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Elimination of large predators and reduced hunter harvest have led to concerns that an increasing ell (Cervus elaphus) population may be adversely affecting vegetation on the low-elevation elk winter range of Rock Mountain National Park, Colorado, USA. Beaver (Castor canadensis) and their impoundments also have declined dramatically (94%) in the same area over the past 50 years coincident with a 20% decline in willow (Salix spp.) cover. From 1994 to 1998, we studied vegetation production responses of willow communities to elk herbivory and water availability. We estimated willow production by measuring current annual growth of shrubs in 9.3-m 2 circu lar plots, and we measured herbaceous production by clipping vegetation within 0.25-m 2 circular plots. Elk her bivory suppressed willow heights, leader lengths, annual production, and herbaceous productivity of willow corn munities. Water impoundment had a positive effect on herbaceous plant production, but little effect on shrubs, possibly because water tables were naturally high on the study sites even without beaver dams. Nevertheless, the winter range environment previously included more riparian willow habitat because of more stream area (47-69%) due to larger beaver populations. Elk herbivory appears to be the dominant force determining vegetation pro ductivity in willow sites, but the effects may he exacerbated by lowered water tables. Fewer elk or protection from browsing, and water enhancement for

Land managers need accurate and quick techniques to identify suitable habitat of species of interest. For species protected by federal or state laws, identification of suitable habitat is critical for developing a conservation strategy that includes reestablishing populations and altering management to address this need. In this research, we quantified vegetative and edaphic habitat of the western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles), a federally listed threatened plant. Lowlands (swales) that supported orchids in our southeastern North Dakota study area were characterized as having a higher soil moisture content within the top 10 cm, when compared to swales devoid of orchids. The vegetative composition of orchid-supporting swales reflected this higher moisture content. These data were then used in developing a logistic regression model to differentiate suitable habitat. The model correctly classified 84% of 38 swales as either orchid-supporting or non-orchid-supporting using 4 variables: percent canopy cover of Baltic rush (Juncus balticus Willd.) and hedge-nettle (Stachys palustris L.), soluble soil magnesium and August surface soil moisture. Land managers can use this model to rapidly assess the suitability of a site in this ecoregion for the orchid. By collecting data on the cover of just Baltic rush, which would take about 45 minutes, and entering it in the equation, a land manager could correctly classify 66% of the orchid swales as either suitable or unsuitable as orchid habitat. This approach, because it incorporates quantitative data and allows managers to rapidly and accurately identify suitable habitats, shows promise for other plant species. DOI:10.2458/azu_jrm_v54i5_wolken

Recent increases in elk (Cervus elaphus L.) herbivory and changes in hydrology towards drier conditions have contributed to declines in willow (Salix spp. L.) communities in the winter ranges for elk in Rocky Mountain National Park. In 1994, we constructed 12 large elk exclosures in 2 watersheds of the winter range for elk in the park, and conducted field experiments from 1995 to 1999 to investigate the effects of herbivory and proximity to surface water on the dynamics of C and N. Litterfall biomass averaged 65.6 and 33.0 g m(-2) inside and outside the exclosures, respectively. Elk herbivory increased (P < 0.05) N concentration of willow litter from 1.25 to 1.49%, but there were no differences in losses of C and N from litterbags placed in grazed and ungrazed plots in any of the growing seasons. Carbon losses from litterbags were higher in lower landscape positions (P = 0.001), in comparison to upper landscape positions. Shoot biomass of willow plants fertilized with N averaged 27.3 g and was higher (P < 0.05) than that of unfertilized plants, which averaged 20.2 g, indicating that N availability limits plant growth in our study sites. Elk herbivory had no effect on soil inorganic N availability, even though we estimated that the return of N to the soil in grazed plots could be as much as 265% of the N return in exclosed plots. In the long-term, greater return of N to the soil combined with increased litter quality in the grazed plots could contribute to increases in N cycling rates and availability, and these changes could affect ecosystem structure and function in the winter range for elk in Rocky Mountain National Park. DOI:10.2458/azu_jrm_v54i4_menezes

Disastrous Environments, Vulnerability and Response Hazardous Environments and Low-Income Neighbourhoods Housing, Environmental Problems and Resources.

The life history, community ecology, population ecology, and pest management of grasshoppers on the typical steppe of Inner Mongolia were compared with those of the Great Plains of North America. Although the life histories of grasshoppers are similar, the Inner Mongolian grasslands have two distinct developmental cohorts, and all species are believed to have four or five nymphal instars. Grasshopper species are not known to overwinter as nymphs on the Asian steppe. A relatively high proportion of Chinese species show sexual dimorphism and brachyptery, although no Asian steppe species have aposematic coloration. The community structure of grasshoppers is similar in both regions, with the flora apparently playing an essential role. However, the Asian fauna is dominated by Gomphocerinae (particularly Chorthippusl while the North American fauna is dominated by both the Gomphocerinae and Melanoplinae (primarily Melanoplus). Thus, Chinese grasshopper communities are principally graminivorous (with no known cannibalism) and no species is perceived to be economically beneficial, while the North American fauna is characterized by both grassand mixed-feeders, some of which consume weeds. Population dynamics in both ecosystems are linked to weather, but North American grasslands appear to support four times more grasshopper biomass per unit of forage than the Asian steppe. Predators and parasites are potentially important regulators of low population densities in both ecosystems, but pathogens appear to play a more significant role in North America. An average of 0.5% of the land is treated (primarily with malathion) each year in both regions. Although the cost of treatment is similar, the economic threshold is perceived to be higher in Inner Mongolia.

Deterrence theory justifies tort law as a cure for market failures related to risky products and services. Negligence liability gives the providers of goods and services an incentive to take all cost-justified precautions in the design and manufacture of what they sell. Strict liability not only creates those incentives, but also brings about the economically correct levels of production: suppliers' prices will reflect the relative riskiness of their goods, making consumers adjust their purchases to the level they would have demanded if they were fully informed about the products' residual hazards.' Thus, under either a negligence or a strict liability system, soft drink and beer manufacturers will take cost-justified steps to prevent bottles and cans from exploding, cutting drinkers' lips, and the like. Under strict liability, if bottles are more dangerous than cans even after these safety measures have been taken, the price differential between the two will reflect the risks and thus spur consumers to adjust their consumption decisions accordingly. The allocation of resources as between bottles and cans will be optimal. The validity of deterrence theory, as applied to claims by people who contract to buy the goods or services that cause their injuries, depends on an assumption about rational consumer ignorance. At least for low-probability risks, for which consumers may "not have much intuitive feel," deterrence theory assumes that consumers will rationally invest little time or effort in informing themselves.2 Moreover, because of the relative unimportance of such risks in comparison to the costs of studying the language of a contract, the consumer may not find it worthwhile to study even a "clear and conspicuous" dis

The use of the collagenase-SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) technique for comparing the condition of collagen in skin tissues is described. The technique was used on untreated skin samples and on others subjected to chemical treatments typically used for the preservation of biological specimens. Compounds examined included aluminum ammonium sulfate, arsenic trioxide, magnesium carbonate, mercuric chloride, potassium nitrate, sodium borate, sodium chloride, sodium fluorosilicate and formaldehyde. Differences were detected between the better preservatives, such as formaldehyde and arsenic trioxide, and others that actually promoted collagen degradation, such as potassium nitrate and mercuric chloride.

We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 species of seed plants, respectively, representing all major taxonomic groups. The data are exclusively from the chloroplast gene rbcL, which codes for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO or RuBPCase). We used two different state-transformation assumptions resulting in two sets of cladograms: (i) equal-weighting for the 499-taxon analysis; and (ii) a procedure that differentially weights transversions over transitions within characters and codon positions among characters for the 475-taxon analysis. The degree of congruence between these results and other molecular, as well as morphological, cladistic studies indicates that rbcL sequence variation contains historical evidence appropriate for phylogenetic analysis at this taxonomic level of sampling. Because the topologies presented are necessarily approximate and cannot be evaluated adequately for internal support, these results should be assessed from the perspective of their predictive value and used to direct future studies, both molecular and morphological. In both analyses, the three genera of Gnetales are placed together as the sister group of the flowering plants, and the anomalous aquatic Ceratophyllum (Ceratophyllaceae) is sister to all other flowering plants. Several major lineages identified correspond well with at least some recent taxonomic schemes for angiosperms, particularly those of Dahlgren and Thorne. The basalmost clades within the angiosperms are orders of the apparently polyphyletic subclass Magnoliidae sensu Cronquist. The most conspicuous feature of the topology is that the major division is not monocot versus dicot, but rather one correlated with general pollen type: uniaperturate versus triaperturate. The Dilleniidae and Hamamelidae are the only subclasses that are grossly polyphyletic; an examination of the latter is presented as an example of the use of these broad analyses to focus more restricted studies. A broadly circumscribed Rosidae is paraphyletic to Asteridae and Dilleniidae. Subclass Caryophyllidae is monophyletic and derived from within Rosidae in the 475-taxon analysis but is sister to a group composed of broadly delineated Asteridae and Rosidae in the 499-taxon study.

utilization of services. Rates must be adjusted frequently to compensate for errors. Most significantly, some major policies are promulgated in the health insurance market based on judgements that are backed up with only limited, if any, firm evidence. Imposition of exclusions and limitations in health insurance contracts is based on common "wisdom" or the concerns of the underwriter about abuse of benefitsm Fears of moral hazard, unexpected disease occurrences in insured population groups, or other factors lead to the imposition of limitations or exclusions creating inaccessibility and imposing undue hardship for the enrollee. Since the cost of removing these barriers is unknown, their true costs and benefits are nearly impossible to measure. This communication reports the results of a large-scale experiment, conducted over a period of four years during which the enrolled population group did not face the usual exclusions and limitations experienced in more traditional insurance programs. An attempt has been made to estimate the effects of some of these limitations using the experiences of this study population. The emphasis is on ambulatory care services which usually are less comprehensive than inpatient care in insurance contracts. Since health behavior is strongly affected by the content of insurance coverage1, these efforts are not in any way "pure" from a scientific perspective yet they shed some light on

The nature and stability of conjugal unions among 425 rural Haitian women were investigated to determine the potential impact of family formation patterns on fertility. Births deaths migrations and union formations were recorded for a four-year interval. Interviews were conducted to corroborate this information and to explore related topics. Findings reflect relative instability of conjugal unions associated with a pattern of serial union formation. Considerable time spent by women out of active union combined with relatively late age at first entry into union appear to be important dampers on fertility in this population. (authors)

Plethodon neomexicanus (Stebbins and Riemer, 1950) and Aneides hardii (Taylor, 1941) are members of the family Plethodontidae that are endemic to the Rocky Mountains of New Mexico. The active season for both species is mainly June, July, and August. Aneides hardii has a male reproductive cycle about 1 month ahead of P. neomexicanus. No male of A. hardii collected had his vasa deferentia packed with sperm, while the majority of males of P. neomexicanus had sperm-packed vasa deferentia. In P. neomexicanus oviposition occurs every other year, while in A. hardii oviposition may occur every 3 years. In P. neomexicanus mating occurs above ground in July and August and oviposition occurs between mid-August and the following spring. In A. hardii mating occurs below ground by the beginning of the active season, oviposition occurs in June and early July, and hatching occurs by August or early September. In P. neomexicanus one clutch of eggs contained seven eggs, with a range of 6.8 to 7.3 mm in diameter and in A. hardii six clutches averaged 4.7 eggs, with a range of 6.4 to 9.1 mm in diameter.