bluuebunny/crossref_metadata_2025 huggingface dataset:
Giant prolactinomas: the therapeutic approach
Authors: Moraes Aline B. , Marques dos Santos Silva Cintia , Vieira Neto Leonardo , Gadelha Mônica R.
Published: May 2013

Background

Giant prolactinomas are an unusual subset of macroprolactinomas and are more commonly found in men. The goal of this review is to propose a giant prolactinoma definition and discuss the available therapeutic options for biochemical and tumour volume control.

Methods

A comprehensive search of all published studies was performed betweenApril andNovember 2012 in electronic databases (PubMed andOvid).

Results

A giant prolactinoma should be defined as an adenoma with a maximum diameter of more than 4 cm that is associated with serum prolactin above 5300mIU/l. Regarding treatment, cabergoline is the preferred dopamine agonist for medical management of giant prolactinomas because of its excellent efficacy and tolerability. Normalization of prolactin level and significant tumour reduction may be achieved in the majority of patients. Combined therapy, particularly cabergoline and surgery, may be necessary due to the large tumour load. Radiotherapy and temozolomide may be used for patients with aggressive giant prolactinomas in whom tumour volume control is not achieved with cabergoline and surgery.

Conclusion

There is a scarcity of large studies about the management of giant prolactinoma. Cabergoline is the first‐line treatment. However, caution should be exercised when comparing efficacy rates among the different treatment modalities due to the variability in study design and data quality. In this scenario, a ‘standard’ definition for giant prolactinomas and larger series may be helpful to assess the real efficacy and safety of each therapeutic modality.
A Survey of Urban Reconstruction
Authors: Musialski P. , Wonka P. , Aliaga D. G. , Wimmer M. , van Gool L. , Purgathofer W.
Published: May 2013

This paper provides a comprehensive overview of urban reconstruction. While there exists a considerable body of literature, this topic is still under active research. The work reviewed in this survey stems from the following three research communities: computer graphics, computer vision and photogrammetry and remote sensing. Our goal is to provide a survey that will help researchers to better position their own work in the context of existing solutions, and to help newcomers and practitioners in computer graphics to quickly gain an overview of this vast field. Further, we would like to bring the mentioned research communities to even more interdisciplinary work, since the reconstruction problem itself is by far not solved.
Urinary C‐peptide creatinine ratio detects absolute insulin deficiency in Type 2 diabetes
Authors: Hope S. V. , Jones A. G. , Goodchild E. , Shepherd M. , Besser R. E. J. , Shields B. , McDonald T. , Knight B. A. , Hattersley A.
Published: May 2013

Aims

To determine the prevalence and clinical characteristics of absolute insulin deficiency in long‐standing Type 2 diabetes, using a strategy based on home urinary C‐peptide creatinine ratio measurement.

Methods

We assessed the urinary C‐peptide creatinine ratios, from urine samples taken at home 2 h after the largest meal of the day, in 191 insulin‐treated subjects with Type 2 diabetes (diagnosis age ≥45 years, no insulin in the first year). If the initial urinary C‐peptide creatinine ratio was ≤0.2 nmol/mmol (representing absolute insulin deficiency), the assessment was repeated. A standardized mixed‐meal tolerance test with 90‐min stimulated serum C‐peptide measurement was performed in nine subjects with a urinary C‐peptide creatinine ratio ≤ 0.2 nmol/mmol (and in nine controls with a urinary C‐peptide creatinine ratio >0.2 nmol/mmol) to confirm absolute insulin deficiency.

Results

A total of 2.7% of participants had absolute insulin deficiency confirmed by a mixed‐meal tolerance test. They were identified initially using urinary C‐peptide creatinine ratio: 11/191 subjects (5.8%) had two consistent urinary C‐peptide creatinine ratios ≤ 0.2 nmol/mmol; 9 of these 11 subjects completed a mixed‐meal tolerance test and had a median stimulated serum C‐peptide of 0.18 nmol/l. Five of these 9 had stimulated serum C‐peptide <0.2 nmol/l and 9/9 subjects with urinary C‐peptide creatinine ratio >0.2 had endogenous insulin secretion confirmed by the mixed‐meal tolerance test. Compared with subjects with a urinary C‐peptide creatinine ratio >0.2 nmol/mmol, those with confirmed absolute insulin deficiency had a shorter time to insulin treatment (median 2.5 vs. 6 years, P=0.005) and lower BMI (25.1 vs. 29.1 kg/m2, P=0.04). Two out of the five patients with absolute insulin deficiency were glutamic acid decarboxylase autoantibody‐positive.

Conclusions

Absolute insulin deficiency may occur in long‐standing Type 2 diabetes, and cannot be reliably predicted by clinical features or autoantibodies. Absolute insulin deficiency in Type 2 diabetes may increase the risk of hypoglycaemia and ketoacidosis, as in Type 1 diabetes. Its recognition should help guide treatment, education and management. The urinary C‐peptide creatinine ratio is a practical non‐invasive method to aid detection of absolute insulin deficiency, with a urinary C‐peptide creatinine ratio > 0.2 nmol/mmol being a reliable indicator of retained endogenous insulin secretion.
Blood pressure levels but not hypertensive complications have increased in Type 1 diabetes pregnancies during 1989–2010
Authors: Klemetti M. M. , Teramo K. , Nuutila M. , Tikkanen M. , Hiilesmaa V. , Laivuori H.
Published: May 2013

Aims

The pre‐pregnancy BMI and the third trimester HbA1c levels increased in Finnish parturients with Type 1 diabetes during 1989–2008. The aim of the present study was to investigate whether these trends have been accompanied by increases in blood pressure or hypertensive complications. Hypertension trends were analysed using the definitions of hypertension of both the American College of Obstetricians and Gynecologists and the American Diabetes Association. The associations of hypertension, as defined by the latter criteria, with perinatal complications were also studied.

Methods

The records of a cohort of 1007 consecutive patients with Type 1 diabetes with a singleton live childbirth during 1989–2010 at the Helsinki University Central Hospital were studied.

Results

The frequencies of hypertensive pregnancy complications did not change, but the mean diastolic blood pressure increased in normotensive parturients in all trimesters. The proportion of patients with systolic blood pressure > 130 mmHg or diastolic blood pressure > 80 mmHg in the first, second and third trimesters of pregnancy increased from 25 to 33%, from 26 to 35% and from 57 to 71%, respectively. Systolic blood pressure of 131–139 mmHg or diastolic blood pressure of 81–89 mmHg in the third trimester was associated with umbilical artery pH < 7.15.

Conclusions

Blood pressure of patients with Type 1 diabetes during pregnancy is increasing. A growing proportion of women with Type 1 diabetes exceed the American Diabetes Association's definition of hypertension during pregnancy.
Pre‐diabetes in adults 45 years and over in Ireland: the Survey of Lifestyle, Attitudes and Nutrition in Ireland 2007
Authors: Buckley C. M. , Madden J. , Balanda K. , Barron S. , Fahy L. , Harrington J. , Perry I. J. , M. Kearney P.
Published: May 2013

Objectives

Pre‐diabetes is an important indicator of future diabetes burden and many countries are reporting prevalence estimates of pre‐diabetes. To date in Ireland, estimates of the prevalence of pre‐diabetes were unavailable. Our objectives were to estimate the prevalence of pre‐diabetes in a nationally representative sample of Irish adults and to explore determinants of pre‐diabetes.

Methods

The Survey of Lifestyle Attitudes and Nutrition 2007 was a cross‐sectional survey on health and lifestyle in a nationally representative sample of Irish adults. Analysis was performed on a subsample of 1132 participants ≥ 45 years who provided blood samples. Determination of pre‐diabetes was based on American Diabetes Association HbA1c cut points of 39–46 mmol/mol (5.7–6.4%). To explore determinants, we modelled pre‐diabetes prevalence as a function of a set of health system and socio‐demographic variables using logistic regression.

Results

The overall weighted prevalence estimate of pre‐diabetes in participants ≥ 45 years was 19.8% (95% CI 16.4–23.9). There was no significant difference between age or gender‐specific prevalence rates. Obesity was significantly associated with pre‐diabetes on univariate and multivariate analysis. Population attributable fraction estimates for excess BMI, physical inactivity and poor diet as causes of pre‐diabetes were 31.3% (95% CI –3.9 to 54.5), 10.0% (95% CI –2.7 to 21.3) and 6.1% (95% CI –4.9 to 15.9), respectively.

Conclusions

The high levels of pre‐diabetes detected in this study are worrying. Population level interventions to address diet and lifestyle factors are needed urgently to prevent progression to diabetes in high‐risk individuals.
Relation of Coronary Flow Reserve and Diastolic Function to Fractional Pulse Pressure in Hypertensive Patients
Authors: Mahfouz Ragab A.
Published: May 2013

Fractional pulse pressure (PPf), is thought to more directly reflect arterial stiffness than pulse pressure. Our aim was to evaluate the relationship between coronary flow reserve (CFR), left ventricular diastolic function (LVDf) and PPf in hypertensive patients with normal coronary arteries. Out of 109 hypertensive patients (aged 52.8 ± 9.4 years), with normal coronary angiography, CFR was calculated successfully in 106 patients. CFR was calculated using transthoracic echo Doppler assessment with hyperemia induced by infusion of dipyridamole at a rate of 0.56 mg/kg over 4 minutes, while diastolic function was evaluated by means of transmitral flow and tissue Doppler imaging. PPf was calculated as pulse pressure divided by mean arterial pressure [Systolic blood pressure − Diastolic blood pressure/Mean arterial pressure (SBP − DBP/MAP)], Hypertensive patients with low CFR (n = 54) compared with those with normal CFR (n = 52) exhibited significantly increased PPf (75.2 ± 11.4 vs. 61.5 ± 6.7 P < 0.001). Moreover, patients with higher PPf had significantly decreased transmitral E/A ratio (P < 0.01), as well as increased E/Em ratio (P < 0.01). In hypertensives with low CFR, PPf was negatively correlated with CFR (r = −0.815, P < 0.0001). After applying multivariate linear regression analysis, PPf turned out to be a powerful independent predictor of CFR. Receiver operating characteristic (ROC) analysis revealed that a PPf of ≥0.63 was the best cutoff value for prediction of CFR <2.0 and E/Em ≥ 8 (AUC = 0.916 and 0.929 respectively; P < 0.001). Increased PPf was associated with impaired CFR and diastolic dysfunction in hypertensive patients with normal coronary arteries. PPf could be used as a simple non‐invasive index for assessment of coronary microcirculation in hypertensives with normal coronary arteries.
Stress intensity and fitness in the parasitoid Aphidius ervi (Hymenoptera: Braconidae): temperature below the development threshold combined with a fluctuating thermal regime is a must
Authors: ISMAIL MOHANNAD , VAN BAAREN JOAN , HANCE THIERRY , PIERRE JEAN‐SEBASTIEN , VERNON PHILIPPE
Published: May 2013

An increasing intensity of stress is expected to affect the fitness traits of an organism more and more negatively, but in particular cases, extremely resistant individuals have been observed. The present study was undertaken to determine the effects of different stress intensities on fitness traits of the parasitoid wasp Aphidius ervi Haliday.

We exposed 1‐day‐old mummies (dead aphids containing the parasitoid pupa) for 4 weeks to combinations of two low temperatures (4 and 0 °C, 0 °C being the most stressful) and two thermal regimes (constant and fluctuating, constant being the most stressful), representing four stress levels.

The present results showed that resistant individuals occurred only in the most stressful treatment (0 °C, constant temperature), which induced a higher mortality rate. These resistant individuals performed almost as well as those of the control, but showed a reduction in their size. The fluctuating regimes, at both temperatures, presented a high emergence rate, but at the expense of higher lipid consumption. Unexpectedly, the fluctuating regime associated with the presumably more stressful temperature (0 °C) produced individuals without any decrease in the measured fitness traits, in contrast to the treatment expected to be less stressful (4 °C, fluctuating temperature).

This result opens a new area of research in stress ecology and could modify the practice of cold storage in biological control.
The Role of Agents in Private Entrepreneurial Finance
Authors: Cumming Douglas J. , Pandes J. Ari , Robinson Michael J.
Published: May 2013

We examine theory and evidence on agents in private–market entrepreneurial financings. After controlling for the endogenous issuer–agent matching and a whole host of other controls, the empirical findings in this paper indicate that agents attract more investors, broaden the geographic investor and capital base, and increase the percentage of investors and capital from investors that are more vulnerable to the costs of information asymmetry. We also find that more capable agents generally provide more valuable benefits to private entrepreneurial firm financings than less capable agents, and that increasing the number of agents in a financing further increases value to issuing firms.
Latitudinal diversity relationships of fiddler crabs: biogeographic differences united by temperature
Authors: Levinton Jeffrey , Mackie Joshua
Published: May 2013

Aim

To investigate whether latitudinal diversity gradients differ among biogeographic realms for members of a closely related clade and to examine whether differences can be explained by environmental differences such as the temperature gradient.

Location

Indo‐Pacific, eastern Pacific and western Atlantic temperate to tropical coastal intertidal.

Methods

We digitized the ranges of fiddler crabs (Decapoda, Ocypodidae, genus Uca) and calculated standing diversity as a function of latitude in the Indo‐west‐Pacific, eastern‐Pacific Americas and western Atlantic regions. We examined correlations between diversity and summer sea surface temperature, water column primary productivity, and also investigated the contribution of spatial autocorrelation.

Results

There was a latitudinal diversity gradient with a peak in the tropics or subtropics, but richness as a function of latitude differed by region. The western Atlantic had a broad zone of equal diversity with a peak that corresponds to the Gulf of Mexico–Caribbean Basin. The eastern Pacific had a distinct peak of diversity at about 10° N latitude corresponding to Panama. The Indo‐west‐Pacific had a broad relatively flat upper level of diversity, reaching a peak at about 20° S latitude corresponding to the north coast of Australia. In both the eastern Pacific and western Atlantic, Northern Hemisphere diversity was greater than Southern Hemisphere. Species richness of the three regions was positively and strongly correlated with air and sea surface temperature at the start of summer. In contrast, diversities were weakly and inconsistently correlated with productivity.

Main conclusions

This paper shows that a physical factor is more important in explaining latitude distributions than regional cladal structure or presumed dispersal patterns. While observed diversity–latitude functions are region specific, the feature seen across regions to most strongly explaining the pattern is temperature.
Persistent Punishment: User Views of Short Prison Sentences
Authors: Armstrong Sarah , Weaver Beth
Published: May 2013

Semi‐structured interviews were conducted with 22 prisoners to gather information about the characteristic features of short prison sentences. Themes raised in comments included: the frequency and quality of sentences, addiction, family, and penal legitimacy. Most of the participants had extensive experience of prison, and the effects of this played out across sentences and years, accumulating and amplifying impacts. And, despite expressions of guilt and remorse, most participants saw their sentence as unjust, and mainly a reaction to offending history. We conclude by suggesting the need for research to shift focus from evaluating individual penal interventions towards more holistic and narrative accounts that cut across sentences.
The Politics of Prisoner Legal Rights
Authors: Scott David
Published: May 2013

The article begins by locating human rights law within the current political context before moving on to critically review judicial reasoning on prisoner legal rights since the introduction of the Human Rights Act 1998. The limited influence of proportionality on legal discourses in England and Wales is then explored by contrasting a number of judgments since October 2000 in the domestic courts and European Court of Human Rights (ECtHR). The article concludes with a discussion of the implications of the restricted interpretation of legal rights for penal reform and proposes an alternative radical rearticulation of the politics of prisoner human rights.
Pure transvaginal natural orifice translumenal endoscopic surgery for renal cyst decortication: Report of initial five cases
Authors: Zou Xiaofeng , Zhang Guoxi , Yuan Yuanhu , Xiao Rihai , Xue Yijun , Wu Gengqing , Wang Xiaoning , Long Dazhi , Yang Jun , Wu Yuting , Xu Hui , Liu Folin , Liu Min , Zhang Xu
Published: May 2013

Objective

To present our initial experience with pure transvaginal natural orifice translumenal endoscopic surgery renal cyst decortication.

Methods

From December 2010 to July 2011, five female patients with symptomatic renal cyst in the anterior portion and lower pole of the kidney were submitted to pure transvaginal natural orifice translumenal endoscopic surgery renal cyst decortication in our center. Under general anesthesia, the patients were placed in the lithotomy position with the affected side elevated by 60°. A 3‐cm incision was made at the posterior vaginal fornix and a modified three‐channel port was deployed across the vaginal incision. The cyst was dissected and the cyst fluid was aspirated using a suction device. The cyst wall was circumferentially excised.

Results

All five procedures were successfully carried out without additional transabdominal trocars. The median operative time was 80 min (range 60–90 min). The median estimated blood loss was 25 mL (range 25–50 mL). The median visual analog scale score was 1 on postoperative day 1. None of the patients required narcotic pain medications beyond postoperative day 2. Intestinal function recovered on postoperative day 1–3. There was no intraoperative or postoperative complication in any of the patients. During the follow‐up visits, all the patients were in good condition. All the patients reported unaltered sexual function after surgery by the Female Sexual Function Index questionnaire.

Conclusion

Our initial experience suggests that pure transvaginal natural orifice translumenal endoscopic surgery renal cyst decortication is feasible and safe in selected patients.
Sentinel lymph node dissection in more than 1200 prostate cancer cases: Rate and prediction of lymph node involvement depending on preoperative tumor characteristics
Authors: Winter Alexander , Kneib Thomas , Henke Rolf‐Peter , Wawroschek Friedhelm
Published: May 2013

Objectives

To stratify the rate and prediction of lymph node involvement in prostate cancer patients undergoing sentinel‐lymphadenectomy depending on preoperative tumor characteristics, and to compare the outcome with the European Association of Urology Guideline indication for lymphadenectomy.

Methods

A total of 1229 patients (median age 66 years) were treated with open sentinel‐lymphadenectomy and prostatectomy between 2005 and 2009. Median preoperative prostate‐specific antigen was 7.4 ng/mL. The rate of lymph node involvement was analyzed for D'Amico risk groups. Multivariable logistic regression was used to estimate the probability of lymph node involvement. Predictor variables included preoperative prostate‐specific antigen, clinical T‐category and biopsy Gleason sum. Predictive accuracy has been quantified (area under the curve) and lymph node positive patients were verified under consideration of the recommended European threshold for lymphadenectomy (nomogram‐predicted lymph node invasion risk of >7%).

Results

The median number of lymph nodes removed was 10 (interquartile range 7–13). Overall, 17.1% of patients had lymph node involvement; 3.2% in low‐, 14.8% in intermediate‐ and 37.4% in high‐risk disease. The predicted risk for lymph node involvement ranged from 2% (prostate‐specific antigen ≤4 ng/mL, T1, Gleason sum ≤6) to 87% (prostate‐specific antigen >20 ng/mL, T3, Gleason sum ≥8). The predictive accuracy was 82.1%. According to the European guidelines, 15.9% of all lymph node involved cases would not have been detected.

Conclusions

The rate of lymph node involvement seems to be higher in the examined sentinel collective than expected according to the European Guideline nomogram. The first sentinel‐based lymph node involvement prediction model can assist in deciding on the indication for sentinel‐lymphadenectomy. The validation of a corresponding sentinel‐based nomogram is still missing.
Nocturia and sleep quality after transurethral resection of the prostate
Authors: Wada Naoki , Numata Atsushi , Hou Kyokushin , Watanabe Masaki , Kita Masafumi , Matsumoto Seiji , Osanai Hiroaki , Fujisawa Makoto , Kakizaki Hidehiro
Published: May 2013

Objectives

To evaluate the clinical efficacy of transurethral resection of the prostate on nocturia and sleep disorders in patients with lower urinary tract symptoms suggestive of benign prostatic obstruction.

Methods

A prospective multicenter study including lower urinary tract symptoms suggestive of benign prostatic obstruction patients with nocturia (twice or more) undergoing transurethral resection of the prostate was carried out. All patients were assessed using the International Prostate Symptom Score and the Pittsburgh Sleep Quality Index at baseline, and 6 months after transurethral resection of the prostate.

Results

Overall, 49 patients were included in the study. A total of 20 of them (41%) had a sleep disorder defined as a score of 5.5 or more on the Pittsburgh Sleep Quality Index global score. The nocturia score significantly correlated with component 4 of the Pittsburgh Sleep Quality Index (habitual sleep efficiency). Nocturia significantly decreased after transurethral resection of the prostate from 3.0 ± 1.2 to 1.9 ± 0.8, whereas the global Pittsburgh Sleep Quality Index score did not. In 20 patients with a sleep disorder before transurethral resection of the prostate, subjective sleep quality (component 1) and habitual sleep efficiency (component 4) significantly decreased after transurethral resection of the prostate, but this was not the case for the global Pittsburgh Sleep Quality Index score. In 16 patients with a persistent sleep disorder after transurethral resection of the prostate, International Prostate Symptom Score, voiding and storage symptoms score were higher than those of patients without a sleep disorder, although the nocturia score improved equivalently in both groups.

Conclusions

Transurethral resection of the prostate diminishes nocturnal urinary frequency and partly improves sleep quality in patients with nocturia and lower urinary tract symptoms suggestive of benign prostatic obstruction. A persistent sleep disorder after transurethral resection of the prostate is associated with persistent voiding and storage symptoms.
Leaf traits and litter flammability: evidence for non‐additive mixture effects in a temperate forest
Authors: de Magalhães Rita M. Q. , Schwilk Dylan W.
Published: May 2013

1. Although it is recognized that plant species vary in their flammability, we currently lack a mechanistic understanding of how plant traits influence fire and how litter mixtures behave in a fire. As modified fire regimes and climate change shift the species composition of communities, a mechanistic perspective is especially important to understand and predict fire in potentially novel plant communities. This work addresses three questions: (i) How do eight species common in Sierra Nevada mixed‐conifer forest differ in their litter flammability? (ii) What leaf traits are associated with various flammability components? and (iii) Do individual species measurements predict multi‐species combinations, or are there non‐additive effects?

2. Leaf litter was collected in Sequoia and Kings Canyon National Parks, California, from eight dominant tree species in mixed‐conifer forest. Controlled flammability tests were performed on reconstructed monospecific litter beds and on mixed litter beds, using litter from three species. We tested for non‐additive effects in multi‐species mixtures using the weighted mean of single‐species measures for each flammability component as a null expectation for each mixture; departures from this null indicated non‐additive effects.

3. Most flammability components fell within two major axes of variation, one relating to total heat release and another to fire intensity. The eight species differed significantly in all flammability components, with large‐leaved species creating litter that burned with higher intensity.

4. Non‐additive species mixture effects are common in this system. Flammability tends to be driven by the most flammable component of the mixture.

5. Synthesis. We have demonstrated positive non‐additive effects in mixtures of leaf litter. The most flammable constituent species of a mixture has disproportionate effects on the fire environment faced by the entire community. This could potentially influence community assembly and alter the selective environment faced by co‐occurring species.
Driving factors of forest growth: a reply to Ferry et al. (2012)
Authors: Toledo Marisol , Poorter Lourens , Peña‐Claros Marielos , Alarcón Alfredo , Balcázar Julio , Leaño Claudio , Licona Juan C. , Llanque Oscar , Vroomans Vincent , Zuidema Pieter A. , Bongers Frans
Published: May 2013

1. In a recent paper, we analysed the effects of climate, soil and logging disturbance on tree and forest growth (Toledo et al. 2011a). We took advantage of one of the largest data sets in the Neotropics, consisting of 165 1‐ha plots and over 62 000 trees distributed over an area of c. 160 000 km2, across large environmental gradients in lowland Bolivia. The main findings were that climate was the strongest driver of spatial variation in tree growth, whereas soils had only a modest effect on growth and that the effect of logging disappeared after a few years.

2. Ferry et al. (2012) suggest that we underestimated the disturbance effects on growth because of a supposedly wrong coding of Time After Logging (TAL) for unlogged plots. Although we have good biological reasons why we coded TAL like we did, we checked Ferry et al.’s suggestions for recoding and found no differences in variables that significantly explained tree and forest growth. We agree, however, that for future research, it is important to go beyond simple descriptors such as time after logging and basal area logged, to better describe the variation in logging impact found in areas under forest management.

3. Ferry et al. claim that we did not define basal area growth properly. We believe this is a semantic issue, as we clearly defined basal area growth as the net change in basal area. This net basal area change in Bolivian forests is indeed relatively high compared to other studies, which may be attributed to the higher soil fertility and biogeographic differences in species composition and their traits.

4. Synthesis. Many apparent discrepancies in the ecological literature arise because tropical forest ecologists tend to see the world from the perspective of their ‘own’ forest (despite clear biogeographic differences) and try to capture the same ecological processes using different variables and measurement protocols. To advance our understanding and go beyond single‐case studies, we need to assemble large databases, quantify forest dynamics and disturbances in similar ways, be aware of differences among forests and analyse environmental dose–response curves.
Trait evolution and the coexistence of a species swarm in the tropical forest understorey
Authors: Sedio Brian E. , Wright S. Joseph , Dick Christopher W.
Published: May 2013

1. A small number of species‐rich plant genera make a substantial contribution to the α diversity of tropical forests. These ‘species swarms’ (Gentry 1982) challenge a view of community assembly that maintains that niche overlap, and hence, the likelihood of competitive exclusion should increase with phylogenetic affinity. Related species may, however, occupy different microhabitats within a forest stand or, alternatively, differ ecologically in ways that allow them to coexist syntopically.

2. To explore the relationship between phylogenetic history and niche differentiation among sympatric, congeneric species, we performed phylogenetic analyses of microhabitat preferences, photosynthetic and hydraulic traits, and experimental responses to light and water availability for 20 species ofPsychotria(Rubiaceae) from Barro Colorado Island (BCI), Panama.

3. ThePsychotriapresent in small (3‐m radius), circular plots were more closely related than expected by chance. Photosynthetic and hydraulic traits were both associated with species habitat distributions, but only hydraulic traits were conserved phylogenetically. Experimental responses to water availability were also conserved phylogenetically. Functional trait analyses revealed little or no evidence of niche partitioning within sites.

4. We conclude thatPsychotriaspecies’ responses to both light and moisture availability determine their microhabitat distributions on BCI and that evolutionarily conserved hydraulic traits lead to phylogenetic clustering of co‐occurring species.

5. Synthesis. The evolutionary conservation of hydraulic traits related to soil moisture tolerance largely explains phylogenetic clustering in the local assembly of the hyperdiverse genusPsychotria. We suggest that close relatives are unlikely to exclude one another from shared habitats because resource availability is determined largely by asymmetric competition with the overstorey, rather than by competition with neighbouring understorey plants. In light of the recent biogeographic admixture in central Panama, the phylogenetic niche conservatism exhibited byPsychotriaon BCI raises the possibility of an association between local microhabitats and the ancestral climatic regimes under which majorPsychotrialineages evolved before arriving in sympatry.
Loss of a dominant nitrogen‐fixing shrub in primary succession: consequences for plant and below‐ground communities
Authors: St. John Mark G. , Bellingham Peter J. , Walker Lawrence R. , Orwin Kate H. , Bonner Karen I. , Dickie Ian A. , Morse Chris W. , Yeates Gregor W. , Wardle David A.
Published: May 2013

1. Many ecosystems are gaining some species and losing others, leading to large shifts in community composition. Plants that support nitrogen (N)‐fixing symbionts (hereafter N‐fixers) are major ecosystem drivers but human‐induced environmental changes can lead to their loss; the impacts of this loss have seldom been studied. In New Zealand, the gain of some invasive herbivorous mammals leads to the loss of N‐fixing shrubs that are pioneers during primary succession.

2. We studied primary successional surfaces caused by river floods and landslides in a remote valley in New Zealand's South Island. We set up and maintained a removal experiment over 10 years, with N‐fixing
Carmichaelia odorata (hereafter
Carmichaelia) either left intact or removed to represent the effects that invasive herbivorous mammals could cause under high densities.

3. Above‐ground effects of 10 years of
Carmichaelia removal included a 7‐fold reduction of woody plant biomass, but had no effect on the shorter non‐woody vegetation. Foliar N concentrations of two woody species were also reduced.
Carmichaelia removal reduced local or α‐diversity but enhanced β‐diversity of the remaining vegetation at the functional group but not the species level.

4. Below‐ground effects of 10 years of
Carmichaelia removal included large reductions in soil carbon (C) and N levels, and biomass or abundance of several groups of soil biota occupying three consumer trophic levels as well as the root‐, bacterial‐ and fungal‐based energy channels. Invertebrate bacterial consumers were more adversely affected than were fungal consumers.
Carmichaelia loss reduced α‐diversity of some below‐ground groups, while β‐diversity was unresponsive or enhanced.

5. Synthesis. Our results reveal that loss of a single functionally distinct plant species, such as occurs through herbivore invasion, can cause substantial effects both above‐ground and below‐ground. This may affect the trajectory of the ecosystem over successional time, especially in primary seres that otherwise have very low soil carbon (C) and nitrogen (N) reservoirs. More generally, our results support the view that the simultaneous gains of some organisms (e.g. invasive herbivorous mammals) and resultant losses of others (e.g. palatable N‐fixing plants) are a major element of human‐induced global change that may be transforming many communities and ecosystems world‐wide.
Strong persistent growth differences govern individual performance and population dynamics in a tropical forest understorey palm
Authors: Jansen Merel , Zuidema Pieter A. , Anten Niels P. R. , Martínez‐Ramos Miguel
Published: May 2013

Persistent variation in growth rate between individual plants can have strong effects on population dynamics as fast growers reach the reproductive size at an earlier age and thus potentially contribute more to population growth than slow growers. In tropical forests, such persistent growth differences have so far been documented for canopy tree species, where they are primarily associated with forest gap dynamics, but not for forest understorey species which are less responsive to gaps. Here, we study persistent growth differences and their demographic consequences for a tropical forest understorey palm,Chamaedorea elegans.

We measured internodes along stems and annual leaf production rates to reconstruct lifetime growth trajectories. Using regression analysis, we determined the relative effect of stem length and past growth rate on vital rates (survival, growth and reproduction). We then simulated population dynamics using integral projection models (IPMs), in which individuals were categorized by both stem length and lifetime past growth rate.

Stem growth differences among individual palms persisted over most of their lifetime. Past growth rate averaged over the palm's lifetime proved to be a very good predictor of growth, reproduction probability and seed production, often much better than stem length or age. The effects of past growth rate were positive, indicating that fast growers maintain high rates of growth and reproduction.

Projected population growth rate (λ) was 1.056, and stable stage distributions closely resembled observed population structures. Separating individuals with above‐median and below‐median past growth rates in IPMs revealed substantial differences in elasticity values. The 50% fastest growers had a 1.8 times higher elasticity, and thus a 1.8 times higher contribution to population growth, compared to slow growers.

Synthesis. Strong and persistent growth differences that are probably associated with environmental (edaphic) and/or genetic factors govern individual performance and population dynamics of a tropical forest understorey palm. Overall, our study shows that strong inter‐individual growth variation is not limited to canopy trees and that it can be generated by other factors than canopy dynamics. It is likely that persistently fast‐growing ‘super performers’ govern population growth of many long‐lived species.
Functional traits and their plasticity predict tropical trees regeneration niche even among species with intermediate light requirements
Authors: Laurans Marilyne , Martin Olivier , Nicolini Eric , Vincent Gregoire
Published: May 2013

Niche differentiation is a key issue in the current debate on community assembly mechanisms. In highly diverse moist tropical forests, tree species sensitivity to canopy openness is thought to be a major axis in niche differentiation. In the past, the syndrome of traits driving the demographic trade‐off involved in the niche‐based theory of coexistence has always been established among species situated at the two extremities of the shade‐tolerance gradient, even though most tropical tree species have intermediate light requirements. In addition, trait plasticity has seldom been linked to tropical tree species distribution along environmental gradients.

This article examines covariations between leaf traits, whole‐plant traits and niche parameters among 14 tree species with intermediate light requirements in French Guiana and across a range of canopy openness. Each functional trait measured under field conditions was characterized by a median value and a degree of plasticity expressed under contrasting light regimes. Niche differentiation was characterized in terms of spatial light gradient. We first examined covariations between functional traits then explored to what degree the median value and plasticity in functional traits could predict light niche characteristics at the sapling stage and the ontogenetic change in light availability estimated by adult stature.

Leaf mass per area (LMA) was positively correlated with leaf life span (LLS); species with higher LMA and higher LLS displayed lower diameter growth rates (GRs) and lower responsiveness to canopy gap at both whole‐plant and population levels. This proved that the relationships previously established over a broader range of species held true within the narrow range of the light requirements covered.

Height GR plasticity accounted for 49% of the variation in light niche optimum. LMA plasticity, unlike LLS plasticity, was significantly correlated with light niche breadth and adult stature.

Synthesis. This study demonstrates the relevance of considering the phenotypic plasticity in functional traits in community ecology, particularly for quantifying breadth of species distribution over environmental gradients. Our findings did not support Hubbell's hypothesis of functional equivalence and suggest that even a rather subtle variation in forest canopy disturbance promotes the coexistence of tropical tree species.
Plant responses to soil heterogeneity and global environmental change
Authors: García‐Palacios Pablo , Maestre Fernando T. , Bardgett Richard D. , de Kroon Hans
Published: May 2013

Recent evidence suggests that soil nutrient heterogeneity, a ubiquitous feature of terrestrial ecosystems, modulates plant responses to ongoing global change (GC). However, we know little about the overall trends of such responses, the GC drivers involved and the plant attributes affected.

We synthesized literature to answer the question: Does soil heterogeneity significantly affect plant responses to main GC drivers, such as elevated atmospheric carbon dioxide concentration (CO2), nitrogen (N) enrichment and changes in rainfall regime?

Overall, most studies have addressed short‐term effects of N enrichment on the performance of model plant communities using experiments conducted under controlled conditions. The role of soil heterogeneity as a modulator of plant responses to elevated CO2 may depend on the plasticity in nutrient uptake patterns. Soil heterogeneity does interact with N enrichment to determine plant growth and nutrient status, but the outcome of this interaction has been found to be both synergistic and inhibitory. The very few studies published on interactive effects of soil heterogeneity and changes in rainfall regime prevented us from identifying any general pattern.

We identify the long‐term consequences of soil heterogeneity on plant community dynamics in the field, and the ecosystem‐level responses of the soil heterogeneity × GC driver interaction, as the main knowledge gaps in this area of research.

To fill these gaps and take soil heterogeneity and GC research a step forward, we propose the following research guidelines: (i) combining morphological and physiological plant responses to soil heterogeneity with field observations of community composition and predictions from simulation models and (ii) incorporating soil heterogeneity into a trait‐based response‐effect framework, where plant‐resource‐use traits are used as both response variables to this heterogeneity and GC, and predictors of ecosystem functioning.

Synthesis. There is enough evidence to affirm that soil heterogeneity modulates plant responses to elevated atmospheric CO2 and N enrichment. Our synthesis indicates that we must explicitly consider soil heterogeneity to accurately predict plant responses to GC drivers.
Effects of disturbance intensity on species and functional diversity in a tropical forest
Authors: Carreño‐Rocabado Geovana , Peña‐Claros Marielos , Bongers Frans , Alarcón Alfredo , Licona Juan‐Carlos , Poorter Lourens
Published: May 2013

Disturbances are widespread and may affect community assembly, species composition, (functional) diversity and hence ecosystem processes. It remains still unclear to what extent disturbance‐mediated species changes scale‐up to changes in community functional properties, especially for species‐rich tropical forests.

A large‐scale field experiment was performed in which the dynamics of 15 000 stems >10 cm in diameter was monitored for 8 years in 44 one‐ha forest plots. Twelve functional effect and response traits were measured for the most dominant tree species. The effects of different intensities of disturbance caused by logging and silvicultural treatments on the species and functional diversity of a Bolivian tropical forest community were evaluated, along with how these changes were driven by underlying demographic processes.

Disturbance treatments did not affect species diversity or functional diversity indices based on multiple traits related to primary productivity and decomposition rate. This result suggests that species richness is conserved, and traitvariationis maintained, which can buffer the community against environmental change.

In contrast, disturbance intensity affected theaverageplant trait values in the community (the community‐weighted mean) for seven of 12 traits evaluated. At high disturbance intensity, the community had a lower wood density of stem and branches, lower leaf toughness and dry matter content, but higher specific leaf area and leaf N‐ and P concentration, with the value of these traits changing on average 6% over the 8‐year period. The functional spectrum of the community changed, therefore, from ‘slow’, conservative, shade‐tolerant species towards ‘fast’, acquisitive, light‐demanding species. These functional changes inmeantrait values may enhance primary productivity and decomposition rate in the short term.

Temporal changes in community functional properties were mainly driven by recruitment, and little by mortality or survival.

Synthesis. Moderate levels of (logging) disturbance neither affected species diversity nor functional diversity per se in the 8‐year period after logging. Disturbance did, however, change the functional community composition towards ‘fast’ species with more acquisitive traits, thus potentially fuelling primary productivity and nutrient and carbon cycling. In conclusion, tropical forest management may contribute to conserving functional biodiversity of trees while providing forest resources.
Plant species diversity and genetic diversity within a dominant species interactively affect plant community biomass
Authors: Crawford Kerri M. , Rudgers Jennifer A.
Published: May 2013

Both plant species diversity and genetic diversity within a plant species can affect community properties and ecosystem processes. However, the relative contribution of species diversity and genetic diversity to ecosystem functioning is poorly known. Furthermore, ecosystem processes may respond non‐additively to interactions between species diversity and genetic diversity. If interactive effects exist, the impact of biodiversity loss may not be predictable from simple assessments of either species diversity or genetic diversity alone.

Here, we addressed how plant species diversity and genetic diversity within a dominant species independently and interactively influenced plant community biomass in a Great Lakes sand dune ecosystem. To test the independent effects of diversity, we established two experiments. In one, we manipulated genetic diversity within the dominant dune species, Ammophila breviligulata. In the other, we manipulated the number of plant species, excluding A. breviligulata. Then, to test for interactive effects, we constructed communities that varied the number of species and levels of genetic diversity within A. breviligulata.

Although there were no independent effects of either species diversity or genetic diversity within A. breviligulata on biomass production in this system, interactive effects of species diversity and genetic diversity significantly influenced overall above‐ground biomass production of the plant communities. Specifically, as genetic diversity within the dominant species increased, the relationship between species diversity and community‐level biomass shifted from negative to positive. Negative non‐additive effects of diversity drove this pattern.

Synthesis. These results show, for the first time, that interactions between plant species diversity and genetic diversity within a dominant species can alter biomass production, highlighting the importance of incorporating interactions between levels of biodiversity into our understanding of how biodiversity influences ecosystem function.
BiologicalFlora of theBritishIsles:Fagus sylvatica
Authors: Packham John R. , Thomas Peter A. , Atkinson Mark D. , Degen Thomas
Published: May 2013

This account presents information on all aspects of the biology ofFagus sylvaticaL. that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of theBiologicalFlora of theBritishIsles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation.

Fagus sylvatica(Beech) is a large usually single‐stemmed deciduous tree native to south‐eastEngland but now growing over almost the whole of theBritish Isles, often planted as a forestry tree on all but the wettest soils. It forms extensive woodlands, where it is dominant over a large altitudinal range, competing primarily withQuercus robur. The outcome of this competition is determined by local soil and climatic conditions leading to a gradation into oak woodlands. It is monoecious, wind‐pollinated and notable for its periodic large seed numbers (mast years); seed is dispersed by birds and mammals but mostly drops below the parent tree.

Fagus sylvaticais hardy, very shade tolerant, casts a deep shade and is fairly resistant to browsing but susceptible to spring frosts.

Due to its shallow rooting and intensive rather than extensive mode of soil water exploitation, it is also susceptible to drought, and this is likely to be the main factor controlling its expected response to climate change.

Fagus sylvaticais facing few conservation problems, and indeed, its range is currently expanding into central Europe. However, in the face of climate change, its range is likely to contract from its extremes in all but the north, andPhytophthoradiseases may become more serious.