bluuebunny/crossref_metadata_2025 huggingface dataset:
Raised serum levels of interleukin-18 is associated with disease progression and may contribute to virological treatment failure in HIV-1-infected patients
Authors: STYLIANOU E , BJERKELI V , YNDESTAD A , HEGGELUND L , WÆHRE T , DAMÅS J K , AUKRUST P , FRØLAND S S
Published: May 2003

To gain further insight into the possible role of interleukin (IL)-18 in HIV-1 infection we examined serum levels of IL-18 in various clinical and immunological stages of HIV-1 infection during cross-sectional (n = 41) and longitudinal testing (n = 20) and during HAART (n = 21, 24 months follow-up). Our main findings were that HIV-1-infected patients had significantly raised IL-18 levels comparing healthy controls, particularly in those with advanced disease, that while HAART induced a marked decline in IL-18, virological treatment failure was associated with persistently raised IL-18 levels during such therapy and that our in vitro experiments showed an IL-18-mediated up-regulation of the HIV-1 coreceptor CXCR4 and the pro-apoptotic mediator TRAIL in PBMC from HIV-1-infected patients receiving HAART. HIV-1 infection appears to be characterized by persistently raised IL-18 levels and during HAART, such a pattern was associated with virological treatment failure, possibly contributing to immunodeficiency and HIV-1 replication in these patients.
Beta-2-glycoprotein I expression on monocytes is increased in anti-phospholipid antibody syndrome and correlates with tissue factor expression
Authors: CONTI F , SORICE M , CIRCELLA A , ALESSANDRI C , PITTONI V , CARONTI B , CALDERARO C , GRIGGI T , MISASI R , VALESINI G
Published: May 2003

It is well known that monocytes may play an active role in thrombogenesis, since they may express on their surface tissue factor, the major initiator of the clotting cascade. The results of this investigation demonstrate beta-2-glycoprotein I (β2-GPI) mRNA expression by human peripheral blood monocytes, indicating that these cells synthesize β2-GPI. In addition, we show β2-GPI expression on cell surface of these cells by flow cytometric analysis, and the presence of this protein in cell lysate by Western blot. Interestingly, β2-GPI expression on monocytes is significantly increased in patients with anti-phospholipid syndrome (APS) or systemic lupus erythematosus (SLE) as against healthy blood donors and correlates with tissue factor expression on monocytes. These findings support the view that monocytes are able to synthesize β2-GPI and suggest that patients with APS may have increased β2-GPI exposure on cell surface, which leads to persistently high monocyte tissue factor expression and consequently to a prothrombotic diathesis.
Diurnal rhythms of serum total, free and bioavailable testosterone and of SHBG in middle‐aged men compared with those in young men
Authors: Diver Michael J. , Imtiaz Komal E. , Ahmad Aftab M. , Vora Jiten P. , Fraser William D.
Published: June 2003

background Conflicting views are reported on the association between advancing age and gradually diminishing concentrations of serum total testosterone in men. The putative loss of diurnal rhythm in serum total testosterone in older men is reported to be in part due to low concentrations in the morning when compared to concentrations found in young men. We have measured total, free and bioavailable testosterone along with SHBG in samples taken every 30 min throughout a 24‐h period in 10 young and eight middle‐aged men.

results Both young and middle‐aged men displayed a significant diurnal rhythm in all variables, with a minimum fall of 43% in total testosterone from peak to nadir in all subjects. Subjecting the data to a time series analysis by least squares estimation revealed no significant difference in mesor (P = 0·306), amplitude (P = 0·061) or acrophase (P = 0·972) for total testosterone between the two groups. Comparing bioavailable testosterone in the two groups revealed no significant difference in mesor (P = 0·175) or acrophase (P = 0·978) but a significant difference (P = 0·031) in amplitude. Both groups display a significant circadian rhythm (middle‐aged group P < 0·001; young group P = 0·014). Free testosterone revealed a highly significant rhythm in both the young group (P < 0·001) and the middle‐aged group (P = 0·002), with no significant difference between the groups in mesor (P = 0·094) or acrophase (P = 0·698). Although analysis of the SHBG data revealed a significant rhythm in the young group (P = 0·003) and the older group (P < 0·001), the acrophase occurred in the mid afternoon in both groups (15·12 h in the young and 15·40 h in the middle‐aged). The older men had a significantly greater amplitude (P = 0·044) but again no significant difference was seen in mesor (P = 0·083) or acrophase (P = 0·477) between the two groups. Acrophases for total, bioavailable and free testosterone occurred between 07·00 h and 07·30 h; for SHBG the acrophase occurred at 15·12 h in the young group and 15·40 h in the middle‐aged group.

conclusions The study suggests that the diurnal rhythm in these indices of androgen status is maintained in fit, healthy men into the 7th decade of life.
Bone mineral density in acromegaly: the effect of gender, disease activity and gonadal status
Authors: Scillitani Alfredo , Battista Claudia , Chiodini Iacopo , Carnevale Vincenzo , Fusilli Saverio , Ciccarelli Enrica , Terzolo Massimo , Oppizzi Giuseppe , Arosio Maura , Gasperi Maurizio , Arnaldi Giorgio , Colao Annamaria , Baldelli Roberto , Ghiggi Maria Rosaria , Gaia Daniela , Di Somma Carolina , Trischitta Vincenzo , Liuzzi Antonio
Published: June 2003

objective Data on bone mineral density (BMD) in acromegaly are conflicting as most previous studies collectively evaluated eugonadal and hypogonadal patients of both sexes, with or without active disease. We have evaluated BMD in 152 acromegalic patients of both sexes with varying disease activity and gonadal status.

design Cross‐sectional, retrospective.

patients We studied 152 acromegalic patients (99 women aged 26–72 years, and 53 men aged 21–75 years), 107 with active and 45 with controlled disease. Eighty‐five patients had normal gonadal status and 67 were hypogonadal.

measurements In all patients we measured serum GH levels by immunoenzimometric assay, and serum IGF‐I levels by radioimmunoassay. BMD was assessed at spine L2–L4 (LS) and at femoral neck (FN) by dual energy X‐ray absorptiometry; results are expressed as Z‐values.

results We evaluated the effect of GH excess on bone at different sites in relation to gonadal status, disease activity and gender. At LS, in respect to the reference population, BMD (mean ± SE) values were higher in eugonadal patients (active: 0·71 ± 0·29, P < 0·02; controlled: 0·65 ± 0·28, P < 0·05) and lower in hypogonadal ones (active: −0·64 ± 0·35, 0·1 < P < 0·05; controlled: −1·05 ± 0·36, P < 0·01), regardless of disease activity. On the contrary, at FN, BMD was higher than in the reference population, both in eugonadal (1·01 ± 0·22, P < 0·001) and hypogonadal (0·63 ± 0·17, P < 0·001) patients only in subjects with active disease, but not in those in which the disease was controlled (eugonadal: 0·31 ± 0·23, P = ns; hypogonadal 0·04 ± 0·28, P = ns). We did not observe any difference in BMD values according to gender both at LS (males vs. females −0·02 ± 0·30 vs. 0·01 ± 0·24, P = ns) or at FN (0·77 ± 0·19 vs. 0·63 ± 0·15, P = ns).

conclusions The anabolic effect of GH excess on bone in acromegalic patients is: (i) gender‐independent; (ii) evident at the spine only in eugonadal regardless of disease activity; (iii) evident at femoral neck only in the presence of active disease regardless of gonadal status.
Seed production and seed quality in a calcareous grassland in elevated CO2
Authors: THÜRIG BARBARA , KÖRNER CHRISTIAN , STÖCKLIN JÜRG
Published: May 2003

In diverse plant communities the relative contribution of species to community biomass may change considerably in response to elevated CO2. Along with species‐specific biomass responses, reproduction is likely to change as well with increasing CO2 and might further accelerate shifts in species composition. Here, we ask if, after 5 years of CO2 exposure, seed production and seed quality in natural nutrient‐poor calcareous grassland are affected by elevated CO2 (650 μL L−1 vs 360 μL L−1) and how this might affect long‐term community dynamics. The effect of elevated CO2 on the number of flowering shoots (+ 24%, P < 0.01) and seeds (+ 29%, P = 0.06) at the community level was similar to above ground biomass responses in this year, suggesting that the overall allocation to sexual reproduction remained unchanged. Compared among functional groups of species we found a 42% increase in seed number (P < 0.01) of graminoids, a 33% increase (P = 0.07) in forbs, and no significant change in legumes (− 38%, n.s.) under elevated CO2. Large responses particularly of two graminoid species and smaller responses of many forb species summed up to the significant or marginally significant increase in seed number of graminoids and forbs, respectively. In several species the increase in seed number resulted both from an increase in flowering shoots and an increase in inflorescence size. In most species, seeds tended to be heavier (+ 12%, P < 0.01), and N‐concentration of seeds was significantly reduced in eight out of 13 species. The fraction of germinating seeds did not differ between seeds produced in ambient and elevated CO2, but time to germination was significantly shortened in two species and prolonged in one species when seeds had been produced in elevated CO2. Results suggest that species specific increases in seed number and changes in seed quality will exert substantial cumulative effects on community composition in the long run.
Production, turnover and mycorrhizal colonization of root systems of three Populus species grown under elevated CO2 (POPFACE)
Authors: LUKAC MARTIN , CALFAPIETRA CARLO , GODBOLD DOUGLAS L.
Published: May 2003

A fast growing high density Populus plantation located in central Italy was exposed to elevated carbon dioxide for a period of three years. An elevated CO2 treatment (550 ppm), of 200 ppm over ambient (350 ppm) was provided using a FACE technique. Standing root biomass, fine root turnover and mycorrhizal colonization of the following Populus species was examined: Populus alba L., Populus nigra L., Populus x euramericana Dode (Guinier). Elevated CO2 increased belowground allocation of biomass in all three species examined, standing root biomass increased by 47–76% as a result of FACE treatment. Similarly, fine root biomass present in the soil increased by 35–84%. The FACE treatment resulted in 55% faster fine root turnover in P. alba and a 27% increase in turnover of roots of P. nigra and P. x euramericana. P. alba and P. nigra invested more root biomass into deeper soil horizon under elevated CO2. Response of the mycorrhizal community to elevated CO2 was more varied, the rate of infection increased only in P. alba for both ectomycorrhizal (EM) and arbuscular mycorrhizas (AM). The roots of P. nigra showed greater infection only by AM and the colonization of the root system of P. x euramericana was not affected by FACE treatment. The results suggest that elevated atmospheric CO2 conditions induce greater belowground biomass investment, which could lead to accumulation of assimilated C in the soil profile. This may have implications for C sequestration and must be taken into account when considering long‐term C storage in the soil.
Thermal acclimation of leaf and root respiration: an investigation comparing inherently fast‐ and slow‐growing plant species
Authors: LOVEYS B. R. , ATKINSON L. J. , SHERLOCK D. J. , ROBERTS R. L. , FITTER A. H. , ATKIN O. K.
Published: May 2003

We investigated the extent to which leaf and root respiration (R) differ in their response to short‐ and long‐term changes in temperature in several contrasting plant species (herbs, grasses, shrubs and trees) that differ in inherent relative growth rate (RGR, increase in mass per unit starting mass and time). Two experiments were conducted using hydroponically grown plants. In the long‐term (LT) acclimation experiment, 16 species were grown at constant 18, 23 and 28 °C. In the short‐term (ST) acclimation experiment, 9 of those species were grown at 25/20 °C (day/night) and then shifted to a 15/10 °C for 7 days. Short‐term Q10 values (proportional change in R per 10 °C) and the degree of acclimation to longer‐term changes in temperature were compared. The effect of growth temperature on root and leaf soluble sugar and nitrogen concentrations was examined. Light‐saturated photosynthesis (Asat) was also measured in the LT acclimation experiment. Our results show that Q10 values and the degree of acclimation are highly variable amongst species and that roots exhibit lower Q10 values than leaves over the 15–25 °C measurement temperature range. Differences in RGR or concentrations of soluble sugars/nitrogen could not account for the inter‐specific differences in the Q10 or degree of acclimation. There were no systematic differences in the ability of roots and leaves to acclimate when plants developed under contrasting temperatures (LT acclimation). However, acclimation was greater in both leaves and roots that developed at the growth temperature (LT acclimation) than in pre‐existing leaves and roots shifted from one temperature to another (ST acclimation). The balance between leaf R and Asat was maintained in plants grown at different temperatures, regardless of their inherent relative growth rate. We conclude that there is tight coupling between the respiratory acclimation and the temperature under which leaves and roots developed and that acclimation plays an important role in determining the relationship between respiration and photosynthesis.
Reduction of forest floor respiration by fertilization on both carbon dioxide‐enriched and reference 17‐year‐old loblolly pine stands
Authors: BUTNOR JOHN R. , JOHNSEN KURT H. , OREN RAM , KATUL GABRIEL G.
Published: May 2003

Elevated atmospheric carbon dioxide (CO2e) increases soil respiration rates in forest, grassland, agricultural and wetland systems as a result of increased growth, root biomass and enhanced biological activity of soil microorganisms. Less is known about how forest floor fluxes respond to the combined effects of elevated CO2and nutrient amendments; until now no experiments have been in place with large forest trees to allow even preliminary investigations. We investigated changes in forest floor respiration (Sff) in aPinus taedaL. plantation fumigated with CO2by using free‐air CO2enrichment (FACE) technology and given nutrient amendments. The prototype FACE apparatus (FACEp; 707 m2) was constructed in 1993, 10 years after planting, on a moderate fertility site in Duke Forest, North Carolina, USA, enriching the stand to 55 Pa (CO2e). A nearby ambient CO2(CO2a) plot (117 m2) was designated at the inception of the study as a reference (Ref). Both FACEp and Ref plot were divided in half and urea fertilizer was applied to one half at an annual rate of 11.2 g N m−2in the spring of 1998, 1999 and 2000. Forest floor respiration was monitored continuously for 220 days – March through November 2000 – by using two Automated Carbon Efflux Systems. Thirty locations (491 cm2each) were sampled in both FACEp and Ref, about half in each fertility treatment. Forest floor respiration was strongly correlated with soil temperature at 5 cm. Rates ofSffwere greater in CO2erelative to CO2a(an enhancement of ∼178 g C m−2) during the measurement period. Application of fertilizer resulted in a statistically significant depression of respiration rates in both the CO2aand CO2eplots (a reduction of ∼186 g C m−2). The results suggest that closed canopy forests on moderate fertility sites cycle back to the atmosphere more assimilated carbon (C) than similar forests on sites of high fertility. We recognize the limitations of this non‐replicated study, but its clear results offer strong testable hypotheses for future research in this important area.
Conversion of hardwood forests to spruce and pine plantations strongly reduced soil methane sink in Germany
Authors: BORKEN WERNER , XU YI‐JUN , BEESE FRIEDRICH
Published: May 2003

Well‐drained forest soils are thought to be a significant sink for atmospheric methane. Recent research suggests that land use change reduces the soil methane sink by diminishing populations of methane oxidizing bacteria. Here we report soil CH4 uptake from ‘natural’ mature beech forests and from mature pine and spruce plantations in two study areas of Germany with distinct climate and soils. The CH4 uptake rates of both beech forests at Solling and Unterlüß were about two–three times the CH4 uptake rates of the adjacent pine and spruce plantations, indicating a strong impact of forest type on the soil CH4 sink. The CH4 uptake rates of sieved mineral soils from our study sites confirmed the tree species effect and indicate that methanotrophs were mainly reduced in the 0–5 cm mineral soil depth. The reasons for the reduction are still unknown. We found no site effect between Solling and Unterlüß, however, CH4 uptake rates from Solling were significantly higher at the same effective CH4 diffusivity. This potential site effect was masked by higher soil water contents at Solling. Soil pH (H2O) explained 71% of the variation in CH4 uptake rates of sieved mineral soils from the 0–5 cm depth, while cation exchange capacity, soil organic carbon, soil nitrogen and total phosphorous content were not correlated with CH4 uptake rates. Comparing 1998–99, annual CH4 uptake rates increased by 69–111% in the beech and spruce stands and by 5–25% in the pine stands, due primarily to differences in growing season soil moisture. Cumulative CH4 uptake rates from November throughout April were rather constant in both years. The CH4 uptake rates of each stand were separately predicted using daily average soil matric potential and a previously developed empirical model. The model results revealed that soil matric potential explains 53–87% of the temporal variation in CH4 uptake. The differences between measured and predicted annual CH4 uptake rates were less than 10%, except for the spruce stand at Solling in 1998 (17%). Based on data from this study and from the literature, we calculated a total reduction in the soil CH4 sink of 31% for German forests due in part to conversion of deciduous to coniferous forests.
Long‐term changes in phytoplankton, zooplankton and salmon related to climate
Authors: BEAUGRAND GRÉGORY , REID PHILIP C.
Published: May 2003

Recently, large‐scale changes in the biogeography of calanoid copepod crustaceans have been detected in the northeastern North Atlantic Ocean and adjacent seas. Strong biogeographical shifts in all copepod assemblages were found with a northward extension of more than ° in latitude of warm‐water species associated with a decrease in the number of colder‐water species. These changes were attributed to regional increase in sea surface temperature. Here, we have extended these studies to examine long‐term changes in phytoplankton, zooplankton and salmon in relation to hydro‐meteorological forcing in the northeast Atlantic Ocean and adjacent seas. We found highly significant relationships between (1) long‐term changes in all three trophic levels, (2) sea surface temperature in the northeastern Atlantic, (3) Northern Hemisphere temperature and (4) the North Atlantic Oscillation. The similarities detected between plankton, salmon, temperature and hydro‐climatic parameters are also seen in their cyclical variability and in a stepwise shift that started after a pronounced increase in Northern Hemisphere Temperature anomalies at the end of the 1970s. All biological variables show a pronounced change which started after circa 1982 for euphausiids (decline), 1984 for the total abundance of small copepods (increase), 1986 for phytoplankton biomass (increase) and Calanus finmarchicus (decrease) and 1988 for salmon (decrease). This cascade of biological events led to an exceptional period, which is identified after 1986 to present and followed another shift in large‐scale hydro‐climatic variables and sea surface temperature. This regional temperature increase therefore appears to be an important parameter that is at present governing the dynamic equilibrium of northeast Atlantic pelagic ecosystems with possible consequences for biogeochemical processes and fisheries.
Accumulation of carbon and nitrogen by old arable land reverting to woodland
Authors: POULTON P. R. , PYE E. , HARGREAVES P. R. , JENKINSON D. S.
Published: May 2003

The accumulation of carbon (C) and nitrogen (N) was measured on two sites on Rothamsted Farm that had been fenced off some 120 years ago and allowed to revert naturally to woodland. The sites had previously been arable for centuries. One had been chalked and was still calcareous; the other had never been chalked and the pH fell from 7.1 in 1883 to 4.4 in 1999. The acidic site (Geescroft wilderness) is now a deciduous wood, dominated by oak (Quercus robor); the calcareous site (Broadbalk wilderness) is now dominated by ash (Fraxinus excelsior), with sycamore (Acer pseudoplatanus) and hawthorn (Craetagus monogyna) as major contributors. The acidic site gained 2.00 t C ha−1 yr−1 over the 118‐year period (0.38 t in litter and soil to a depth of 69 cm, plus an estimated 1.62 t in trees and their roots); the corresponding gains of N were 22.2 kg N ha−1 year−1 (15.2 kg in the soil, plus 6.9 kg in trees and their roots). The calcareous site gained 3.39 t C ha−1 year−1 over the 120‐year period (0.54 t in the soil, plus an estimated 2.85 t in trees and roots); for N the gains were 49.6 kg ha−1 yr−1 (36.8 kg in the soil, plus 12.8 kg in trees and roots). Trees have not been allowed to grow on an adjacent part of the calcareous site. There is now a little more C and N in the soil from this part than in the corresponding soil under woodland. We argue from our results that N was the primary factor limiting plant growth and hence accumulation of C during the early stages of regeneration in these woodlands. As soil organic N accumulates and the sites move towards N saturation, other factors become limiting. Per unit area of woodland, narrow strips; that is, wide hedges with trees, are the most efficient way of sequestering C – provided that they are not short of N.
Stoichiometric impacts of increased carbon dioxide on a planktonic herbivore
Authors: URABE JOTARO , TOGARI JUN , ELSER JAMES J.
Published: May 2003

The partial pressure of carbon dioxide (pCO2) in lake ecosystems varies over four orders of magnitude and is affected by local and global environmental perturbations associated with both natural and anthropogenic processes. Little is known, however, about how changes in pCO2 extend into the function and structure of food webs in freshwater ecosystems. To fill this gap, we performed laboratory experiments using the ecologically important planktonic herbivore Daphnia and its algal prey under a natural range of pCO2 with low light and phosphorus supplies. The experiment showed that increased pCO2 stimulated algal growth but reduced algal P : C ratio. When feeding on algae grown under high pCO2, herbivore growth decreased regardless of algal abundance. Thus, high CO2‐raised algae were poor food for Daphnia. Short‐term experimental supplementation of PO4 raised the P content of the high CO2‐raised algae and improved Daphnia growth, indicating that low Daphnia growth rates under high pCO2 conditions were due to lowered P content in the algal food. These results suggest that, in freshwater ecosystems with low nutrient supplies, natural processes as well as anthropogenic perturbations resulting in increased pCO2 enhance algal production but reduce energy and mass transfer efficiency to herbivores by decreasing algal nutritional quality.
Changes in flowering and abundance of Delphinium nuttallianum (Ranunculaceae) in response to a subalpine climate warming experiment
Authors: SAAVEDRA FRANCISCA , INOUYE DAVID W. , PRICE MARY V. , HARTE JOHN
Published: May 2003

High‐altitude and high‐latitude sites are expected to be very sensitive to global warming, because the biological activity of most plants is restricted by the length of the short snow‐free season, which is determined by climate. Long‐term observational studies in subalpine meadows of the Colorado Rocky Mountains have shown a strong positive correlation between snowpack and flower production by the forb Delphinium nuttallianum. If a warmer climate reduces annual snowfall in this region then global warming might reduce fitness in D. nuttallianum. In this article we report effects of experimental warming on the abundance and flower production of D. nuttallianum. Plant abundance (both flowering and vegetative plants) was slightly greater on warmed than control plots prior to initiation of the warming treatment in 1991. Since 1994 experimental warming has had a negative effect on D. nuttallianum flower production, reducing both the abundance of flowering plants and the total number of flowers per plant. Flower bud abortion was higher in the heated plots than the controls only in 1994 and 1999. Results from both the warming experiment and analyses of unmanipulated long‐term plots suggest that global warming may affect the fecundity of D. nuttallianum, which may have cascading effects on the pollinators that depend on it and on the fecundity of plants that share similar pollinators.
Large seasonal changes in Q10 of soil respiration in a beech forest
Authors: JANSSENS IVAN A. , PILEGAARD KIM
Published: May 2003

We analyzed one year of continuous soil respiration measurements to assess variations in the temperature sensitivity of soil respiration at a Danish beech forest. A single temperature function derived from all measurements across the year (Q10 = 4.2) was adequate for estimating the total annual soil respiration and its seasonal evolution. However, Q10's derived from weekly datasets ranged between three in summer (at a mean soil temperature of 14 °C) and 23 in winter (at 2 °C), indicating that the annual temperature function underestimated the synoptic variations in soil respiration during winter. These results highlight that empirical models should be parameterized at a time resolution similar to that required by the output of the model. If the objective of the model is to simulate the total annual soil respiration rate, annual parameterization suffices. If however, soil respiration needs to be simulated over time periods from days to weeks, as is the case when soil respiration is compared to total ecosystem respiration during synoptic weather patterns, more short‐term parameterization is required.

Despite the higher wintertime Q10's, the absolute response of soil respiration to temperature was smaller in winter than in summer. This is mainly because in absolute numbers, the temperature sensitivity of soil respiration depends not only on Q10, but also on the rate of soil respiration, which is highly reduced in winter. Nonetheless, the Q10 of soil respiration in winter was larger than can be explained by the decreasing respiration rate only. Because the seasonal changes in Q10 were negatively correlated with temperature and positively correlated with soil moisture, they could also be related to changing temperature and/or soil moisture conditions.
Relationships between carbon turnover and bioavailable energy fluxes in two temperate forest soils
Authors: CURRIE WILLIAM S.
Published: May 2003

Recent research has shown that the broad empirical relationships used in many ecosystem models to predict carbon turnover and stabilization in soils can fail to capture differences across vegetation types or climates. Theoretically, because energy flow is fundamental to the function of decomposer organisms and ecosystems, energetics could provide complimentary fundamental constraints on soil C dynamics. Often, however, C is considered as a surrogate for energy in studies of detrital decay and C turnover in soil. Bomb calorimetry has long been used to measure stored energy in organic matter, but in detritus not all of the energy is bioavailable. Here I outline an approach to quantify the flux of bioavailable energy dissipated by resident heterotrophic communities in soil organic horizonsin situ. I used the principle of energy balance together with a biogeochemical process model parameterized through calorimetric analysis of field samples. I also tested relationships between C and energy across samples of forest detritus (foliar and fine root litter, well‐decayed Oea material, and woody debris), across decay stages, and between a deciduous and coniferous forest at the Harvard Forest, MA, USA. As a first approximation, energy and C concentrations were closely related (within ca. 10%), as were ratios of heterotrophic energy dissipation to C mineralization across types of detritus (within 16%). Differences in energy content and energy : C ratios were measurable in forest detritus (particularly woody vs nonwoody), but did not vary reliably enough between forest types or through detrital stages to indicate that soil C models could be improved by including energetics. Model results indicated that there are strong similarities in energy flows and storage in the O horizons of the contrasting forest types studied at this location. Future research could focus on broader patterns across climates or biomes.
The input and fate of new C in two forest soils under elevated CO2
Authors: HAGEDORN FRANK , SPINNLER DIETER , BUNDT MAYA , BLASER PETER , SIEGWOLF ROLF
Published: May 2003

The aim of this study was to estimate (i) the influence of different soil types on the net input of new C into soils under CO2 enrichment and (ii) the stability and fate of these new C inputs in soils. We exposed young beech–spruce model ecosystems on an acidic loam and calcareous sand for 4 years to elevated CO2. The added CO2 was depleted in 13C, allowing to trace new C inputs in the plant–soil system. We measured CO2‐derived new C in soil C pools fractionated into particle sizes and monitored respiration as well as leaching of this new C during incubation for 1 year. Soil type played a crucial role in the partitioning of C. The net input of new C into soils under elevated CO2 was about 75% greater in the acidic loam than in the calcareous sand, despite a 100% and a 45% greater above‐ and below‐ground biomass on the calcareous sand. This was most likely caused by a higher turnover of C in the calcareous sand as indicated by 30% higher losses of new C from the calcareous sand than from the acidic loam during incubation. Therefore, soil properties determining stabilization of soil C were apparently more important for the accumulation of C in soils than tree productivity. Soil fractionation revealed that about 60% of the CO2‐derived new soil C was incorporated into sand fractions. Low natural 13C abundance and wide C/N ratios show that sand fractions comprise little decomposed organic matter. Consistently, incubation indicated that new soil C was preferentially respired as CO2. During the first month, evolved CO2 consisted to 40–55% of new C, whereas the fraction of new C in bulk soil C was 15–23% only. Leaching of DOC accounted for 8–23% of the total losses of new soil C. The overall effects of CO2 enrichment on soil C were small in both soils, although tree growth increased significantly on the calcareous sand. Our results suggest that the potential of soils for C sequestration is limited, because only a small fraction of new C inputs into soils will become long‐term soil C.
Spatial variation in regional CO2 exchange for the Kuparuk River Basin, Alaska over the summer growing season
Authors: VOURLITIS GEORGE L. , VERFAILLIE JOSEPH , OECHEL WALTER C. , HOPE ALLEN , STOW DOUGLAS , ENGSTROM RYAN
Published: May 2003

The spatial and temporal patterns in CO2 flux for the Kuparuk River Basin, a 9200‐km2 watershed located in NE Alaska were estimated using the Regional Arctic CO2 Exchange Simulator (RACES) for the 1994–1995 growing seasons. RACES uses non‐linear models and a Geographical Information System database (GIS) consisting of the normalized difference vegetation index (NDVI) and dynamic temperature and radiation maps. The spatial and temporal patterns in the NDVI during both growing seasons suggest that ecosystem development occurred 2–4 weeks earlier and was relatively more rapid in the southern portion of the Kuparuk River Basin. Rates of gross primary production (GPP) and whole‐ecosystem respiration (R) were 2–4 fold higher in the southern basin than along the arctic coastal plain depending on time of year. The higher rate of GPP estimated for the southern basin was primarily due to higher NDVI values, while the higher R estimated for the southern basin was due in part to higher temperature and the NDVI. While GPP and R showed strong latitudinal trends, spatial and temporal trends in net ecosystem CO2 exchange (NEE) were much more variable. Thus, while spatial trends in carbon gain (GPP) and loss (R) were highly correlated, small spatial and temporal differences in these large fluxes (GPP and/or R) lead to corresponding large spatial variations in the NEE.
Seasonal changes in the effects of elevated CO2 on rice at three levels of nitrogen supply: a free air CO2 enrichment (FACE) experiment
Authors: KIM HAN‐YONG , LIEFFERING MARK , KOBAYASHI KAZUHIKO , OKADA MASUMI , MIURA SHU
Published: May 2003

Over time, the stimulative effect of elevated CO2 on the photosynthesis of rice crops is likely to be reduced with increasing duration of CO2 exposure, but the resultant effects on crop productivity remain unclear. To investigate seasonal changes in the effect of elevated CO2 on the growth of rice (Oryza sativa L.) crops, a free air CO2 enrichment (FACE) experiment was conducted at Shizukuishi, Iwate, Japan in 1998–2000. The target CO2 concentration of the FACE plots was 200 µmol mol−1 above that of ambient. Three levels of nitrogen (N) were supplied: low (LN, 4 g N m−2), medium [MN, 8 (1998) and 9 (1999, 2000) g N m−2] and high N (HN, 12 and 15 g N m−2). For MN and HN but not for LN, elevated CO2 increased tiller number at panicle initiation (PI) but this positive response decreased with crop development. As a result, the response of green leaf area index (GLAI) to elevated CO2 greatly varied with development, showing positive responses during vegetative stages and negative responses after PI. Elevated CO2 decreased leaf N concentration over the season, except during early stage of development. For MN crops, total biomass increased with elevated CO2, but the response declined linearly with development, with average increases of 32, 28, 21, 15 and 12% at tillering, PI, anthesis, mid‐ripening and grain maturity, respectively. This decline is likely to be due to decreases in the positive effects of elevated CO2 on canopy photosynthesis because of reductions in both GLAI and leaf N. Up to PI, LN‐crops tended to have a lower response to elevated CO2 than MN‐ and HN‐crops, though by final harvest the total biomass response was similar for all N levels. For MN‐ and HN‐crops, the positive response of grain yield (ca. 15%) to elevated CO2 was slightly greater than the response of final total biomass while for LN‐crops it was less. We conclude that most of the seasonal changes in crop response to elevated CO2 are directly or indirectly associated with N uptake.
Changing Childbirth: a pilot project
Authors: Hicks Carolyn , Spurgeon Peter , Barwell Fred
Published: June 2003

Objective. To compare the outcomes of an adapted pilot Changing Childbirth initiative providing continuity of care by a group of known midwives with traditional maternity care.

Design. Between‐groups trial to compare levels of satisfaction and clinical outcomes for two groups of women, cared for either under this Changing Childbirth scheme or the traditional model of care.

Method. Of the 200 women who agreed to participate in the project, 100 were randomly allocated to the pilot scheme and 100 to the traditional care package. During the postpartum period, information was collected via a questionnaire about participants’ levels of satisfaction with a variety of aspects of care provided during the antenatal, delivery and postpartum periods. Data about clinical outcomes for the two groups were also obtained.

Results. Women in the pilot group had significantly more continuity of care throughout each of the three periods, were generally more satisfied with their care, felt that they had more choice over a variety of aspects of care and experienced no compromise in clinical outcomes (P = 0·05 or less in each case).

Implications for practice. Many previous attempts to introduce the Changing Childbirth initiative have revealed significant problems, particularly with regard to the continuity of carer requirement. Taking account of local health care needs and existing provision, the present study adapted this concept to continuity of care. This did not apparently affect any of the guiding principles contained in the original document, and yet enhanced satisfaction. It would appear that the Changing Childbirth agenda can be adapted and integrated with local health care situations without sacrificing any of the overarching principles.
Sexual harassment of nurses and nursing students
Authors: Bronner Gila , Peretz Chava , Ehrenfeld Mally
Published: June 2003

Background. Nursing has dealt with sexual harassment long before the term was coined during the 1970s. The current study investigated sexual harassment of nurses and nursing students in Israel following new legislation against sexual harassment in the workplace.

Methods. A self‐report questionnaire was administered to 281 nurses and 206 nursing students (80% women) from five medical centres in Israel. Seven types of sexual harassment behaviour patterns were evaluated.

Findings. Frequency of sexual harassment decreased as the behaviour became more intimate and offensive. Ninety percent of subjects reported experiencing at least one type of sexual harassment and 30% described at least four types. A significant difference was found between nurses and nursing students. Furthermore, ‘severe’ types of behaviour were experienced by 33% of nurses, in comparison with 23% of nursing students. Women were significantly more exposed than men to ‘mild’ and ‘moderate’ types of sexual harassment, while 35% of men vs. 26% of women were exposed to ‘severe’ types of harassment. However, women responded significantly more assertively than men to ‘severe’ sexual harassment.

Conclusions. Particular attention is needed when sexual harassment occurs to male students and nurses because they may be subjected to the more offensive sexual conducts and at the same time may lack the ability to respond assertively.
Reducing the density of breeding gulls influences the pattern of recruitment of immature Atlantic puffinsFratercula arcticato a breeding colony
Authors: Finney S. K. , Harris M. P. , Keller L. F. , Elston D. A. , Monaghan P. , Wanless S.
Published: June 2003

By acting as both competitors and predators, gulls (Larusspp.) are generally considered to reduce significantly the attractiveness of potential breeding sites for other birds. This perceived threat posed by gulls to other breeding birds has led to the implementation of gull control procedures at many seabird colonies. However, the extent to which reducing gull numbers benefits other species has received little rigorous scientific investigation.

During a gull control programme (1972–89), gull nest density on the Isle of May, south‐east Scotland, was reduced by between 30% and 100% in different sections of the island. Following termination of the original programme in 1989, several sections were maintained as gull‐free by repeated removal of nests.

We used data collected over a 23‐year period to determine the extent to which the spatial variation in puffinFratercula arcticarecruitment was influenced by changes in the density and spatial distribution of breeding gulls resulting from the control programme.

The presence of breeding gulls significantly affected the pattern of recruitment of puffins to the colony. Puffin recruitment rate was highest in the sections of the island where gull nest density was low. Gull density explained 21% of the variation in puffin recruitment rate.

These results suggest that the reduction in the number of breeding gulls substantially increased the attractiveness of areas of the colony as breeding sites for puffins, and is thus likely to have played an important role in the pattern of expansion of the puffin population on the island.

Synthesis and applications.Following a recent increase in the conservation status of both herringL. argentatusand lesser black‐backed gullsL. fuscus, there has been a move to make management decisions more objective. This has highlighted the need for studies such as this, aimed at assessing the impact of gulls and their removal on other breeding birds, to ensure that any future control programmes are both necessary and effective.
Population dynamics in European hare: breeding parameters and sustainable harvest rates
Authors: Marboutin E. , Bray Y. , Péroux R. , Mauvy B. , Lartiges A.
Published: June 2003

Hares are considered to be a valuable game species in most European countries. Hunting needs to be sustainable and sound management of hare populations requires some knowledge of the species’ demographic variability, especially regarding the breeding output, which is highly time‐ and space‐dependent and may govern the population size and exploitability.

Using shooting bag analysis and placental scar counts, mean fecundity and leveret survival were estimated at four study sites with contrasting hare numbers and density trends. These demographic parameters, harvest rates and adult natural survival rates (from the literature) were incorporated into a matrix projection model to analyse the population growth rate (λ) sensitivity and to derive indices of sustainable harvest rate (ISHR, i.e. rates compatible with λ≥ 1).

The age structure comprised 48–69% young; fecundity varied between 12·2 and 15·0 leverets per breeding female; and 85–100% of adult females bred. These data combined gave a birth‐to‐autumn leveret survival index of 0·14–0·29 and, when loaded into the matrix model, resulted in simulated λs that matched the density changes observed in the study areas. The model structure, although simple, accounted for most of the relevant biological information.

ISHR was 30% when derived iteratively as a function of mean values of those parameters with largest elasticities (leveret survival and doe fecundity). When environmental and demographic stochasticity were included in the model, the proportion of endangered trajectories where the density threshold was < 1 km2 over 50 km2 varied sharply, with small changes in harvest rate or initial population size. Small populations could only sustain ≤ 20% harvest rates.

Demographic parameters derived from killed animals during year t can be used a posteriori to understand the species’ dynamics and as a baseline to modulate the shooting scheme in year t+ 1. An actual sustainable shooting scheme would require an additional real‐time local process that, automatically, would take all sources of change in numbers into account. A two‐stage management strategy (e.g. first computing a catch‐effort estimator of population size based on numbers killed very early in the shooting period, then defining flexible harvest quotas) would help managers to cope with the unpredictable dynamics of the species and resulting fluctuations in hare numbers.

Synthesis and applications. The results of this exploratory study suggest that sustainable shooting of hares is possible provided some local data about their dynamics are available and slightly conservative quotas are used. Modelling approaches have potential in assessing the latter, but also as a check on the coherence of the estimates of the former (comparison of observed and modelled λ).
Changes in the rhizome system of bracken subjected to long‐term experimental treatment
Authors: Duc M. G. LE , Pakeman R. J. , Marrs R. H.
Published: June 2003

Bracken Pteridium aquilinum is a serious weed of upland and marginal land. Its extensive rhizome system and large carbohydrate reserves make control difficult. This paper reports the results of seven long‐term experiments, established in four diverse UK locations, to test control and vegetation restoration treatments.

Samples were obtained from 580 rhizome pits between 1998 and 2000. Total dry mass per unit area (M, a measure of performance) and ratio of frond‐bearing to total rhizome dry mass (R, a relative measure of investment in frond production) were measured.

The range of means for M in untreated bracken was 1·8–5·1 kg m−2, greater than that reported by others (1·2–3·0 kg m−2). Measured values for R were 0·24–0·42, again differing from other reports (0·10–0·38), probably due to our policy of avoiding advancing bracken fronts.

Randomization tests were used to check for non‐independence of sampling units. They confirmed the general adequacy of the anova results; there was little detectable interference between plots. Two regions contained matching pairs of experiments, thus variation within region was tested and differences were found in one region.

Five bracken control treatments (cutting, herbicide application and combinations) were employed at all but one experiment. Cutting once or twice per year generally gave the best results, reducing M by c. 60% after ≤ 5 years. Some subtreatments designed mainly for vegetation restoration, notably surface disturbance, also affected M.

R was reduced by herbicide treatment, for example from 0·30 to 0·16. Such low values of R are typical of invading bracken and are thought to represent rejuvenated and invasive rhizomes. Follow‐up treatments are needed in such situations. Despite large differences between untreated M at matching experiments on Cannock Chase (Staffordshire), treatment effects were similar at both sites (cutting twice per year or cutting together with herbicide application were best). At Sourhope (Cheviot Hills) a different pattern of response was obtained, with cutting alone giving better results than treatments involving herbicide.

The ratio of rhizome to frond dry mass per unit area was 10 : 1 in good conditions for growth, but the proportionate size of rhizomes could be reduced in poor growing conditions such as wet summers.

Synthesis and applications. In order to develop a national control strategy the following must be considered: rhizome mass differs between sites and in response to control treatments; cutting twice per year is generally most effective; where cutting is impossible, herbicide treatment should be applied. Weather may affect rhizome mass, with wet years being detrimental. This raises the possibility that bracken may increase under the drier conditions that may occur with global warming.