bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Pasture Trees on Soil Nitrogen and Organic Matter: Implications for Tropical Montane Forest Restoration
Authors: Rhoades Charles C. , Eckert Gregory E. , Coleman David C.
Published: March 2003

In lower‐montane ecosystems of Ecuador, Setaria sphacelata (foxtail grass), the predominant introduced pasture species, forms a tussock grassland that reduces soil nitrogen and resists recolonization of forest vegetation. We compared the influence of individual trees or small clusters of nitrogen‐fixing (Inga sp., Fabaceae) and non‐nitrogen‐fixing trees (Psidium guajava L., guava) on the soil and abiotic conditions that affect further regeneration of forest vegetation within pastures. Pasture trees ameliorated air temperature and light intensity to levels similar to those in adjacent intact forest. Beneath Inga, soil NO3−‐N was four times higher than in open pasture. Nitrification was five times higher under Inga canopies than in open pastures for both field and laboratory incubations. This suggests that the increased soil N transformations under Inga are derived mainly from improved soil rather than microenvironmental conditions. Psidium canopies slightly increased field nitrification but had no effect under laboratory conditions. We also compared the natural abundance 13C signature and the carbon and nitrogen content of subcanopy soil with adjacent open pasture soil. Inga increased the C and N content of the upper 5 cm of soil and increased by 7% the fraction of soil organic matter derived from C3 plants. The improved soil and abiotic conditions beneath the canopies of N‐fixing pasture trees favor the establishment and growth of woody montane species, suggesting that these trees could be used to accelerate forest regeneration within abandoned pastures.
Deriving Restoration Goals for Acidified Lakes from Ataxonomic Phytoplankton Studies
Authors: Steinberg C. E. W. , Schäfer H. , Beisker W. , Brüggemann R.
Published: March 2003

The ataxonomic phytoplankton composition and abundance (biomass classes) in lakes of differing acidity were examined by flow cytometry. The ataxonomic parameters applied here were photosynthesis pigments and cellular protein content. Up to 1000 cells per second can be assessed by this method. Consequently, enough cells to create biomass spectra can be counted within only a few minutes. Photosynthesis pigment autofluorescence was used to separate algal cells from detritus and to classify the phytoplankton organisms into different pigment groups. Chlorophyll fluorescence ratio (CFR) at different excitation wave lengths proved to be a sensitive tool. As expected, the diversity of CFR‐determined pigment groups decreased with increasing acidification. Some groups were acid‐insensitive and occurred even at pH below 3.0. However, picoplanktic cyanobacteria (Synechoccocus/Synechocystis‐like particles [SLPs]) were absent at pHs below 4.5–4.0, with their accompanying high metal concentrations. Thus, the reappearance of cyanobacterial picoplankton may serve as a first major restoration goal in strongly acidified lakes. Protein staining using fluorescein isothiocyanate enables fast estimates of phytoplankton biomass and establishment of biomass spectra as an estimate of the integrity of plankton communities. Although the phytoplankton investigations presented are only snapshots of the situation on the sampling days, the feasibility of flow cytometrical methods for preparing phytoplankton biomass spectra has been demonstrated. The completeness of such biomass spectra, such as the presence or absence of SLP‐picoplankters, as well as the variances around regression lines (linear or parabolic), may serve as goals in restoring lakes acidified to different degrees.
Water and Nutrient Outflow Following the Ecological Restoration of a Ponderosa Pine‐Bunchgrass Ecosystem
Authors: Kaye Jason P. , Hart Stephen C. , Cobb Richard C. , Stone Joseph E.
Published: March 2003

In the late 1800s, fire suppression, livestock grazing, and a wet and warm climate led to an irruption of pine regeneration inPinus ponderosaLaws. (ponderosa pine) forests of the southwestern United States. Pines invaded bunchgrass openings, causing stand structure changes that increased the number of stand‐replacing fires. Ecological restoration, via thinning and prescribed burning, is being used to decrease the risk of stand‐replacing fires and ameliorate other effects of pine invasion. The effects of aboveground restoration on belowground processes are poorly understood. We used a hydrologic model and soil water nutrient concentrations, measured monthly below the rooting zone, to estimate restoration effects on nutrient losses by leaching from a mature ponderosa pine forest near Flagstaff, Arizona. Replicated restoration treatments included thinning to pre‐1880 stand densities (partial restoration), thinning plus forest floor fuel reduction followed by a prescribed burn (complete restoration), and an untreated control. Water outflow occurred only between January and May and was lowest from the control (47 and 28 mm in 1995 and 1996) and highest from the partial restoration treatment (67 and 59 mm in 1995 and 1996). The concentrations (typically <0.10 mg/ L) and estimated annual losses (<0.02 kg/ha) of NH4+‐N, PO43−‐P, and organic P were similar among treatments. Nitrate and organic N concentrations were as high as 0.80 mg N/L; however, these concentrations and estimated annual losses (<0.13 kg N/ha) were similar among treatments. Our results suggest that restoration will not enhance nutrient loss by leaching or alter stream chemistry in ponderosa pine forests.
A Historical Perspective and Future Outlook on Landscape Scale Restoration in the Northwest Wisconsin Pine Barrens
Authors: Radeloff Volker C. , Mladenoff David J. , Boyce Mark S.
Published: March 2003

The concurrent discussions of landscape scale restoration among restoration ecologists, and of historic disturbance pattern as a guideline for forest management among forest scientists, offer a unique opportunity for collaboration between these traditionally separated fields. The objective of this study was to review the environmental history, early restoration projects, and current plans to restore landscape patterns at broader scales in the 450,000 ha northwest Wisconsin Pine Barrens. The Pine Barrens offer an example of a landscape shaped by fire in the past. In northwestern Wisconsin historically the barrens were a mosaic of open prairie, savanna, and pine forests on very poor, sandy soils. The surrounding region of better soils was otherwise heavily forested. Six restoration sites have been managed since the middle of this century using prescribed burns to maintain the open, barrens habitat. However, these sites are not extensive enough to mimic the shifting mosaic of large open patches previously created by fire. Extensive clear‐cuts may be used as a substitute for these large fire patches so that presettlement landscape patterns are more closely approximated in the current landscape. We suggest that such silvicultural treatments can be suitable to restore certain aspects of presettlement landscapes, such as landscape pattern and open habitat for species such as grassland birds. We are aware that the effects of fire and clear‐cuts differ in many aspects and additional management tools, such as prescribed burning after harvesting, may assist in further approximating the effect of natural disturbance. However, the restoration of landscape pattern using clear‐cuts may provide an important context for smaller isolated restoration sites even without the subsequent application of fire, in this formerly more open landscape.
Translocations as a Tool for Restoring Populations of Bighorn Sheep
Authors: Singer Francis J. , Papouchis Christopher M. , Symonds Kate K.
Published: March 2003

We analyzed factors that contributed to the success of 100 translocations of bighorn sheep within six western states between 1923 and 1997. We categorized the populations as unsuccessful (i.e., extirpated or remnant, <29 animals), moderately successful (30–99 animals), and successful (100–350 animals) by the end of the study period in 1997. Thirty of the translocated populations were unsuccessful (n= 13 were extirpated andn= 17 were remnant), 29 were moderately successful, and 41 were successful (21 ± 1.3 [SE] years of information per translocation). Translocations were less successful when domestic sheep were located within 6 km of the known bighorn sheep use areas (logistic regression,p= 0.052). Grazing of cattle on the same range also negatively influenced success (p= 0.004). Use of indigenous versus previously translocated source stocks increased success (p= 0.084). The translocation was twice as likely to be successful when indigenous herds were used as sources (p= 0.043), but mixing genetic stocks (p= 0.381) or later additional augmentations did not influence success (p= 0.095). Annual migrations by newly established translocated populations increased success (p= 0.014). We recommend translocations of founder groups of bighorn sheep from indigenous sources into large patches of habitat that promote movements and migrations, and with no domestic sheep present in the area.
Effects of Disease, Dispersal, and Area on Bighorn Sheep Restoration
Authors: Gross John E. , Singer Francis J. , Moses Michael E.
Published: March 2003

We simulated population dynamics of bighorn sheep (Ovis canadensis) inhabiting six discrete habitat patches in the Badlands ecosystem, South Dakota. Modeled populations were subjected to a range of potential management actions and rates of disease‐causing infection. Simulated disease varied in severity from mild (∼12% mortality) to severe (∼67% mortality), with infections imposed once, at regular intervals, or with a fixed probability each year. In the absence of disease, 200‐year extinction rates were uniformly low and insensitive to changes in colonization rate or area of suitable habitat. A single infection, accompanied by change in the area of suitable habitat or colonization rate, resulted in extinction rates of up to 40%, and large changes in average population size (up to 10‐fold with changes in area; 4‐fold with changes in colonization rate). Simulations with multiple infections, which are probably most realistic, generally resulted in extinction rates that exceeded 20% over a 200‐year period. Model results clearly showed that efforts directed toward reducing the frequency or severity of disease are of highest priority for improving the success of attempts to restore bighorn sheep populations. Increases in areas of suitable habitat or improvements to corridors between existing habitat patches were far less likely to improve persistence of simulated sheep populations than reductions in the impact of disease. Although theory predicts that enhanced movements may exacerbate effects of disease, increased colonization rates resulted in relatively small but consistent increases in persistence and average population size for all combinations of parameters we examined.
Degraded Softwater Lakes: Possibilities for Restoration
Authors: Brouwer E. , Roelofs J. G. M.
Published: March 2003

In the Netherlands, the characteristic flora of shallow softwater lakes has declined rapidly as a consequence of eutrophication, alkalization and acidification. The sediment of most lakes has become nutrient rich and anaerobic. We expected that, if a vital seed bank was still present, restoration of the original water quality and sediment conditions would lead to the return of softwater macrophytes. The restoration of 15 degraded, shallow, softwater lakes in the Netherlands was monitored from 1983 to 1998. In eutrophied as well as in acidified lakes, removal of accumulated organic matter from the sediment and shores was followed by rapid recolonization of softwater macrophytes present in the seedbank. After isolation from alkaline water and subsequent mud removal, this recovery was also observed in alkalized lakes. Further development of softwater vegetation correlated strongly with the water quality. When renewed eutrophication was successfully prevented, softwater macrophytes could expand. However, in acidified lakes, Juncus bulbosus and Sphagnum species became dominant after restoration. Liming of an acidified lake was followed by re‐acidification within 3 years. Recolonization by softwater macrophytes was inhibited by high turbidity of the water column and spreading of large helophytes on the shore. As an alternative, controlled inlet of alkaline, nutrient‐poor groundwater was studied in a few lakes. The pH of those lakes increased, the carbon and nitrogen availability decreased and softwater macrophytes returned. Successful restoration has contributed considerably to maintaining biodiversity in softwater lakes in the Netherlands.
Achieving Restoration Success: Myths in Bottomland Hardwood Forests
Authors: Stanturf John A. , Schoenholtz Stephen H. , Schweitzer Callie Jo , Shepard James P.
Published: March 2003

Restoration of bottomland hardwood forests is the subject of considerable interest in the southern United States, but restoration success is elusive. Techniques for establishing bottomland tree species are well developed, yet problems have occurred in operational programs. Current plans for restoration on public and private land suggest that as many as 200,000 hectares could be restored in the Lower Mississippi Alluvial Valley alone. The ideal of ecological restoration is to reestablish a completely functioning ecosystem. Although some argue that afforestation is incomplete restoration, it is a necessary and costly first step but not an easy task. The 1992 Wetlands Reserve Program in Mississippi, which failed on 90% of the area, illustrates the difficulty of broadly applying our knowledge of afforestation. In our view, the focus for ecological restoration should be to restore functions, rather than specifying some ambiguous natural state based on reference stands or pre‐settlement forest conditions. We view restoration as one element in a continuum model of sustainable forest management, allowing us to prescribe restoration goals that incorporate landowner objectives. Enforcing the discipline of explicit objectives, with restoration expectations described in terms of predicted values of functions, causal mechanisms and temporal response trajectories, will hasten the development of meaningful criteria for restoration success. We present our observations about current efforts to restore bottomland hardwoods as nine myths, or statements of dubious origin, and at best partial truth.
Responses of Jeffrey Pine on a Surface Mine Site to Fertilizer and Lime
Authors: Walker R. F.
Published: March 2003

Controlled‐release fertilization with two formulations, Forestcote 22‐4‐6 + Minors and Gromax 21‐6‐2 + Minors, and dolomitic lime were evaluated for their capacity to facilitate establishment and enhance nutrition of bareroot Jeffrey pine (Pinus jeffreyiGrev. & Balf.) on an acidic Sierra Nevada surface mine. All amendments were applied at outplanting to the backfill of augered planting holes, with a low rate of 8 g and a high rate of 16 g per seedling for the two fertilizer formulations, whereas a single rate of 30 g was used for lime. Liming induced excessive seedling mortality throughout the study, whereas both fertilizer formulations also reduced survival but only as an interactive effect with the lime amendment. Growth stimulation by the fertilizer applications was readily apparent after three growing seasons, with the response to the high rate surpassing that to the low rate and the response to the Forestcote formulation exceeding that to Gromax. Conversely, the lime amendment depressed seedling growth, and it is likely that a propensity to exacerbate the stress imposed by dry growing season soils through interference with water uptake accounts for the overall poor performance of the seedlings that received this amendment. Improved N and P nutrition, with the former likely the most critical, was largely responsible for the growth stimulation resulting from fertilization. However, this treatment also suppressed the absorption of certain micronutrients as well as that of Al, and the amelioration of potential phytotoxicities may have also contributed to the favorable performance of fertilized seedlings. Further evidence for this conclusion was supplied by base cation/metallic element molar ratios involving Al and Mn, which were frequently increased by fertilization. In contrast, the influence of the lime amendment on seedling nutrition was marginal, with positive responses too infrequent to improve seedling performance.
Fifteen Years of Vegetation and Soil Development after Brackish‐Water Marsh Creation
Authors: Craft Christopher , Broome Stephen , Campbell Carlton
Published: March 2003

Aboveground biomass, macro‐organic matter (MOM), and wetland soil characteristics were measured periodically between 1983 and 1998 in a created brackish‐water marsh and a nearby natural marsh along the Pamlico River estuary, North Carolina to evaluate the development of wetland vegetation and soil dependent functions after marsh creation. Development of aboveground biomass and MOM was dependent on elevation and frequency of tidal inundation. Aboveground biomass ofSpartina alterniflora, which occupied low elevations along tidal creeks and was inundated frequently, developed to levels similar to the natural marsh (750 to 1,300 g/m2) within three years after creation.Spartina cynosuroides, which dominated interior areas of the marsh and was flooded less frequently, required 9 years to consistently achieve aboveground biomass equivalent to the natural marsh (600 to 1,560 g/m2). Aboveground biomass ofSpartina patens, which was planted at the highest elevations along the terrestrial margin and seldom flooded, never consistently developed aboveground biomass comparable with the natural marsh during the 15 years after marsh creation. MOM (0 to 10 cm) generally developed at the same rate as aboveground biomass. Between 1988 and 1998, soil bulk density decreased and porosity and organic C and N pools increased in the created marsh. Like vegetation, wetland soil development proceeded faster in response to increased inundation, especially in the streamside zone dominated byS. alterniflora.We estimated that in the streamside and interior zones, an additional 30 years (nitrogen) to 90 years (organic C, porosity) are needed for the upper 30 cm of created marsh soil to become equivalent to the natural marsh. Wetland soil characteristics of theS. patenscommunity along upland fringe will take longer to develop, more than 200 years. Development of the benthic invertebrate‐based food web, which depends on organic matter enrichment of the upper 5 to 10 cm of soil, is expected to take less time. Wetland soil characteristics and functions of created irregularly flooded brackish marshes require longer to develop compared with regularly flooded salt marshes because reduced tidal inundation slows wetland vegetation and soil development. The hydrologic regime (regularly vs. irregularly flooded) of the “target” wetland should be considered when setting realistic expectations for success criteria of created and restored wetlands.
Acid Stream Water Remediation Using Limestone Sand on Bear Run in Southwestern Pennsylvania
Authors: LeFevre Susan R. , Sharpe William E.
Published: March 2003

Instream limestone sand application is used at many sites in Pennsylvania to neutralize acidic stream water resulting from acid deposition. However, questions remain about the effectiveness of limestone sand in the treatment of acid waters, such as reduced contact time at high flow, remobilization of aluminum, and adverse effects on macroinvertebrates. A 1‐year evaluation of limestone sand application to Bear Run, an acidic stream in southwestern Pennsylvania, was begun in 1999. Another nearby acid stream, Linn Run, served as a control. Water quality during baseflow and episodic acidification events, along with fish and macroinvertebrates, were monitored to evaluate impacts of the sand application. Hydrogen ion (H+) concentration and total dissolved aluminum (TDA) were significantly reduced, and acid neutralizing capacity was significantly increased downstream of the limestone sand application compared with the upstream site on Bear Run. These parameters at the downstream sites were also different (∝ 0.10) from the comparable sites on the control stream. TDA and hydrogen ion concentrations were significantly decreased (∝ 0.10) compared with concentrations before the sand application to Bear Run but not on the control stream. No fish were present upstream of the sand application site, and only a few fish were found downstream at the mouth of Bear Run. Standing crop, number of taxa, and Shannon‐Weaver diversity index values indicated that macroinvertebrate populations were negatively impacted 300 m downstream from the sand application and improved at the site 1,600 m downstream. Although water quality was improved on Bear Run, benefits to macroinvertebrates depended on downstream location, and fish populations did not show improvement.
Modeling Habitat Change in Salt Marshes After Tidal Restoration
Authors: Boumans R. M. J. , Burdick D. M. , Dionne M.
Published: March 2003

Salt marshes continue to degrade in the United States due to indirect human impacts arising from tidal restrictions. Roads or berms with inadequate provision for tidal flow hinder ecosystem functions and interfere with self‐maintenance of habitat, because interactions among vegetation, soil, and hydrology within tidally restricted marshes prevent them from responding to sea level rise. Prediction of the tidal range that is expected after restoration relative to the current geomorphology is crucial for successful restoration of salt marsh habitat. Both insufficient (due to restriction) and excessive (due to subsidence and sea level rise) tidal flooding can lead to loss of salt marshes. We developed and applied the Marsh Response to Hydrological Modifications model as a predictive tool to forecast the success of management scenarios for restoring full tides to previously restricted areas. We present an overview of a computer simulation tool that evaluates potential culvert installations with output of expected tidal ranges, water discharges, and flood potentials. For three New England tidal marshes we show species distributions of plants for tidally restricted and nonrestricted areas. Elevation ranges of species are used for short‐term (<5 years) predictions of changes to salt marsh habitat after tidal restoration. In addition, elevation changes of the marsh substrate measured at these sites are extrapolated to predict long‐term (>5 years) changes in marsh geomorphology under restored tidal regimes. The resultant tidal regime should be designed to provide habitat requirements for salt marsh plants. At sites with substantial elevation losses a balance must be struck that stimulates elevation increases by improving sediment fluxes into marshes while establishing flooding regimes appropriate to sustain the desired plants.
An Analysis of Forest Restoration 120 Years after Reforestation on Badlands in the Southwestern Alps
Authors: Vallauri Daniel R. , Aronson James , Barbero Marcel
Published: March 2003

We report the results of descriptive and functional analyses of a representative forest and watershed in the southwestern Alps, where the Forest Service has attempted reforestation of badlands for erosion control since 1860, relying on the non‐nativePinus nigrassp.nigra(Austrian black pine). One hundred twenty years after the first tree plantings, the plant communities are still early seral assemblages for the most part, with Austrian black pine occurring alone in the canopy. In contrast, most of the marly soils have physically recovered part of their total depth, with layers of fragmented and altered material equal to 50 cm, but their structure and chemical fertility is still poor. Autogenic soil restoration is proceeding however, largely engineered by earthworms (up to 49 individuals and 27 g/m2). Two dominant species are presumed keystone:Lumbricus terrestrisandOctolasion cyaneum(Lumbricidae). The reestablishment of indigenous tree species is apparently not inhibited by site fertility or lack of nearby seed pools. We hypothesize that excessive stand density is responsible for the poor regeneration because it discourages the birds and rodents that control seed dissemination. Mortality of pines due to infestation byViscum albumsubsp.austriacum(mistletoe) is creating large openings and should be specially managed. One hundred twenty years after the first plantings, the nineteenth‐century vision that restoration of badlands was ecologically feasible is validated, as is the strategy to establish pioneer tree species. Here Austrian black pine acts as a nurse stand and enables the return of indigenous broad‐leaved trees and a wide array of herbaceous species as well. However, our results clearly indicate that appropriate silvicultural tactics should now consist of tree thinning to promote the true restoration of native biodiversity and ecosystem functions.
Drainage and Elevation as Factors in the Restoration of Salt Marsh in Britain
Authors: Crooks Stephen , Schutten Johan , Sheern Glenn D. , Pye Kenneth , Davy Anthony J.
Published: March 2003

Intertidal restoration through realignment of flood defenses has become an important component of the U.K. coastal and estuarine management strategy. Although experimentation with recent deliberate breaches is in progress, the long‐term prognosis for salt marsh restoration can be investigated at a number of sites around Essex, southeast England where salt marshes have been reactivated (unmanaged restoration) by storm events over past centuries. These historically reactivated marshes possess higher creek densities than their natural marsh counterparts. Both geomorphology and sedimentology determine the hydrology of natural and restored salt marshes. Elevation relative to the tidal frame is known to be the primary determinant of vegetation colonization and succession. Yet vegetation surveys and geotechnical analysis at a natural marsh, where areas with good drainage exist in close proximity to areas of locally hindered drainage at the same elevation, revealed a significant inverse relationship between water saturation in the root zone and the abundance of Atriplex portulacoides, normally the physiognomic dominant on upper salt marsh in the region. Elsewhere in Essex natural and restored marshes are typified by very high sediment water contents, and this is reflected in low abundance of A. portulacoides. After a century of reestablishment no significant difference could be discerned between the vegetation composition of the storm‐reactivated marshes and their natural marsh counterparts. We conclude that vegetation composition may be restored within a century of dike breaching, but this vegetation does not provide a reliable indicator of ecological functions related to creek structure.
Use of Restored Small Wetlands by Breeding Waterfowl in Prince Edward Island, Canada
Authors: Stevens C. E. , Gabor T. S. , Diamond A. W.
Published: March 2003

AbstractSince 1990 under the Eastern Habitat Joint Venture over 100 small wetlands have been restored in Prince Edward Island, Canada. Wetlands were restored by means of dredging accumulated sediment from erosion to emulate pre‐disturbance conditions (i.e., open water and extended hydroperiod). In 1998 and 1999 we compared waterfowl pair and brood use on 22 restored and 24 reference wetlands. More pairs and broods of Ring‐necked Ducks, Gadwall, Green‐winged Teal, and American Black Ducks used restored versus reference wetlands. In restored wetlands waterfowl pair density and species richness were positively correlated with wetland/cattail area, percent cattail cover, and close proximity to freshwater rivers. In addition, a waterfowl reproductive index was positively correlated with percent cattail cover. Green‐winged Teal pair occurrence in restored wetlands was positively correlated with greater amounts of open water and water depths. American Black Duck pairs occurred on most (86%) restored wetlands. Restored small wetlands likely served as stopover points for American Black Duck broods during overland or stream movements, whereas they likely served as a final brood‐rearing destination for Green‐winged Teal broods. We suggest that wetland restoration is a good management tool for increasing populations of Green‐winged Teal and American Black Ducks in Prince Edward Island.
Convergence Between Dung Beetle Assemblages of a Post‐Mining Vegetational Chronosequence and Unmined Dune Forest
Authors: Davis Adrian L. V. , Van Aarde Rudi J. , Scholtz Clarke H. , Delport Jaco H.
Published: March 2003

AbstractIn Maputaland, South Africa vegetative and microclimatic changes on mined dunes drive the composition of the dung beetle fauna toward convergence with that in natural dune forest on unmined dunes. We assessed the pattern of these changes using a 23‐year vegetational chronosequence on mined dunes, which passes from grassland (approximately 1 year) to openAcaciashrubland thicket toAcacia karroo‐dominated woodland (approximately 9 years). Across this sequence, which represents successional stages in the restoration of dune forest, there was a sequential trend toward convergence in dung beetle species composition in both the entire species complement and, particularly, in shade specialist species. However, species abundance patterns showed a trend toward convergence only in early chronosequenceAcaciawoodland, followed by a decline in similarity between dung beetle assemblages of olderAcaciawoodland and unmined natural forest. This trend toward divergence was common both to the entire species complement, which includes widespread taxa, and to species endemic to Maputaland or the east coast. These trends in similarity and dissimilarity between dung beetle assemblages closely parallel the greater physiognomic and microclimatic similarity between earlyAcaciawoodland and natural forest and the relative dissimilarity of olderAcaciawoodland. In conclusion, although percentage similarities between dung beetle assemblages of approximately 12‐year woodland and natural forests were comparable with those between each natural forest stand, decline in similarity in older woodland stands suggests that lasting convergence in dung beetle species abundance will only be attained once theAcaciawoodland is replaced by secondary natural forest.
Increased CML Deposition, Rage Expression, And NF‐κB Activation In Diabetic Neuropathy
Authors: Bierhaus A , Haslbeck Km , Morcos M , Schiekofer S , Andrassy M , Chen J , Humpert PM , Möller W , Tritschler H , Dehmer T , Neundörfer B , Heuss D , Schwaninger M , Häring H‐U , Schleicher E , Nawroth Pp
Published: March 2003

There is growing evidence that upregulation of NF ‐ κB‐controlled adhesion molecules and cytokines contributes to neuropathic pain and diabetic neuropathy. Since AGE/RAGE‐interactions activate NF ‐ κB, we asked whether deposition of the defined AGE‐adduct CML, upregulation of RAGE, and NF ‐ κB activation is evident in peripheral nerves in human and animal models of diabetes mellitus. When immunohistology was performed on sural nerve biopsies from diabetic patients, local accumulation of CML, prominent upregulation of RAGE and strong activation of NF ‐ κB was observed in the perineurium and the vascular endothelium. This colocalisation was not observed in control patients. Schwann cells also demonstrated increased RAGE expression, but no staining for CML and NF ‐ κB. In mouse models of diabetes mellitus, histological examination confirmed upregulation of NF ‐ κB in the perineurium, but was also evident in Schwann cells. In the mouse model, NF ‐ κB activation could be reversed by the antioxidant α‐lipoic acid. These data demonstrate that NF ‐ κB activation occurs in hyperglycemia, but affects different neuronal cells in human and mice. Hyperglycemia dependent activation of NF‐κB results in enhanced NF ‐ κB dependent gene expression in transgenic mice, carrying a β‐globin reporter transgene controlled by NF ‐ κB. Infusion of AGE‐albumin also led to induction of the β‐globin‐gene and could be blocked in the presence of soluble RAGE, neutralizing anti‐RAGE‐antibodies and α‐lipoic acid. These studies provide evidence that the AGE‐RAGE‐NF‐κB axis is upregulated in diabetic neuropathy. NF ‐ κB‐activation and subsequent induction of NF ‐ κB‐dependent gene expression can be reduced by treatment with α‐lipoic acid.
Is There A Relationship Between Baroreflex Sensitivity, Cardiac Autonomic Function And Cardiac Repolarisation In Type 1 Patients?
Authors: Harris Nd , Lee Spc , Yeoh Ls , Leathard A , Heller Sr
Published: March 2003

Established diabetic autonomic neuropathy (DAN) carries a poor prognosis, with an increased risk of sudden death. Recently, baroreflex sensitivity (BRS) has been proposed as a sensitive marker of autonomic function in diabetes (DM). An association between DAN and abnormal cardiac repolarisation, manifest by increases in QT interval and/or QT dispersion on the ECG, has also been described. The aim of this study was to investigate the relationship between BRS and QT parameters. We have studied 28 Type 1 DM subjects (age 39 ± 10yrs (mean ± SD), DM duration 14 ± 11yrs, HbA1c 8.5 ± 1.3%) with normal cardiac autonomic function tests (DAN–) and 8 subjects (age 49 ± 13yrs, duration 22 ± 9yrs, HbA1c 9.5 ± 1.1%) with abnormal tests using standard criteria (DAN+). We measured supine BRS using sequence analysis of systolic blood pressure and pulse interval. Rate‐corrected QT (QTc) interval was measured using a high‐resolution ECG system, and QT dispersion from a 12‐lead ECG recorded at 50mm/s. Results are summarised below.

Regression analysis revealed no correlation between BRS and QTc interval or QT. In summary, DAN+ patients had significantly lower BRS (p < 0.001) and increased QT dispersion (p < 0.01) compared to DAN− subjects, but no difference in QTc. In contrast to BRS, changes in QTc and QT dispersion may occur relatively late in the disease.

BRS ms/mmHg
QTc interval
QT dispersion

DAN−
12.7 ± 6.6 (n=28)
411 ± 22 ms (n=28)
38 ± 12 ms (n=28)

DAN+
3.9 ± 1.9 (n=8)
409 ± 22 ms (n=8)
54 ± 12 ms (n=6)
Vibration Perception Thresholds: Comparison Of Case IV And Neurothesiometer Measurements
Authors: Bril V , Perkins Ba
Published: March 2003

Purpose: Vibration perception thresholds (VPT) are used frequently to assess somatosensory pathways in clinical trials. Different equipment, testing paradigms, and stimulation sites produce varying results which make comparisons between trials and patient populations challenging. Information comparing the VPT obtained with the Neurothesiometer to that with the Vibratron is available, but not for a similar comparison with the CASE IV1. Methods: 478 subjects including reference, non‐neuropathic subjects with diabetes mellitus (DM), and diabetic patients with mild, moderate and severe neuropathy had VPT measured with the CASE IV and Neurothesiometer, as well as the criterion standard sural nerve conduction studies all on the same day. The dorsum of the foot was stimulated for the CASE IV determination and the distal phalanx of the first toe for the Neurothesiometer. Results: VPT by the CASE IV correlate with the Neurothesiometer values (R2 = 0.547, p < 0.0001). VPT determined by both Neurothesiometer and CASE IV correlate with the sural nerve amplitude (R2 = 0.456 and 0.461, P < 0.0001 for both). Conclusions: Results demonstrate a significant correlation of VPT values obtained by the two methods. Similar correlations between VPT and electrophysiological parameters are observed indicating that both methods are valid, and thus the Neurothesiometer is favored due to the ease and rapidity of testing by this method.

1 Bril V, Kojic J, Ngo M, Clark K. (1997). Comparison of the Neurothesiometer and Vibratron in Measuring Vibration Perception Threshold and Relationship to Nerve Conduction Studies. Diabetes Care, 20:1360–1362.
Hyperalgesia In Diabetic Rats Is Alleviated By A Prosaposin‐Derived Peptide
Authors: Freshwater J , Calcutt Na
Published: March 2003

The saposin C‐derived peptide TX14(A) prevents onset of functional and structural disorders in the peripheral nerve of diabetic rats. We have now investigated the ability of TX14(A) to alleviate behavioral indices of abnormal pain perception in adult female rats 4‐6 weeks after onset of STZ‐induced diabetes. Untreated diabetic rats exhibited tactile allodynia (response threshold = 3 ± 1 g) compared to age‐matched controls (10 ± 1g). A single ip injection of TX14(A) transiently alleviated tactile allodynia, with an effect that was maximal 6 hours (11 ± 1g) after injection and diminished within 48 hours. Maximal efficacy was seen with a 1 mg/kg dose while no effects were noted in control rats. Control rats exhibited a transient thermal hyperalgesia (77 ± 5% of baseline paw withdrawal latency) 15 minutes after intrathecal delivery of substance P (30 nmol) that resolved within 30 minutes. Untreated diabetic rats exhibited substance P evoked thermal hyperalgesia of similar magnitude (82 ± 5% at 15 minutes) but of greater duration (83 ± 4% at 1 hour). Intrathecal delivery of TX14(A) 30 minutes before intrathecal substance P was without effect on the transient thermal hyperalgesia in control rats (74 ± 9% at 15 minutes). In diabetic rats, the prolonged thermal hyperalgesia was abolished by prior intrathecal delivery of TX14(A), although the transient thermal hyperalgesia (72 ± 8% at 15 minutes) remained. These studies show that TX14(A) can rapidly allevate diabetes‐induced allodynia and hyperalgesia for up to 48 hours.
Aldose Reductase‐Deficient Mice Are Protected From Reduction Of Nerve Conduction Associated With Diabetes
Authors: Ho Ecm , Lam Ksl , Chung Ssm , Chung Sk
Published: March 2003

Previously, we have shown that aldose reductase (AR) mRNA is strongly expressed by Schwann cells and not expressed by the endothelial cells in the sciatic nerve. Additional over‐expression of AR in the Schwann cells lead to further reduction of motor nerve conduction velocity (MNCV) in diabetic and more prominently in galactosemic mice, suggesting AR's contribution to hyperglycemic and galactosemic lesions in the nerve. Here, we report the deletion of AR gene in mice to study its physiological functions and to understand its role in the pathogenesis of diabetic neuropathy. The homozygous AR‐deficient mice showed no apparent developmental or reproductive abnormalities except they drink and urinate significantly more than their wildtype littermates due to a partially defective urinary concentrating ability. These AR knockout mice are then converted to become diabetic by streptozotocin (STZ) treatment to determine the effects of AR‐deficiency on the MNCV. The diabetic mice, whether they are AR deficient or wildtype mice, drank and urinated similarly. Whereas the wildtype showed significant reduction in MNCV after 4 weeks of STZ treatment (p < 0.01), the AR‐deficient mice did not show any significant reduction in MNCV. Interestingly, the AR‐deficient mice have less body weight reduction after 4 weeks of diabetes compared to those of wildtype mice treated to STZ (p < 0.05) suggesting that AR deficiency has an overall beneficial effect on diabetic mice.
Diabetic Neuropathy: Pathogenetic Mechanisms And Treatment Implications
Authors: Low Pa , Nickander Kk , Kihara M , Schmelzer Jd , Nagamatsu M , Sasaki H , H‐J Tritschler
Published: March 2003

Chronic hyperglycemia underlies the pathogenesis of diabetic neuropathy (DN). Recent research emphasizes the roles of ischemia‐hypoxia, oxidative stress, glycation, ω6 fatty acid metabolism and the interacting roles of excessive lipolysis, hyperactive polyol pathway and PKC activity and deficiencies of growth factors. In DN, oxidative stress is due primarily to nerve ischemia and auto‐oxidation/glycation, but all the above mechanisms are interactive and all can cause oxidative stress. Oxidative stress appears to be a particularly important mechanism in the pathogenesis of DN. Antioxidant enzymes are reduced in peripheral nerve and are further reduced in DN. That lipid peroxidation will cause neuropathy is supported by the development of neuropathy de novo when normal nerve is rendered α‐tocopherol deficient. Recent studies emphasize the prominent pathological alterations in dorsal root ganglion (DRG) and nerve roots of experimental DN. DRG mitochondrial cytopathy is suggested to result. Histochemical studies of DRG shows defective respiratory enzyme activity, TUNEL staining and caspase‐3 immunostaining, suggesting apoptosis, especially apoptosis lente, a process that results in impairment of funtion with modest and slow cellular loss. These pathogenetic observations have spawned clinical trials with aldose reductase inhibitors, growth factor, protein glycation, γ‐linolenic acid, PKC‐β, and α‐lipoic acid. Clinical trials on human diabetic neuropathy have been underpowered, especially with the short duration of the studies. Treatment with antioxidants have been especially efficacious in experimental diabetes, mainly in a preventive role. In established human DN, a minimum of 2 years is likely required to demonstrate benefit. A 4 year study of α‐lipoic acid in human DN is underway.
Future Progress In Diabetic Neuropathy
Authors: Ward Jd
Published: March 2003

Over three decades much knowledge regarding the pathogenesis of diabetic neuropathy has been gathered but sadly this has led to very little understanding. This final review lecture of the symposium will attempt to analyse why progress has been so slow and look to the future for signs of inventive improvement. Papers presented during the symposium will be reviewed to allow estimate of future success and where perhaps efforts should be focused. At present the best we can do for our patients is to control blood glucose as rigidly as possible for preventative therapy and logical interventional drugs are not available. Hopefully the symposium will provide new insights into future investigations and potential pathways.
Age‐Induced Neuropathy In Rats
Authors: Yagihashi S , Nishizawa Y , Baba M , Takeuchi M.
Published: March 2003

We studied the effects of exogenously administered advanced glycation end‐products (AGE) on the peripheral nerve function and structure in normal rats. Normal Wistar rats aged 6 weeks were injected intraperitoneally with purified AGE (20 mg/kg/day) produced by incubation of glucose with bovine serum albumin (BSA) for 12 weeks. Control rats were treated with BSA alone. One of AGE‐treated groups was co‐treated with 50 mg/kg aminoguanidine (AG). During the experimental period, body weight and blood glucose levels were not affected in AGE‐treated rats. Serum AGE levels were elevated two fold in AGE‐treated group whereas BSA treated rats maintained normal levels, whereas tissue AGE levels in sciatic nerve were not increased in treated group. AG did not alter the levels of serum AGE. AGE‐treated rats exhibited significant delay of motor nerve conduction velocity by 30% and reduction of sciatic nerve in Na,K‐ATPase activity by 25% in AGE‐treated rats. AG treatment significantly inhibited these changes. Immunostains on the cross‐sections of sciatic nerve demonstrated significant increase in cells positive for 8 hydroxy‐deoxyguanosine, a marker of oxidative stress‐induced DNA injury, in AGE‐treated group. AG treatment significantly inhibited this reaction. There was no difference in morphometric data on myelinated fibers in sural nerve among the experimental groups. AGE‐injected rats thus showed the neuropathic changes, similar to those found in experimentally‐induced diabetic animals and it is therefore suggested that AGE have a pathogenetic role in the development of diabetic neuropathy through induction of excessive oxidative stress.

Supported by Juvenile Diabetes Foundation International (1‐2000‐263), Japan Diabetes Foundation, Japanese Ministry of Science, Education, Sports and Culture.
Microcirculatory Responses To Electrical Spinal Cord Stimulation In Painful Diabetic Neuropathy And Other Painful Conditions
Authors: Harris Nd , Eaton Sem , Selmi F , Patel Ka , MacFarlane Ia , Ward Jd , Tesfaye S.
Published: March 2003

Electrical spinal cord stimulation (ESCS) has been used to provide pain relief in a number of conditions, including painful diabetic neuropathy (PDN). ESCS has also been shown to increase microvascular blood flow in peripheral vascular disease. If nerve hypoxia contributes to pain in PDN, ESCS may relieve this by increasing nerve blood flow. We have therefore investigated skin and sural nerve microvascular responses to ESCS. We studied subjects implanted with ESCS for pain relief, 4 had PDN and 7 were controls with other painful conditions. Blood flow, before and during stimulation, was assessed using Laser Doppler flowmetry. Only one (PDN) subject showed a statistically significant increase in skin blood flow during stimulation. The three remaining PDN subjects showed significant reductions in skin blood flow, as did 3/7 of controls. Sural nerve blood flow was measured on a separate occasion. During stimulation nerve blood flow increased in 1 (control) subject, decreased in 1 (PDN) subject and did not change in the other 5 tested (3 PDN and 2 control). In summary, ESCS did not produce any consistent increase in skin or nerve microvascular blood flow. ESCS reduces pain in a variety of different conditions, however this does not appear to be mediated by changes in blood flow. Until a thorough understanding of the pathogenic mechanisms causing PDN is achieved, therapy will be limited to providing symptomatic relief.
Peripheral And Central Conduction Abnormalities In Diabetes Mellitus
Authors: Suzuki C , Ozaki I , Tanosaki M , Baba M.
Published: March 2003

Objectives: To investigate peripheral and central somatosensory conduction in diabetic patients. Methods: We recorded sensory nerve action potentials and 5‐channel somatosensory evoked potentials (SEPs) with non‐cephalic reference after median nerve stimulation in 55 diabetic patients and 41 age/height matched normal subjects. We determined onset latencies of the spinal N13‐P13 and the cortical N20‐P20 components, and obtained the central conduction time (CCT). Results: Onset latencies of all SEP components were prolonged in diabetic patients. The mean onset CCT in the diabetic group was 6.3 ± 0.5ms (mean ± SD), being significantly longer than that in the control group (6.1 ± 0.2 ms). The peripheral sensory conduction velocity was also decreased in the diabetic group, but there was no significant correlation between peripheral conduction slowing and the onset CCT prolongation. Conclusions: Diabetes affects conductive function in the central as well as peripheral somatosensory pathways. The CCT abnormality does not coincide with lowering of the peripheral sensory conduction. The present results do not favor the hypothesis that a central‐peripheral distal axonopathy plays an important role in development of diabetic polyneuropathy.