Ecosystem management is positioned as the modern paradigm of resource management. Fire management activities within the natural resource management agencies, under the adoption of an ecosystem management approach, supports an increased focus upon prescribed and manager-ignited fire programs. A review of past national fire policies and the effects they have had upon ecosystem conditions today further supports the role for prescribed fire. Under an ecosystem management approach, resource managers need to consider the effects of fire management activities over longer temporal and broader spatial scales. Examining the ecological, social, political, and economic aspects surrounding fire management activities on these scales will help ensure healthier ecosystems in perpetuity. Although the suppression of wildfires will remain a necessary component to fire management activities today, there needs to be an increased effort to reintroduce fire into ecosystems and to recognize fire as a natural component vital to maintaining ecosystem health.

The research accomplished in this dissertation used both mathematical and statistical techniques to extract and evaluate measures of landscape temporal dynamics and spatial structure from remotely sensed data for the purpose of mapping wildlife habitat. By coupling the landscape measures gleaned from the remotely sensed data with various sets of animal sightings and population data, effective models of habitat preference were created. Measures of temporal dynamics of vegetation greenness as measured by National Oceanographic and Atmospheric Administration's Advanced Very High Resolution Radiometer (AVHRR) satellite were used to effectively characterize and map season specific habitat of the Sonoran pronghorn antelope, as well as produce preliminary models of potential yellow-billed cuckoo habitat in Arizona. Various measures that capture different aspects of the temporal dynamics of the landscape were derived from AVHRR Normalized Difference Vegetation Index composite data using three main classes of calculations: basic statistics, standardized principal components analysis, and Fourier analysis. Pronghorn habitat models based on the AVHRR measures correspond visually and statistically to GIS-based models produced using data that represent detailed knowledge of ground-condition. Measures of temporal dynamics also revealed statistically significant correlations with annual estimates of elk population in selected Arizona Game Management Units, suggesting elk respond to regional environmental changes that can be measured using satellite data. Such relationships, once verified and established, can be used to help indirectly monitor the population. Measures of landscape spatial structure derived from IKONOS high spatial resolution (1-m) satellite data using geostatistics effectively map details of Sonoran pronghorn antelope habitat. Local estimates of the nugget, sill, and range variogram parameters calculated within 25 x 25-meter image windows describe the spatial autocorrelation of the image, permitting classification of all pixels into coherent units whose signature graphs exhibit a classic variogram shape. The variogram parameters captured in these signatures have been shown in previous studies to discriminate between different species-specific vegetation associations. The synoptic view of the landscape provided by satellite data can inform resource management efforts. The ability to characterize the spatial structure and temporal dynamics of habitat using repeatable remote sensing data allows closer monitoring of the relationship between a species and its landscape.

The primary goal of my study was to evaluate strategies for promoting local support for wildlife conservation in Masai Mara National Reserve (MMNR) and the adjacent group ranches. This was done by determining the effects of the changing land tenure from communal to individual on the Maasai lives and wildlife, and the role of the revenue sharing program in enhancing support for wildlife conservation. The study used local people's suggestions to recommend strategies for improving revenue sharing. A combination of literature review, questionnaire-based surveys and participant observation methods were used to achieve these goals. The maintenance of a viable ecosystem in Mara has succeeded due to the traditionally benign relationship between the Maasai and wildlife. However, various factors continue to strain this relationship. First, increasing human population and encroachment of agriculture has diminished areas available for livestock and wildlife grazing. Second, the absence of compensation for loss of life and property to wildlife and inadequacy of the revenue sharing has increased people's antagonism towards wildlife. Third, since the local people are excluded from the management of MMNR and wildlife in general, they consider these activities external impositions. Fourth, subdivision of group ranches will severely reduce the land available for livestock and wildlife grazing and eliminate the traditional resource sharing strategy that has sustained the Maasai for centuries. This study also revealed that although the Maasai harbor many negative feelings towards MMNR, they consider it an important asset. Further, they are unwilling to give up pastoralism and expect to continue with communal grazing after subdivision which, is good for wildlife conservation. In view of this, I made the following recommendations: implement a regional land management system with a core wildlife area (the reserve) and a wildlife management-pastoral area surrounding the core, and designated zones for agriculture; support the above system with firm government policies and incentives; redesign the revenue sharing program to cover all the affected people; promote policies that encourage diversified wildlife-based enterprises including consumptive use; transfer much of the wildlife management responsibilities to the local people.

In contrast to documented increases in woody plant dominance of former savannas and grasslands of North America, oak (Quercus L.) savannas that form lower treelines in the southwestern United States and northwestern Mexico have been relatively stable over the past millennium. This research identified potential biotic and abiotic constraints on seedling recruitment of Quercus emoryi Torr. (Emory oak) within the context of potential shifts in lower treeline. Field surveys were used to describe seedling distribution at and below lower treeline, and to determine the potential for acorn dispersal from lower treeline into adjacent grassland. Field and greenhouse experiments designed to determine constraints on seedling establishment included reciprocal soil transfers, nutrient amendment studies, provision of artificial shade, and manipulation of seasonal precipitation inputs. Results indicate that rates of Q. emoryi recruitment within grasslands below treeline are relatively low, and are constrained by low rates of seed dispersal coupled with a low probability of seedling emergence. Seedling recruitment rates were directly correlated with quantity of summer precipitation, but were independent of winter precipitation. Results of this and complementary research suggest that lower treeline in southern Arizona is stabilized by self-enhancing feedback mechanisms of overstory shade, seed dispersal, and seedling establishment coupled with strong abiotic constraints beyond the current ecotone. The observed shift in treeline in the last millennium was less likely the result of slow, spatial progression of autogenic safe sites than the result of episodic and infrequent allogenic processes that simulated, or negated the importance of, conspecific, biogenic safe sites. Increases in summer precipitation are one such process that would facilitate (historic or potential future) downslope shifts in lower treeline. This interpretation is consistent with observations that downslope shifts in lower treeline which occurred 700-1700 ybp coincided with a period of particularly high summer precipitation in the region (i.e., the "Medieval Warm" period, 645-1295 ybp).

It has long been asserted that taxation distorts the production decisions of timber land owners. More recently, claims have been that this does not occur because the tax is fully shifted into sawlog prices. This paper constructs a model of landowner choice between a property tax programme and a modified yield tax programme under the assumption of tax capitalization. Under tax shifting, the landowner will be indifferent between tax regimes. With tax capitalization owners of younger stands will elect to classify their stands for the modified yield tax programme. An empirical model of binary choice is evaluated using cross sectional forty level data from Cowlitz County, Washington immediately after implementation of the Reforestation Act of 1931. The empirical results suggest that landowners are responsive to differences in the taxing pattern in a manner conforming to the theoretical predictions consistent with tax capitalization. Additional results suggest that implementation of the alternate tax regime may have had little effect on tax defaults. The tax capitalization result is extended to derive expressions for pigouvian taxes designed to influence stand management, consistent with the increasing timber prices encountered in the postwar world.

Because recent conflicts over U.S. Forest Service decisions may indicate that the public lacks confidence in the agency, this study sought to discover the level of and reasons for confidence in the Forest Service. Results of a nationwide mail survey of participants in Forest Service planning showed that 43% of respondents had a low level of confidence in their local Forest Service office and 55% had a low level of confidence in the agency at the national level. The survey also revealed that participants' judgments of the procedural fairness of the planning process had an important influence on confidence in the agency at both the local and national level. Judgments about the fairness of agency procedures were much more important determinants of confidence than the level of benefits participants received from the forests or their policy preferences, judgments about distributive fairness, socio-demographic characteristics or styles of participation.

I quantified microhabitat conditions used by Yaqui chub (Gila purpurea), Yaqui topminnow (Poeciliopsis occidentalis sonoriensis), and beautiful shiner (Cyprinella lutrensis) on the San Bernardino National Wildlife Refuge, Arizona. Different species and different lifestages used different microhabitats. Smaller fish selected shallower water than adults. Yaqui topminnow and Yaqui chub showed seasonal variation in microhabitats used. Yaqui topminnows were found closer to cover when in the presence of beautiful shiners. Close proximity to cover may indicate a negative interaction. Yaqui chubs did not use microhabitats differently when in the presence of the other two species. Microhabitats used by Yaqui chubs in the ponds and Leslie Creek did not differ. Yaqui chub preferred pools with little or no flow. Management of aquatic environments on the refuge should focus on vegetative thinning. Stocking of beautiful shiner with Yaqui topminnow should be postponed until further research is conducted on the interactions between the two species.

Pandora moth (Coloradia pandora Blake) is a phytophagous insect, defoliating ponderosa pine trees in the western United States. However, long-term studies of this insect and its effects on the forest ecosystem have not been conducted. Using dendrochronological techniques, I examined past timing and intensity of defoliation through its effects on radial growth of trees in the forests of south central Oregon. Pandora moth leaves a distinctive ring-width "signature" that was easily identifiable in the wood. The growth for the first year of the signature was half the normal ring-width with narrow latewood. The following two years produced extremely narrow rings, with the entire suppression lasting from 4 to 18 years. Twenty-two individual outbreaks were reconstructed from this 620 year chronology. I found that pandora moth outbreaks were episodic on individual sites, with a return interval of 9 to 156 years. Conversely, on the regional scale of south central Oregon, outbreaks demonstrated a 37-year periodicity. On average, pandora moth defoliation caused a 29% mean periodic growth reduction in defoliated ponderosa pine trees. Spread maps of the first year that sites demonstrated suppression were plotted revealing an apparent annual spread of the outbreaks. Examination of a fire history on one pandora moth outbreak site suggested that pandora moth outbreaks delay fire by interrupting the needle fall needed for fire spread. Superposed epoch analysis showed that the year that the outbreak was first recorded was significantly dry and the fourth year prior was significantly wet. Therefore, climate may be a triggering factor in pandora moth outbreaks. The stem analysis demonstrated that the percent volume reduction was greatest at the base of the tree and declined further up the bole. The percent volume reduction in the canopy of the trees was variable with outlying high and low values. The mean volume reduction per outbreak was .053 m³ per tree. Although this insect is considered a forest pest and causes inconvenience for people living nearby, pandora moth is not as widespread and damaging as some other phytophagous insects. However, its very distinctive ring-width signature and the length of the ponderosa pine record enables reconstruction of very long outbreak histories, which may deepen our understanding of the interaction between defoliating insects and their ecosystem.

Sap flow, leaf gas exchange, and micrometeorological parameters were evaluated during 1997 in riparian forest at perennial and ephemeral stream sites on the San Pedro River in southeastern Arizona, USA. At the perennial stream site, measurements of sapwood area based transpiration and sapwood area/canopy area of clusters of Populus fremontii and Salix goodingii were used to estimate transpiration across the stand. Stand structural heterogeneity resulted in as much as 30% variation in mean transpiration across the stand. Transpiration of cottonwood was more dependent upon vapor pressure deficit at the ephemeral stream site which had an open, less dense canopy compared to that at the perennial stream site. This may be due to differences in advection properties and canopy feedback processes between sites. Conversely, transpiration in willow was less dependent upon vapor pressure at the ephemeral stream site than that at the perennial stream site. This may be due to water stress associated with deeper depth to groundwater.

The Endangered Species Act of 1973 (ESA) reflects society's concern over the rate of species extinction and aims to halt or reverse this trend. Several policies of the ESA protect listed species over resource development projects. Due to this protection, several listed species have recently experienced a recovery. Two have been removed, or delisted, from the federal Endangered Species list. Once a recovered species becomes delisted, the majority of these protections are removed. This paper analyzes the political implications of such delistings utilizing formal interviews, personal experiences, and a literature search. Through analysis, it is found that two specific policies seem to protect delisted species. It is concluded that a quantitative analysis may be premature at this time due to the small number of recovered species and that these policies must be effected to their fullest potential to ensure the long-term success of the federal endangered species program.