Tesi sul tema "Forest ecology"

The capercaillie is a rare species of forest bird which is once again facing extinction in Britain. Working pine forests are thought to represent the future for capercaillie in Scotland. However, few studies have focused on capercaillie within working forests and as a result current management recommendations are based on studies conducted within semi-natural pinewoods. Therefore study of the ecology of capercaillie within working forests is vital for the survival of the species in Scotland. The present study investigated the ecology of capercaillie, based on indirect measures of capercaillie use, within Morangie Forest, a pine plantation managed by the Forestry Commission. Monthly dropping counts were collected over a 30 month period to gain insight into the capercaillie population at Morangie Forest, and to explore the use of faecal counts as a non-invasive monitoring tool. Habitat analysis, dietary analysis of droppings and genetic analysis of feathers were further conducted to fully explore ecology of capercaillie within Morangie Forest. Results showed that the capercaillie population in Morangie Forest was subject to seasonal movements and that movements were not confined to the bounds of the forest. Substantial mixing occurred with capercaillie from neighbouring Novar Forest. In addition, capercaillie within Morangie Forest selected habitat at a radius of 50m and beyond. The population of capercaillie at Morangie Forest was estimated at around 65 individuals based on measures from dropping counts and genetic determination of individuals from feathers. Results also suggested that winter dropping counts could represent a useful tool for forest managers to monitor the size and movement of capercaillie populations frequenting their forests. In addition winter dropping counts could be used in conjunction with habitat data to plan management of habitat for capercaillie. The present study contributes towards future management strategies for the conservation of capercaillie within working forests and suggests further research priorities for capercaillie in Scotland, particularly those focused at a landscape scale.

Thesis (M.A.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains vi, 43 p. : map. Includes abstract. Includes bibliographical references (p. 40-43).

Dry cloud forests on the western slopes of the Peruvian Andes were mapped from aerial photographs, 306 stands being recorded from 4^o50'S to 12^o47'S. The frequency and area of these stands, as well as most parameters analyzed in the eight sample sites, show a steep decreasing latitudinal trend and are strongly correlated with the latitudinal rainfall gradient. The mean area of the forest stands decreases from 115 ha in northern Peru to 42 ha in central Peru. The number of species recorded decreases along the study area from 52 to 13 and there is a well defined latitudinal sequence of species. Mean density and basal area per hectare of stems ≥10 cm gbh decreases from 2995 individuals and 79.91 m^2 in the north to 500 individuals and 17.27 m^2 in central Peru. The vertical structure is similar throughout the study area, emergent trees reaching on average 22 m and the main canopy 12 m in the north and 13 m and 7 m respectively in central Peru. Regeneration is very active in northern Peru. Juveniles have been found for a high proportion of species, including all common ones, and most species show a logarithmic decline in number of stems with increasing girth. There is a steep decreasing trend towards central Peru, where few species regenerate, mostly shrubs. The pattern found may be the result of the combined effect of grazing and a climatic change towards drier conditions evidenced in the regeneration pattern of most sites.

Thesis (Ph. D.)--University of New South Wales.
Photocopy of original held in Defence Academy Library, University College, University of New South Wales. Includes bibliographical references. Also issued online.

Thesis (Ph.D.) - University of Glasgow, 2008.
Ph.D. thesis submitted to the Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, 2008. Includes bibliographical references.

The aim of this study was to document the bird communities of six 'scarce forest habitats' in an upland spruce forest (Kielder, in Northumberland) and to compare them to the bird communities that were associated with its conifer plantations. Features of the scarce forest habitats considered to be important to their bird communities were investigated. The implications of these findings for future forest management are discussed, particularly in relation to the contributions these habitats make to the overall diversity of forest avifauna. Up to 76 study plots were selected randomly from six scarce forest habitat types; broad-leaved woodland, mixed broad-leafed/conifer woodland, windthrown conifer stands, streams with unplanted riparian strips, unplanted land and streams with broad-leaved riparian strips. Five-minute point counts, with up to 60 m radius, were used to estimate the relative abundance of species. Counts were carried out between 1992 and 1994, in winter (November to December), early spring (April to mid May) and late spring (mid May to mid June). Each study plot was visited once in each of these seasons, under similar weather conditions. There were few widespread species amongst the different habitats, only the chaffinch Fringilla coelebs was recorded consistently in more than 50% of spring plots. The commonest species in the scarce forest habitats were the same as those found in the adjacent conifer plantations. The majority of the species recorded occurred in a small proportion of plots such that variation in their numbers could not be analysed statistically. However, these less abundant species were classified arbitrarily into two groups, 'uncommon' species (occurring in only 3-10 plots in any one season) and 'occasional' species (occurring in only 1-2 plots in any one season). Unplanted riparian strips held greater numbers of these species during the spring than did the other scarce forest habitats.

Les comunitats fúngiques dels sòls juguen un paper vital en molts processos ecosistèmics forestals, així com en el manteniment de les poblacions d'espècies vegetals. Amb l'aparició de noves tècniques moleculars és possible estimar la diversitat i composició d'aquestes comunitats de forma més precisa i conèixer la seva resposta a pertorbacions com la gestió forestal o els canvis en el clima. L'objectiu principal d'aquesta tesi va ser descriure l'efecte de dos factors en les comunitats fúngiques de sòls forestals: la gestió forestal (concretament les aclarides) i el clima. A més, hem desenvolupat un mètode per analitzar la diversitat i composició d'espores de fongs a l'aire, així com els seus canvis en el temps i en l’espai. Aquesta tesi doctoral es va realitzar sobre un dispositiu experimental consistent en 28 parcel·les forestals localitzades en el Paratge Natural d’Interès Nacional de Poblet i dominades per Pinus pinaster de 60 anys, on es van aplicar aclarides de diverses intensitats. Mitjançant l'ús de diverses tècniques moleculars com la PCR en temps real (qPCR), seqüenciació massiva d'ADN (PacBio RS II, Illumina MiSeq) i l'extracció d'ergosterol, hem descrit les dinàmiques de biomassa i composició fúngica d'aquests sòls forestals, així com de la comunitat aèria (espores). Les dades obtingudes s'han analitzat en un gradient d'humitat i temperatura del sòl, així com també en les aclarides realitzades l’any 2009. Pel que fa a la part metodològica d'aquesta tesi, observem com liofilitzant els sòls es va recuperar el màxim d'ADN i es va evitar el creixement de floridures. Un cop establert el millor tractament d'assecat, es va observar com la sequera d'estiu afectava negativament la biomassa fúngica del sòl i causava importants canvis funcionals i estructurals en les comunitats de fongs. Entre les espècies més resistents a la sequera figuraven els fongs ectomicorízics, probablement per la seva relació simbiòtica amb arbres hoste. Els màxims valors de biomassa fúngica en sòl es van observar a la tardor, coincidint amb majors abundàncies de fongs ectomicorízics, molt probablement a causa d'una redistribució del carboni al sòl per part de la planta hoste. D'altra banda, la majoria de fongs sapròfits es van veure afavorits sota condicions d’alta humitat i baixes temperatures al sòl. A diferència dels factors climàtics, les aclarides realitzades l’any 2009 no van afectar a la composició de fongs als sòls, possiblement degut a que es va deixat un nombre d’arbres suficients per mantenir la comunitat. Finalment, les comunitats d'espores en l'aire variaven a escala espaial però sobretot a escala temporal. Les variacions temporals d'aquesta comunitat es veien condicionades en gran part per la fenologia de la comunitat de bolets. Moltes espècies que produïen cossos fructífers van poder ser detectades a les trampes d'espores, i per tant aquesta tècnica es podria utilitzar per detectar l'emergència de bolets. En base a aquests resultats es pot concloure que 1.- La liofilització és el mètode d'assecat que millor preserva l'ADN de fongs específics i evita el creixement de floridures. 2.- El cicle anual de certes espècies de fongs es pot veure modificat en un context de canvi climàtic, amb menor biomassa fúngica a l'estiu però major biomassa durant l’hivern i primavera. 3.- Les condicions climàtiques afecten les comunitats de fongs segons els seus trets funcionals, essent els fongs ectomicorrízics els que suporten millor les condicions de sequera estiuenca. 4.- Increments d'humitat afavoreixen la proliferació de sapròfits i fongs degradadors de miceli. 5.- Les aclarides no afecten de manera significativa les poblacions de fongs del sòl si es deixen en peu el nombre suficient d'arbres. 6.- Mitjançant l'ús de tècniques moleculars i trampes d'espores, és possible estudiar la comunitat d'espores a l'aire, essent aquesta altament afectada per la fenologia dels cossos fructífers de fongs i mostrant variabilitat espaial i temporal.
Las comunidades fúngicas de los suelos juegan un papel vital en muchos procesos ecosistémicos forestales, así como en el mantenimiento de las poblaciones de especies vegetales. Con la aparición de nuevas técnicas moleculares es posible estimar la diversidad y composición de estas comunidades de forma más precisa y conocer su respuesta a perturbaciones como la gestión forestal o los cambios en el clima. El objetivo principal de esta tesis fue describir el efecto de dos factores en las comunidades fúngicas de suelos forestales: la gestión forestal (concretamente las claras forestales) y el clima. Además, hemos desarrollado un método para analizar la diversidad y composición de esporas de hongos en el aire, así como sus cambios espacio-temporales. Esta tesis doctoral se realizó sobre un dispositivo experimental consistente en 28 parcelas forestales localizadas en el Paraje Natural de Interés Nacional de Poblet y dominadas por Pinus pinaster de 60 años, en las que se aplicaron diferentes intensidades de claras. Mediante el uso de varias técnicas moleculares como la PCR en tiempo real (qPCR), secuenciación masiva de ADN (PacBio RS II, Illumina MiSeq) y la extracción de ergosterol, hemos descrito las dinámicas de biomasa y composición fúngica de estos suelos forestales, así como de la comunidad aérea (esporas). Los datos obtenidos se han analizado en un gradiente de humedad y temperatura del suelo, así como también en las claras realizadas el año 2009. En cuanto a la parte metodológica de esta tesis, observamos como liofilizando los suelos se recuperó el máximo de ADN y se evitó el crecimiento de mohos. Una vez establecido el mejor tratamiento de secado, se observó como la sequía de verano afectaba negativamente la biomasa fúngica del suelo y causaba importantes cambios funcionales y estructurales en las comunidades de hongos. Entre las especies más resistentes a la sequía figuraban los hongos ectomicorrízicos, probablemente por su relación simbiótica con los árboles huésped. Los máximos valores de biomasa fúngica en suelo se observaron en otoño, coincidiendo con mayores abundancias de hongos ectomicorrízicos, muy probablemente debido a una redistribución del carbono en el suelo por parte de la planta huésped. Por otro lado, la mayoría de hongos saprófitos se vieron favorecidos en condiciones de alta humedad y bajas temperaturas en suelo. A diferencia de los factores climáticos, las claras realizadas en 2009 no afectaron a la composición de hongos en suelos, posiblemente debido a que se dejó un número de árboles suficiente para mantener la comunidad. Finalmente, las comunidades de esporas en el aire variaban a escala espacial, pero sobre todo a escala temporal. Asimismo, comprobamos como las variaciones temporales de estas comunidades se veían condicionadas en gran parte por la fenología de la comunidad de setas. Muchas de las especies que producían cuerpos fructíferos pudieron ser detectadas en las trampas de esporas, y por lo tanto creemos que esta técnica podría ser utilizada para detectar la emergencia de setas. En base a estos resultados se puede concluir que 1.- La liofilización es el método de secado de muestras de suelo que mejor preserva el ADN de hongos específicos y previene el crecimiento de mohos. 2.- El ciclo anual de ciertas especies de hongos se puede ver modificada en un contexto de cambio climático, con menor biomasa fúngica en verano, pero mayor durante invierno-primavera. 3.- Las condiciones climáticas afectan a las comunidades de hongos según sus rasgos funcionales, siendo los hongos ectomicorrízicos los que soportan mejor las condiciones de sequía estival. 4.- Incrementos de humedad favorecen la proliferación de saprófitos y hongos degradadores de micelio. 5.- Las claras no afectan de manera significativa las poblaciones de hongos del suelo si se dejan en pie el número suficiente de árboles. 6.- Mediante el uso de técnicas moleculares y trampas de esporas, es posible estudiar la comunidad de esporas en el aire, siendo esta altamente afectada por la fenología de los cuerpos fructíferos de hongos y mostrando una elevada variabilidad espacio-temporal.
Fungal communities inhabiting soils play a vital role in many forest ecosystem processes, as well as in the maintenance of plant species. With the emergence of new molecular techniques, it is possible to estimate the diversity and composition of these communities more precisely and study their responses to disturbances such as forest management or changes in climate. The main objective of this thesis was to describe the effect of two factors in the soil fungal communities: forest management (specifically forest thinnings) and climate. In addition, we have developed a method to study the diversity and composition of airborne fungal spores, as well as their spatio-temporal changes. This doctoral thesis was carried out in an experimental set-up consisting of 28 forest plots located in the Natural Park of Poblet, dominated by 60-year-old Pinus pinaster trees, where thinnings were applied under different intensities. Using several molecular techniques such as real-time PCR (qPCR), high-throughput DNA sequencing (PacBio RS II, Illumina MiSeq) and ergosterol extraction, we have described the fungal biomass dynamics and fungal composition of these forest soils, as well as from the airborne community (spores). The data obtained have been analyzed in a gradient of soil moisture and temperature, as well as in the forest thinnings made in 2009. Regarding the methodological part of this thesis, we observed how maximum DNA recovery and lowest growth of molds occurs under freeze-drying treatments. Once the best drying treatment was established, we observed how summer drought negatively affected the soil fungal biomass and caused important functional and structural changes in the fungal community. Ectomycorrhizal fungi were the most resistant species to drought, probably because of their symbiotic relationship with host trees. The maximum soil fungal biomass was observed in autumn, coinciding with higher abundances of ectomycorrhizal fungi, most likely due to a redistribution of soil carbon by the host plant. On the other hand, most saprotrophic fungi were promoted under conditions of high soil moisture and low temperatures. Unlike climatic factors, the forest thinnings made in 2009 did not affect the soil fungal community, likely because a sufficient number of trees were left to support the community. Finally, the airborne spore community changed at spatial scale, but especially at temporal scale. We verified how the temporal variations of these communities were largely determined by fruiting body emergence. Many of the species that produced fruiting bodies could be detected in the spore traps, and therefore this technique could be used to detect fruiting body emergence Based on these results, it can be concluded that 1.- Freeze-drying is the method that best preserves the DNA of specific fungi and prevents the growth of molds. 2.- The annual cycle of specific fungal species can be modified in a context of climate change, with predicted lower fungal biomass in summer, but higher biomass during winter-spring. 3.- Micro-climatic soil conditions affect fungal communities according to their functional traits, with ectomycorrhizal fungi being the ones that better resist summer drought conditions. 4.- High soil moisture promote the proliferation of saprotrophs. 5.- Forest thinnings does not affect significantly the soil fungal communities if enough trees are left standing. 6.- It is possible to study the airborne spore community using spore traps and molecular techniques, being these communities highly affected by the phenology of the fruiting bodies and showing spatio-temporal variability.

This project provides a fire ecology lesson to accompany a hike for student groups from fourth through eighth grade. The lesson plan will acquaint students with the beneficial aspects of forest fires.

Thesis (Ph.D.)--Michigan State University. Dept. of Forestry Program in Ecology, Evolutionary Biology and Behavior, 2008.
Title from PDF t.p. (viewed on July 13, 2009) Includes bibliographical references (p. 170-184). Also issued in print.

The Forest Service faces significant climate change-related management challenges. Understanding employee perspectives on climate change will inform potential strategies to address these challenges. By analyzing data from key informant interviews and an internet survey of Forest Service employees in the Intermountain West, this study examined how Forest Service employees view and approach climate change, assessed how they perceive barriers to and opportunities for climate change adaptation within the National Forest System, and compared their perspectives across the organizational hierarchy, from district level to national policy making. The results show that although forest managers consider climate change a concern for the agency in general, they do not necessarily see how it affects the work they do personally. Although they tend to agree that climate change should be a high priority for the agency, their own ability to incorporate adaptive practices into managing a National Forest is limited by various constraints, including a lack of time, funding, and personnel, a lack of direction for on-the-ground management, and a communication gap, which has inhibited climate change-related knowledge transfer within the agency. Thus, more effective communication is needed to help forest managers see how climate change affects various aspects of forest ecosystem health in their own National Forests or districts, how climate change poses challenges to forest resilience, and what can be done to incorporate climate change considerations into their own work. The agency needs to focus on building trust, especially across its hierarchical structure, and on encouraging both vertical and horizontal information flow among employees to facilitate scientific knowledge sharing and to enhance formal and informal social networking for increased collaboration. The agency also needs to create more opportunities for district-level employees to provide feedback and get involved in climate change-related policy making, as they are a crucial source of local knowledge and experience and can be invaluable in problem-solving within the National Forest System. The insights from this study not only contribute to the Forest Service’s continuous efforts to adapt to climate change but also shed light on strategies that can be tailored by other natural resource agencies to address various management challenges within the context of global environmental change.

Scientia Silvica extension series was started in 1997 by Karel Klinka, a silvics professor at the University of British Columbia. He saw the need for a friendly way of distributing current research results to the forestry community. Each extension pamphlet represents a 2-4 page summary of research findings in the field of forest ecology. Topics range from humus form and ecosystem classification to forest productivity, regeneration, stand structure, soil nutrient regimes, coarse woody debris, and plant diversity. Included in each summary is a reference to the more technical original report or scientific paper and contact information for those who wish further information. Also included in the series are several full colour comprehensive reports on ecosystem classification. All pamphlets and reports are in Adobe Acrobat (PDF) format for on-screen viewing or printing. Forest Renewal British Columbia provided the funding for this version of Scientia Silvica extension series.

Upland soils are a significant sink of atmospheric methane, but the organisms responsible for methane consumption have yet to be identified. The ecology of methanotrophs was investigated in a beech forest soil which exhibited atmospheric-methane-uptake. Maximal methane-oxidation was observed in the upper mineral layer between the organic and inorganic horizons at a rate of 3.1 +/- 0.3 nmoles CH 4 g [fresh wt soil]-1 d-1. A clone bank of the methanotroph pmoA gene was constructed by PCR amplification from soil DNA extracts. The PCR primers used coamplify the related amoA gene of ammonia-oxidizers. The clones recovered grouped into three clusters: Nitrosospira-like sequences, a group somewhat related to alpha-Proteobacteria methanotrophs and previously referred to as the RA14 group, and a cluster which could not be characterized as either amoA or pmoA sequences. No pmoA genes closely related to genera of cultured methanotrophs were obtained. The 16S rDNA was also targeted using eubacterial and methanotroph-specific primers. 16S rDNA sequence analysis revealed the presence of organisms distantly related to known methanotrophs. Methanotroph enrichment cultures were established by inoculating mineral salts medium with soil and incubating under an atmosphere of 10% methane in air. Gene sequencing from the enrichments indicated the presence of organisms belonging to the genera Methylosinus and Methylocystis. The results suggest that the dominant methanotrophs in the forest soil are not related to known organisms and do not grow under conditions typically used to isolate methanotrophs.

This thesis quantifies aspects of shade tolerance in tree seedlings of species native to the Caledonian pinewood ecosystems of Glen Affric (Highland Region, Inverness-shire). Growth, allocation and morphological responses of 15 species to irradiance under simulated forest canopy light were investigated in a nursery-based shade house experiment. The same responses of four of the 15 species (Ilex aquifolium, Alnus glutinosa, Sorbus aucuparia and Betula pubescens) to different developmental stages of Pinus sylvestris woodland were investigated in the field. The spatial and temporal growth responses of naturally regenerating S. aucuparia seedlings to shade and gap microhabitats were also studied. Data from the shade house experiment enabled further detailed exploration of the relationship between relative growth rates (RGR) and irradiance and potential cross-overs of ranks of growth in high and low light conditions.

Management, under the concepts of multiple-use and adaptive management, requires the assessment of potentials and limitations of the natural ecosystems to provide satisfaction to human needs, to protect long term productivity, and preserve biological diversity. Overstory-understory relationships were developed for ponderosa pine (Pinus ponderosa) ecosystems to help managers to evaluate herbage production potentials. Secondary data sources from the Beaver Creek and the Heber Watersheds were divided as follows: igneous soils, igneous clay loam, igneous loam-sandy loam, sedimentary soils, alluvium, and sandstone. Regression models were fitted to the raw data by the least squared method. The dependent variables were herbage production (lb/ac) by component; namely total, grass and grass like plants, forbs and half shrubs, and shrubs. The independent variables were total and ponderosa pine basal area (ft 2 /ac). Semilogarithmic models fitted the data from igneous soils, while logarithmic transformations of hyperbolic models fitted the data from sedimentary soils. For igneous soils, ponderosa pine basal area suffice for adequate predictions of herbage production. Significant differences were found between equations for alluvium and sandstone. The resulting equations for ponderosa pine integrate the core of the model UNDER. Mathematical functions developed elsewhere are included in UNDER to compute herbage production in pinyon-juniper and mixed conifer ecosystems. UNDER is linked to other simulators by MICROSIM. MICROSIM, a multiple-resource simulation model, is a tool to assist in the assessment of potentials of forest and woodlands of Arizona. MICROSIM is a menu driven program for IBM or compatibles it contains the module Flora, for estimating plant responses, and module Fauna, to evaluate impacts on animals. Further development of MICROSIM should include the linkage to more modules and models, and to Geographical Information Systems.

This thesis presents the results of a study to examine long-term forest dynamics in the high-altitude mountains of West-Central Mexico. Vegetation dynamics on temporal scales ranging from 10² to 10³ years were reconstructed in order to provide essential information on the temporal variability of ecological patterns and processes in these forests; information that is of direct relevance for their current and future conservation and management strategies. Vegetation and palaeoecological methods undertaken included fossil and modern pollen analysis, vegetation surveys, microfossil charcoal analysis, magnetic susceptibility, inorganic and organic geochemistry, radiocarbon and ²¹⁰Pb dating. These were used to evaluate the long-term dynamics of three forest types; Pine Forest, Cloud Forest and Transitional Forest on timescales spanning the past 4260, 1340 and 1230 years respectively. The main drivers of change were climate and disturbance events induced by climate fluctuations, for example increased fire frequency. The reconstructed records indicate that the sequences from the Cloud Forest and the Transitional Forest spanned two wet and one dry climatic interval while the Pine Forest sequence spanned two dry and two wet periods. The impact of these climatic fluctuations was significant on all three forest types and resulted in variations in forest diversity, taxonomic turnover and successional change. The climate change episodes observed in these records seem to be the local manifestation of climatic events that were occurring throughout Mexico at these intervals in time. Human influences were evident in the three forests through the appearance of cultural taxa, particularly during the driest period (~ 1200 yr BP). There is little evidence from these records, however, to suggest a widespread clearance of the landscape for agriculture. Results from this study support the current conservation and management recommendations for Cloud Forest to exclude timber extraction, grazing and agricultural activities from this forest type. In the Pine Forest, human interventions such small-scale agriculture, prescribed burning and silvicultural actions are in agreement with the longterm pine ecology and as such, total exclusion of human activities is not necessary. For the Transitional Forest, results from this study suggest that there needs to be the establishment of adequate plans to reduce frequent fires to arrest the development of prone-to-fire taxa.

Climate warming is increasing fire severity in boreal forests and can alter forest structure and carbon (C) dynamics in Cajander larch ( Larix cajanderi) forests of Siberia, which occur over C and ice-rich yedoma permafrost. Altered forest structure may impact understory vegetation through changing canopy cover, permafrost thaw depth, and soil temperatures. The primary objective of this study was to assess the long-term impacts of fire-driven changes in tree density on understory composition, diversity, and C pools and the underlying soil organic layer (SOL). Shrubs dominated low density stands, likely from reduced canopy cover and thaw depth, while mosses dominated high density stands. Consequently, understory C pools decreased from 415.46 to 158.87 g C m^–2. Total SOL C pools remained unchanged as tree density increased. These findings suggest that fire-driven changes in tree density may alter understory composition and C pools, which could impact nutrient/water cycling and permafrost stability.

Effective stewardship of forest ecosystems make it imperative to measure, monitor, and predict the dynamic changes of forest ecology. Measuring and monitoring provides us a picture of a forest's current state and the necessary data to formulate models for prediction. However, societal and natural events alter the course of a forest's development. A simulation environment that takes into account these events will facilitate forest management. In this thesis, we describe an efficient parallel implementation of a land cover use model, Mosaic, and discuss the development efforts to incorporate spatial interaction and succession dynamics into the model. To evaluate the performance of our implementation, an extensive set of simulation experiments was carried out using a dataset representing the H.J. Andrews Forest in the Oregon Cascades. Results indicate that a significant reduction in the simulation execution time of our parallel model can be achieved as compared to uni-processor simulations.

The forests of south-eastern Australia, having evolved in one of the most fire-prone environments in the world, are characterized by many adaptations to recovery following burning. Thus forest ecosystems are characterized by rapid regenerative capacity, from either seed or re-sprouting, and mechanisms to recover nutrients volatilized, including an abundance of N2 fixing plants in natural assemblages. Soil physical, chemical and biological properties are directly altered during fire due to heating and oxidation of soil organic matter, and after fire due to changes in heat, light and moisture inputs. In natural ecosystems, carbon (C) and nitrogen (N) lost from soil due to fires are recovered through photosynthesis and biological N2 fixation (BNF) by regenerating vegetation and soil microbes.
This study investigated post-fire recovery of soil C and N in four structurally different sub-alpine plant communities (grassland, heathland, Snowgum and Alpine ash) of south-eastern Australia which were extensively burnt by landscape-scale fires in 2003. The amount and isotopic concentration of C and N in soils to a depth of 20 cm from Alpine ash forest were assessed five years after fire in 2008 and results were integrated with measurements taken immediately prior to burning (2002) and annually afterwards.
Because the historical data set, comprised of three soil samplings over the years 2002 to 2005, consisted of soil total C and N values which were determined as an adjunct to 13C and 15N isotopic studies, it was necessary to establish the accuracy of these IRMS-derived measurements prior to further analysis of the dataset. Two well-established and robust methods for determining soil C (total C by LECO and oxidizable C by the Walkley-Black method) were compared with the IRMS total C measurement in a one-off sampling to establish equivalence prior to assembling a time-course change in soil C from immediately pre-fire to five years post-fire. The LECO and IRMS dry combustion measurements were essentially the same (r2 >0.99), while soil oxidizable C recovery by the Walkley-Black method (wet digestion) was 68% compared to the LECO/IRMS measurements of total C. Thus the total C measurement derived from the much smaller sample size (approximately 15 mg) combusted during IRMS are equivalent to LECO measurement which require about 150 mg of sample.
Both total C and N in the soil of Alpine ash forests were significantly higher than soils from Snowgum, heathland and grassland communities. The ratio of soil NH4+ to NO3- concentration was greater for Alpine ash forest and Snow gum woodland but both N-fractions were similar for heathland and grassland soils. The abundance of soil 15N and 13C was significantly depleted in Alpine ash but both isotopes were enriched in the heathland compared to the other ecosystems. Abundance of both 15N and 13C increased with soil depth.
The natural abundance of 15N and 13C in the foliage of a subset of non-N2 fixing and N2 fixing plants was measured as a guide to estimate BNF inputs. Foliage N concentration was significantly greater in N2 fixers than non-N2 fixers while C content and 13C abundance were similar in both functional groups. Abundance of 15N was depleted in the N2 fixing species but was not significantly different from the non-N2 fixers to confidently calculate BNF inputs based on the 15N abundance in the leaves.
The total C pool in soil (to 20 cm depth) had not yet returned to the pre-fire levels in 2008 and it was estimated that such levels of C would be reached in another 6-7 years (about 12 years after the fire). The C and N of soil organic matter were significantly enriched in 15N and 13C isotopes after fire and had not returned to the pre-fire levels five years after the fire. It is concluded that the soil organic N pool can recover faster than the total C pool after the fire in the Alpine ash forests.

This paper explores the characterization of a riparian bottomland forest in north central Texas in two ways: field study, and computer simulation with the model ZELIG. First, context is provided in Chapter One with a brief description of a southern bottomland forest, the ecological services it provides, and a history of bottomland forests in Texas from the nineteenth century to the present. A report on a characterization study of the Lake Ray Roberts Greenbelt forest comprises Chapter Two. The final chapter reviews a phytosocial study of a remnant bottomland forest within the Greenbelt. Details of the ZELIG calibration process follow, with a discussion of ways to improve ZELIG's simulation of bottomland forests.

This project was designed to examine the stability of stream ecosystems in response to forest disturbance and subsequent succession. Stability was defined as the ability of streams to retain particulate organic matter and nutrients during storms. I hypothesized that forest streams are least stable during the intermediate stages of forest succession because particulate organic matter accumulations in streams are lowest at that time. This hypothesis was tested by examining stream stability in relation to forest succession. Stream surveys indicated fewer debris dams and organic matter accumulations in streams draining early and intermediate successional forests compared to reference sites. The abundance of large wood declined within 10 years of forest disturbance and continued to decline for at least 30-40 years through the intermediate stages of forest succession. Comparisons of inputs with standing stocks of organic matter indicated that streams draining early and intermediate successional sites receive less litter from their watersheds and processed it faster. Decreases in stream obstructions combined with changes in litter inputs and processing resulted in relatively high storm transport of fine organic matter from disturbed streams. Storm organic matter export from disturbed streams averaged 4.22 g AFDW/m² and from reference streams averaged 1.83 g AFDW/m². Storm nutrient budgets, constructed by measuring nutrient inputs (soil water, throughfall) and outputs (stream discharge) during individual storms indicated that streams draining early and intermediate successional forest were less retentive of nitrogen and phosphorus than reference sites. Nitrogen loss from disturbed streams averaged 58.04 mg/m²/storm and from reference streams averaged 16.52 mg/m²/storm. Phosphorus loss from disturbed streams averaged 32.52 mg/m²/storm and from reference sites averaged 7.14 mg/m²/storm. A majority of the nitrogen and phosphorus loss was in association with organic particles. There was no difference between disturbed and reference streams in potassium, calcium, or sulfate retention during storms. However, disturbed streams tended to lose more particulate organic potassium and calcium than reference sites. These results indicate that forest disturbance has a Iong-term impact on stream ecosystems by reducing their stability for many years following forest clearing.
Ph. D.

This thesis is an intersectional study of forest rights of forest-dwellers in the tribal territory of Koraput, India. The thesis is developed around a piece of path-breaking legislation, the Forest Rights Act (FRA) of India 2006, under which land titles and resource use rights are being granted to many forest-dwelling households and communities. This work exclusively deals with the individual title holders of forest land under the FRA. It explores three important questions: 1) what is the history of forest-rights delineation in Koraput?, 2) how are the rights of forest-dwelling people being settled under FRA? and, 3) what are the complexities of land use in these tribal forestlands?} The thesis has used a mixed-methods approach to build and connect its three focus areas. Historical aspects of local forest rights have been explored through the lens of colonial and post-colonial forest policy analysis. The investigation of the various aspects of FRA implementation and ground realities combines cross-disciplinary approaches from political and gendered micro geography. The analysis of emerging land use on forest lands allotted under FRA is influenced by the Sen’s theory of entitlements, endowments and capabilities {Sen, 2001}. A multi-approach assessment methodology has been used by analysing a wide range of data streams including historical documents, household surveys, interviews, participatory maps, observations, group discussions and secondary data sets. Key findings that have emerged from this thesis are, 1) the consequences of the implementation of colonial and post-colonial forest policy measures on Koraput's forest-dwellers are substantial and unique geography of Koraput has produced new insights to the existing knowledge of history of forest rights in India, 2) FRA is a promising piece of legislation that has achieved significant political and bureaucratic collaboration in Koraput, but it is marred by major operational inefficiencies, and 3) the newly created FRA-lands will provide opportunities for policy makers and title owners to reconsider many existing norms including legal versus illegal occupation of forest land, forest-farming practices on FRA lands, and a need for renewed forest and land management goals for FRA territories in tribal India.

Thesis (M.S.)--Southern Oregon State College, 1994.
Typescript. Includes bibliographical references (leaves 73-80). Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

High-severity disturbances are the primary drivers of Engelmann spruce-subalpine fir ecosystems in the southern Rocky Mountain. Recently, an unprecedented, landscape-wide (at least 250 km2) spruce beetle outbreak killed virtually all the Engelmann spruce on the Markagunt Plateau in southwestern Utah, USA. Results from dendroecological analyses suggested the combination of antecedent disturbance history and drought-driven stand development was responsible for creating suitable host conditions prior to the recent outbreak. Multiple and consistent lines of evidence suggested mixed- and high-severity fires shaped the development of the Markagunt Plateau. Subsequent stand development, influenced by species-specific differential tree-ring response to drought, resulted in the gradual increase of Engelmann spruce dominance across the landscape. Spatiotemporal outbreak dynamics included the early, independent and spatially synchronous building of beetle populations in moist sites with large Engelmann spruce across the landscape. As the outbreak evolved over time, it is likely temperature anomalies accelerated beetle population growth, leading to more rapid spruce mortality. In the wake of the spruce beetle outbreak, results from simulated potential fire behavior suggested there was a reduction in probability of active crown fire for one or two decades on near-pure Engelmann spruce sites after the outbreak. This counterintuitive result suggested extreme fire behavior is not an inevitable consequence of spruce beetle outbreaks. Regardless of the occurrence of fire, forest response is likely to be dominated by advance regeneration in the seedling bank. Furthermore, because spruce was virtually absent from the understory, forest reorganization is likely to be dominated by subalpine fir. In response to recent outbreaks such as the Markagunt Plateau, silviculturists are questioning what they can do to limit the loss from these likely inevitable spruce beetle outbreaks. Concepts of resistance and resilience can be used in planning vegetation management intended to indirectly control beetle populations by manipulating their habitat (vegetation). Resilient landscapes will ideally have spruce age class diversity and size class diversity in spatially discontinuous patches.