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To question the statistical significance of return predictability, we cannot specify a null that simply turns off that predictability, leaving dividend growth predictability at its essentially zero sample value. If neither returns nor dividend growth are predictable, then the dividend-price ratio is a constant. If the null turns off return predictability, it must turn on the predictability of dividend growth, and then confront the evidence against such predictability in the data. I find that the absence of dividend growth predictability gives much stronger statistical evidence against the null, with roughly 1-2% probability values, than does the presence of return predictability, which only gives about 20% probability values. I argue that tests based on long-run return and dividend growth regressions provide the cleanest and most interpretable evidence on return predictability, again delivering about 1-2% probability values against the hypothesis that returns are unpredictable. I show that Goyal and Welch's (2005) finding of poor out-of-sample R does not reject return forecastability.

Climatic changes are predicted to significantly affect the frequency and severity of disturbances that shape forest ecosystems. We provide a synthesis of climate change effects on native bark beetles, important mortality agents of conifers in western North America. Because of differences in temperature-dependent life-history strategies, including cold-induced mortality and developmental timing, responses to warming will differ among and within bark beetle species. The success of bark beetle populations will also be influenced indirectly by the effects of climate on community associates and host-tree vigor, although little information is available to quantify these relationships. We used available population models and climate forecasts to explore the responses of two eruptive bark beetle species. Based on projected warming, increases in thermal regimes conducive to population success are predicted for Dendroctonus rufipennis (Kirby) and Dendroctonus ponderosae Hopkins, although there is considerable spatial and temporal variability. These predictions from population models suggest a movement of temperature suitability to higher latitudes and elevations and identify regions with a high potential for bark beetle outbreaks and associated tree mortality in the coming century.

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Summary Conifers are long‐lived organisms, and part of their success is due to their potent defense mechanisms. This review focuses on bark defenses, a front line against organisms trying to reach the nutrient‐rich phloem. A major breach of the bark can lead to tree death, as evidenced by the millions of trees killed every year by specialized bark‐invading insects. Different defense strategies have arisen in conifer lineages, but the general strategy is one of overlapping constitutive mechanical and chemical defenses overlaid with the capacity to up‐regulate additional defenses. The defense strategy incorporates a graded response from ‘repel’, through ‘defend’ and ‘kill’, to ‘compartmentalize’, depending upon the advance of the invading organism. Using a combination of toxic and polymer chemistry, anatomical structures and their placement, and inducible defenses, conifers have evolved bark defense mechanisms that work against a variety of pests. However, these can be overcome by strategies including aggregation pheromones of bark beetles and introduction of virulent phytopathogens. The defense structures and chemicals in conifer bark are reviewed and questions about their coevolution with bark beetles are discussed. Contents Summary 353 I. Introduction 354 II. Integrating defense strategies 354 III. Constitutive defense systems: first tier of defense 356 IV. Inducible defense systems: second tier of defense 363 V. Genetics and physiology of bark defense 365 VI. Bark beetles: diminutive but deadly 367 VII. The arms race: coevolution of conifer defense and bark beetle strategies 367 VIII. Bark‐beetle‐vectored blue‐stain fungi: multiple attacks against multiple defenses 369 IX. Conclusions 370 Acknowledgements 371 References 371

Perhaps because negative emotions are frequently expressed in physiological reactions, psychosomatic theories have often identified Neuroticism and its component traits (including anxiety, anger, and depression) as causal influences on the development of disease. These views are apparently supported by correlations between physical symptom reports and measures of Neuroticism in males. Data from 347 adult women in the Baltimore Longitudinal Study of Aging replicate this finding for total physical complaints and for most body systems. However, analyses of mortality in the literature and in the present article show no influence of Neuroticism, suggesting that symptom reporting may be biased by Neuroticism-related styles of perceiving and reporting physiological experiences. Researchers in this area are urged to employ objective measures of medical status, and to be alert to possible biases of self-selection and selective perception in interpreting associations between Neuroticism and disease.

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Carbohydrate binding properties of a new plant lectin isolated from elderberry (Sambucus nigra L.) (SNA) bark were studied using the techniques of quantitative precipitation, hapten inhibition, and equilibrium dialysis. Purified SNA precipitates highly sialylated glycoproteins such as fetuin, orosomucoid, and ovine submaxillary mucin, but not their asialo derivatives. Hapten inhibition experiments showed that both D-Gal and D-GalNAc are weak inhibitors of SNA-glycophorin precipitation, but neither New5Ac nor Neu5Gc is an inhibitor. A series of oligosaccharides which contain the terminal Neu5Ac(alpha 2-6)Gal sequence showed an extremely high inhibitory potency (1,600-10,000 times more inhibitory than Gal). On the other hand, oligosaccharides with the Neu5Ac(alpha 2-3)Gal linkage were only 30-80 times more inhibitory than Gal, thus showing a marked preference for the 2,6-linked isomer. Hapten inhibition with Gal and its epimers suggested that the equatorial OH at C-3 and the axial OH at C-4 of the D-pyranose ring are strict requirements for binding. Conversion of the Neu5Ac residue to its 7-carbon analogue by selective periodate oxidation of its glyceryl side chain, followed by NaBH4 reduction, completely destroyed the ability of fetuin and orosomucoid to precipitate with SNA. Moreover, the same treatment of Neu5Ac(alpha 2-3)lactitol also abolished its ability to inhibit the precipitation reaction, suggesting that the glyceryl side chain of NBu5Ac (especially the C-8 and/or C-9 portion) is an important determinant for SNA. The increased inhibitory potency of various glycosides with beta-linked nonpolar aglycons suggested the presence of a hydrophibic interacting region adjacent to the carbohydrate binding site. The results of equilibrium dialysis using [3H] Neu5Ac(alpha 2-6)lactitol as ligand showed the presence of two equivalent, noninteracting carbohydrate binding sites in this tetrameric glycoprotein lectin (Ka = 3.9 X 10(5) M-1).

Bark beetles use a complex chemical communication system to locate a new host, upon which they can feed, mate, and reproduce. Because the food resource may be either ephemeral (7) or not available until the tree dies, these beetles have evolved a pheromone that elicits behavior resulting in aggregation of the population on the new host. This population aggregation must be both timely and, with tree-killing species, of a sufficient magnitude to exploit the new resource. Because of their capacity to kill living trees, often over very large areas, bark beetles influence age, size, and species distributions, and thus are a significant factor in forest succession. Scolytidae is one of very few insect families in which the adult can penetrate the protective outer bark of woody plants. This behavior facilitates the introduction of pathogenic and decay-causing fungi, which are essential to recycling nutrients from these longest-lived plants.

▪ Abstract Scolytid bark beetles that colonize living conifers are frequently associated with specific fungi that are carried in specialized structures or on the body surface. These fungi are introduced into the tree during the attack process. The continuing association suggests that there is mutual benefit to the fitness of both beetles and fungi. The fungal species may benefit from the association with the beetles by transport to new host trees. Beetle species may benefit from the association with fungi by feeding on the fungi, or by the fungi contributing to the death of the host trees through mycelial penetration of host tissue, toxin release, interactions with preformed and induced conifer defenses, or the combined action of both beetles and fungi during colonization. Extensive research has been directed towards characterizing the interactions of beetle-fungal complexes with live host conifers and determining the ecological advantages for maintaining the associations. However, differences among systems and how species interact under different population and environmental conditions make it difficult to generalize about the importance of the separate biological components in successful host colonization.

Unlike most phytophagous insects, the reproduction of primary bark beetles (Coleoptera: Scolytidae) is contingent on host mortality. Consequently, there have been intense selective pressures on trees for properties which confer resistance to attack, and likewise, on the insect for increased behavioral complexity by which to overcome these defenses. In this study, we examined the relationship between the physiology of Pinus contorta var. latifolia and the behavior of the bark beetle, Dendroctonus ponderosae. Host mortality is a discrete outcome which is contingent on the quantitative interaction between host resistance and beetle numbers. At low attack densities, trees respond by confining beetles and their associated fungi within necrotic lesions containing toxic or inhibitory compounds. Beyond a critical "threshold of attack," however, the defensive capacity of the tree is exhausted, and mortality occurs. This threshold occurred at °40 galleries/m 2 in our experimental stands. The reproductive success of the bark beetle is directly related to the depletion of host defenses through concentrated attack. At sufficiently high attack densities, °80 galleries/m 2 , the potential suppressive effect of the host on brood development is not manifested. Increased beetle numbers, however, cause an exponential decline in brood production due to intraspecific competition. Consequently, there is an optimal density, °62 attacks/m 2 at which reproduction and survival of the beetle is maximized. Dendroctonus ponderosae utilize defensive secretions as precursors and synergists of aggregation pheromones, and thereby, elicit maximum responses from flying beetles while the host's production of toxins is at its maximum. This mechanism also ensures that the attack will terminate once the tree has been rendered suitable for brood development and, thus, minimizes the deleterious effect of intraspecific competition. Such an interaction, in which all trees could theoretically be colonized regardless of their resistance capacity, cannot result in a stable host—parasite system. Conifers, however, seem to be able to interfere with bark beetle communication. Pheromone synthesis within the hindgut and emission from the entrance site are distinct events, and beetles contained within a copious flow of resin seem unable to elicit attraction. This ability to interrupt the beetles' communication sequence, however, is inversely related to the number of beetles initiating localized attacks. Consequently, the colonization sequence reflects the outcome of a dynamic interaction between the tree and the initial "pioneer" beetles.

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Charred bark of Acacia mangium (bark charcoal), which is made of wood waste from pulp production, was applied as soil amendment for the cultivation of maize, cowpea and peanut to examine its effects on crop yield and soil chemical properties in South Sumatra, Indonesia. The yields of maize and peanut significantly increased after the application of bark charcoal under a fertilized condition in an infertile soil environment. In addition, increases in the root amount and colonization rate of arbuscular mycorrhizal (AM) fungi after bark charcoal application were also observed in maize. In general, the application of bark charcoal induced changes in soil chemical properties by increasing the pH value, total N and available P2O5 contents, cation exchange capacity, amounts of exchangeable cations and base saturation, and by decreasing the content of exchangeable Al3+. The amelioration of the soil chemical properties could be effective in highly weathered infertile tropical soils. The application of charcoal in agriculture is expected to lead to the formation of a carbon sink in soil and to increase crop yield because it has been suggested that charcoal is highly resistant to abiotic and biotic degradation, even in a soil environment.

Abstract Bark from trees is considered a worthless raw material. However, this resource could be economically beneficial if utilized efficiently due to its rich chemical compounds. In this study, an ethanol toluene-soluble extractive, alpha-cellulose and lignin obtained from Leucaena leucocephala bark were characterized to determine their chemical functional groups. Based on FTIR spectral analysis, the results indicated that the bands of the functional groups of the extractive from the original bark remain unchanged; however, the absorbance intensity was found to be weaker in the group frequency and fingerprint regions. Removal of extractive, pectin, hemicellulose and lignin from the bark indirectly increased the strong absorbance intensity of cellulose. Broad peaks of OH stretching found in all spectra were assigned to the presence of phenolic OH and aliphatic structures for extractive and aromatic structures of lignin. It was revealed that aromatic functional groups were mainly found in the extractive, while water, carbonyl and ether were the dominant groups in cellulose, and methyl, methylene, carbonyl and carboxyl groups were enriched in lignin. Graphic abstract

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