Natural Recovery Process Research Articles

Especies de hormigas del suelo en el Parque Nacional Natural Gorgona, Pacífico Colombiano

Gorgona is one of the two insular areas of the Colombian tropical rain forest at the Pacific and is amongst the most diverse biogeographic regions of the world, the Choco. This study compiles information on ant species from published (1991) and unpublished (2006) studies and provides new records for ant species collected in 2010. Ants were sampled and information was obtained from 15 sites in Gorgona island (13.82km2), including the Gorgonilla atoll (0.49km2). Collecting methods included pitfall traps, tuna baits, mini-Winkler extraction of leaf litter, Malaise traps, entomological net and direct search. The soil and understory ant inventory resulted in 107 ant species and morphospecies, 46 genera in 12 subfamilies. Myrmicinae held the highest species richness (37 species), followed by Ponerinae (27) and Formicinae (12). The richest genera were Pachycondyla (15 species), Camponotus (nine) and Pheidole (eight), while 30 genera were represented by a single species. Twelve species were very common (both in distribution and time): Azteca sp., Atta cephalotes, Camponotus sericeiventris, Eciton vagans, Ectatomma goninion, Gnamptogenys annulata, Odontomachus bauri, Pachycondyla bugabensis, P. harpax, P. verenae, Paraponera clavata and Wasmannia auropunctata. Direct search was the most efficient method to collect diferent species and was responsible for 52% of the total species found. Compared to other Neotropical islands, Gorgona holds a suprisingly high number of ant species, none of them invasive. The invasive Monomorium floricola, which was collected 20 years ago, was not found in 2010. These evidences suggest that ecological mechanisms and natural recovery processes in the ecosystem have generated microhabitats allowing their coexistence. Rev. Biol. Trop. 62 (Suppl. 1): 265-276. Epub 2014 February 01.

Histological Quantification of Angiogenesis after Focal Cerebral Infarction: A Systematic Review

Ischemic stroke is a leading cause of disability, and current treatments to improve recovery are limited. Part of the natural recovery process after brain injury is angiogenesis. The formation of new blood vessels around the infarct appears to be important for restoration of adequate perfusion to allow for healing of brain tissue. Many potential restorative treatments may affect, and be affected by, angiogenesis, so accurate quantification of this outcome is needed. We performed a systematic review of histological methods to quantify angiogenesis after cerebral infarction. We found reports of the use of a variety of histological and general and immunostaining techniques in conjunction with a variety of analysis methods. We found no direct comparison studies and concluded that more research is needed to optimize the assessment of this important stroke outcome.

Restoration recovers population structure and landscape genetic connectivity in a dispersal‐limited ecosystem

SummaryEcological restoration assists the recovery of degraded ecosystems; however, restoration can have deleterious effects such as outbreeding depression when source material is not chosen carefully and has non‐local adaptations.We surveyed 23 eelgrass (Zostera marinaL.) populations along the North American Atlantic coast to evaluate genetic structure and connectivity among restored and naturally recruited populations.While populations along the North America Atlantic coast were genetically distinctive, significant migration was detected among populations. All estimates of connectivity (FST, migration rate base on rare alleles, and Bayesian modelling) showed a general north to south pattern of migration, corresponding to the typical long‐shore currents in this region.Individual naturally recruited meadows in the Virginia coastal bays appear to be the result of dispersal from different meadows north of the region. This supports the hypothesis that recruitment into this region is typically a slow, episodic process rather than a permanent, continuous connection between the populations.While natural recovery of populations that were catastrophically lost in the 1930s has been slow, large‐scale seed‐based restoration has been very successful at quickly restoring landscape‐scale areal coverage (over 1600 ha in just 10 years). Our results show that restoration was also successful at restoring meadows with high genetic diversity. Naturally recruited meadows were less diverse and exhibited signs of genetic drift.Synthesis. Our analyses demonstrate that metapopulation dynamics are important to the natural recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales; however, natural recovery processes are slow and inefficient at recovering genetic diversity and population structure when recruitment barriers exist, such as a limited seed source. Seed‐based restoration provides a greater abundance of propagules, rapidly facilitates the recovery of populations with higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. First‐order estimates indicated that the genetic diversity achieved by active restoration in 10 years would have otherwise taken between 125 and 185 years to achieve through natural recruitment events.

Harnessing Natural Recovery Processes to Improve Restoration Outcomes: An Experimental Assessment of Sponge-Mediated Coral Reef Restoration

BackgroundRestoration is increasingly implemented to reestablish habitat structure and function following physical anthropogenic disturbance, but scientific knowledge of effectiveness of methods lags behind demand for guidelines. On coral reefs, recovery is largely dependent on coral reestablishment, and substratum stability is critical to the survival of coral fragments and recruits. Concrete is often used to immobilize rubble, but its ecological performance has not been rigorously evaluated, and restoration has generally fallen short of returning degraded habitat to pre-disturbance conditions. Fragments of erect branching sponges mediate reef recovery by facilitating rubble consolidation, yet such natural processes have been largely overlooked in restoring reefs.MethodsOn two reefs in Curacao, four treatments - coral rubble alone, rubble seeded with sponge fragments, rubble bound by concrete, and concrete “rubble” bound by concrete - were monitored over four years to investigate rubble consolidation with and without sponges and the ecological performance of treatments in terms of the number and diversity of coral recruits. Species specific rates of sponge fragment attachment to rubble, donor sponge growth and tissue replacement, and fragment survival inside rubble piles were also investigated to evaluate sponge species performance and determine rates for sustainably harvesting tissue.Findings/SignificanceRubble piles seeded with sponges retained height and shape to a significantly greater degree, lost fewer replicates to water motion, and were significantly more likely to be consolidated over time than rubble alone. Significantly more corals recruited to sponge-seeded rubble than to all other treatments. Coral diversity was also greatest for rubble with sponges and it was the only treatment to which framework building corals recruited. Differences in overall sponge species performance suggest species selection is important to consider. Employing organisms that jump start successional pathways and facilitate recovery can significantly improve restoration outcomes; however, best practices require techniques be tailored to each system.

Recycling of Cellulose Ethers from Skim Natural Rubber Recovery Process

Recycling of Cellulose Ethers from Skim Natural Rubber Recovery Process

Monitoring vegetation recovery after China's May 2008 Wenchuan earthquake using Landsat TM time‐series data: a case study in Mao County

AbstractThe Wenchuan earthquake (Richter scale 8) on 12 May 2008 in southwestern China caused widespread ecosystem damage in the Longmenshan area. It is important to evaluate natural vegetation recovery processes and provide basic information on ecological aspects of the recovering environment after the earthquake. To circumvent the weather limits of remote sensing in the Wenchuan earthquake‐hit areas, and to meet the need for regional observation analyses, three Landsat TM images pre‐ and post‐earthquake in Mao County were used for analysis. Post‐earthquake normalized difference vegetation index (NDVI) values were compared to pre‐earthquake values with an NDVI‐based index differencing method to determine the extent to which the vegetation was damaged in relation to the pre‐earthquake pattern, and the rate of recovery was evaluated. The spatial characteristics of vegetation loss and natural recovery patterns were analyzed in relation to elevation, slope and aspect. The results indicated that severely damaged sites occurred mainly in river valleys, within a range of 1,500–2,500 m elevation and on slopes of 25–55°. The distance from rivers, rather than the distance from active faults, controls the damage patterns. After 1 year of natural regeneration, 36 % of the destroyed areas showed a decrease in NDVI value, 28.8 % showed very little change, 19.1 % showed an increase, and 16.1 % also increased with a recovery rate greater than 100 %. Moreover, there is a good correlation between recovery rate and both slope and elevation, but recovery patterns in the damaged area are complicated. Our results indicate that natural recovery in this arid valley is a slow process.

How predictable is the response of ant assemblages to natural forest recovery? Implications for their use as bioindicators

Environmental indicators can be used to evaluate natural recovery processes. Although several studies have used ant assemblage metrics as environmental indicators, few try to explain the response of these insect assemblages to forest recovery. Thus, we carried out a vertical ant sampling design to verify the sensitivity of ant assemblages from different microhabitats (epigeic, arboreal and hypogeic) to natural forest recovery. We also verified whether changes to the diversity measures (species richness, composition and evenness) of these assemblages could be predictable and explained by changes in the resource quantity and conditions, and structural and resource heterogeneity that also occur along the natural forest recovery gradient. Additionally, we verified the potential of ant species as indicators of forest recovery. We sampled ants in a pasture and seven forest remnants with different recovery times that represent a forest recovery gradient along a chronosequence. Although, the non response of species richness and evenness, species composition changed along the recovery gradient and the dissimilarity between the ant species composition of pasture and forest habitats increased with the age of the forest remnant. This was supported by ant species indicators of pasture and forest areas pointed out by the IndVal test. The variation of ant species composition of the two groups of habitat types (pasture and forest) could be explained by the different responses of open habitat and forest specialist ants to the increase in vegetation cover along the recovery gradient. Therefore, species composition and indicator species by habitat type seems to be the most predictable data for the use of ants in environmental monitoring programs.

Investigation of Ghosting Recovery Mechanisms in Selenium X-ray Detector Structures for Mammography

The ghosting recovery mechanisms in multilayer selenium X-ray detector structures for mammography are experimentally and theoretically investigated. The experiments have been carried out under low positive applied electric field <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$(\sim 1\ {\rm V}/\mu{\rm m})$</tex></formula> . A ghost removal technique is investigated by reversing the bias polarity during the natural recovery process. The theoretical model considers accumulated trapped charges and their effects (trap filling, recombination, detrapping, structural relaxation and electric field dependent electron-hole pair creation), and effects of charge injection from the metal contacts. Carrier trapping in both charged and neutral defect states has been considered in the model. It has been found that the X-ray induced deep trap centers are charged defects. A faster sensitivity recovery is found by reversing the bias during the natural recovery process. During the reverse bias, a huge number of carriers are injected from the metal contacts, and fill the existing trap centers. This results in an abrupt recovery of the relative sensitivity. However, the relative sensitivity slightly decreases with time after this abrupt recovery due to the release of the trapped electrons as well as the long recovery time of the induced trap centers. The theoretical model shows a very good agreement with the experimental results.

Design and Optimization of Natural Gas Liquefaction and Recovery Processes for Offshore Floating Liquefied Natural Gas Plants

A natural gas liquefaction and liquid recovery sequence is proposed for top-side offshore floating liquefied natural gas processing. During liquefaction, a single mixed refrigerant is separated into heavy and light key components, separately compressed after the main cryogenic heat exchanger and then mixed again to make a single mixed refrigerant. The proposed liquefaction cycle has a simple, compact structure and is suitable for power-efficient, offshore, floating liquefied natural gas liquefaction. The natural gas liquid recovery process employs space- and energy-efficient dividing wall columns for the integration of depropanization and debutanization. The columns were optimized by response surface methodology. A compact top dividing wall column configuration could reduce total annual costs. A combined process integrating natural gas liquefaction and liquid recovery is finally proposed.

Soil and vegetation recovery after a well blowout and salt water release in northeastern British Columbia

Leskiw, L. A., Sedor, R. B., Welsh, C. M. and Zeleke, T. B. 2012. Soil and vegetation recovery after a well blowout and salt water release in northeastern British Columbia. Can. J. Soil Sci. 92: 179–190. The impact of brine release on soil and vegetation due to a gas well blowout in December 1999 near Fort Nelson, British Columbia was evaluated over a 10 year period. The objectives were to study spatial and temporal distribution of soil salinity and vegetation and determine whether reclamation would occur through a natural recovery process. Soil salinity and vegetation diversity indices were measured on six study sites and one control. Average electrical conductivity declined with time from approximately 3.0 dS m−1 and has remained below 2.0 dS m−1 since 2002. Cycling of ions between leaf litter and plant tissue resulted in high variability in topsoil electrical conductivity. Sodium adsorption ratio in the leaf litter and A horizons was low (&lt;7), but remained high in B and C horizons (&gt;14) after 2004. From 2002 to 2010 moss cover increased 40%, whereas shrubs decreased 30%. The most impacted plot showed higher diversity than the least impacted plots and the control (Shannon diversity index = 1.49, 1.36, 1.11 for most impacted, least impacted and control, respectively). Soil and vegetation indicated salt-affected plots were recovering naturally. Results from this study could potentially provide guidelines for future remediation and reclamation practices.

Soil and vegetation recovery after a well blowout and salt water release in northeastern British Columbia

Leskiw, L. A., Sedor, R. B., Welsh, C. M. and Zeleke, T. B. 2012. Soil and vegetation recovery after a well blowout and salt water release in northeastern British Columbia. Can. J. Soil Sci. 92: 179-190. The impact of brine release on soil and vegetation due to a gas well blowout in December 1999 near Fort Nelson, British Columbia was evaluated over a 10 year period. The objectives were to study spatial and temporal distribution of soil salinity and vegetation and determine whether reclamation would occur through a natural recovery process. Soil salinity and vegetation diversity indices were measured on six study sites and one control. Average electrical conductivity declined with time from approximately 3.0 dS m-1 and has remained below 2.0 dS m-1 since 2002. Cycling of ions between leaf litter and plant tissue resulted in high variability in topsoil electrical conductivity. Sodium adsorption ratio in the leaf litter and A horizons was low ( 14) after 2004. Fro...

GIS APPLIED TO THE STUDY OF TEMPORAL RECOVERY OF BURNED AREAS IN THE MUNICIPALITY OF PAI PEDRO LOCATED IN REGION NORTH OF THE STATE OF MINAS GERAIS

The northern region of Minas Gerais is considered a transition area between the biomes Caatinga and Savanna, with predominance of the Savanna and its variations. It is common to the occurrence of fires, which can be caused naturally or by anthropogenic actions, resulting in changes in the landscape. In this sense, the study aims to evaluate from time series of LANDSAT-5/TM and MODIS/TERRA images the process of natural recovery of vegetation after the identification of operational pixels corresponding to the burned areas. The results of the research are based on the response of the municipality test of Pai Pedro/MG. We can observe that was detected a hotspots pixel on the day 08/04/2008 through images MOD14A1, which validation was performed from the survey of burned areas conducted by INPE - National Institute of Space Research. From the identification of operational pixel of burned was evaluated the dynamics of recovery of the area through the vegetation index NDVI (Normalized Difference Vegetation Index), generated by images MODIS/TERRA, product MOD13Q. The scars of burned analyzed, approximately 52% were detected. Despite this limitation, much of the area impacted was identified. The errors of omission were considered satisfactory, with a view to the technical limitations of spatial resolution of the sensors used.

Using a historical aerial photograph analysis to inform trout habitat restoration efforts

ABSTRACTRestoration of the upper Strawberry River included bank stabilization techniques because it was assumed that excessive bank erosion was degrading spawning habitat for Bonneville cutthroat trout (BCT). Using a long‐term aerial photograph record, the historical range of variability in bank erosion rates and channel geometry was determined, and this information was used to assess present‐day conditions and the rationale for restoration. Relative to historical variability, the channel planform was relatively stable and bank erosion rates were the lowest recorded in the post‐disturbance era. Although a historical loss of riparian vegetation coincided with a shift to a wider and more sinuous channel, lateral migration rates declined and the channel narrowed as riparian cover increased in the decades before restoration, indicating a process of natural recovery. Furthermore, it was found that the percentage of fine sediment in the streambed before restoration was insufficient to affect BCT spawning success. Together these results suggest that bank erosion and fine sediment did not affect the quality of spawning habitat or the abundance of BCT on the upper Strawberry River. The results highlight how a historical analysis can be used to identify the sources of habitat degradation and inform the selection of restoration goals and strategies. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Trauma reactivity, avoidant coping, and PTSD symptoms: A moderating relationship?

In the immediate aftermath of a traumatic event, many individuals experience physiological reactivity in response to reminders of the traumatic event that typically lessens over time. However, an overreliance on avoidant coping strategies may interfere with the natural recovery process, particularly for those who are highly reactive to trauma reminders. In the current investigation, we examined avoidant coping as a moderator of the association between heart rate reactivity to a trauma monologue measured shortly after a traumatic event and severity of posttraumatic stress disorder (PTSD) symptoms measured several months later. Fifty-five female survivors of assault completed PTSD diagnostic interviews and a self-report coping measure and participated in a trauma monologue procedure that included continuous heart rate measurement. These procedures were completed within 1 month of the assault and again 3 months postassault. After we controlled for the effect of initial symptom levels, the interaction of heart rate reactivity to the trauma monologue and avoidant coping measured at Time 1 was associated with PTSD symptom severity at Time 2. Individuals who are relatively highly reliant on avoidant coping strategies and relatively highly reactive to trauma reminders may be at greatest risk of maintaining or potentially increasing their PTSD symptoms within the first few months following the trauma. These findings may help inform early intervention efforts for survivors of traumatic events.

Assessing the natural recovery of a lake contaminated with Hg using estimated recovery rates determined by sediment chronologies

Abstract Deer Lake is an impoundment located near Ishpeming, Michigan, USA. Iron mining assay laboratories located in Ishpeming disposed of Hg salts to the city sewer whose outfall was located along an inlet to Deer Lake. An effort to remediate the system in the mid 1980s which consisted of drawing down water in the impoundment in order to volatize Hg from the sediments did not result in recovery of the system. Since the mid 1990s, the remediation strategy has been to allow the continual burial of the contaminated sediments, i.e., natural recovery. The goal of this study was to assess the effectiveness of this strategy. This was accomplished by investigating the state of the system in terms of its recovery and estimating the time frame for recovery. Sediment cores were collected in 2000 to determine historical trends in accumulation rates and concentrations of Hg and other metals. Sedimentation rates and sediment ages were estimated using 210 Pb. Event-based dating (e.g., peak of 137 Cs in 1963) was used to supplement 210 Pb data due to non-monotonic features in the 210 Pb profile and activities that were not at supported levels at the base of the core. Selected results are that: (1) drawdown significantly influenced sedimentation patterns causing slopes for 210 Pb profiles that reflected the influx of older sediment, (2) periods of Fe production correlate to Hg loading indicating the point source for contamination, a relationship not previously identified, (3) Hg:Al ratios indicate a recent change to a watershed pathway for Hg loading and (4) Hg concentrations had decreased from their peak, remain elevated, and were increasing after 1997. The cause of the recent Hg concentrations may be related to influx of contaminated watershed soils or sediments. Estimating the time frame for recovery is challenging in this system because the process of natural recovery seems to have been arrested and deeper, uncontaminated sediments, were not recovered as a basis for reference. However, a recovery to background conditions is likely not achievable since rates of Hg loading to nearby lakes and the current rate of atmospheric deposition are greater than an estimate of background conditions for Deer Lake. Assuming recovery continued after 2000, estimates of the time required for recovery varied based on the system state used to define it (e.g., recent rates of wet Hg deposition or Hg surface concentrations/fluxes from similar systems), but were less than 12 a. However, the recent increasing values of recovery indicators (e.g., Hg concentrations) suggests that these estimates are conservative and will be longer if recovery remains arrested, which may in part be due to the legacy of Hg contamination on the landscape. This study shows that estimates of recovery of highly disturbed lake systems can be made in the absence of within lake reference conditions by using comparisons to reference systems and challenges of estimating ages from atypical 210 Pb activity profiles can be overcome in part using event-based dating techniques.

Efficiency of an integrated habitat stabilisation approach to coastal erosion management

The present paper describes the technical solution adopted for habitat stabilisation as an integrated approach to erosion mitigation aimed at improving ecological and environmental aspects of the tropical and subtropical shorelines. Any man-made structure on the beach could have an environmental impact on the habitat and the associated biota. However, when the habitat is considered in the design process, a coastal erosion management plan can provide an effective means of coastline stabilisation and habitat enhancement. Therefore, in this study a combination of low crested breakwaters and a mangrove restoration plan was applied to an intertidal beach on the west coast of the state of Selangor, Malaysia. The study was aimed at protecting the beach and enhancing the habitat. The presence of the breakwater resulted in sediment deposition on the beach and the substrate elevation increased to a height appropriate for mangrove establishment. The calm area protected by the breakwater was also conducive to restoration work on the exposed coast. The approach provided suitable conditions for coastal rehabilitation, facilitating the natural recovery process of the coastal ecosystem.

Review of thin‐layer placement applications to enhance natural recovery of contaminated sediment

This article provides a review of thin-layer placement applications to enhance the natural recovery of contaminated sediment. Three principal case studies are presented in which thin-layer placement has been implemented as a component of enhanced monitored natural recovery (EMNR). EMNR is defined as the application of engineered means such as thin-layer placement or broadcasting of capping material to accelerate natural recovery processes in locations not appropriate for application of monitored natural recovery (MNR) alone. Case studies examine factors affecting the implementation of EMNR, including the impact of site conditions on stable and successful thin-layer placement of clean sediment or other capping material, as well as the challenges in development and implementation of monitoring plans that chart progress toward achieving remedy success. Pilot-scale or demonstration studies of thin-layer placement of clean sand or sediment are subsequently assessed to highlight a range of potentially successful strategies for placement and post-placement monitoring. The primary difference between the pilot-scale or demonstration sites and the 3 primary EMNR case studies is that monitoring at the demonstration sites has focused more explicitly on understanding mechanisms of material placement and/or chemical migration, rather than assessing longer-term or more comprehensive remedial action objectives (RAOs) such as reductions in human health or ecological risk. All sites discussed in this review appear to have demonstrated reductions in the surface sediment concentration of at least some chemicals of concern following thin-layer placement; however, the achievement of human and ecological risk reduction has been inconsistent or is still under evaluation. Effective monitoring as an integral component of EMNR continues to represent a challenge. For cap material stability, monitoring typically focuses on surface sediment chemistry and the persistence of the cap material, whereas monitoring of ecological recovery tends to be limited or difficult and is not always correlated with successful placement of the thin-layer, especially in the short term. Recontamination of the newly placed cap material has been a relatively common occurrence in many of the sites considered herein, and has led to exceedance of remedial targets. However, in no case did recontamination return surface sediment chemical concentrations to pre-placement levels. Where the placement of cap material is stable and there is no evidence of chemical migration through the cap, recontamination signals a need to update conceptual site models to better reflect sediment and contaminant transport processes in areas in which EMNR has been implemented.

Exercise training after lung transplantation: A systematic review

Lung transplant recipients experience persistent impairments in exercise capacity and skeletal muscle function despite a vast improvement in lung function after transplantation. Exercise training may be beneficial in improving exercise capacity in lung transplant recipients. A systematic review was undertaken to examine the evidence for exercise training on functional outcomes in lung transplant recipients. Studies were identified by searching electronic databases and scanning reference lists. Only randomized controlled trials, controlled trials, and prospective cohorts were included in the review. Seven studies met the inclusion criteria. Study quality was assessed using the Physiotherapy Evidence Database, Jadad, and Downs scales. The overall quality of studies was fair to moderate in assessing the effect of exercise training on maximal and functional exercise capacity, skeletal muscle function, and lumbar bone mineral density. Every study reported significant improvements in these outcomes. Some studies lacked randomization and/or a control group, so it was not possible to separate the effects of training with the natural recovery process after lung transplantation. Some evidence was found to support that a period of structured exercise training could improve maximal and functional exercise capacity, skeletal muscle strength, and lumbar bone mineral density in lung transplant recipients. Further studies are needed to determine the potential for exercise training to optimize these functional outcomes and to develop optimal guidelines for exercise prescription in the lung transplant population.

Evolving restoration principles in a changing world

Evolving restoration principles in a changing world

Potential re-establishment of diadromous fish species in the River Scheldt (Belgium)

This study (2002) documents on the inland penetration off diadromous fish species into the tidal and non-tidal part of the River Scheldt and on the impact of two lock-weir complexes. Long-term trends in oxic conditions show the river is undergoing a natural recovery process, nevertheless five of ten diadromous species recorded were still restricted to the brackish part of the estuary. Despite poor conditions, five species reached the upper freshwater part of the estuary. Erratic free-flowing conditions at the tidal weir offered limited opportunities for some diadromous species to migrate into the non-tidal part of the river. Upstream migration over the second barrier is almost completely blocked. Rehabilitation schemes to restore self-sustaining populations of diadromous fish in the cross-border River Scheldt need to include the building of fish bypasses and improved wastewater treatment and habitat restoration programmes.