein and absence of oestrogen and progesterone receptors.

Conclusions 

Alteration in the p53 tumour suppressor gene was an early event in the process of carcinogenesis in the polyp of this patient. This was associated with loss of steroid receptors and c‐erb B2 amplification.
Microendoscopy in gynaecology: a critical review
Authors: O’Donovan Peter J. , McGurgan Paul , Gupta Janesh K.
Published: March 2003

Microendoscopy is defined in this review as the use of instruments with an outer sheath of <2 mm; as such it represents the leading edge of fibreoptic and instrument design technology. Although still in its infancy, it has been proposed as the new standard instrument for outpatient hysteroscopy, abdominal entry, and for the performance of some diagnostic and therapeutic procedures. Microendoscopes are already the instruments of choice for performing conscious laparoscopic procedures. The instruments’ small size makes them versatile, but it is important that they are used appropriately; in this way microendoscopy can offer significant advantages over conventional endoscopy for surgeon and patient alike.
Follow‐up of complaints and recurrence after laparoscopic surgery of benign adnexal tumours
Authors: Weemhoff Mirjam , Van Beek Johannes J.
Published: March 2003

Objective To examine the long‐term experience of laparoscopic cystectomy for benign adnexal tumours by analysing follow‐up visits, ultrasound re‐examination and questionnaires.

Results Recurrence of benign nonfunctional ovarian cysts treated by cystectomy, after an average follow‐up of 23 months, was 4.8%, and 3% of the patients had some minor postoperative complications. Of the women who wanted to become pregnant after conservational treatment, 51% succeeded. Complaints decreased significantly after the operation and these changes persisted.

Conclusion After conservational laparoscopic surgery of adnexal cysts, complaints decreased significantly and the patients fulfilled the desire of pregnancy in around 50% of cases. The recurrence rate is low and only a few postoperative complications occurred.
Operative transvaginal hydrolaparoscopy of a large ovarian endometrioma
Authors: Gordts Stephan , Campo Rudi , Brosens Ivo
Published: March 2003

Objectives 

The purpose of this case report is to describe the feasibility of transvaginal underwater surgery for reconstruction of the ovary with a large endometrioma.

Design 

Descriptive study.

Setting 

Tertiary referral centre for reproductive medicine.

Interventions

Transvaginal hydrolaparoscopy and bipolar surgery were used as the techniques for access and surgery of a large ovarian endometrioma.

Results 

A two‐step procedure was performed with the first step under general anaesthesia and the second under conscious sedation. Transvaginal hydrolaparoscopy allowed easy access, bloodless dissection of the adhesions and marsupialization and coagulation of the endometrioma.

Conclusions 

The report proves the feasibility of reconstruction of the ovary with a large endometrioma using the new technique of transvaginal hydrolaparoscopy. The technique has the advantage of easy access to the endometrioma and accurate dissection and coagulation of adhesions. The low morbidity makes a two‐step technique more acceptable to the patient.
Hysteroscopy in women aged 30 years or less
Authors: Miskry Tariq , Ruach Meir , Magos Adam
Published: March 2003

Objective 

To determine the incidence of intrauterine pathology at hysteroscopy in women aged 30 years or less.

Design 

Retrospective review.

Setting 

Minimal access surgery unit at a tertiary referral centre.

Subjects 

Women aged 30 years or less with persistent menstrual disturbance presenting for outpatient hysteroscopy.

Intervention 

All patients had diagnostic pelvic ultrasound and diagnostic hysteroscopy.

Main outcome measure 

Incidence of intrauterine pathology amenable to surgery.

Results 

41 instances of women presenting with abnormal bleeding were analysed. Hysteroscopy demonstrated intrauterine pathology in 16 patients (39%). Surgical treatment was suitable in 10 (24.4%). In over 20% of cases, hysteroscopy findings failed to agree with ultrasound appearances.

Conclusions 

Hysteroscopy should be considered in women under 30 presenting with persistent menstrual disturbance irrespective of the ultrasound findings.
Three minimal access procedures to treat menorrhagia in one patient: bipolar myolysis, uterine artery embolization and a transcervical fibroid resection
Authors: Jones Kevin , Walker Woodruff J. , Sutton Christopher
Published: March 2003

Objective 

To report the case history of a patient who underwent bipolar myolysis, uterine artery embolization and a transcervical fibroid resection, to treat menorrhagia.

Methods

The clinical records of the patient were reviewed.

Results

The clinical and radiological findings demonstrated large intramural fibroids that decreased in size, but were not removed completely following each of the three minimal access procedures.

Conclusion

This is the only case reported in the literature of three minimal access procedures being carried out in one patient to treat symptomatic fibroids.
Use of the ultrasonically activated scalpel in laparoscopic resection of a noncommunicating rudimentary uterine horn
Authors: Creighton Sarah , Minto Catherine L. , Cutner Alfred
Published: March 2003

Objective 

This case report describes for the first time a method of laparoscopic removal of a rudimentary uterine horn using the ultrasonically activated scalpel.

Conclusions

This instrument cuts and coagulates with minimal tissue injury and excellent haemostasis and, in conjunction with the electronic morcellator, significantly reduced our operating time. This report also highlights the common misdiagnosis of congenital müllerian anomalies, leading to increased morbidity and inappropriate surgery. We would like to alert clinicians to the importance of adequate investigation, including hysteroscopy and magnetic resonance imaging, to optimize surgical evaluation and maximize future reproductive potential.