bluuebunny/crossref_metadata_2025 huggingface dataset:
How man makes God in West Africa: Yoruba attitudes towards the Orisa
Authors: Barber Karin
Published: April 2006

Opening Paragraph

The idea that gods are made by men, not men by gods, is a sociological truism. It belongs very obviously to a detached and critical tradition of thought incompatible with faith in those gods. But Yoruba traditional religion contains built into it a very similar notion, and here, far from indicating scepticism or decline of belief, it seems to be a central impulse to devotion. The òrìṣà (‘gods’) are, according to Yoruba traditional thought, maintained and kept in existence by the attention of humans. Without the collaboration of their devotees, the òrìṣà would be betrayed, exposed and reduced to nothing. This notion seems to have been intrinsic to the religion since the earliest times. How can such an awareness be part of a devotee's ‘belief’? Rather than speculate abstractly, as Rodney Needham does (Needham 1972), about whether people of other cultures can be said to ‘believe’ at all, it seems more interesting to take a concrete case like the Yorba one where there is an unexpected–even apparently paradoxical–configuration of ideas, and to ask how these ideas are constituted. Only by looking at them as part of a particular kind of society, with particular kinds of social relationships, can one see why such a configuration is so persuasive. The notion that men make gods is by no means unique to Yoruba thought. It is present to some degree in a number of traditional West African religions, and in some, such as the Kalahari one, it can be seen in an even more explicit form than in the Yoruba one. A comparison may help to show how it is the constitution of social relationships which makes such a notion not just acceptable but central to the religious thought of the society.
Capital formation and management among the Muslim Hausa traders of Kano, Nigeria
Authors: Yusuf Ahmed Beita
Published: April 2006

Introduction

This paper attempts to comment on the various techniques by which Kano Hausa traders and businessmen raise capital and invest it for diverse economic and social returns. Rather than proposing anything new, I will seek mainly to point to areas of needed future research among the Hausa traders. Moreover, although the paper is primarily concerned with the economic behaviour of a particular people, no clear effort is made at quantification, since very little statistics for Kano trade exist at the time of writing.
Accumulation, wealth and belief in Asante history: I. To the close of the nineteenth century
Authors: McCaskie T. C.
Published: April 2006

Opening Paragraph

The present article is intended as the first of two contributions to the economic and social– but above all to the intellectual– history of the West African forest kingdom of Asante or Ashanti (now located in the Republic of Ghana). Both papers will attempt to pull together and to situate in a ‘mentalist’ framework a number of recent and confessedly disparate research findings concerning a cluster of concepts, ideas and beliefs that, merely for the sake of brevity at this point, I will assign simply to the embracing ‘neutral’ rubric of general transformations in the ideology (or ideologies) of wealth. The first article will be concerned with developments in Asante society up to the close of the nineteenth century (defined here interpretatively rather than in strictly chronological terms); its successor will concentrate on a highly detailed examination of a sequence of crucially telling events in the early colonial period, and upon selected developments thereafter in the twentieth century. The articles are designed and intended to be read sequentially; the first, it is hoped, will assist in making sense of the significantly denser context (and more detailed content) of the second.
Women in Freetown politics, 1914–61: a preliminary study
Authors: Denzer LaRay
Published: April 2006

Opening Paragraph

The study of women in Sierra Leone has been well launched. Except for the work of Carol P. MacCormack (formerly Hoffer) on political leadership and socio-economic development among Mende and Sherbro women (1972, 1974, 1975, 1976, 1977, 1978, 1979, 1981, 1982), most of this scholarship focuses on women in Freetown, mainly the Krio. Filomena Steady (1975, 1976) has analysed Krio women's leadership in church and political organisations. The history of their economic contribution to the evolution of the city has been discussed by E. Frances White (1976, 1978, 1981a, b). Gender relationships in modern marriage have been examined by Barbara Harrell-Bond (1975). In addition, there are a number of biographical studies of prominent leaders: Paramount Chief Madam Yoko (Hoffer, 1974), Adelaide Casely Hayford (Okonkwo, 1985; Cromwell, 1986), Constance A. Cummings-John (Denzer, 1981, forthcoming a, b), Hannah S. Benka Coker (Metzger, 1973: 50–2), and Lottie Hamilton-Hazeley (Metzger, 1973: 52–3). On the basis of this body of work it is possible to study more closely the contribution of women in modern politics in Freetown and the socioeconomic forces behind their participation. This account covers the period from the emergence of the proto-nationalist movement, the National Congress of British West Africa (NCBWA), up to the campaign for independence.
Marital sexual relationships and birth spacing among two Yoruba sub-groups
Authors: Adeokun Lawrence A.
Published: April 2006

Opening Paragraph

This article is about the marital sexual relationships (MSR) and the timing of the next child among the Ekiti and Ikale sub-groups of the Yoruba. Contrasts in post-partum sexual practices between the two groups allow us to demonstrate the importance of parents' perception of their child's growth and their observance of prohibitions on sexual intercourse during the wife's lactation as factors shaping their decision to have another child. It is argued that the similarity in birth spacing among the two groups, derived from contrasting attitudes to post-partum abstinence, is evidence of an explicit decision on the timing of the next child. Such a decision takes account of the role of the child's growth and social development as it affects adults in the performance of their daily social and economic routines and goes beyond an unquestioned response to quasi-religious taboos. The implications of the findings for fertility prospects are also discussed.
Sex, fertility and menstruation among the Beng of the Ivory Coast: a symbolic analysis
Authors: Gottlieb Alma
Published: April 2006

Opening Paragraph

Menstrual blood has proved a popular subject for discussion in the anthropological literature but, surprisingly, only a single theme has emerged: societies either do or do not consider menstrual blood and menstruating women to be polluting. If they are not considered polluting, it is taken as a sign of sex-role egalitarianism; conversely, if they are considered polluting, it is taken as a sign of women's lower status vis-a-vis men and/or of the potential danger or threat that women represent to men (e.g. Kessler, 1976: 72-4; Meggitt, 1964; Ortner, 1974; Sacks, 1974; Young, 1965: 155). Friedl (1975: 29) goes so far as to suggest that menstruating women are viewed as threatening and polluting because menstrual blood is a symbol of death: when a woman menstruates, it is a sign that she has not conceived a child and thus during this time she is ‘the antithesis of life’.
From Pagan to Pullo: ethnic identity change in northern Cameroon
Authors: Schultz Emily A.
Published: April 2006

Opening Paragraph

This paper explores the nature of ethnic identity in the small town of Guider in northern Cameroon. It focuses on the process of ethnic identity change, specifically upon the incorporation into the Fulbe (sing. Pullo) ethnic group of individuals who originate outside it. Ethnic group change of this kind is not unknown in Africa (see Little, 1951; Richards, 1954; Banton, 1957; Wallerstein, 1960; Burnham, 1972; Salamone, 1975; Nicolas, 1975; Vaughan, 1981). The data in this study contribute to a growing body of literature concerned with ethnic boundary crossing, but, I shall argue, they suggest that we re-examine certain widely held assumptions about ethnicity and the process of ethnic assimilation.
Struggles over water, Struggles over meaning: cattle, water and the state in Botswana
Authors: Peters Pauline E.
Published: April 2006

Introduction

In a recent paper on ‘The state and social processes in Africa’, Lonsdale (1981) convincingly demonstrates the poverty of assuming that any one ‘grand theory’ is able to explain the complex relations among state, social process and class struggle and other equally complex social phenomena. Images of the state as parasitic (as in formulations of the ‘Asiatic mode of production’), as an epiphenomenon of property relations or as a neutral mediator, individually fail to grasp the complexity of states' organization and action (Jessop, 1977), yet each clearly evokes an important dimension of that complexity. The fact of political and economic domination has to be dealt with but equally the often contradictory quality of state power reflects the fact that the mediating institutions and ideologies between dominating and dominated are the objects and arenas for competition and struggle among different social groups and categories. The recognition that one has to deal analytically not with a monolithic entity but a set of institutions that are subject to being ‘redefined, added to and patched’ (Lonsdale, 1981: 2) is important. The challenge, then, is to devise analytical means that capture such processes and allow us to unravel the dynamic of contradictions rather than merely note their pervasive character.
Post-socialist micro-politics: Kilimanjaro, 1993
Authors: Moore Sally Falk
Published: April 2006

In what sense are current African politics explicable as efforts to ‘domesticate’ modernity? In Tanzania the post-socialist liberalisation has opened space for new forms and objects of competition. A scramble for control and for resources in the Kilimanjaro—Mem area in 1993 is described here. The variety of competitive activities involved is encapsulated in events in four radically different organisational arenas: in Chadema, a new national political party; in the Lutheran Church; in a sub-village on Kilimanjaro; and in a local patrilineage. These organisational frameworks are approached as partially autonomous, locally specific, sites of political activity. Each is visibly marked by a historical past while also being rapidly propelled to respond to immediate changes of circumstance in a large environment. The details suggest that classical theoretical definitions of ‘modernity’ do not always stand up as useful analytic devices.
Communal tenure in Zimbabwe: divergent models of collective land holding in the Communal Areas
Authors: O'Flaherty Michael
Published: April 2006

This article discusses the historical construction of land tenure patterns in the Communal Areas of Zimbabwe, previously the Reserves of colonial Rhodesia. In many respects the form of communal tenure found in the Communal Areas today emerged during the early colonial period. While being glossed as ‘traditional’, communal tenure is a contradictory amalgam of local, regional and state initiatives. The discussion outlines the historical development of present tenure relations in the Communal Areas, reviews their multiple sources of legitimacy and suggests that common property regimes in Zimbabwe are not simply the artefact of colonial indirect rule.
Individual‐Based Model for Growth of Young‐of‐the‐Year Walleye: A Piece of the Recruitment Puzzle
Authors: Madenjian Charles P. , Carpenter Stephen R.
Published: April 2006

Young—of—the—year (YOY) walleye (Stizostedion vitreum vitreum) growth is a vital step in walleye recruitment. An individual—based model (IBM) was developed to describe the growth of YOY walleye in Oneida Lake (New York, USA) and Lake Mendota (Wisconsin, USA). In Oneida Lake the only prey species included in the model was yellow perch (Perca flavescens), whereas both yellow perch and bluegill (Lepomis macrochirus) were prey species in the model for Lake Mendota. IBM predictions for length frequencies of the YOY walleye population at the end of the growing season showed good agreement with observed length frequencies. A theoretical relationship was derived between the encounter rate, @l, used in the IBM and the half—saturation constant, k, used in a type II functional response model. Estimates of k from the two models showed good agreement, thus corroborating the value of ° chosen for the IBM application to Oneida Lake. The mean length of the YOY walleye cohort and the percentage of larger (@> 175 mm in total length) walleyes in the cohort at the end of the growing season were most sensitive to gross growth efficiency, bioenergetics parameters for maximum daily consumption by walleyes, and the ratio of prey length to predator length at which the prey is susceptible to predation. In Lake Mendota the vulnerability of bluegills to predation by YOY walleyes was especially important in determining the growth of walleyes during their first growing season. The IBM approach was valuable for modeling those stages of life history in which characteristics of the individual were critical in determining recruitment.
Lessons from NAPAP
Authors: Russell Milton
Published: April 2006

NAPAP was an institutional innovation of great benefit in bringing the United States to a decision on acid precipitation control. The nation's return from the $600 000 000 investment in NAPAP will be greater still if the lessons learned in the course of its existence are put to proper use in the future. This essay concentrates on the lessons learned about the interface between science and public policy as experienced in NAPAP.
Soil Chemistry in a Loblolly/Longleaf Pine Forest with Interval Burning
Authors: Binkley Dan , Richter Dan , David Mark B. , Caldwell Bruce
Published: April 2006

We examined the 30—yr cumulative effects of prescribed fires at intervals of 1, 2, 3, and 4 yr in a loblolly and longleaf pine forest in the Coastal Plain of South Carolina. The fine fraction of the forest floor (Oe + Oa horizons) contained much more carbon and nitrogen per unit area in the control plots (1.7 and 0.05 kg/m2, respectively) than in the 1—yr burn interval plots (0.4 and 0.007 kg/m2, respectively). Mineral soils (0—0.2 m depth) were highly variable in chemistry, and showed only slight differences across the burning treatments for nitrogen and sulfur. No trends were apparent for phosphorus in the forest floor or mineral soil; differences in acidity and extractable cations were also slight. The nutrient content of foliage was generally low, with no differences across burning intervals. Our results are consistent with earlier studies that showed the biogeochemical effects of repeated surface fires in southern pine forests are generally limited to the forest floor, with the possible exception of overall reductions in nitrogen cycling.
Experimental Policies for Water Management in the Everglades
Authors: Walters Carl , Gunderson Lance , Holling C. S.
Published: April 2006

Marshland drainage and water regulation have greatly altered the Florida Everglades. One of the most visible ecological impacts has been a drastic decline in nesting populations of wading birds, and several specific hypotheses have been advanced to explain the decline. Recent efforts at ecological restoration have concentrated on reestablishing more natural seasonal hydropatterns in freshwater marsh areas now used extensively by the wading birds. However, nesting colonies were originally concentrated along the estuarine mangrove edge of the system rather than around upstream marshes. Hydrological simulation models have been used to reconstruct what hydrological conditions might have been like in the natural system, and these simulations indicate that freshwater pools near and flows to the estuary have been drastically reduced, especially late in the annual spring drying season. An experimental program of increased water releases to the estuary could be used to test whether estuarine restoration is a necessary condition for recovery of wading bird populations. This program would require a substantial commitment to deliver runoff from the Everglades Agricultural Area into the marshes, and to minimize water diversions for flood control and well field recharge.
Application of Herbivore Optimization Theory to Rangelands of the Western United States
Authors: Painter Elizabeth L. , Belsky A. Joy
Published: April 2006

Ecological research can be misinterpreted by the popular press and misapplied in land management. One example of this concerns the controversial concepts of overcompensation by grazed plants and herbivore optimization of plant productivity (or, as popularly phrased, the idea that plants benefit from being grazed). Although available evidence indicates that whole—plant overcompensation and optimization of productivity rarely occur and may have little or no evolutionary or applied significance, these concepts have been accepted by some popular writers and land managers, and are being used to justify heavy livestock grazing on western North American rangelands. There may be many reasons for this acceptance of unsubstantiated hypotheses, including uncritical reading and overly broad extrapolations by writers and managers, as well as failure by scientists to clearly and accurately communicate results and conclusions.
Further Considerations on the Debate Over Herbivore Optimization Theory
Authors: DeAngelis Donald L. , Huston Michael A.
Published: April 2006

Criticism of the basis and use of the herbivore optimization theory is discussed. It is argued here that evidence from theory and agricultural practice support the view that compensation and overcompensation of total primary production can occur in plant populations and communities subjected to grazing. However, whether this will occur depends on specific circumstances. Modeling and carefully designed field studies should be used to determine the responses of rangeland systems under a variety of environmental conditions and grazing intensities.
Compensating Growth of Grazed Plants and Its Relevance to the Use of Rangelands
Authors: Noy-Meir Imanuel
Published: April 2006

There are several well—known mechanisms by which grazing can reduce the subsequent growth rate of plants, and several other well—documented mechanisms by which grazing can enhance plant growth rate. The net effect of single or repeated grazing events on the cumulative growth of plants may thus be zero, negative, or positive, depending on availability of leaf area, meristems, stored nutrients, and soil resources, and on the frequency and intensity of defoliation. Plants are preadapted to compensate, up to a certain point, for losses due to grazing, by virtue of their modular structure and development. Reports of "overcompensation" to grazing, as one extreme of a wide range of responses observed in natural grasslands, need not be treated with special skepticism; neither are they a solid base for a general theory of evolved grass–grazer mutualism. The question of compensatory growth is of relevance to management of Western rangelands for livestock production, but of relatively little relevance to conservation goals. No region—wide answers can be expected. Any drastic change in grazing intensity in either direction requires evaluation by community—specific and long—term research.
A Model of the Effects of Tillage on Emergence of Weed Seedlings
Authors: Mohler Charles L.
Published: April 2006

A simple model is developed in which the density of weed seedlings emerging in a field is related to (1) the ability of seedlings to emerge from various depths in the soil, (2) the survival of seeds at different depths, and (3) the depth of seed burial in no tillage, rotary tillage, and plow tillage. Other tillage regimes are considered by analogy. Literature is reviewed to determine biologically reasonable functions describing seedling emergence, seed survival, and distribution of seeds with depth, and parameters of these equations are estimated from data in the literature. Problems related to the mathematical description of these phenomena are discussed, and it is noted that some commonly held beliefs regarding survival of seeds in the soil are mutually incompatible. Although many studies have investigated the persistence of seeds as a function of depth in the soil, few have distinguished death from the production of seedlings. The model indicates that in the first year following input of seeds to the soil, no tillage will have more seedlings than tillage, but in later years no tillage will likely have fewer seedlings unless innate or induced dormancy is high or seed survival near the soil surface is unusually good. If seed return is allowed, no tillage or minimum tillage will have more seedlings perennially. Recovery of good weed control following a year with substantial seed input may be easiest if the soil is plowed deeply to bury the seeds, and then shallow or no tillage is used in subsequent years to avoid returning seeds to the surface. Much of the literature on the effects of tillage on weed density is difficult to interpret because little indication is given of the vertical distribution of seeds in the soil at the beginning of the experiment.
Maximization of Aboveground Grassland Production: The Role of Defoliation Frequency, Intensity, and History
Authors: Turner C. L. , Seastedt T. R. , Dyer M. I.
Published: April 2006

Production of tallgrass prairie vegetation was measured on experimental plots in which defoliation intensity and frequency were manipulated by mowing and using movable exclosures on areas chronically grazed by cattle. Defoliation history largely controlled whether or not defoliated plants overcompensated (exhibited enhanced production compared to undefoliated controls) for tissue removal. Plants on chronically grazed sites only compensated for foliage removed by grazers. Production on plots mowed prior to the year of measurement was similar to that on chronically grazed sites, while previously unmowed plots exhibited substantial aboveground overcompensation. Aboveground production was maximized by the most frequent mowing treatment and by intermediate mowing heights. Nitrogen and phosphorus concentrations and amounts in aboveground tissues were increased by mowing and grazing. Current mowing regime was more important than mowing history in determining nitrogen concentrations except very early in the growing season. Effects of grazing and mowing on belowground biomass were inconsistent, but frequent mowing appeared to limit accumulation of belowground N reserves and biomass. In North American grasslands, overcompensation is a nonequilibrium plant response to grazing. Photosynthate that would be stored as reserves and used for root growth and flower and seed production instead is used to replace lost leaf area, thereby resulting in higher foliage productivity. However, under chronic grazing or mowing, vegetation is prevented from maintaining high nutrient and water uptake capacity (large root biomass) and accumulating reserves that allow overcompensation responses.
Carbon Fluxes in Plant‐Soil Systems at Elevated Atmospheric CO2 Levels
Authors: van Veen J. A. , Liljeroth E. , Lekkerkerk L. J. A. , van de Geijn S. C.
Published: April 2006

The flow of carbon from photosynthesizing tissues of higher plants, through the roots and into the soil is one of the key processes in terrestrial ecosystems. An increased level of CO2 in the atmosphere will likely result in an increased input of organic carbon into the soil due to the expected increase in primary production. Whether this will lead to accumulation of greater amounts of organic carbon in soil depends on the flow of carbon through the plant into the soil and its subsequent transformation in the soil by microorganisms. In this paper the major controls of carbon translocation via roots into the soil as well as the subsequent microbial turnover of root—derived carbon are reviewed. We discuss possible consequences of an increased CO2 level in the atmosphere on these processes.
Herbivory by Canada Geese: Diet Selection and Effect on Lawns
Authors: Conover Michael R.
Published: April 2006

Flocks of free—ranging Canada Geese (Branta canadensis) often are considered nuisances when they graze on lawns because they litter the sites with fecal material, and their grazing often is perceived to be detrimental to the turf. I tested whether goose grazing had changed the composition of grass species at 20 sites in Connecticut where geese were considered nuisances. At these sites Kentucky bluegrass (Poa pratensis) was less prevalent in areas grazed heavily by geese than in areas of the same lawn that received light grazing. At six sites where up to several hundred geese wait daily for food handouts, 46% of the ground was devoid of vegetation except for a moss. I examined the palatability of different grass species to Canada Geese by giving captive birds the opportunity to feed in plots of five cool—season turf—grass species. The birds spent more time feeding in plots of Kentucky bluegrass and less time feeding in plots of tall fescue (Festuca Araneidae cv. K—31) that would have been expected if the geese were grazing among plots at random. Time spent grazing in plots of colonial bent grass (Agrostis tenuis cv. Highland), perennial ryegrass (Lolium peatland), and red fescue (F. rubra) did not differ from the expected. Feeding preferences for grass species were negatively correlated with the ash content of the leaves and with the amount of force required to sever a specific leaf mass. Captive Canada Geese would not feed on common periwinkle (Inca minor), Japanese pachydermum (pachydermum terminals), or English ivy (headnotes helix). These results suggest that Canada Goose numbers can be reduced at sites where they are foraging on turf if lawns are replaced by an unpalatable ground cover, or, to a lesser extent, with a tough—leaf grass species such as tall fescue.
Interaction Between Sensory and Postingestional Repellents in Starlings: Methyl Anthranilate and Sucrose
Authors: Clark Larry , Mason J. Russell
Published: April 2006

Ingestion of concentrated sucrose solutions causes sickness in sucrase—deficient birds. As a result, some suggest that sucrose may represent an environmentally safe avian repellent. In the present experiments, we compared the repellency of sucrose to that of methyl anthranilate (MA), a known avian repellent. We also tested mixtures of sucrose and MA to investigate whether repellency could be enhanced, relative to sucrose or MA presented alone. The results showed that the MA was strongly avoided in both drinking and feeding trials. Conversely, only high sucrose concentrations were avoided, and only in drinking trials. No combination of MA and sucrose was as effective as MA alone. We conclude that sucrose is not sufficiently aversive to serve as an avian repellent in the field.
Inputs of Sediment and Carbon to an Estuarine Ecosystem: Influence of Land Use
Authors: Howarth Robert W. , Fruci Jean R. , Sherman Diane
Published: April 2006

Estuaries and coastal marine ecosystems receive large inputs of nutrients, organic carbon, and sediments from non—point—source runoff from terrestrial ecosystems. In the tidal, freshwater Hudson River estuary, such inputs are the major sources of organic carbon, driving ecosystem metabolism, and thus strongly influencing dissolved oxygen concentrations. We used a watershed simulation model (GWLF) to examine the controls on inputs of organic carbon and sediment to this estuary. The model provides estimates of water discharge, sediment inputs, and organic carbon inputs that agree reasonably well with independent estimates of these fluxes. Even though the watershed for the Hudson River estuary is dominated by forests, the model predicts that both sediment and organic carbon inputs come overwhelmingly from urban and suburban areas and from agricultural fields. Thus changes in land use within the Hudson River basin may be expected to altering inputs to the estuary, thereby altering its metabolism. Precipitation is important in controlling carbon fluxes to the estuary, and so climate change can be expected to alter estuarine metabolism. However, the day—to—day and seasonal patterns of precipitation appear more important than annual mean precipitation in controlling organic carbon fluxes.
Habitat‐Specific Resilience of the Invasive Shrub Amur Honeysuckle (Lonicera Maackii) During Repeated Clipping
Authors: Luken James O. , Mattimiro Daniel T.
Published: April 2006

In the development of novel strategies for control of invasive plant species, researchers might first consider plant performance throughout a range of habitats and then concentrate management activities in habitats where plants are least resilient. We determined the relative resilience of forest— and open—grown populations of the invasive shrub Lonicera maackii (Caprifoliaceae) growing in northern Kentucky. Resilience was assessed by imposing a clipping regime (once each year from 1986 to 1989) during which shrub resprouting abilities were measured. Habitat—specific population regeneration from seeds in the seed bank was also measured. Forest—grown L. maackii shrub were less resilient than open—grown shrubs when stressed by repeated clipping, due presumably to exhaustion of stored reserves in shrub bases. This suggests that forests are secondary habitats for L. maackii. However, resprouting potential and seed production in forests appear sufficient to regenerate populations after most common disturbances. The ability to modify sprouting patterns while maintaining resprounting ability and some seed production over a wide range of habitats is an important adaptation of this invasive shrub. Management suggestions for shrub eradication are provided.
Contaminant Transport through Agroecosystems: Assessing Relative Importance of Environmental, Physiological, and Management Factors
Authors: Breshears David D. , Kirchner Thomas B. , Whicker F. Ward
Published: April 2006

Agroecosystems can become contaminated by atmospherically released radionuclides. The subsequent concentrations of radionuclides in foods are dependent on numerous environmental, physiological, and management factors. We compared four approaches for estimating the relative importance of several of these factors in determining concentrations of 131I and 137Cs in milk. A series of sensitivity analyses with Monte Carlo and full—factorial sampling designs was conducted on the PATHWAY model, which simulates radionuclide transport through an agroecosystem. Sensitivity of time—integrated concentrations in milk was estimated as a function of the time of year that fallout was deposited and as a function of time following a spring deposition. The dominant parameters affecting time—integrated concentrations of 131I in milk were the initial fraction of radionuclides deposited on vegetation, timing and amount of pasture consumption, and the production rate of milk. For time—integrated concentrations of the longer—lived 137Cs in milk, resuspension was a dominant parameter and pasture use was less important. The sampling designs were compared by ranking the parameters to which the model output is sensitive. The three sampling designs based on parameter variances produced sets of ranks that were similar to each other but differed from the ranking produced by the sampling design based on parameter magnitude. The results indicate which data are most crucial for real—time calculations following an accident and how subsequent dose from ingestion can be most effectively reduced, provide insight into model behavior, and help prioritize future research. This paper demonstrates the importance of variance—based sensitivity analysis.
Response of Woody Plant Communities in Power‐Line Corridors to Frequent Anthropogenic Disturbance
Authors: Luken James O. , Hinton Andrew C. , Baker Douglas G.
Published: April 2006

Ecological theory predicts that diversity should decline as disturbance frequency increases beyond an intermediate level. However, few data exist on the responses of deciduous forests to high—frequency disturbance. We compared regenerating woody plant communities in northern Kentucky power—line corridors to adjacent second—growth forests to determine if high—frequency disturbance (5—6 yr mechanical or manual cutting cycle) modifies forest development. Black locust (Robinia pseudoacacia) and white ash (Fraxinus americana) dominated corridor communities. Still, many species present in adjacent forests persisted in corridors, with the result that 15 of 20 corridor samples were classified by TWINSPAN close to samples taken from adjacent forests. Of the most important tree species found in the study sites, sugar maple (Acer saccharum) was least favored by high—frequency cutting. In general, high—frequency cutting did not totally inhibit regeneration of a single species, diversity showed a small but nonsignificant increase, and several early—successional, shade—intolerant species established anew. When forests are repeatedly cut before stems reach the stem exclusion stage, individualistic patterns of sprouting and carbon allocation will likely determine dominance. White ash and black locust will assume greater importance in fragmented forests as disturbance frequencies increase.
Long‐Term Forage Production of North American Shortgrass Steppe
Authors: Lauenroth W. K. , Sala O. E.
Published: April 2006

We evaluated the relationship between annual forage production and annual and seasonal precipitation and temperature at a shortgrass steppe site in north—central Colorado using a long—term data set (52 yr). We also constructed a relationship between forage production and aboveground net primary production (ANPP). Precipitation fluctuated randomly, but temperature had clear warming and cooling trends including a 17—yr warming trend from 1974 to 1990. Forage production was significantly related to both annual and seasonal precipitation but not temperature. Precipitation events between 15 and 30 mm accounted for most of the variability in production because they accounted for most of the variability in precipitation and because they wetted the soil layers that have the largest effect on production. Forage production amplified variability in annual precipitation. Production showed time lags of several years in responding to increases in precipitation. Change in vegetation structure has a characteristic response time, which contrains production responses in wet years. Constraint caused by vegetation structure is the reason why regional ANPP—precipitation models have a steeper slope than long—term models and point out a weakness of exchanging space for time in predicting production patterns.
Effect of the Focal Taxon on the Selection of Nature Reserves
Authors: Ryti Randall T.
Published: April 2006

Among the numerous site—ranking or reserve selection approaches is to select reserves based on the current distribution of a suite of species. This approach only requires distribution data for the species in the "focal taxon." To what extent is the proposed reserve network dependent on the species included in the focal taxon? Can a suite of species act as an umbrella or indicator for other species whose distribution was not directly considered? A simple reserve selection algorithm was applied to species lists from sites where multiple taxa were sampled. The algorithm selected sites so that each species in the focal taxon was represented in at least one reserve. The species lists were complied for birds, mammals, reptiles, and plants on islands in the Gulf of California, and for birds, mammals, and plants in canyons in San Diego County, California. Within both data sets, there were significant rank correlations (P < .01) between the number of species in different taxa per potential reserve. Yet the number of proposed reserves that satisfied the selection algorithm differed strongly between taxa. For example, 2 of 25 canyons were in the San Diego bird reserve network, but 10 of 25 canyons were in the native plant reserve network. The area of the proposed reserves selected by the algorithm ranged from a minimum of 3.2% of the total area for San Diego bird reserves to a maximum of 98.3% of the total area for the Gulf of California plant reserves. The bird reserves included only 45—78% of the species in the other taxa. Conversely, the plant reserve network would contain 88—100% of the vertebrate species. Thus, plants were better indicators than birds for reserve establishment. Plant occurrences were less ordered than bird occurrences, and there were 10 or 20 times more plant species than bird species. The better umbrella taxon was more speciose or had less pattern to species occurrences. Rather than a literal application of plants as reserve indicators, a better approach would be to collect some preliminary distribution data for a number of taxa in the potential reserve network and use these preliminary data to define the focal taxon (or taxa).
Competition for Resources Between Understory Vegetation and Overstory Pinus Ponderosa in Northeastern Oregon
Authors: Riegel Gregg M. , Miller Richard F. , Krueger William C.
Published: April 2006

The objective of this research was to determine which environmental resources, light, water, and/or nutrients, control understory plant production in a Pinus ponderosa forest in northeastern Oregon. A split—plot experimental design, with three 5.0—ha blocks, four treatments, and 44 plots, was established in the summer of 1985. Twenty plots (4 X 4 m) were trenched (root—reduction treatment) °1 m in depth, and 24 non—trenched plots (root—control treatment) were used to assess the effects of root competition of overstory trees on understory plants. Trees were commercially thinned (canopy—reduction treatment) in half of each block (2.5 ha) during the winter and early spring of 1986, from a density of 345 to 148 trees/ha to increase light levels to the understory. Thinning significantly increased photosynthetically active radiation, decreased midday relative humidity, and increased midday air temperatures. Xylem potential of the dominant graminoid (Carex geyeri), soil water potential, mineralizable nitrogen, and pH were increased within the root—reduction vs. the root—control treatments. Micro— and macronutrients in C. geyeri and Symphoricarpos albus, the dominant shrub, were influenced in both treatments. Increasing light did not increase understory biomass production. Reducing root competition for soil water and nutrients increased understory aboveground biomass by 53 and 94% in 1986 and 1987, respectively. This research demonstrated that belowground resources were the primary controlling factors of understory production in P. ponderosa forests in northeastern Oregon.
Analyzing Historic Ecotonal Shifts
Authors: Crumley Carole L.
Published: April 2006

Complex chains of mutual causation in human—environment relations may be analyzed by tracing past human interaction with the environment at the global, regional, and local scales. Historical analogues can be effectively employed to model the range of potential climate anywhere in the world. Their advantages include the use of actual regional airmass, hydrology, pedology, topography, and species distributional data, in addition to archaeology, documents, and ethnography. Of mediating importance are regions and landscapes, which manifest past and present human—environment relations and focus practical contemporary questions. The shifting position of ecotones is a convenient temporal and spatial marker of inclusive ecosystemic change. Ongoing research in Burgundy (France) is offered as an example.
A Reassessment of Areal Variability of Throughfall Deposition Measurements
Authors: Lawrence Gregory B. , Fernandez Ivan J.
Published: April 2006

Throughfall deposition in a low—elevation red spruce—balsam fir stand in east—central Maine was measured for 10 chemical constituents over four sampling seasons to evaluate areal variability of throughfall deposition measurements. Forty collectors within one stand were sampled weekly and combined to provide 40 monthly samples. Areal variation in measurements of throughfall deposition differed greatly among chemical constituents and from month to month. Sulfate showed the least areal variability of the chemical constituents; K+ showed the most. Water volume measurements consistently showed less areal variability than any of the chemical constituents. Mean SO42— deposition calculated from 15 collectors was within 20% of the mean value calculated from 40 collectors (with 90% confidence) in 22 out of 23 sampling months; mean K+ deposition calculated from 28 collectors was within 20% of the mean of the 40 collectors (with 90% confidence) in 21 out of 23 mo. Chemical deposition showed less areal variability when calculated on a seasonal basis than when calculated on a monthly basis. Mean seasonal SO42— deposition calculated from 15 collectors was within 12.1% of the mean 40 collectors (90% confidence); mean K+ deposition calculated from 28 collectors was within 21% of the mean of 40 collectors (90% confidence) for the same three seasons. Contrary to the conclusions of previous studies, excessively large numbers of collectors are not needed to obtain the accuracy and precision adequate for most forest deposition studies. This is significant in light of the growing dependence on throughfall measurements for estimating atmospheric deposition.
Remote Sensing of Seasonal Leaf Area Index Across the Oregon Transect
Authors: Spanner Michael , Johnson Lee , Miller John , McCreight Richard , Freemantle Jim , Runyon John , Gong Peng
Published: April 2006

Remotely sensed data acquired from four remote—sensing instruments on three different aircraft platforms over a transect of coniferous forest stands in Oregon were analyzed with respect to seasonal leaf area index (LAI). Data from the four instruments were corrected for the varying seasonal and geographic atmospheric conditions present along the transect. Strong logarithmic relationships were observed between seasonal maximum and minimum LAI and the simple ratio (SR) (near infrared/red reflectance) calculated from the broad—spectral—band Thematic Mapper Simulator (TMS), as well as from the narrow—spectral—band Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), the Compact Airborne Spectrographic Imager (CASI), and the Spectrom SE590 spectro—radiometer (R2 = 0.82—0.97). The TMS SR reached an asymptote at an LAI of °7—8. However, the SE590 and the CASI SR continued to increase up to the maximum LAI of 10.6. The variability of the relationship between the AVIRIS SR and LAI increased at stands with LAIs >7, making a trend in the AVIRIS SR—LAI relationship at LAIs >7 difficult to discern. The SRs of the coniferous forest stands measured by the narrow—spectral—band instruments were higher than they were from the broad—spectral—band TMS. This is attributed partially to the integration of the TMS over a broad wavelength region in the red and more strongly to calibration differences between the sensors. Seasonal TMS SR trends for four time periods for some of the stands deviated from the expected seasonal LAI trends, possibly because of smoke and very low sun angles during some of the acquisition periods. However, the expected SR differences for the seasonal minimum and maximum LAI were observed for all of the sensors for nearly all of the forest stands. This study demonstrates that remotely sensed data from both broad— and narrow—spectral—band instruments can provide estimates of LAI for use in forest ecosystem simulation models to estimate evapotranspiration, photosynthesis, canopy turnover, and net primary production over large areas.
Remote Sensing of Leaf Area Index and Radiation Intercepted by Understory Vegetation
Authors: Law Beverly E. , Waring Richard H.
Published: April 2006

To estimate leaf area index (LAI), intercepted radiation, and other related characteristics of vegetation, ecologists often require separate consideration of the understory and overstory components of vegetation. In the open ponderosa pine (Pinus ponderosa) forests of east—central Oregon, bitterbrush (Purshia tridentata) and manzanita (Arctostaphylos patula) are major understory species. We constructed artificial canopies of these two species and determined whether remotely sensed properties of canopy reflectance might be used to estimate LAI and the fraction of photosynthetically active radiation intercepted (fIPAR). Although the two species differed in their canopy structures and leaf characteristics, they showed similar light extinction coefficients, varying only from 0.52 for bitterbrush to 0.46 for manzanita as derived from the Beer—Lambert Law. The relationship between fIPAR and LAI was asymptotic at an LAI of 6 for both species. The normalized—difference vegetation index (NDVI) provided a good linear estimate of fIPAR(R2 = 0.86 for manzanita and 0.83 for bitterbrush), and the simple ratio of near infrared to red (SR) permitted a linear estimate of LAI (R2 = 0.86 for manzanita and 0.74 for bitterbrush) of this vegetation growing on soils with uniform reflectance properties. Aerial estimates of overstory and understory cover derived from aircraft or satellites provide a basis for assessing the proportional contribution of understory shrub cover to the total vegetation, given that basic relationships between spectral reflectance, LAI, and fIPAR have been established, as in this study.
Seasonal Patterns and Remote Spectral Estimation of Canopy Chemistry Across the Oregon Transect
Authors: Matson Pamela , Johnson Lee , Billow Christine , Miller John , Pu Ruiliang
Published: April 2006

We examined seasonal changes in canopy chemical concentrations and content in conifer forests growing along a climate gradient in western Oregon, as part of the Oregon Transect Ecosystem Research (OTTER) study. The chemical variables were related to seasonal patterns of growth and production. Statistical comparisons of chemical variables with data collected from two different airborne remote—sensing platforms were also carried out. Total nitrogen (N) concentrations in foliage varied significantly both seasonally and among sites; when expressed as content in the forest canopy, nitrogen varied to a much greater extent and was significantly related to aboveground net primary production (r = 0.99). Chlorophyll and free amino acid concentrations varied more strongly than did total N and may have reflected changes in physiological demands for N. Large variations in starch concentrations were measured from pre— to post—budbreak in all conifer sites. Examination of remote—sensing data from two different airborne instruments suggests the potential for remote measurement of some canopy chemicals. Multivariate analysis of high—resolution spectral data in the near infrared region indicated significant correlations between spectral signals and N concentration and canopy N content; the correlation with canopy N content was stronger and was probably associated in part with water absorption features of the forest canopy. The spectral bands that were significantly correlated with lignin concentration and content were similar to bands selected in the other laboratory and airborne studies; starch concentrations were not significantly related to spectral reflectance data. Strong relationships between the spectral position of specific features in the visible region and chlorophyll were also found.