Burn Treatment (burn + treatment)

Distribution by Scientific Domains
Life Sciences75%

Selected Abstracts

Responses to Fire in Selected Tropical Dry Forest Trees,

BIOTROPICA, Issue 5 2006
Sarah M. Otterstrom
ABSTRACT Fire is a frequent disturbance in the tropical dry forests of Central America, yet very little is known about how native species respond to such events. We conducted an experimental burn in a tropical dry forest of western Nicaragua to evaluate plant responses to fire with respect to survivorship and recruitment. Measurements of woody vegetation of all size classes were carried out prior to the prescribed burn and three successive years post fire. We selected the 15 most abundant species <10 cm DBH to assess percent survivorship and sprouting responses post fire. Changes in seedling densities for these 15 most abundant species and the 15 least abundant species were analyzed using a repeated measure ANOVA. We also assessed changes in seedling densities for three species of international conservation concern. We found three major fire-coping strategies among common dry forests plants: resisters (low fire-induced mortality), resprouters (vigorous sprouting), and recruiters (increased seeding post-fire). While survivorship was generally high relative to tropical moist forest species, those species with lower survivorship used either seeding or sprouting as an alternative strategy for persisting in the forest community. Seed dispersal mechanisms, particularly wind dispersal, appear to be an important factor in recruitment success post-fire. Burn treatment led to a significant increase in the density of seedlings for two species of conservation concern: Guaiacum sanctum and Swietenia humilis. Results of this study suggest that common dry forest species in western Nicaragua are fire tolerant. Further study of individual species and their fire responses is merited. RESUMEN El incendio forestal causa perturbación frecuente en los bosques secos tropicales de Centroamérica, sin embargo se conoce poco del comportamiento de las especies nativas a ésta perturbación. Nosotros llevamos a acabo una quema experimental en un bosque seco tropical de Nicaragua occidental para evaluar el comportamiento de la flora con respecto a la sobrevivencia y reclutamiento de las especies después de la quema. Se midió todas las clases diamétricas de la vegetación leñosa antes de la quema controlada y durante 3 años consecutivos después de la quema. Seleccionamos las 15 especies más abundantes en la clase diametrica <10 dap para evaluar el porcentaje de sobrevivencia y la actividad de rebrote después de la quema. Cambios en la densidad de plántulas para las 15 especies más abundantes y para las 15 especies menos abundantes fueron analizadas utilizando el análisis de varianza de medición repetido (ANOVA). También, evaluamos cambios en la densidad de plántulas para tres especies de interés a nivel internacional con respecto a su conservación. En la flora común del bosque seco se encontró tres estrategias principales utilizadas por las especies para contender con los incendios forestales, estas fueron: resistores (baja mortalidad por el incendio), rebrotadores (rebrotamiento vigoroso), y reclutores (reclutamiento elevado pos-incendio). Mientras la sobrevivencia de especies en el bosque seco en general fue relativamente alta a la de especies de bosque húmedo tropical, las especies con menor sobrevivencia utilizaron el reclutamiento ó rebrotamiento como estrategia para persistir en la comunidad boscosa. El mecanismo de dispersión de semilla, particularmente la dispersión eólica, parece ser un factor importante en el éxito de reclutamiento después de la quema. Las quemas controladas produjeron un aumento significativo en la densidad de plántulas para dos de las especies de interés para la conservación: Guaiacum sanctum L. (Zygophyllaceae) y Swietenia humilis Zucc. (Meliaceae). Resultados de esta investigación sugieren que las especies comunes del bosque seco de Nicaragua son tolerantes al fuego. Por lo tanto, es merecido hacer más estudios de estas especies y su comportamiento ante la perturbación del fuego. [source]

Bacteriotherapy with Lactobacillus plantarum in burns

INTERNATIONAL WOUND JOURNAL, Issue 1 2009
Maria C Peral
Abstract Bacterial colonisation and infection remain the major causes of delayed healing and graft rejection following burns. Topical treatment is necessary to reduce the incidence of burn wound infection. Silver sulphadiazine (SD-Ag) is an often used microbicidal agent. However, this treatment produces adverse reactions and side-effects. On the basis of experimental data and clinical application of lactobacilli as probiotics, we performed this exploratory study to establish the effectiveness of bacteriotherapy with topical application of the innocuous bacteria Lactobacillus plantarum cultured in De Man, Rogosa and Sharpe medium to provide an alternative method for burn treatment using SD-Ag as a reference. These innocuous bacteria would compete with other bacteria that are wound pathogens and would modify the wound environment and promote tissue repair. Eighty burned patients from the Plastic Surgery and Burns Unit were grouped into infected (delayed) second- and third-degree and non infected (early) third-degree burns and treated with L. plantarum or SD-Ag. The proportion of patients with delayed second-degree burns was 0·71 for L. plantarum and 0·73 for SD-Ag (relative rate: ,2·72%) with respect to the decrease in bacterial load (<105 bacteria/g of tissue), promotion of granulating tissue wound bed and healing. In early third-degree burns, the values were 0·75 for L. plantarum and 0·84 for SD-Ag (relative rate: ,1·07%) in preventing wound infection and promotion of granulation tissue, 0·90 in graft taking for both treatments (relative rate: 0%) and 0·75 for L. plantarum and 0·77 for SD-Ag (relative rate: ,2·60%) in healing. In delayed third-degree burns, values were 0·83 for L. plantarum and 0·71 for SD-Ag (relative rate: +16·90%) with respect to the decrease in the bacterial load (<105 bacteria/g of tissue) and providing a granulating tissue wound bed, 0·90 in graft taking for both treatments (relative rate: 0%) and 0·75 for L. plantarum and 0·64 for SD-Ag (relative rate: + 17·19%) in healing. Although the number of patients (between 12 and 15 per group) did not enable the application of a power statistical test, these results suggest that the L. plantarum treatment should be studied in greater depth and could be used as a valid alternative for the topical treatment of burns. [source]

Detection, survival rates and dynamics of a cryptic plant, Asclepias meadii: applications of mark-recapture models to long-term monitoring studies

JOURNAL OF ECOLOGY, Issue 2 2009
Helen M. Alexander
Summary 1Analysis of population trajectories is central to assessing risk in populations of conservation concern. In animal studies, researchers realize that probabilities of detection of individuals are often less than one. Plants can also escape detection due to dormancy, herbivory, or observer error, but such information is rarely incorporated into population studies. 2We monitored a population of Asclepias meadii, a rare long-lived prairie perennial. Despite standardized methods, numbers of observed plants fluctuated greatly from 1992 to 2006. Individual plants often had periods of 1,5 years between initial and final sighting when no stems were found. To determine the actual population trajectories, we estimated rates of survival and population growth using mark-recapture models. We also estimated initial and resighting probabilities of detection. In 2007, we repeated surveys to identify reasons for low detection probabilities. 3We estimated 95% annual survival and a population growth rate of 1.023. Probabilities of initial detection were low (typically from 0.120 to 0.311 depending on prairie burn treatment), whereas average probability of detection for marked plants was 0.728. 4Comparisons of survival estimates from 15- and 8-year data sets revealed that survival estimates decline in the final years of a multi-year period, probably due to heterogeneity in encounter histories. 5By conducting three different surveys in 2007, we found that both herbivory over a multiple-week period and observer error contributed substantially to gaps in detection. 6Synthesis. Probabilities of detection that are less than one complicate interpretation of population dynamics, whether of mobile animals or inconspicuous plants. Our work illustrates three general points that could apply to many plant population studies: (i) mark-recapture models may provide insights on vital rates and population trajectories despite the extreme variability in count data that can arise because of low detectability, (ii) probabilities of initial detection can be quantified and can be considerably less than probabilities of resighting, and (iii) repeated surveys can help researchers determine the degree to which dormancy, herbivory, or observer error contribute to low probabilities of detection. Consideration of these points can improve the design and analysis of monitoring programs. [source]

Effects of invasion of fire-free arid shrublands by a fire-promoting invasive alien grass (Pennisetum setaceum) in South Africa

AUSTRAL ECOLOGY, Issue 8 2009
S. J. RAHLAO
Abstract Arid shrublands in the Karoo (South Africa) seldom accumulate sufficient combustible fuel to support fire. However, as a result of invasion by an alien perennial grass (Pennisetum setaceum), they could become flammable. This paper reports on an experiment to assess the effects of fire following invasion by P. setaceum. We established 10 plots (5 × 10 m) separated by 2.5 m, and added grass fuel to five plots (5 and 10 tons ha,1 to alternate halves of the plot) leaving the remaining five plots as interspersed controls. Plots with fuel added were burnt, and fire behaviour was measured during the burns. Rates of fire spread were generally low (0.01,0.07 m s,1) and did not differ significantly between burn treatments. Mean fireline intensities were higher in the high compared with the low fuel treatments (894 and 427 kW m,1, respectively). We recorded plant species and their cover before and after burning on each of the plots. After 15 months of follow-up monitoring in the burn plots, only two species, the dwarf shrub (Tripteris sinuata) and the perennial herb (Gazania krebsiana) resprouted. Most individuals of other species were killed and did not reseed during the 15-month study. The mass of added fuel load (high or low) did not influence vegetation recovery rates after fire. Should future invasions by P. setaceum lead to similar fuel loads in these shrublands, inevitable fires could change the vegetation and may favour spread of the flammable grass. Our results have important implications for predicting the effects of invasive alien plants (especially grasses) on fire-free ecosystems elsewhere. The predicted impacts of fire may alter species composition, ultimately affecting core natural resources that support the Karoo economy. [source]