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This research project develops a theoretical approach to the study of the experience of environmental quality. The approach is derived from the transactional perspective of perception and uses the concepts of mergence and barriers to explain how people's experience of a place relates to their judgment of environmental quality. It assumes that people value environments which facilitate positive emotional experiences and that the judgment of environmental quality is related to the potentialities of the environment to provide a context for valued experiences. The implications of this theory are discussed with regard to the differences between the experience of built versus natural environments, an experiential versus value system approach to environmental quality, and the value of high quality natural environments. The first study used a structured interview to examine people's experience and evaluation of high and low quality built and natural environments in the Tucson area. The second study examined the use of photographic surrogates for the study of environmental quality by comparing objective photographs with subjective photographs taken by people visiting environments. The results support the view that the human valuing process is an affective, synthesizing, and concretizing process. The experiential differences between built and natural environments were examined with regard to the degree of interrelatedness of the physical, social, and functional aspects of the environment. The experiential and value system approaches to studying environmental quality were shown to be complementary, and some potential problems with the value system approach were examined. The value of high quality natural environments was shown to relate to the symbolic, spiritual and experiential meaning which people attribute to them. Although there were differences between the two methods of photographically simulating environments, both methods were shown to be useful for providing surrogates for the study of environmental quality. Overall, this research demonstrated the value of a holistic experiential framework for the study of environmental quality which helps to unite scientific research with people's experience of the environment.

Studies were conducted on the dynamics of live, standing recent dead, and standing old dead herbage for a desert grassland site in the southwestern United States. Data were collected at eleven sample dates from August 24, 1979 to October 18, 1980. Coefficients of variation for biomass data for most species exceeded 400% with only the most abundant species sampled with coefficients of variation less than 100%. Coefficients of variation generally were less than 80% for the perennial grasses as a group. The mean rate of transfer of biomass from live herbage to standing recent dead herbage was 0.21% per day for 203 days when expressed as a percentage of the peak live herbage. A rate of transfer of 0.53% per day of live herbage to standing dead for 109 days for perennial grasses in the desert grassland was found during early vegetative growth. A high proportion of leaves to culms was present during this period as compared to the summer growing season. Heavy precipitation in the early part of September accelerated growth of live herbage, and also accounted for losses of standing recent dead and standing old dead herbage to the surface litter component. The loss of dry leaves from standing grass culms due to rainfall impact contributes to an underestimate of net primary production. Standing old dead biomass accumulated following the depression in September. Transformation of the recent dead herbage to an appearance of old dead late in the summer also contributed to underestimating of current year production based on peak crop method due to the identification of recent dead herbage as the old dead component. Summation of growth increments by sample periods provided the highest estimate of aboveground net primary productivity when compared to estimates based on peak standing crop, summation of species peaks, and summation of significant growth increments by sample periods. Estimates of net productivity were 186% of the estimate at peak standing crop. Estimates of net production based on significant growth increments by sample periods yield the lowest value for net production, because poor precision of samples restricted data to few significant values. Based on the peak periods for standing biomass of lifeform groups, a minimum of four sample dates are recommended to estimate aboveground net primary production for semidesert grassland in southeastern Arizona. These sample dates include: (1) late April to sample spring peaks by perennial grasses, annual forbs and annual grasses; (2) late June to capture the spring trough; (3) late September to sample peak crops of perennial forbs, and half-shrubs; and (4) mid to late October to sample the fall peak for perennial grasses. Net production estimates by the peak crop method for perennial grasses varied from 18.7 g/m² in 1979 to 86.1 g/m² in 1980. This variability was attributed to the differences in the amount of rainfall in 1979 and 1980. This factor, therefore, largely influenced the repeatability of biomass estimates from one year to another. The large amount of time (approximately 644 man-hours) needed to sample and separate live and dead components by species for 20 quadrats at each harvest date, together with the year-to-year variability and the need for a minimum of four sample dates to effectively sample the desert grassland community, makes biomass data impractical for general use as a data base in land-use planning. However, this effort should be looked at from the standpoint of research studies describing the dynamics of range systems based on temporal characteristics and transfer functions to provide data which can help design management strategies for these range ecosystems.

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