bluuebunny/crossref_metadata_2025 huggingface dataset:
Bringing Computational Models of Word Naming Down to the Item Level
Authors: Spieler Daniel H. , Balota David A.
Published: April 2006

Early noncomputational models of word recognition have typically attempted to account for effects of categorical factors such as word frequency (high vs low) and spelling-to-sound regularity (regular vs irregular) More recent computational models that adhere to general connectionist principles hold the promise of being sensitive to underlying item differences that are only approximated by these categorical factors In contrast to earlier models, these connectionist models provide predictions of performance for individual items In the present study, we used the item-level estimates from two connectionist models (Plaut, McClelland, Seidenberg, & Patterson, 1996, Seidenberg & McClelland, 1989) to predict naming latencies on the individual items on which the models were trained The results indicate that the models capture, at best, slightly more variance than simple log frequency and substantially less than the combined predictive power of log frequency, neighborhood density, and orthographic length. The discussion focuses on the importance of examining the item-level performance of word-naming models and possible approaches that may improve the models' sensitivity to such item differences
Decision Affect Theory: Emotional Reactions to the Outcomes of Risky Options
Authors: Mellers Barbara A , Schwartz Alan , Ho Katty , Ritov Ilana
Published: April 2006

How do people feel about the outcomes of risky options? Results from two experiments demonstrate that the emotional reaction to a monetary outcome is not a simple function of the utility of that outcome Emotional responses also depend on probabilities and unobtained outcomes Unexpected outcomes have greater emotional impact than expected outcomes Furthermore any given outcome is less pleasant if an unobtained outcome is better We propose an account of emotional experiences associated with outcomes of decisions called decision affect theory It incorporates utilities expectations and counterfactual comparisons into hedonic responses Finally we show that choices between risky options can be described as the maximization of expected emotional experiences as predicted by decision affect theory That is people choose the risky option for which they expect to feel better on average
Planting False Childhood Memories: The Role of Event Plausibility
Authors: Pezdek Kathy , Finger Kimberly , Hodge Dandle
Published: April 2006

Two experiments tested and confirmed the hypothesis that events will be suggestively planted in memory to the degree that they are plausible and script-relevant knowledge exists in memory In Experiment 1, 22 Jewish and 29 Catholic high school students were read descriptions of three true events and two false events reported to have occurred when they were 8 years old One false event described a Jewish ritual, and one described a Catholic ritual Results for the false events showed the predicted asymmetry Whereas 7 Catholics but 0 Jews remembered only the Catholic false event, 3 Jews but only 1 Catholic remembered only the Jewish false event Two subjects recalled both events In Experiment 2 20 confederates read descriptions of one true event and two false events to a younger sibling or close relative The more plausible false event described the relative being lost in a mall while shopping the less plausible false event described the relative receiving an enema Three events were falselv remembered, all were the more plausible event We conclude by outlining a framework that specifies the cognitive processes underlying suggestively planting false events in memory
Needed: A Ban on the Significance Test
Authors: Hunter John E.
Published: April 2006

The significance test as currently used is a disaster Whereas most researchers falsely believe that the significance test has an error rate of 5%, empirical studies show the average error rate across psychology is 60%–12 times higher than researchers think it to be The error rate for inference using the significance test is greater than the error rate using a coin toss to replace the empirical study The significance test has devastated the research review process Comprehensive reviews cite conflicting results on almost every issue Yet quantitatively accurate review of the same results shows that the apparent conflicts stem almost entirely from the high error rate for the significance test If 60% of studies falsely interpret their primary results, then reviewers who base their reviews on the interpreted study “findings” will have a 100% error rate in concluding that there is conflict between study results
On the Surprising Longevity of Flogged Horses: Why There Is a Case for the Significance Test
Authors: Abelson Robert P.
Published: April 2006

Criticisms of null-hypothesis significance tests (NHSTs) are reviewed Used as formal, two-valued decision procedures, they often generate misleading conclusions However, critics who argue that NHSTs are totally meaningless because the null hypothesis is virtually always false are overstating their case Critics also neglect the whole class of valuable significance tests that assess goodness of fit of models to data Even as applied to simple mean differences, NHSTs can be rhetorically useful in defending research against criticisms that random factors adequately explain the results, or that the direction of mean difference was not demonstrated convincingly Principled argument and counterargument produce the lore, or communal understanding, in a field, which in turn helps guide new research Alternative procedures–confidence intervals, effect sizes, and meta-analysis–are discussed Although these alternatives are not totally free from criticism either, they deserve more frequent use, without an unwise ban on NHSTs
Rules of Evidence: A Larger Context for the Statistical Debate
Authors: Scarr Sandra
Published: April 2006

Statistical tests define rules of evidence in psychological science Agreed-upon rules of evidence are needed to discuss what is true Statistics are probability statements about the reliability of associations In public and journalistic debates about psychological topics, the need for statistical rules is evident Anecdotes, intuitions, and sensational and unlikely events often dominate popular discussions Psychological science demands that the probability of events and associations be evaluated by statistical means Understanding of statistical tests can be improved by abandoning the term significance, which means reliability to psychologists, but in everyday English, means importance The importance of a result depends on magnitude of association, not on whether the event has a nonzero chance of recurring Given large samples and multiple measures, statistical tests are used too often to draw misleading conclusions about the importance of research results Better uses of statistics would focus on the magnitude of effects and error estimates
Impulsivity and Inhibitory Control
Authors: Logan Gordon D. , Schachar Russell J. , Tannock Rosemary
Published: April 2006

We report an experiment testing the hypothesis that impulsive behavior reflects a deficit in the ability to inhibit prepotent responses Specifically, we examined whether impulsive people respond more slowly to signals to inhibit (stop signals) than non-impulsive people In this experiment, 136 undergraduate students completed an impulsivity questionnaire and then participated in a stop-signal experiment, in which they performed a choice reaction time (go) task and were asked to inhibit their responses to the go task when they heard a stop signal The delay between the go signal and the stop signal was determined by a tracking procedure designed to allow subjects to inhibit on 50% of the stop-signal trials Reaction time to the go signal did not vary with impulsivity, but estimated stop-signal reaction time was longer in more impulsive subjects, consistent with the hypothesis and consistent with results from populations with pathological problems with impulse control
Seeing Two as One: Linking Apparent Motion and Repetition Blindness
Authors: Chun Marvin M. , Cavanagh Patrick
Published: April 2006

Object tokens are episodic visual representations that mediate the ability to track visual events as they move about and change over time. Multiple tokens also allow the viewer to individuate multiple instances of a single type of object. In the present study, we established a functional link for object tokens in two seemingly disparate visual phenomena: apparent motion and repetition blindness (RB). In RB, repeated items are more difficult to perceive than unrepeated items. Using displays in which two sets of alphanumeric characters streamed in opposite directions across a computer screen in apparent motion, we found increased RB for targets appearing within a single apparent motion stream, relative to targets in different apparent motion streams. The results are inconsistent with refractory period or memory retrieval accounts of RB and support the role of object tokens in both apparent motion and RB.
Knowledge of the Ordinal Position of List Items in Rhesus Monkeys
Authors: Chen Shaofu , Swartz Karyl B. , Terrace H.S.
Published: April 2006

What is learned during mastery of a serial task: associations between adjacent and remote items, associations between an item and its ordinal position, or both? A clear answer to this question is lacking in the literature on human serial memory because it is difficult to control for a “naive” subject's linguistic competence and extensive experience with serial tasks. In this article, we present evidence that rhesus monkeys encode the ordinal positions of items of an arbitrary list when there is no requirement to do so. First, monkeys learned four nonverbal lists (1–4), each containing four novel items (photographs of natural objects). The monkeys then learned four 4-item lists that were derived exclusively and exhaustively from Lists 1 through 4, one item from each list. On two derived lists, each item's original ordinal position was maintained. Those lists were acquired with virtually no errors. The two remaining derived lists, on which the original ordinal position of each item was changed, were as difficult to learn as novel lists. The immediate acquisition of lists on which ordinal position was maintained shows that knowledge of ordinal position can develop without the benefit of language, extensive list-learning experience, or explicit instruction to encode ordinal information.
Violations of Branch Independence in Judgments of the Value of Gambles
Authors: Birnbaum Michael H. , Beeghley Darin
Published: April 2006

Branch independence is weaker than Savage's “sure thing” principle. It requires that judgments of gambles with a common outcome produced by the same probability-event must not reverse order when that common outcome is changed. Subjects judged 168 gambles from viewpoints of both buyer (highest buying price) and seller (lowest selling price). Judgments violated branch independence in both viewpoints. Violations also changed systematically between viewpoints, consistent with the theory that viewpoint affects configural weighting but not the utility function. Violations of branch independence were opposite those predicted by the model of cumulative prospect theory. The middle of three equally likely outcomes received the most weight in the seller's viewpoint. In the buyer's, lower outcomes received greater weights. In both viewpoints, the ratio of weights of the middle outcome to the highest outcome exceeded the ratio of weights of the lowest outcome to the middle outcome.
Priming from the Attentional Blink: A Failure to Extract Visual Tokens but Not Visual Types
Authors: Shapiro Kimron , Driver Jon , Ward Robert , Sorensen Robyn E.
Published: April 2006

When people must detect several targets in a very rapid stream of successive visual events at the same location, detection of an initial target induces misses for subsequent targets within a brief period. This attentional blink may serve to prevent interruption of ongoing target processing by temporarily suppressing vision for subsequent stimuli. We examined the level at which the internal blink operates, specifically, whether it prevents early visual processing or prevents quite substantial processing from reaching awareness. Our data support the latter view. We observed priming from missed letter targets, benefiting detection of a subsequent target with the same identity but a different case. In a second study, we observed semantic priming from word targets that were missed during the blink. These results demonstrate that attentional gating within the blink operates only after substantial stimulus processing has already taken place. The results are discussed in terms of two forms of visual representation, namely, types and tokens.
Incidental Language Learning: Listening (and Learning) Out of the Corner of Your Ear
Authors: Saffran Jenny R. , Newport Elissa L. , Aslin Richard N. , Tunick Rachel A. , Barrueco Sandra
Published: April 2006

Two experiments investigated the performance of first-grade children and adults on an incidental language-learning task. Learning entailed word segmentation from continuous speech, an initial and crucial component of language acquisition. Subjects were briefly exposed to an unsegmented artificial language, presented auditorily, in which the only cues to word boundaries were the transitional probabilities between syllables. Subjects were not told that they were listening to a language, or even to listen at all; rather, they were engaged in a cover task of creating computer illustrations. Both adults and children learned the words of the language. Moreover, the children performed as well as the adults. These data suggest that a statistical learning mechanism (transitional probability computation) is able to operate incidentally and, surprisingly, as well in children as in adults.
Involuntary Listening AIDS Hearing
Authors: Ward Lawrence M.
Published: April 2006

In two experiments, I simultaneously measured response time, accuracy, and response bias in an auditory intensity discrimination task to look for evidence of stimulus-driven attention orienting in auditory frequency space. The results demonstrated that a cue tone caused an apparently involuntary orienting of attention to the cue's frequency region, allowing faster and more accurate processing of a subsequent target tone when it occurred at the same frequency as the cue than when it occurred at a different frequency. Relationships between response time, accuracy, and bias measures also allowed masking and other effects to be separated from attention-orienting effects in these experiments.
Concept Learning and Learning Strategies
Authors: Wright Anthony A.
Published: April 2006

Concept learning and learning strategies of pigeons were manipulated in a matching-to-sample task. Groups of 4 pigeons responded either 0, 1, 10, or 20 times to a sample stimulus, and then chose between a matching comparison stimulus and a nonmatching comparison stimulus. Tests with unfamiliar arrangements of the three training stimuli showed that learning was not by if-then rules. Tests with novel stimuli showed that as the number of sample responses increased, learning about the configural pattern of each display gave way to more learning about the sample-comparison relationship and more concept learning. Pigeons making the most sample responses showed complete concept learning.
A Measurement of the Adaptation of Color Vision to the Spectral Environment
Authors: Boker Steven M.
Published: April 2006

An exploratory factor analysis of the reflectance spectral distributions of a sample of natural and man-made objects yields a factor pattern remarkably similar to psychophysical color-matching curves. The goodness-of-fit indices from a maximum likelihood confirmatory factor model with fixed factor loadings specified by empirical trichromatic color-matching data indicate that the human visual system performs near to an optimum value for an ideal trichromatic system composed of three linear components. An unconstrained four-factor maximum likelihood model fits significantly better than a three-factor unconstrained model, suggesting that a color metric is better represented in four dimensions than in a three-dimensional space. This fourth factor can be calculated as a nonlinear interaction term between the first three factors: thus, a trichromatic input is sufficient to compute a color space of four dimensions. The visual system may exploit this nonlinear dependency in the spectral environment in order to obtain a four-dimensional color space without the biological cost of a fourth color receptor.
Digital Image Correlation: from Displacement Measurement to Identification of Elastic Properties – a Review
Authors: Hild F. , Roux S.
Published: April 2006

Abstract:  The current state of the art of digital image correlation, where displacements can be determined for values less than one pixel, enables one to better characterise the behaviour of materials and the response of structures to external loads. A general presentation of the extraction of displacement fields from pictures taken at different instants during an experiment is given. Different strategies can be followed to determine subpixel displacements. New identification procedures are then devised making use of full‐field measurements. A priori or a posteriori routes can be followed. They are illustrated on the analysis of a Brazilian disk test.
The periphery‐dominated centre
Authors: GARVIN TOM , MAIR PETER
Published: April 2006

Abstract Irish political parties cannot be easily fitted into a conventional left‐right framework. The Lipset‐Rokkan centre‐periphery concept is employed to explain this situation, and, in particular, to throw light on the persistent success of Fianna Fáil, the nationalist‐populist party which has dominated the system since 1932. It is argued that Ireland affords an example of a polity in which the political concerns and style of the rural periphery came to ‘invade’ and dominate the urban centre for more than a generation. Evidence from a study of urban party activists indicates a persistence of rural political styles and ideological perspectives in a social context which has been for well over half a century.
The dynamics of European party systems
Authors: Pedersen Mogens N. , KATZ RICHARD S. , RATTINGER HANS
Published: April 2006

Abstract In recent years it has become increasingly difficult to maintain that die European party systems are stable and that they reflect the societal cleavage structures of the past. One developmental aspect of the party systems is singled out for description and analysis in this paper. It is argued that European party systems in terms of electoral volatility, i.e., rates of net change in the electorates, are drifting away from each other. Some of the party systems which have traditionally been considered volatile, apparently are becoming less so, while some other systems are taking on the character of highly volatile party systems. A simple set of hypotheses, based upon the notion of party space, is proposed in order to account for the variation observed. The data lend support to the hypothesis that electoral volatility is a function of the format of the party system and of short‐term changes in that format.
Does politics matter?
Authors: Castles Frank , McKinlay Robert D. , ROBERTS GEOFFREY K. , CASTLES FRANCIS G.
Published: April 2006

Abstract The overriding conclusion of the majority of recent policy studies is that political factors play an insignificant role in influencing policy outputs. We establish a number of models, comprising both economic and political variables, which are used in an attempt to indicate the relative salience of rival determinants of public welfare commitment in advanced democratic states. Though we cannot dismiss some influence of economic factors, the main findings run counter to the conventional wisdom of policy studies in indicating the greater salience of political factors as determinants of public welfare outputs.
Second‐order elections
Authors: Reif Karlheinz , Schmitt Hermann , NORRIS PIPPA
Published: April 2006

Abstract The composition of the directly elected European Parliament does not precisely reflect the ‘real’ balance of political forces in the European Community. As long as the national political systems decide most of what there is to be decided politically, and everything really important, European elections are additional national second‐order elections. They are determined more by the domestic political cleavages than by alternatives originating in the EC, but in a different way than if nine first‐order national elections took place simultaneously. This is the case because European elections occur at different stages of the national political systems’ respective ‘electoral cycles’. Such a relationship between a second‐order arena and the chief arena of a political system is not at all unusual. What is new here, is that one second‐order political arena is related to nine different first‐order arenas. A first analysis of European election results satisfactorily justifies the assumption mat European Parliament direct elections should be treated as nine simultaneous national second‐order elections.
A new political system
Authors: Duverger Maurice , LIJPHART AREND , PASQUINO GIANFRANCO
Published: April 2006

Abstract This article aims at defining the concept of ‘semi‐presidential government’ and detailing the diversity of its practices. There are in fact three types of semi‐presidential regimes: the president can be a mere figurehead, or he may be all‐powerful or again he can share his power with parliament. Using four parameters ‐ the content of the constitution, tradition and circumstances, the composition of the parliamentary majority and the position of the president in relation to the majority ‐ the author seeks to explain why similar constitutions are applied in a radically different manner.
Political competition
Authors: Schofield Norman , LAVER MICHAEL
Published: April 2006

Abstract Many previous theoretical analyses of multiparty coalition behaviour have been based either on one‐dimensional policy model or on a constant‐sum game interpretation. For theoretical and empirical reasons this paper focusses on a competitive two‐dimensional model. In this model parties are concerned with policy outcomes but choose party positions both with a view to electoral consequences and as a basis for coalition bargaining. The political heart is proposed as the set of possible coalition outcomes. The heart is either the core of the political game or is determined by a small number of party positions. Under certain conditions an equilibrium in the choice of party positions can be shown to exist. The model suggests that parties can be categorized as either strong or weak core parties, anti‐core parties or peripheral parties. This categorization of parties implies a typology of party systems, which gives some theoretical foundation for the occurrence of minority, minimal winning and surplus coalitions in many of the European countries in the postwar period.
The shift to the right: Neo‐liberalism in argumentation and language in the Swedish public debate since 1969
Authors: BORÉUS KRISTINA
Published: April 2006

Abstract. In this article, a study is presented of the ideological shift to the right that took place in the Swedish elite‐dominated public debate between 1969 and 1989. The first aim of the article is to present the results of a number of analyses of the shift. Two questions guided the analyses: first, what was the ideological content of this swing to the right? Second, how comprehensive was it? The results indicate that the shift could best be described as a neo‐liberalization of the debate, and that conservative ideas were still virtually absent from the arenas of public debate in the late 1980s. The comprehensiveness of the shift was studied (a) as the proportion of neo‐liberal ideas put forward as explicit statements in the debate arenas, and (b) as influence on the normative and descriptive use of political terms such as the Swedish words for “democracy”, “justice” and “equality”. The results showed a ‘neo‐liberalization’ of the usage of some of the terms. The second aim of the article is to suggest, by example, certain methods for the analysis of ideological change and to evaluate those methods.
Agenda setting power and moral hazard in principal‐agent relationships: Evidence from hospital budgeting in Norway
Authors: HAGEN TERJE P.
Published: April 2006

Abstract. The article addresses a public sector principal‐agent relationship under a financial regime of block grants. Two types of questions arise in principal‐agent relations in this setting. The first is whether a public sector agent can force the principal to approve budgets that are away from the principal's ideal point, or if it is the principal that is the strong party in the relationship and can determine the agent's budget. The second is whether the agent can exploit a situation of asymmetric information or neglect from the principal, to lower efficiency. Predictions from different assumptions of the principal‐agent relationship are empirically tested on data from counties and county run hospitals in Norway. Results show that counties have the upper hand in the relationship and can set hospital budgets. However, agents reduce efficiency when budgets are increased and counties can not prevent efficiency from falling by monitoring the agent. Under a block grant financing system counties face a tradeoff between cost‐efficiency and production. Low budgets lead to high efficiency and low production. High budgets lead to low efficiency and high production.
The impact of parties in government on legislative output in Italy
Authors: KREPPEL AMIE
Published: April 2006

Abstract. Frequent government crisis and high legislative output have distinguished Italy for over forty years. Previous explanations of the Italian legislative process have focused on the institutions established since the Second World War. In particular, the ability of the parliamentary committees to pass legislation, and the ‘polarized’ nature of the Italian party system have received a great deal of attention. This type of structural analysis has proved unable to successfully explain the significant variations in legislative output which have occurred since the early 1950s. This paper attempts to add to previous structural models by demonstrating that much of the variation which has occurred can be linked to the number of parties participating in the governing coalition. Furthermore, the paper questions previous interpretations of leggine (small laws) and the role they play within the legislative process by demonstrating their positive relationship to regular legislation.
Twelve tongues, one voice: An evaluation of European political cooperation
Authors: SCHNEIDER GERALD , SEYBOLD CLAUDIA
Published: April 2006

Abstract. Traditional integration theories disagree over the scope of the main foreign policy instrument of the European Union (EU), the so‐called European Political Cooperation (EPC). While intergovernmentalism suggests that EPC actions are weak, neofunctionalism maintains that cooperation within the EPC framework is characterised by strong measures. In this article, we present a game‐theoretic and statistical analysis of these conflicting propositions and show that European foreign policy making is much more diversified than predicted by the predominating theoretical approaches. A signalling game demonstrates that the exploitation of uncertainty by a possible profit‐seeker outside the organisation can cause inadequate EPC decisions. The formal model also explores the extent to which joint interest in closer foreign policy coordination can help to overcome diverging national policy preferences. The empirical test of some game‐theoretic hypotheses shows that European foreign policy making has become more intensive. The increasing number of declarations is, however, also a sign of the proliferation of non‐committing statements. Logit regressions reveal a close relationship between the economic salience of an EPC target nation to the European Union and the intensity of an EPC reaction.
Restoration and Rehabilitation of Degraded Ecosystems in Arid and Semi‐Arid Lands. I. A View from the South
Authors: Aronson J. , Floret C. , Le Floc'h E. , Ovalle C. , Pontanier R.
Published: April 2006

A general model is presented describing ecosystem degradation to help decide when restoration, rehabilitation, or reallocation should be the preferred response. The latter two pathways are suggested when one or more “thresholds of irreversibility” have been crossed in the course of ecosystem degradation, and when “passive” restoration to a presumed predisturbance condition is deemed impossible. The young but burgeoning field of ecological restoration, and the older field of rehabilitation and sustainable range management of arid and semiarid lands (ASAL), are found to have much in common, especially compared with the reallocation of lands, which is often carried out without reference to pre‐existing ecosystems. After clarifying some basic terminology, we present 18 vital ecosystem attributes for evaluating stages of degradation and planning experiments in the restoration or rehabilitation of degraded ecosystems. Finally, we offer 10 hypotheses concerning ecological restoration and rehabilitation as they apply to ASAL and perhaps to all terrestrial ecosystems.
Phosphorus Removal from Natural Waters Using Controlled Algal Production
Authors: Adey W. , Luckett C. , Jensen K
Published: April 2006

A series of experiments designed to demonstrate the potential of using managed, attached algal production to permanently remove excess phosphorus from agricultural run‐off is described. The experiments were carried out on a secondary canal in the New Hope South region of the Florida Everglades Agricultural Area from October, 1991, to May, 1992. Natural algal populations of periphyton, including species of the genera Cladophora, Spirogyra, Enteromorpha, Stigeoclonium, and a variety of filamentous diatoms such as Eunotia and Melosira, were grown on plastic screens in raceways, under a wave surge regime. Considerable biomass production of algae occurred, and the resulting algal canopy also trapped plankton and organic particulates from the water column. A seven‐ to eight‐day harvest interval was determined to be optimal, and both hand harvesting and vacuum harvesting were employed. The vacuum device is applicable to large scale‐up. In source water having total phosphorus concentrations of 0.012–0.148 ppm, mean macro‐recovery dry biomass production levels of 15–27 g/m2/day were achieved. The lower rates occurred in the winter, the higher rates in the late spring. Two techniques were employed to reduce losses of fine material at harvest during the March to May period. Gravity sieving increased mean dry production levels to 33–39 g/m2/day. The mean phosphorus content of harvested biomass ranged from 0.34% to 0.43%. Total phosphorus removal rates during the spring period of average solar intensity and low nutrient supply, by methods demonstrated in this study, ranged from 104 to 139 mgTP/m2/day (380–507 kgP/ha/year). Over the incoming nutrient range studied, phosphorus removal was independent of concentration and was 16.3% of total phosphorus for 15 m of raceway. Up‐stream‐downstream studies of overflowing water chemistry (total P, total dissolved ‐P, orthophosphate ‐P) showed highly ‐significant reductions of all phosphorus species. Total phosphorus reduction closely correlated with phosphorus yield from biomass removal. Yearly, minimum phosphorus removal rates are predicted that are 100–250 times that achieved both experimentally and in long‐term, large‐area wetland systems. Engineering scale‐up to systems of hundreds of acres is being studied.
Restoration of Stipa pulchra Grasslands: Effects of Mycorrhizae and Competition from Avena barbata
Authors: Nelson Laura L. , Allen Edith B.
Published: April 2006

Experiments were conducted in the field and the greenhouse to determine whether vesicular‐arbus‐cular mycorrhizae affect growth and competition between the native perennial Stipa pulchra and the introduced annual Avena barbata. Soils in the greenhouse were steam‐sterilized, and in the field they were treated with the fungicide benomyl. Stipa pulchra showed decreased shoot dry mass and increased root mass when inoculated, while A. barbata showed the opposite response, increased shoot mass and decreased root mass. Mycorrhizal A. barbata also produced more seeds. Mycorrhizae did not alleviate the negative effects of competition of A. barbata on S. pulchra, as has been demonstrated for other pairs of weedy and nonweedy species. The same three species of mycorrhizal fungi were present in annual and perennial grasslands, but their relative composition was different. When inoculum from the two grassland types were tested in the field, the fungal species began to revert within five months to the species composition found in grasslands of the host plant. This indicates that, once annual grassland has been revegetated with the native S. pulchra, the original fungal species composition may return relatively quickly. Where A. barbata dominates, inoculation with mycorrhizal fungi alone will not suffice for establishing S. pulchra, and the usual practices for control of weed competition need to be employed.
Small‐Scale Wetland Restoration in the High Arctic: A Long‐Term Perspective
Authors: Forbes Bruce C.
Published: April 2006

Results are presented using vegetative shoots and bryophyte sods to restore floristically impoverished high arctic wet sedge‐moss meadows that had suffered intense damage from vehicle activity during the period 1960–1967. Clonal transplants of Carex aquatilis var. stans, a native sedge, were planted with and without bryophyte sods in vehicle ruts in 1972. After nearly two decades, there was less Carex cover in the planted ruts with flowing water than in the contiguous controls. This pattern was slightly reversed in planted plots with standing water. Reinvasion of Eriophorum angustifolium occurred in treated ruts, but cover was less in both treatments than in controls in 1990. The unexpected recruitment of Eriophorum scheuchzeri from the seed bank in moss‐sodded plots is discussed in terms of its local and regional importance. Total plant cover in restored ruts was nearly equal to that of controls, but biomass was somewhat less than that in control plots. Plots with bryophytes were environmentally distinct, due primarily to increases in organic mat depth relative to controls. After 18 years, restoration efforts resulted in increased plant cover in treated ruts compared to naturally recovering ruts.

The composition of no two patches of vegetation is precisely the same [and] neither are the seed banks. Successsion on different patches of disturebed ground in the same locality frequently proceeds quite differently because of such differences.

—J. Miles, Vegetation Dynamics, 1979
Mycorrhizae in Prairie Restoration: Response of Three Little Bluestem (Schizachyrium scoparium) Populations to Mycorrhizal Inoculum from a Single Source
Authors: Anderson Roger C. , Roberts Karl J.
Published: April 2006

In prairie restoration, use of seeds from nonlocal sources has been of concern to restorationists. We examined the specificity between vesicular‐arbuscular mycorrhizal fungi obtained from a single location and little bluestem obtained from three localities. Seed was obtained from three sources: (1) a commercial seed supplier in Nebraska, (2) Sand Ridge State Forest (SRSF), Mason County, Illinois, the site from which the experimental soil containing the mycorrhizal inoculum was obtained, and (3) Sand Prairie Scrub Oak Nature Preserve (SPSO), 32 km southwest of SRSF. Plants were grown in three substrates: (1) autoclaved soil, (2) autoclaved soil to which a mycorrhizal fungal‐free sieving of nonautoclaved soil was added, and (3) nonautoclaved soil. All plants grown in nonautoclaved soil were colonized by mycorrhizal fungi, whereas none of those grown in other substrates were colonized. Plants grown from SRSF seeds produced significantly (p < 0.05) more biomass than those grown from Nebraska seeds (X̄± SE, SRSF = 0.54 ± 0.04 g, SPSO = 0.49 ± 0.03 g, Nebraska = 0.37 ± 0.03 g). Plants grown in nonautoclaved soil, regardless of seed source, produced less biomass (0.27 ± 0.02 g) than plants grown in autoclaved soil (0.58 ± 0.03 g) or autoclaved soil plus sievings (0.59 ± 0.03 g).

The results provide no clear indication of a host‐endophyte specificity. However, the data suggest that the local genotypes of S. scoparium are better adapted to their native soil environment than are genotypes from other localities.
Restoring the Pygmy Pine Forests of New Jersey's Pine Barrens
Authors: Fimbel Robert A. , Kuser John E.
Published: April 2006

The Pinelands National Reserve and UNESCO Biosphere encompass a large portion of southern New Jersey's Pine Barrens. Within the core preservation zone of these Reserves lies the Warren Grove Weapons Range, a military installation where exercises during the past 50 years have devastated portions of the indigenous pygmy pine‐oak forest. In 1987, restoration efforts were initiated to identify materials and techniques that promote a diverse and productive native plant community atop drastically disturbed portions of the range. We used trial plantings to examine fertilizer and sewage compost fertility amendments, the effect of different native plant mixtures (including the dwarfed race of pitch pine,Pinus rigida), the influence of the ectomycorrhizal fungusPisolithus tinctoriuson the growth of pines and associated species, and mulch applications to conserve moisture and add organic matter. Following two growing seasons, test plantings exhibited 25% of the vegetation production found in the surrounding pine‐oak community, 50% canopy closure, and levels of diversity comparable to the reference site. Maximum biomass and cover were achieved following the application of 16 Mg/ha compost and the establishment of pitch pine seedlings. Pitch pine was the dominant species in all plots where it was planted, with herbaceous species comprising the balance of the developing vegetation. Amendments of seeded grasses,P. tinctorius, and mulch influenced species composition but failed to enhance total plant production. We recommend restoring drastically disturbed sites in the pine plains with cultural input of compost to the spoils and planting of pitch pines and other woody species to accelerate the structural blending of reforested sites with the surrounding native vegetation.
Vegetation of Restored Rock‐Plowed Wetlands of the East Everglades
Authors: Dalrymple Nancy K. , Dalrymple George H. , Fanning Kathy A.
Published: April 2006

Results of a short‐term study of the revegetation of illegally rock‐plowed wetlands in the East Everglades are reported. Comparisons of the plant communities on a restored site, an unrestored site, and the natural control areas directly adjacent to these sites were made using line intercept transects. On the site where removal of the rock‐plowed material and grading of the surface to below original elevation were required for restoration, less than 20% of plant cover was of nonwetland species, and the occurrence of exotic species was low. On the rock‐plowed site where no restoration efforts were performed, 61% of plant cover was of nonwetland species, and there was a higher occurrence of exotic species compared to the restored rock‐plowed and the control sites.
Seed Stores for Restoration of Species‐Rich Shrubland Vegetation Following Mining in Western Australia
Authors: Bellairs Sean M. , Bell David T.
Published: April 2006

The extreme species richness of native shrubland vegetation (kwongan) near Eneabba, Western Australia, presents a major problem in the restoration of sites following mineral sand mining. Seed sources available for post‐mining restoration and those present in the native kwongan vegetation were quantified and compared. Canopy‐borne seeds held in persistent woody fruits were the largest seed source of perennial species in the undisturbed native vegetation and also provided the most seeds for restoration. In undisturbed vegetation, the germinable soil seed store (140–174 seeds · m−2) was only slightly less than the canopy‐borne seed store (234–494 seeds · m−2), but stockpiled topsoil provided only 9% of the germinable seeds applied to the post‐mining habitat. The age of stockpiled soil was also important. In the three‐year‐old stockpiled topsoil, the seed bank was only 10.5 seeds · m−2 in the surface 2.5 cm, compared to 56.1 to 127.6 seeds · m−2 in fresh topsoil from undisturbed vegetation sites. In the stockpiled topsoil, most seeds were of annual species and 15–40% of the seeds were of non‐native species. In the topsoil from undisturbed vegetation, over 80% of the seeds were of perennial species, and non‐native species comprised only 2.7% of the seed bank. Additional seeds of native species were broadcast on restoration areas, and although this represented only 1% of the seed resources applied, the broadcast seed mix was an important resource for increasing post‐mining species richness. Knowledge of the life‐history characteristics of plant species may relate to seed germination patterns and assist in more accurate restoration where information on germination percentages of all species is not available.
Wildlife‐Habitat Restoration in an Urban Park in Southern California
Authors: Morrison Michael L. , Scott Thomas A. , Tennant Tracy
Published: April 2006

Within an urban park in southern California, the relationship between the structure and floristics of vegetation and the distribution, abundance, and behavior of wildlife was studied in relatively undisturbed areas (San Luis Rey) and in contiguous areas (Guajome Park) in need of restoration. These data were used to develop recommendations for the enhancement of native animal species in the park. The abundance of amphibians and reptiles was highest in native upland scrub and willow (Salix)‐riparian vegetation types, and lowest in dry, disturbed sites. Western fence lizards (Sceloporus occidentalis) were the most abundant reptile throughout both study areas. Overall, bullfrogs (Rana catesbiana), an exotic species, were the dominant amphibians; the native Pacific treefrog (Hyla regilla) was rare throughout. At both study areas, the small mammal community was dominated by western harvest mice (Reithrodontomys megalotis) and deer mice (Peromyscus maniculatus) and, to a lesser extent, by brush mice (P. boylii) and exotic house mice (Mus musculus). Negative correlations in abundance existed between house mice and harvest mice, and between house mice abundance and overall small mammal abundance. In riparian sites, cottonwood (Populus fremontii) and various height classes of willow were the dominant factors in the majority of bird abundance–habitat‘correlations and where foraging activities were concentrated. Recommendations for enhancing native animal species include reduction of marsh sedimentation, removal of feral species, and development of connections between the park and nearby natural areas. A corridor of native riparian vegetation (primarily cottonwood‐willow) should be developed to replace the existing agricultural fields, thereby linking Guajome with the San Luis Rey River.
Construction of Sand Shinnery Oak Communities of the Llano Estacado: Animal Disturbances, Plant Community Structure, and Restoration
Authors: Dhillion Shivcharn S. , McGinley Mark A. , Friese Carl F. , Zak John C.
Published: April 2006

In land restoration it is imperative to study the potential role of disturbances, biotic or abiotic, that may provide sites for colonization by specific plants. Disturbances can alter community composition by removing species or allowing others to become established. In communities where animal‐generated disturbances open sites for seedling establishment, animals may have important indirect effects on several aspects of plant community structure. Animal disturbances in Quercus havardii communities of western Texas appear to open sites for colonization by herbaceous species. These animal disturbances vary in spatial distribution, density, and abiotic and biotic characteristics. The abundance of herbaceous plant seedlings is positively related to bare ground and the number of distinct disturbances. Thus, the density and the spatial distribution of these disturbances may be expected to have an important influence on the abundance and dispersion of plant species. Therefore, successful restoration efforts of sand shinnery oak communities and other similar habitats must consider the effects of animal disturbances and the role of plant‐animal and plant‐soil microbe interactions on plant community composition and the maintenance of plant species diversity.
Rehabilitation of Tropical Lands: A Key to Sustaining Development
Authors: Brown Sandra , Lugo Ariel E.
Published: April 2006

Land rehabilitation is proposed as a management strategy to reverse the negative consequences of tropical deforestation and land degradation. We first define the concepts associated with ecosystem modification—conversion, damage, and degradation—and those associated with ecosystem repair—restoration, rehabilitation, and reclamation. We then present a scheme of sustainable land use in the tropics, with illustrations of how rehabilitation and restoration activities fit into the overall scheme of the use of land. Because damaged lands cannot contribute effectively to sustained economic development, land rehabilitation is a necessary step for increasing the chances of attaining sustainability. Approaches for rehabilitating ecosystems are discussed, including the management of stressors and subsidies in relation to their point of interaction in the ecosystem. Finally, we illustrate the concepts of ecosystem rehabilitation of damaged, degraded, and derelict lands with examples of case studies from dry to humid life zones in island and continental situations throughout the tropics. The case studies demonstrate that opportunities for success exist, even with severely degraded lands, but a considerable amount of research remains to be done before we have a full understanding of the complexity of the task facing us.
Bioindication of Soil Fertility and a Mathematical Model for Restoration Assessment
Authors: Růžek Lubomír
Published: April 2006

This article contributes to the worldwide trend of using microbiological methods for bioindication of the influence of abiotic, biotic, and anthropogenic factors on the soil environment, especially on the plough layer of soils. It compares two approaches to assess microbial biomass‐C: (1) chemical treatment of soil samples by CHCl3 vapor, followed by extraction, and (2) heat treatment in the range of 62–65°C for 24 hours, followed by extraction. It recommends the analysis of different forms of organic carbon, the total carbon of soil organic mass, and microbial biomass‐C and other forms of organic carbon extractable with 0.5 M K2SO4 and 0.5 M (NH4)2SO4 respectively. It presents a simple mathematical model suitable for assessment of microbial recuperation of the topsoil (0–15 cm) after restoration. The relation between the measured values and the values calculated with the model expressed as percentages expresses the quality of restoration achieved and the stage of disturbance of the living microbial part of the topsoil. It indicates not only the ecological impact but also the deficit and stress situations, to which the living microbial part of the topsoil is exposed in the long term.