Rarity of all sorts piques the curiosity of humans. Rare objects, whether discoveries of natural origin or artifacts of cultures, arc avidly sought by collectors and are treasured, housed, and exhibited for the benefit of others. This fascination with that which is rare may partially explain the naturalists' and systematists' time-honored preoccupation with rare and endemic taxa. To be sure, there are sound justifications for acquiring and studying rare organisms. But we suspect that the rarity-seeking syndrome in humans has fostered much of the biologist's preoccupation with rare and endemic plants and animals. The late twentieth century has witnessed exceptional concern for rare organ­ isms and at the same time has seen many rare plants and animals brought close to extinction (22) . The extirpation of rare taxa as well as efforts to preserve rare organisms is the product of the vast human influence on the world's biota. Threatened or endangered taxa have received prime press coverage and, in some instances, legal protection. The Rare and Endangered Species Act of 1973 (US 92nd Congress) and subsequent congressional actions constitute one such response to the threatened loss of the rarer examples of biological divers­ ity. We have no problem, then, in finding a wealth of literature on efforts to conserve rare species. Sources of information on what is rare and on the magnitude of the threat to survival range from the Federal Register's list of

Biological Aspects of Endemism in Higher Plants

Summary
Information is reviewed on the life histories and demographic patterns of shade-tolerant herbs of temperate deciduous forest. Most of the species that have been studied are deciduous perennials. These species generally have a juvenile (non-flowering) period of several years followed by an extended period of flower and seed production. About half the species reviewed are self-incompatible, the others are at least partially self-compatible. Although vegetative reproduction is common, replacement does not always occur by vegetative spread; many species appear to be able to replace themselves by seed. Sexual reproductive effort ranges from 1–5 to 50 % among the species reviewed; seed weight averages 2–6 mg. Short dormancy periods (one season) are most common, with germination rates generally below 50%.

Mortality rates of small plants are high, but decline as plant size increases. ‘Ageing’ does not appear to occur. No information exists on population growth rates of temperate deciduous forest herbs, or on the temporal stability of their population sizes or structures. The transition matrix model is suggested as a promising approach to future studies in plant demography.

Life histories and demography of shade‐tolerant temperate forest herbs: a review

A geographic information system (GIS) approach was used in conjunction with forest-plot data to develop an integrated moisture index (IMI), which was then used to predict forest productivity (site index) and species composition for forests in Ohio. In this region, typical of eastern hardwoods across the Midwest and southern Appalachians, topographic aspect and position (rather than elevation) change drastically at the fine scale and strongly influence many ecological functions. Elevational contours, soil series mapping units, and plot locations were digitized for the Vinton Furnace Experimental Forest in southeastern Ohio and gridded to 7.5-m cells for GIS modeling. Several landscape features (a slope-aspect shading index, cumulative flow of water downslope, curvature of the landscape, and water-holding capacity of the soil) were used to create the IMI, which was then statistically analyzed with site-index values and composition data for plots. On the basis of IMI values for forest land harvested in the past 30 years, we estimated oak site index and the percentage composition of two major species groups in the region: oak (Quercus spp.), and yellow poplar (Liriodendron tulipifera) plus black cherry (Prunus serotina). The derived statistical relationships were then applied in the GIS to create maps of site index and composition, and verified with independent data. The maps show the oaks will dominate on dry, ridge top positions (i.e., low site index), while the yellow poplar and black cherry will predominate on mesic sites. Digital elevation models with coarser resolution (1:24K, 1:100K, 1:250K) also were tested in the same manner. We had generally good success for 1:24K, moderate success for 1:100K, but no success for 1:250K data. This simple and portable approach has the advantage of using readily available GIS information which is time-invariant and requires no fieldwork. The IMI can be used to better manage forest resources where moisture is limiting and to predict how the resource will change under various forms of ecosystem management.

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A GIS-derived integrated moisture index to predict forest composition and productivity of Ohio forests (U.S.A.)

Mediterranean-type ecosystems have provided ecologists with some of the most scientifically-rewarding opportunities to formulate and evaluate hypotheses about large and small-scale ecological phenomena. Comparison of mediterranean-type climate ecosystems in different parts of the world has not only permitted a strong test for ecological convergence, but also critical understanding of key ecophysiological and population processes.

/pdf/ecology-and-biogeography-of-mediterranean-ecosystems-in-c4q0retg7w.pdf

Ecology and biogeography of mediterranean ecosystems in Chile, California, and Australia

Seasonal changes in water balance, energetics, food consumption, daily behavior, diet, osmoregulation and body mass were measured using doubly labeled water, radiotelemeters, and field behavior observations of tortoises (Gopherus agassizii) through a year (1976-1977) in Rock Valley, Nevada. Aboveground activity extended over the warm seasons (between March and November), and tortoises hibernated in burrows through winter. In spring, tortoises were active for about 3 h every fourth day. Some drank rainwater and they all gained weight while eating succulent annual plants, which provided excess water and potassium that were stored in the urinary bladder, but energy intake was less than required to meet energy expenses via respiration, and body solids declined. As food plants dried in late spring, tortoises eventually achieved positive energy balance while eating grasses, but body masses declined due to negative water balance. Bladder urine became isosmotic with blood plasma, and both became more concentrated. As the summer drought continued, feeding diminished and tortoises spent progressively more time estivating in burrows. Thundershowers in July triggered emergence from estivation, and tortoises drank much rainwater, voided concentrated urine, accumulated dilute urine, restored normal plasma osmotic concentration, resumed feeding on the still-dry grasses and forbs, and accumulated much surplus energy. However, body masses declined during this time due to negative water balance, and osmotic concentrations in bladder urine increased. More rain in September again relieved this osmotic stress as tortoises drank, urinated, and stored dilute urine. Energy balance remained strongly positive until tortoises began feeding on the succulent new sprouts of annual plants that germinated in late September, and the tortoises returned to a spring-like physiological situation through mid-November when hibernation began. Tortoises apparently relinquish maintenance of internal homeostasis on a daily basis during most of the year, while tolerating large imbalances in their water, energy and salt budgets. This ability enables them to exploit resources that are only available periodically, while balancing their water and salt budgets on an annual basis and showing an energetic profit. The environmental properties of rainfall (beneficial to tortoises) and dietary potassium content (deleterious) appear to have major effects on the health of these impressive reptiles.

https://www.jstor.org/stable/info/3892239

Physiological ecology of desert tortoises in southern Nevada

The physical environment of the Nevada Test Site and surrounding area is described with regard to physiography, geology, soils, and climate A discussion of plant associations is given for the Mojave Desert, Transition Desert, and Great Basin Desert The vegetation of disturbed sites is discussed with regard to introduced species as well as endangered and threatened species Collections of vascular plants were made during 1959 to 1975 The plants, belonging to 1093 taxa and 98 families are listed together with information concerning ecologic and geographic distributions Indexes to families, genera, and species are included (HLW)

Vascular Plants of the Nevada Test Site and Central Southern Nevada: Ecologic and Geographic Distributions

The Primeval Forests of a Periglacial Area in the Allegheny Plateau (Vinton and Jackson Counties, Ohio).

A list is presented of 706 vascular plant taxa collected at the Nevada Test Site from 1959 through 1972. A list of 1,107 taxa found in central and southern Nevada is included. (CH)

Check list of vascular plants of the Nevada Test Site and central-southern Nevada

Nearly everyone is familiar in some way with plants which are green in winter in the Deciduous Forest region. The evergreen conifers, especially the pines, spruces, firs and cedars, planted extensively for landscape purposes, are probably the most widely recognized. In fact, the terms evergreen and conifer are commonly used by the layman as synonyms. Winter wheat, and the bluegrass and dandelions of lawns are likewise familiar species which add greenness to landscapes in a season when the leaves of most plants have withered and died. Overwintering leaves of candytuft, foxglove, sweet william, chrysanthemum, and others are well-known to gardeners and nurserymen. Botanists have long been aware of the winter-green leaves of such shrubs as Rhododendron, Kalmia, and others of the Heath Family, as well as the frequency of winter-greenness among ferns, and the conspicuous greenness of mosses, as a group, in the winter aspect of almost any forest. During the months of November through February, however, when snow cover is absent, there is a large population of green herbaceous plants in field and forest which appear little or none the worse for the presumed rigors of the season. Far from being devoid of herbaceous plants in the winter, the ground is dotted with green nearly everywhere. This population consists of many different kinds of plants, and the species, genera, or families to which they belong often cannot be ascertained by the usual vegetative characters customarily used in their identification. These are the plants with which this paper is concerned.

The Winter-Green Herbaceous Flowering Plants of Ohio

The shrub, tree, and cactus vegetation of 59 selected study sites in eight drainage basins of the Nevada Test Site was documented in 1963, and again in 1975 Vegetation of the sites, which span the range of 3076 to 7425 ft elevation, is assigned to five plant associations, and intergrades, on the 25 Mojave Desert sites; eight associations on the 10 Great Basin Desert sites; and six associations, and ecotonal types, on the 24 sites of the desert transition The data presented are for numbers of plants crossing the lines, mean height of plants, and calculated percentage cover of the ground All data are summarized by site, species, and year for each of the vegetation categories, and for living and dead plants combined and dead plants only Apparent from the data are increases in the numbers, height, and percentage cover on nearly all sites, and in essentially all species, during the 12-year period, and a decrease in the proportions of dead plants Species composition or relative proportions of the species did not change The increases appear to be directly related to rainfall during the time interval It is concluded that in desert vegetation numbers and size of shrubs vary significantlymore » with climatic fluctuations through time, and reflect especially the rainfall history of a given site at any point in time« less

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Janice C. Beatley

Papers

Vascular Plants of the Nevada Test Site and Central Southern Nevada: Ecologic and Geographic Distributions

The Primeval Forests of a Periglacial Area in the Allegheny Plateau (Vinton and Jackson Counties, Ohio).

Check list of vascular plants of the Nevada Test Site and central-southern Nevada

The Winter-Green Herbaceous Flowering Plants of Ohio

Shrub and tree data for plant associations across the Mojave/Great Basin Desert transition of the Nevada Test Site, 1963--1975