bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fire and the relative roles of weather, climate and landscape characteristics in the Great Lakes‐St. Lawrence forest of Canada
Authors: Drever C. Ronnie , Drever Mark C. , Messier Christian , Bergeron Yves , Flannigan Mike 
Published: December 2007

AbstractQuestion:In deciduous‐dominated forest landscapes, what are the relative roles of fire weather, climate, human and biophysical landscape characteristics for explaining variation in large fire occurrence and area burned?Location:The Great Lakes‐St. Lawrence forest of Canada. Methods: We characterized the recent (1959–1999) regime of large (≥ 200 ha) fires in 26 deciduous‐dominated landscapes and analysed these data in an information‐theoretic framework to compare six hypotheses that related fire occurrence and area burned to fire weather severity, climate normals, population and road densities, and enduring landscape characteristics such as surficial deposits and large lakes.Results:392 large fires burned 833 698 ha during the study period, annually burning on average 0.07%± 0.42% of forested area in each landscape. Fire activity was strongly seasonal, with most fires and area burned occurring in May and June. A combination of antecedent‐winter precipitation, fire season precipitation deficit/surplus and percent of landscape covered by well‐drained surficial deposits best explained fire occurrence and area burned. Fire occurrence varied only as a function of fire weather and climate variables, whereas area burned was also explained by percent cover of aspen and pine stands, human population density and two enduring characteristics: percent cover of large water bodies and glaciofluvial deposits.Conclusion:Understanding the relative role of these variables may help design adaptation strategies for forecasted increases in fire weather severity by allowing (1) prioritization of landscapes according to enduring characteristics and (2) management of their composition so that substantially increased fire activity would be necessary to transform landscape structure and composition.
Thicket clumps: A characteristic feature of the Kagera savanna landscape, East Africa
Authors: Bloesch U. 
Published: December 2007

AbstractQuestion: What are the genesis and development of thicket clumps within a savanna landscape at geomorphically different locations and what are the driving forces?Location: The Kagera Region, in the border area of Rwanda, Uganda and Tanzania.Methods: The vegetation of 32 dry evergreen thicket clumps and their surrounding savannas have been analysed at different geomorphic locations. At each vegetation plot Na+, K+, Mg2+, Ca2+, Al3+, Fe2+/3+, H+, P, C, N, bulk density and particle size were determined for each soil horizon. The impact of soil and termite mounds on thicket clump dynamics on seasonally waterlogged plains, gentle slopes and stony hillsides were assessed.Results: Thicket clumps and their surrounding savannas have a distinct structure and floristic composition. They also have distinct soil properties although parent materials are the same. On seasonally waterlogged plains, new thicket clumps can develop on Macrotermitinae mounds; on stony hillsides, Trinervitermes and Macrotermes show a uniform distribution pattern and may initiate the genesis of thicket clumps.Conclusions: Geomorphology broadly determines the significance and interactions of the main factors affecting site‐specific vegetation dynamics. On seasonally waterlogged plains, thicket clumps are restricted to termite mounds. Since intra‐species competition dictates a minimal distance between neighbouring Macrotermitinae colonies, thicket clumps do not coalescence. By contrast, on stony hillsides, the vegetation mosaic is highly dynamic and determined by the interplay of several factors. The growth of thicket clumps is mainly a function of the fire regime and the browsing intensity. At the present time, frequent cool, early dry season fires and the near absence of large browsers have favoured the advance and coalescence of thicket clumps and forest patches on stony hillsides.
Species richness in boreal swamp forests of SE Norway: The role of surface microtopography
Authors: Økland Rune H. , Rydgren Knut , Ø kland Tonje 
Published: December 2007

AbstractQuestion: What is the relative importance of environmental gradients and surface microtopography (variation in vertical level within sampling units) for fine‐scale plant species richness in Picea abies swamp forests?Location: 11 swamp forests in SE Norway.Methods: We recorded species richness (number of species of vascular plants, mosses, Sphagnum and hepatics), depth to water table, soil base status and vertical range (microtopographic relief) in 2400 microplots, (each 1/16 m2), in 150 1‐m2 plots in the 11 swamp forests. Relationships between species richness and environmental predictors were modelled by GLMM.Results: Moss and hepatic species richness increased with increasing microtopographic relief, most strongly for wet acid sites, in which similar trends were also found for Sphagnum. Relief was a poor predictor of vascular plant species richness.Conclusions: Microtopographic relief is a good predictor of local species richness in Picea abies swamp forests, partly because larger vertical variability means higher within‐plot habitat diversity with respect to the wet‐dry gradient, and partly because qualitatively new microhabitats associated with steep slopes are added in drier sites. The relationship between species richness and microtopographic relief is context dependent, differing in complex ways among species groups and among sites with different environmental conditions.
Spatial patterns in cushion‐dominated plant communities of the high Andes of central Chile: How frequent are positive associations?
Authors: Fajardo Alex , Quiroz Constanza L. , Cavieres Lohengrin A. 
Published: December 2007

AbstractQuestion:In stressful abiotic environments positive plant interaction is expected to be a frequent and an important process driving community composition and structure. In the high Andes in central Chile, the cushion plantAzorella madreporicadominates plant communities and appears to benefit the assemblage of species that grows within it. However, there are also many other species that grow outside this nurse cushion plant, which may or may not interact with this species. What is the prevailing type of spatial associations among the plant species that are not growing inside the nurse plant? What is the type of interactions between cushion plants and those species growing outside them?Location:Molina River basin (33°20'S, 70°16’ W, 3600 m a.s.l.), in the Andes of central Chile, ca. 50 km east of Santiago.Methods:Two accurate mapping plots of individual plants of different species were located at two summits (Franciscano and Tres Puntas sites). The spatial distributions and associations between species growing outside cushions and within cushions at each site were estimated by point‐pattern analyses using the univariate and bivariate transformations of Ripley'sK‐functions.Results:We found both positive and, especially, negative spatial associations (8 out of 12 species in Franciscano site) betweenA. madreporicacushions and plants growing outside them. However, most of the species showed positive spatial associations among them. The variation in spatial association was site‐specific and also depended on the type of plants involved.Adesmiaspp., the second most abundant non‐cushion species, displayed negative associations with cushions and positive associations with other species growing outside cushions.Conclusions:Our study suggests very complex interactions among species, which ranged from positive to negative, and are also affected by abiotic environmental conditions.
Are traits measured on pot grown plants representative of those in natural communities?
Authors: Mokany Karel , Ash Julian 
Published: December 2007

AbstractQuestion: The quantification of functional traits in natural communities can be difficult (e.g. root traits, RGR). Can functional traits measured on pot grown plants be reliably applied to natural communities? Alternatively, can below‐ground plant traits be predicted from above‐ground traits?Location: Southeastern Australia.Methods: We compared 17 shoot, root and whole‐plant morphological traits measured on 14 plant species in a native grassland community to those measured under two different pot conditions: unfertilised and fertilised.Results: The majority of trait values for pot grown plants differed to plants in the field, however, species ranking remained consistent for most leaf traits between the field and the two pot growing conditions. In contrast, species ranking was not consistent for most whole plant traits when comparing field plants to fertilised pot grown plants, providing a caution against the tendency to grow plants in controlled conditions at ‘optimal’ (high) resource levels. Moderate to strong correlations were found between below‐ground and above‐ground plant traits, including between root dry matter content and leaf dry matter content, and between specific root area and specific leaf area.Conclusions: The utility of pot grown plants to quantify traits for field plants is highly dependent on the selection of the growing conditions in the controlled environment. The consistency we observed between above‐ground and below‐ground trait strategies suggests that below‐ground traits may be predictable based on above‐ground traits, reducing the need to quantify root traits on cultured plants.
Scale‐dependence of vegetation‐environment relationships in semi‐natural grasslands
Authors: Auestad Inger , Rydgren Knut , Økland Rune H. 
Published: December 2007

AbstractQuestions: Which environmental and management factors determine plant species composition in semi‐natural grasslands within a local study area? Are vegetation and explanatory factors scale‐dependent?Location: Semi‐natural grasslands in Lærdal, Sognog Fjordane County, western Norway.Methods: We recorded plant species composition and explanatory variables in six grassland sites using a hierarchically nested sampling design with three levels: plots randomly placed within blocks selected within sites. We evaluated vegetation‐environment relationships at all three levels by means of DCA ordination and split‐plot GLM analyses.Results: The most important complex gradient determining variation in grassland species composition showed a broad‐scale relationship with management. Soil moisture conditions were related to vegetation variation on block scale, whereas element concentrations in the soil were significantly related to variation in species composition on all spatial scales. Our results show that vegetation‐environment relationships are dependent on the scale of observation. We suggest that scale‐related (and therefore methodological) issues may explain the wide range of vegetation‐environment relationships reported in the literature, for semi‐natural grassland in particular but also for other ecosystems.Conclusions: Interpretation of the variation in species composition of semi‐natural grasslands requires consideration of the spatial scales on which important environmental variables vary.
Facilitation of Quercus ilex recruitment by shrubs in Mediterranean open woodlands
Authors: Smit Christian , den Ouden Jan , Díaz Mario 
Published: December 2007

AbstractQuestion: Insufficient tree regeneration threatens the long‐term persistence of biodiverse Mediterranean open oak woodlands. Could shrubs, scarce due to decades of management (clearing and ploughing), facilitate holm oak recruitment at both acorn and seedling stages?Location: Open oak woodlands in Central Spain.Methods: Plots with four acorns were planted: (1) under the canopy of the spiny shrub Genista hirsuta, (2) in a small cage, protecting against ungulates, (3) in a shaded cage, protecting against ungulates and sun, and (4) in open grassland. Sets of these four treatments were spatially grouped according to a randomised block design, with 16 blocks near (< 10 m) and 16 away from (> 20 m) parent trees to test for distance‐related survival. Plots were regularly checked for seed removal. After emergence one seedling per plot (97 in total) was selected and its survival monitored.Results: Three months after sowing, 199 of 512 acorns were removed, predominantly by rodents. Acorn removal occurred at each treatment but was highest under shrubs. Eight months after sowing, seedling survival was highest under shrubs (50%), followed by shaded cages (16%), open grassland (4%) and cages (0%). Main mortality cause was drought (90%), killing most seedlings between June and July. No seedlings died from ungulate browsing.Conclusion: Shrubs demonstrated clear net facilitative effects for Quercus ilex recruitment, despite higher seed removal. Shading appears the crucial factor facilitating seedling survival. We therefore propose that lack of shrubs contributes largely to tree recruitment failure in Mediterranean open woodlands; management should aim at conserving shrubs.
Tolerance of Pinus taeda and Pinus serotina to low salinity and flooding: Implications for equilibrium vegetation dynamics
Authors: Poulter Benjamin , Christensen Norman L. , Qian Song S. 
Published: December 2007

AbstractQuestions: 1. Do pine seedlings in estuarine environments display discrete or continuous ranges of physiological tolerance to flooding and salinity? 2. What is the tolerance of Pinus taeda and P. serotina to low salinity and varying hydrologic conditions? 3. Are the assumptions for ecological equilibrium met for modeling plant community migration in response to sea‐level rise?Location: Albemarle Peninsula, North Carolina, USA.Methods: In situ observations were made to quantify natural pine regeneration and grass cover along a salinity stress gradient (from marsh, dying or dead forest, to healthy forest). A full‐factorial greenhouse experiment was set up to investigate mortality and carbon allocation of Pinus taeda and P. serotina to low‐salinity conditions and two hydrology treatments over 6 months. Treatments consisted of freshwater and two salinity levels (4 ppt and 8 ppt) under either permanently flooded or periodically flushed hydrologic conditions.Results: Natural pine regeneration was common (5–12 seedlings per m2) in moderate to well‐drained soils where salinity concentrations were below ca. 3.5 ppt. Pine regeneration was generally absent in flooded soils, and cumulative mortality was 100% for 4 and 8 ppt salinity levels under flooded conditions in the greenhouse study. Under weekly flushing conditions, mortality was not significantly different between 0 and 4 ppt, confirming field observations. Biomass accumulation was higher for P. taeda, but for both pine species, the root to shoot ratio was suppressed under the 8 ppt drained treatment, reflecting increased below‐ground stress.Conclusions: While Pinus taeda and P. serotina are commonly found in estuarine ecosystems, these species display a range of physiological tolerance to low‐salinity conditions. Our results suggest that the rate of forest migration may lag relative to gradual sea‐level rise and concomitant alterations in hydrology and salinity. Current bioclimate or landscape simulation models assume discrete thresholds in the range of plant tolerance to stress, especially in coastal environments, and consequently, they may overestimate the rate, extent, and timing of plant community response to sea‐level rise.
Combined transconjunctival–eyebrow approach providing minimally invasive access to all orbital quadrants
Authors: Koerbel Andrei , Ferreira Veralucia R. , Kiss André 
Published: December 2007

✓Surgical approaches to treat orbital disease should provide a good exposure of intraorbital anatomical structures, allow their functional preservation, and provide good cosmetic results. The authors describe a minimally invasive, combined transconjunctival–eyebrow approach to all orbital quadrants in a step-wise manner. The indications, advantages, and limitations of the technique are highlighted.
A transconjunctival approach via the postseptal area is described. It allows exposure of the medial, inferior, and lateral parts of the orbit. Depending on the orbital space to be exposed, a lateral or a medial eyebrow incision is then made. The eyebrow and the conjunctival incisions are connected by subperiosteal dissection. This combined access provides exposure to all intraconal muscles and to the superior, medial, lateral, and inferior portions of the optic nerve.
The combined transconjunctival–eyebrow approach provides an excellent orbital exposure, with minimal damage to the circumjacent structures. It requires less operative time than other approaches and yields good cosmetic results. Intracranial or intrafacial tumor extension and tumors located purely in the orbital apex are limitations for the use of this technique.
Orbital tumors treated using transcranial approaches: surgical technique and neuroophthalmogical results in 41 patients
Authors: Margalit Nevo , Ezer Haim , Fliss Dan M. , Naftaliev Elvira , Nossek Erez , Kesler Anat 
Published: December 2007

Object
Orbital tumors can be divided schematically into primary lesions, originating from the orbit itself, and secondary lesions, extending to the orbit from neighboring structures. These tumors are variable in their biological nature and in their location. The authors evaluate 41 cases of benign and malignant tumors involving the orbit and discuss the surgical challenge, which involves tumor removal, preserving visual function and cosmetic reconstruction.

Methods
The authors performed a retrospective analysis of a series of all cases involving patients who underwent surgery for treatment of orbital tumors in their hospital between December 2003 and December 2006. Data were collected from the patients' files in the hospital's outpatient clinic, operative notes, and pre- and postoperative imaging studies.

Results
The authors identified 41 patients who met the inclusion criteria (age range 14–82 years, mean 42.2 years, standard deviation 22.4 years). The most common presenting symptoms were proptosis and/or partial ptosis (11 cases [27%]) and headache (7 cases [17%]). In 5 (12%) cases, the tumors were primary intraorbital lesions, and in 34 cases (83%) they were secondary. Two patients had metastases to the orbit. The most common lesion types were meningioma (10 cases [24%]) and osteoma (7 cases [17%]). In 24 cases a midline approach through a frontal craniotomy or a subcranial approach was used; in 13 a lateral approach was used; and in 4 a biopsy procedure was performed. Maxillectomy through a Weber–Ferguson approach or a facial degloving approach was added in 5 cases to complete tumor removal. Duration of follow-up was 1–38 months (mean 20 months). None of the patients died as a result of the procedure, and there were relatively few complications. Excluding the patients who underwent orbital exenteration, none of the patients had visual deterioration following surgery, and most had no change in their visual condition. Two patients had temporary diplopia, 1 had a cerebrospinal fluid leak, and 1 had enophthalmos following removal of an orbital osteosarcoma.

Conclusions
Orbital tumors can be treated safely using transcranial approaches in many cases. Preoperative imaging can accurately define the compartments involved and the surgical approach needed for tumor removal. A multidisciplinary team of surgeons facilitates optimal tumor removal and skull base sealing as well as good cosmetic results.
Visual outcomes comparing surgical techniques for management of severe idiopathic intracranial hypertension
Authors: Feldon Steven E. 
Published: December 2007

Object
The object of this study was to compare surgical techniques for management of visual loss in idiopathic intracranial hypertension (IIH) unresponsive to medical treatment.

Methods
The published literature was reviewed using electronic and manual search techniques. Articles were categorized based upon the surgical procedure performed, including optic nerve sheath decompression (ONSD), also called optic nerve sheath fenestration; intracranial venous sinus stent placement; ventriculoperitoneal (VP) shunt placement; and lumboperitoneal (LP) shunt placement. Demographic data and visual outcome of the cumulative experience were compiled and compared for each type of surgical intervention.

Results
Seventeen patients treated by stent placement, 31 by VP shunt placement, 44 by LP shunt placement, and 252 patients by ONSD were identified in the literature; average follow-up ranged from 11.8 months for patients treated with stents to 57.2 months for those treated with LP shunts. Improved or resolved vision deficit was noted in 38.7% of patients after VP shunt placement, 47% of patients after stent placement, 44.6% of patients after LP shunt placement, and 80% of eyes after ONSD. Visual worsening was rare for all procedures evaluated.

Conclusions
There is a paucity of information regarding visual outcomes from intracranial venous stent placement and cerebrospinal fluid diversion procedures. Visual outcomes from ONSD are better documented and appear to be superior to other surgical techniques for management of IIH. Further studies with improved data collection regarding visual outcomes are needed for surgical procedures other than ONSD in order to assess their possible value as treatments for visual loss in IIH.
A review of ocular manifestations in intracranial hypotension
Authors: Zada Gabriel , Solomon Thomas C. , Giannotta Steven L. 
Published: December 2007

Object
Intracranial hypotension (ICH) can present with a wide variety of visual symptoms and findings. Deficits in visual acuity and visual fields as well as ophthalmoplegia due to cranial nerve dysfunction have been frequently described. The aim of this review was to identify the most commonly reported ocular manifestations associated with ICH.

Methods
The authors conducted a review of the literature to date to identify all studies of patients with ICH and ocular manifestations.

Results
The most commonly encountered cranial nerve deficit resulting from ICH (> 80% of reported cases) is an abducens nerve paresis, which may occur unilaterally or bilaterally. Although less common, oculomotor and trochlear nerve palsies have been reported as well. The optic nerve complex is frequently involved in ICH and may manifest as deficits in visual acuity and field cuts. Visual deficits and ophthalmoplegia improved following appropriate management in 97% of reported cases.

Conclusions
Intracranial hypotension can present with a wide spectrum of visual deficits, the causes of which are multifactorial. Cranial nerve paresis, especially of the abducens nerve, is frequently reported. The majority of symptoms and cranial nerve deficits reviewed respond favorably to conservative management, epidural blood patch administration, or in a minority of cases, surgical intervention.
Pyruvate–Ferredoxin Oxidoreductase
Authors: Chabriere Eric , Cavazza Christine , Contreras‐Martel Carlos , Fontecilla‐Camps Juan C. 
Published: December 2007

Abstract

Pyruvate decarboxylation in many anaerobic organisms is catalyzed by the thiamine diphosphate (ThDP)‐dependent pyruvate–ferredoxin oxidoreductase. We have determined the native structure of this ancient enzyme, as well as of several reaction intermediates, by soaking crystals in a pyruvate‐containing solution. As the reaction progresses, ThDP approaches the substrate and cleaves a CC bond generating an acetyl‐ThDP radical intermediate and CO
2
. The comparison of this structure with a similar intermediate in transketolase (TK), another ThDP‐dependent enzyme, reveals significant differences in the cofactor conformation.