There is a critical need for more studies to identify socio-ecological drivers that affect conservation and management of fire adapted ecosystems, yet studies that identify such variables and explore their interaction in specific systems are not only scarce but limited to only a few systems. Although information on the socio-ecological effects of prescribed fire application exists, there is no integrative framework that simultaneously considers the interplay between social and ecological factors affecting the use of prescribed fires. Fire suppression, together with other human and natural disturbances in grassland systems that are adapted to episodic fire, are the major factors that have contributed to the recruitment of woody species into grasslands worldwide. Even though the ecology of restoring these fire prone systems back to a grassland state is becoming clearer, the major hurdle to reintroducing historic fire at a landscape scale is its social acceptability. To address these deficiencies, I studied the socio-ecological factors influencing the use of prescribed fire in Texas, USA and Chihuahua, Mexico using a combination of quantitative and qualitative approaches to examine how social and ecological factors affect ecosystem conservation and management of semi-arid grassland systems. For the Texas case study I used quantitative survey data analyzed using logistic regression models and structural equation models. For the Mexico case study I used qualitative interviews gathered using a snowball network sampling approach and coded them based on the analytic themes of land cover change, institutional failure, market drivers, and population dynamics. Results from the Texas case study suggest that risk taking orientation and especially, perceived support from others when implementing prescribed burns, play important roles in determining attitudes towards the use of high-intensity prescribed fires, which are sometimes needed to restore ecosystems. Results from the Texas case study also highlight how membership in Prescribed Burn Associations (PBAs) influence land manager decisions regarding the use of prescribed fire by reducing concerns over lack of skills, knowledge and resources. Results emphasize the potential for PBAs to reduce risk concerns regarding the application of prescribed fire and are relevant to management of brush encroached areas. Through PBAs, effective landscape-scale solutions to the brush encroachment problem can be achieved in Texas. Results from the Mexico case study show how fire stopped effectively being a driving factor on this system decades ago. Socio-political and ecological changes at the national, and international level produced changes in land use disrupting historical fire patterns and contributing to the ecological deterioration of the area. Droughts combined with poor management practices have depleted the fuel needed to carry a fire. Landowners also face safety and legal concerns but in most cases, even if a landowner decided to implement a prescribed burn, an ecological threshold has been crossed and current fine fuel loads (grass) are insufficient to carry a fire that is sufficiently intense to reduce brush cover and restore grassland and savanna ecosystems. Based on my findings I can conclude that ecologically sound adaptive management and social capital are fundamental components of the livelihoods of landowners and land managers in both case studies. Work and investment that is focused on strengthening this social capital will have the most profound effects in maintaining the integrity of grassland systems at a landscape scale.

Thesis (Ph. D.)--Oregon State University, 2004. / Printout. Includes bibliographical references (leaves 188-192). Also available online.

No description available.

Call number: LD2668 .T4 1979 P482 / Master of Science

Master of Science / Division of Biology / David A. Haukos / Sericea lespedeza (Lespedeza cuneata) is an invasive forb that reduces native grass and forb abundance in tall-grass prairie by up to 92%. Controlling invasions is difficult because traditional land management tools used in the Flint Hills, broad spectrum herbicides, spring prescribed fire, and cattle grazing, are ineffective against sericea. Recent research has demonstrated, however, that mid- and late summer prescribed fire and spring fire with early season grazing by steers followed by late season grazing by sheep are effective at reducing sericea whole plant mass, number of seeds produced, and seed mass. Field results were from two separate experiments conducted in tall-grass prairie study sites in the Flint Hills. On a Geary County, Kansas, study site, the utility of 1) spring fire (control), 2) mid-summer fire, and 3) late summer fire on sericea control were compared. On a Woodson County, Kansas, study site, the utility of 1) spring fire with early season steer grazing followed by rest (control) and 2) spring fire with early season steer grazing and late season sheep grazing on sericea control were compared. At the same study sites, I measured responses by the native wildlife community to use of summer fire and sheep grazing, relative to their controls, to manage sericea lespedeza. Specifically, my objectives were to compare grassland songbird density, grassland songbird nest survival, and grassland butterfly species composition and density among treatments at both study sites. I also related patterns in the vegetation community of each treatment for each study site to respective patterns in grassland bird and butterfly communities. Within study sites, density, nest density, and nest success of grassland bird communities responded similarly to treatments and controls, with the exception that densities of Grasshopper Sparrows (Ammodramus savanarrum) were 3.4- and 2.2-fold greater in mid- and late summer fire plots than spring fire plots, respectively, in the Geary County study site. Species compositions of butterfly communities were similar across treatments within experiments, but grassland specialist species comprised only 8.6 and 1.2% of all butterfly observations in the Geary County and Woodson County experiments, respectively. Grassland specialist butterfly species may benefit from summer fire, as their nectar sources were more abundant in Summer Fire plots than Spring Fire plots. Overall, within each experiment, grassland bird and butterfly communities were similar across treatments, suggesting that treatments did not negatively affect grassland songbird and butterfly communities. I additionally demonstrated that Dickcissel (Spiza americana) nest sites contain a lower proportion of sericea than random points, the first evidence that the invasion is detrimental to grassland songbird species. Lacking control, the continued sericea invasion will out compete cumulatively more forb plants resulting in declining quality of grassland bird nesting habitat on the landscape. Controlling sericea lespedeza invasions will allow native forb species to increase in abundance and improve the condition of grasslands for native wildlife and livestock producers. Therefore, I advocate use of summer fire or spring fire with a combination of cattle and sheep grazing to control sericea lespedeza with the long-term goal of tall-grass prairie restoration.

There has been a critical decline in grassland bird populations due to habitat fragmentation and deterioration, and suppression of natural fires. Alteration of the disturbance cycle may lead to changes in vegetation structure and thus habitat suitability for breeding grassland birds. Management practices at the Mississippi Sandhill Crane National Wildlife Refuge, including the use of prescribed fire, are in need of evaluation. My study asked what frequency of prescribed burns is necessary to support breeding grassland birds and whether vegetation structure varies among burn units. In this study, bird abundance and species richness did not differ significantly among burn units and vegetation cover-type was not a strong predictor of these factors either. There was evidence of site utilization by breeding grassland birds immediately following a burn, which suggests that the bird community is able to recovery quickly post-fire and these units may serve as viable habitat for breeding grassland birds.

O fogo é um fator ecológico essencial no Cerrado e promotor de sua evolução. Não apenas a incidência do fogo afeta as respostas dos ecossistemas, mas principalmente o regime de queima, composto por componentes temporais, espaciais e de magnitude. O manejo por meio de queimadas controladas é legalmente permitido no Brasil, mas ainda é encarado com restrições. Como consequência, há uma lacuna no conhecimento das respostas da vegetação ao fogo. Este projeto avaliou o efeito da época do fogo na comunidade nativa de um campo sujo com presença de espécies invasoras na Estação Ecológica de Itirapina, SP. Estabelecemos 16 parcelas (15 x 15 m) e determinamos 3 tratamentos de queima - precoce, modal e tardia - e controle, cada qual com 4 réplicas. Em cada parcela, foram instaladas 10 sub-parcelas fixas (1 x 1 m), nas quais foram obtidos dados de estimativa de cobertura de graminóides, arbustos, herbáceas não graminóides, palmeiras, solo nu e necromassa. Os resultados mostram que diferentes épocas de queima geraram diferentes efeitos em gramíneas e solo nu, mas essas diferenças não se mantiveram um ano após as queimas. Constatamos a diminuição dos valores iniciais de cobertura de necromassa e o aumento na cobertura de arbustos para todos os tratamentos de queima. Não obtivemos resultados conclusivos para herbáceas não graminóides e vimos que a cobertura de palmeiras não foi afetada pelo fogo. Os resultados evidenciam a resiliência do Cerrado, já que o estrato herbáceo-arbustivo se regenerou dentro de 1 ano. A recuperação da vegetação pôde ser explicada pela sazonalidade climática, sendo que uma estação chuvosa foi suficiente para que as diferenças entre as épocas de queima desaparecessem. O manejo de fogo para redução de material combustível foi comprovado e vimos que pode ser realizado em qualquer época do ano. Obtivemos indícios de que a queima pode aumentar a susceptibilidade de invasão por Urochloa brizantha e indicamos que o manejo de fogo em ambientes invadidos por U. brizantha seja realizado com cautela, até que tenhamos certeza de que o fogo não facilita a proliferação dessa espécie invasora / Fire is an essential ecological factor that has promoted the evolution of Cerrado vegetation. Not only the incidence of fire affects the ecosystem, but mainly the fire regime, which is characterized by variability in space, time, and magnitude. Time, specifically, is related to fire frequency and seasonality. The use of fire as a management tool is legally admitted in the Brazilian protected areas, but it is still seen with great restrictions. As a consequence there is a knowledge gap on the vegetation responses to fire. This project evaluated short time effects of fire season on the herbaceous community of a “campo sujo” (open savanna), in the Itirapina Ecological Station, a protected area in the State of São Paulo, Brazil. We established 16 plots (15 x 15 m) and three fire treatments - burning in the early, middle or late dry season - and control (not burning), each treatment with four replicates. In each plot we established ten fixed subplots (1 x 1 m), where we estimated the vegetation cover of grasses, shrubs, forbs, palms, as well as bare soil and dead biomass, before burning and every four months during 12 months. We found that grasses and bare soil cover responded differently to the fire season, but differences among treatments disappeared after one year. Litter cover decreased and shrubs cover increased in every fire treatment after one year. Palms were not affected by any fire treatment, and we did not obtain conclusive results for forbs. Our results show that Cerrado vegetation is very resilient, since the components of the herbaceous community recovered within a year. The vegetation recovery was influenced by climate seasonality, and differences among fire seasons disappeared after just one rainy season. When considered as a management tool, fire was efficient in decreasing the amount of dead biomass after one year, and for this purpose it can be applied at any time of the year. Evidence suggested that fire might increase the invasion by Urochloa brizantha, an African grass. For this reason we suggest caution when using fire as a management tool in invaded ecosystems until one is sure that fire will not trigger or facilitate invasion processes by U. brizantha

First order fire effects in mixed grass and tallgrass prairies may differ between current and historic fire regimes. To determine potential differences, the thermal dynamics of nine prescribed grassland fires and six experimental fires were evaluated. Fires were instrumented with dataloggers and arrays of up to twelve thermocouples set at heights ranging from -5 cm to 300 cm. Soil moisture and texture were documented, along with fuel characteristics. A series of experimental fires allowed soil moisture to be manipulated while minimizing other variables. Maximum temperature for the prescribed fires was 875°C at 75cm, and for the experimental fires 920°C at 10 cm. In experimental fires, the greatest temperature difference was at the surface with the dry substrate averaging 130°C higher than saturated. Average temperatures at -1 cm differed by 33°C. At 60°C, residence times in dry substrate averaged almost four minutes, while the average for saturated treatment was only 1 second. Surface residence times on dry substrate averaged over 7 minutes, almost 3 times longer than saturated. Soil moisture was shown to influence relative humidity and fine fuel moisture near the ground surface. An increased evaporation of soil water at the surface is suggested by a slight drop in subsurface temperatures as the flaming front moves over the surface. These data suggest that soil moisture affects fire intensity, decreasing temperatures at all levels of a fire. Temperatures and residence times were compared with data from studies documenting temperatures significantly affecting seed germination and edaphic effects at and below the surface. Temperatures increasing the germination of some seeds were found at all heights. Temperatures documented can be expected to decrease organic matter content and aggregate stability at the surface, slightly increasing erodibility. Thermal dynamics from the fires in this study represent a broad range of grassland fires under conditions common for prescribed fire. Soil moisture appears to significantly affect temperatures and residence times below, at, and above the soil surface. Data were compared with output from FOFEM 5.2 to access the applicability of FOFEM for use in mixed grass and tallgrass prairie. FOFEM consistently underestimated soil heating by up to 419°C.

"Professional paper presented in partial fulfillment of the requirements for the degree of Master of Science in Environmental Studies, the University of Montana, Missoula, MT, fall 2006." / Title from PDF t.p. (viewed on Feb. 26, 2007). Includes bibliographical references (p. 77-90).

Prescribed burns are employed in the southern boreal forest of northwest Ontario, Canada, as a method of re-instating fire in this fire-dependent landscape. They are also used to manage fuel loads associated with tree mortality from defoliating insects and from blow-downs, as well as in-site preparation following harvest. The natural fire season in boreal Canada typically runs from April through September and is most often characterized by stand replacing fires. However, prescribed burns in northwestern Ontario are mostly scheduled for October when fire crews and equipment are available and fire hazard is reduced. In this study, three recent fires: a spring prescribed natural fire, a summer wildfire, and a fall prescribed burn were examined to assess the effect of season on post-fire legacies in red-pine mixedwood stands in Quetico Provincial Park, northwestern Ontario. Legacies were assessed by tree, shrub and herb species composition, and by measurements of structure such as litter depth, basal areas of live trees and coarse woody debris. Tree species diversity was nearly identical. Post-fire stand structure varied widely between the different sites. The spring treatment experienced the least mortality of trees (10% of basal area dead); the summer treatment had the highest mortality (100%); and the fall prescribed burn was intermediate with 49% dead. The effect of the fall burn on the forest was probably more intense than that of a comparable natural fall fire because of the way in which it was managed, thus partly compensating for the late season. <br /><br /> This research suggests that all fires are not equal. Different post-fire structure will have lasting ecological implications such as varying edge to interior ratios, and forest habitats. From a policy perspective this is important because maintaining ecological processes including fire is mandated for some provincial parks. In addition, the new Fire Policy for Ontario has established targets to limit wildfires, and permit ecologically renewing fires, without recognition of the variability of the effects of fire or fire legacies.