bluuebunny/crossref_metadata_2025 huggingface dataset:
Parental Divorce and Child Mental Health Trajectories
Authors: Strohschein Lisa
Published: November 2005

A process‐oriented approach to parental divorce locates the experience within the social and developmental context of children's lives, providing greater insight into how parental divorce produces vulnerability in some children and resiliency in others. The current study involves prospectively tracking a nationally representative sample of Canadian children of ages 4–7 and living with two biological parents at initial interview in 1994 (N = 2,819), and comparing the mental health trajectories of children whose parents remain married with those whose parents divorce by 1998. Results from growth curve models confirm that, even before marital breakup, children whose parents later divorce exhibit higher levels of anxiety/depression and antisocial behavior than children whose parents remain married. There is a further increase in child anxiety/depression but not antisocial behavior associated with the event of parental divorce itself. Controlling for predivorce parental socioeconomic and psychosocial resources fully accounts for poorer child mental health at initial interview among children whose parents later divorce, but does not explain the divorce‐specific increase in anxiety/depression. Finally, a significant interaction between parental divorce and predivorce levels of family dysfunction suggests that child antisocial behavior decreases when marriages in highly dysfunctional families are dissolved.
High Hopes but Even Higher Expectations: The Retreat From Marriage Among Low‐Income Couples
Authors: Gibson‐Davis Christina M. , Edin Kathryn , McLanahan Sara
Published: November 2005

This study examines why low‐income, unmarried parents who say that they plan to marry at the time their child is born do not follow through on their plans. We use data from a nationally representative birth cohort survey—the Fragile Families and Child Wellbeing Study (N =3,710)—combined with data from an embedded qualitative study—Time, Love, Cash, Caring, and Children (n =47)—to explore the reasons behind this apparent discrepancy. We find that some of the difference between parents’ expectations and behavior may be because of the overstatement of intentions at the time of the birth. Most of the discrepancy, however, results from parents’ perceived social and economic barriers to marriage. Specifically, unmarried parents have a long list of financial and relationship prerequisites they believe must be met in order for them to wed. Combined with other factors, these standards lead to an indeterminate delay in marriage.
In the Face of Conflict: Work‐Life Conflict and Desired Work Hour Adjustments
Authors: Reynolds Jeremy
Published: November 2005

This study helps integrate the work‐life and work hours literatures by examining competing predictions about the relationship between work‐life conflict and the desire for paid work. Using data from the 1997 National Study of the Changing Workforce (N =2,178), I find that work‐life conflict makes women want to decrease the number of hours they work whether the conflict originates at home or at work. Men only want to decrease their hours when work‐life conflict originates at work, and some men facing frequent conflict actually want to increase their hours. I also find that having children does not increase the likelihood of wanting to work fewer hours but having a higher income does.
Stress in Childhood and Adulthood: Effects on Marital Quality Over Time
Authors: Umberson Debra , Williams Kristi , Powers Daniel A. , Liu Hui , Needham Belinda
Published: November 2005

We work from a stress and life course perspective to consider how stress affects trajectories of change in marital quality over time. Specifically, we ask whether stress is more likely to undermine the quality of marital experiences at different points in the life course. In addition, we ask whether the effects of adult stress on marital quality depend on childhood family stress experiences. Growth curve analysis of data from a national longitudinal survey (Americans’ Changing Lives, N =1,059 married individuals) reveals no evidence of age differences in the effects of adult stress on subsequent trajectories of change in marital experiences. Our results, however, suggest that the effects of adult stress on marital quality may depend on childhood stress exposure. Stress in adulthood appears to take a cumulative toll on marriage over time—but this toll is paid primarily by individuals who report a more stressful childhood. This toll does not depend on the timing of stress in the adult life course.
The Challenges of Multidisciplinary Consulting to Family-Owned Businesses
Authors: Swartz Stephen
Published: November 2005

Consulting to family firms in multidisciplinary teams promotes an understanding of family issues, business issues, and their ongoing interaction.
The Parting Patriarch of a Family Firm
Authors: Sonnenfeld Jeffrey A. , Spence Padraic L.
Published: November 2005

Chief executive succession presents special challenges for family businesses. This article proposes a typology of retirement styles and recommends strategies for planning and managing the succession process.
The Dynamics of Management Succession: A Model of Chief Executive Succession in the Small Family Firm
Authors: McGivern Chris
Published: November 2005

The author develops a model for analyzing succession plans in different types of family firms.
An Examination of the Challenges Daughters Face in Family Business Succession
Authors: Vera Carolina F. , Dean Michelle A.
Published: November 2005

The literature on daughter successors of family-owned businesses suggests that they face many challenges. The purpose of this article is to determine the extent to which daughters face these challenges and discover new areas for study. Qualitative data were gathered via interviews with 10 female family business owners. Respondents encountered employee rivalry, experienced work-life balance difficulties, and never assumed they would one day be the successor. Although participants reported few problems with their fathers upon succession, many experienced difficulties succeeding their mothers. An interesting finding was the daughter's likelihood of being compared with her mother's managerial style. Future research directions are offered.
Sexual limitations in people living with Parkinson's disease
Authors: Mott Sarah , Kenrick Marita , Dixon Miriam , Bird Graham
Published: November 2005

Objectives:  To explore disease sequelae and usage of support services in people living with Parkinson's disease (PD).

Methods:  A 31‐item survey was administered to a convenience sample of people with PD recruited through Parkinson's NSW Inc. and its support groups.

Results:  Four hundred and forty‐four responses were received. Sexual limitations were reported by 73.5% of people with PD. Additionally, respondents indicated that health professionals did not necessarily understand what it is like to live with the disease.

Conclusions:  Movement problems are most often presented as the major sequelae of PD. This study shows that for a large proportion of sufferers, sexual limitations are an issue. Additionally, it is important for health professionals to provide ample opportunity for the discussion of these difficulties.
Individual differences in the experience of burden in caring for relatives with dementia: role of personality and mastery
Authors: Helmes Edward , Green Bev , Almeida Osvaldo P
Published: November 2005

Objective:  We explored individual differences in caregiver outcome according to the personality and behavioural style of the carer. Current models of caregiver burden fail to consider such factors.

Methods:  This cross‐sectional, exploratory study used carer variables of personality traits and mastery and patient variables of cognitive, functional and neurobehavioural status to predict scores on an established measure of burden in a sample of 51 people with dementia and their carers.

Results:  Hierarchical multiple regression showed a significant association between behavioural disturbance and neuroticism and burden, but not with mastery.

Conclusions:  The primary findings in this study are that models of caregiver outcome need to take an individual differences perspective in accounting for caregiver mental health risk factors: personality characteristics do play a part in the way caregivers manage this difficult role.
Accommodation options in later life: retirement village or community living?
Authors: Gardner Ian L , Browning Colette , Kendig Hal
Published: November 2005

Objectives:  To assess retirement villages as an accommodation option for older people by examining the impact on quality of life of moving to a village.

Method:  A cross‐sectional survey of three groups: residents of independent living units of two retirement villages and a group of older people who considered moving but decided to remain living in the community.

Results:  The quality of life of all groups at interview was high. However, the village group's overall satisfaction with life, and satisfaction with friendships and social life, was better after moving, whereas the community group were more likely to say that their quality of life was the same or worse since looking at moving to a village.

Conclusions:  Retirement villages can be a viable accommodation option in later life and enhance quality of life. The results of this study have implications for government policy, public and private housing providers, and older people.
Substrate specificity of vaccinia virus thymidylate kinase
Authors: Topalis Dimitri , Collinet Bruno , Gasse Cécile , Dugué Laurence , Balzarini Jan , Pochet Sylvie , Deville‐Bonne Dominique
Published: November 2005

Anti‐poxvirus therapies are currently limited to cidofovir [(S)‐1‐(3‐hydroxy‐2‐phosphonylmethoxypropyl)cytosine], but drug‐resistant strains have already been characterized. In the aim of finding a new target, the thymidylate (TMP) kinase from vaccinia virus, the prototype of Orthopoxvirus, has been overexpressed in Escherichia coli after cloning the gene (A48R). Specific inhibitors and alternative substrates of pox TMP kinase should contribute to virus replication inhibition. Biochemical characterization of the enzyme revealed distinct catalytic features when compared to its human counterpart. Sharing 42% identity with human TMP kinase, the vaccinia virus enzyme was assumed to adopt the common fold of nucleoside monophosphate kinases. The enzyme was purified to homogeneity and behaves as a homodimer, like all known TMP kinases. Initial velocity studies showed that the Km for ATP‐Mg2+ and dTMP were 0.15 mm and 20 µm, respectively. Vaccinia virus TMP kinase was found to phosphorylate dTMP, dUMP and also dGMP from any purine and pyrimidine nucleoside triphosphate. 5‐Halogenated dUMP such as 5‐iodo‐2′‐deoxyuridine 5′‐monophosphate (5I‐dUMP) and 5‐bromo‐2′‐deoxyuridine 5′‐monophosphate (5Br‐dUMP) were also efficient alternative substrates. Using thymidine‐5′‐(4‐N′‐methylanthraniloyl‐aminobutyl)phosphoramidate as a fluorescent probe of the dTMP binding site, we detected an ADP‐induced conformational change enhancing the binding affinity of dTMP and analogues. Several thymidine and dTMP derivatives were found to bind the enzyme with micromolar affinities. The present study provides the basis for the design of specific inhibitors or substrates for poxvirus TMP kinase.
Mutagenesis of catalytically important residues of cupin type phosphoglucose isomerase from Archaeoglobus fulgidus
Authors: Hansen Thomas , Schlichting Bettina , Grötzinger Joachim , Swan Michael K. , Davies Christopher , Schönheit Peter
Published: November 2005

Recently, cupin type phosphoglucose isomerases have been described as a novel protein family representing a separate lineage in the evolution of phosphoglucose isomerases. The importance of eight active site residues completely conserved within the cPGI family has been assessed by site‐directed mutagenesis using the cPGI from Archaeoglobus fulgidus (AfcPGI) as a model. The mutants T63A, G79A, G79L, H80A, H80D, H82A, E93A, E93D, Y95F, Y95K, H136A, and Y160F were constructed, purified, and the impact of the respective mutation on catalysis and/or metal ion binding as well as thermostability was analyzed. The variants G79A, G79L, and Y95F exhibited a lower thermostability. The catalytic efficiency of the enzyme was reduced by more than 100‐fold in the G79A, G79L, H80A, H80D, E93D, Y95F variants and more than 15‐fold in the T63A, H82A, Y95K, Y160F variants, but remained about the same in the H136A variant at Ni2+ saturating conditions. Further, the Ni2+ content of the mutants H80A, H80D, H82A, E93A, E93D and their apparent Ni2+ binding ability was reduced, resulting in an almost complete loss of activity and thus underlining the crucial role of the metal ion for catalysis. Evidence is presented that H80, H82 and E93 play an additional role in catalysis besides metal ion binding. E93 appears to be the key catalytic residue of AfcPGI, as the E93A mutant did not show any catalytic activity at all.
New Design of a Ceramic Filter for Diesel Emission Control Applications
Authors: Pyzik Aleksander J. , Li Cheng G.
Published: November 2005

Diesel particulate filters (DPF) made from an advanced ceramic material (ACM) based on mullite have demonstrated high filtration efficiency, low‐pressure drop, high‐temperature handling capability, and excellent mechanical integrity at a porosity of 60% or higher. Due to the ability to control microstructure, total porosity, and particle size distribution, Dow's acicular mullite can be tailored to meet requirements for deep bed filtration and fine particles emission control. In addition, the ACM DPF is suitable for catalyzed applications and it can retain its performance with a broad range of catalysts and over a wide range of catalyst loadings. This study describes a material selected for a DPF design that meets current diesel particulate emission control requirements as well as a four‐way NOx control system.
Novel CO2 Absorbents Using Lithium‐Containing Oxide
Authors: Kato Masahiro , Nakagawa Kazuaki , Essaki Kenji , Maezawa Yukishige , Takeda Shin , Kogo Ryosuke , Hagiwara Yoshikazu
Published: November 2005

We have discovered a series of lithium‐containing oxides that immediately react with ambient carbon dioxide (CO2) up to 700°C. The products react and return reversibly to the oxides at a temperatures higher than about 700°C. The absorption capacity surpasses that of other CO2 absorbents by a factor of 10. Utilizing these absorbents, the possibility of a CO2 separation system that operates at around 500°C is proposed. It is generally believed that a CO2 separation process operable at temperatures higher than 500°C has the special benefit of a small energy penalty. Moreover, the absorption also proceeds at ambient temperature in the atmospheric environment. This property offers the possibility of many other applications, such as air cleaners or cartridges. Therefore, we think these materials have the potential to make a valuable contribution to the realization of CO2 emission control.
Preparation and Characterization of Novel Mesoporous Lanthanide–Transition Metal Mixed Oxides
Authors: Sinha Anil K. , Suzuki Kenichirou
Published: November 2005

We report a cationic supramolecular templating route to prepare thermally stable mixed oxides of lanthanides–transition metals, and characterization of such materials. The materials have three‐dimensional wormhole‐like mesoporosity with a partly crystalline lanthanide phase but an X‐ray diffraction‐invisible transition metal oxide phase that are probably finely dispersed as <3 nm crystallites. The materials had high surface areas with a narrow pore‐size distribution in the mesoporous range after calcination up to 973 K. The materials were active for volatile organic compounds (toluene) removal at room temperature, with mesoporous ceria–titania showing the highest activity. These results suggest that these mesoporous mixed oxides are promising for air‐purification applications.
Worldwide SOFC Technology Overview and Benchmark
Authors: Blum Ludger , Meulenberg Wilhelm A. , Nabielek Heinz , Steinberger‐Wilckens Robert
Published: November 2005

Solid oxide fuel cells (SOFC) are generally considered to be a promising future electricity‐generation technology due to their high electrical efficiency. They also display a multi‐fuel capability (hydrogen, carbon monoxide, methane, etc.), may play a role in carbon sequestration strategies, and may render the highest electricity generation efficiency in power station design if coupled with a gas turbine. Nevertheless, their development still faces various problems with high‐temperature materials, design of cost‐effective materials and manufacturing processes, and efficient plant design. This article summarizes world wide efforts in the field of SOFC, presenting an overview of the main SOFC designs and the main developers active in this field. Based on data published in proceedings of international conferences during the last few years, a comparison is made of the results achieved in cell, stack, and system development.
Fundamental Understanding of Processes Involved in Optical Fiber Manufacturing Using Outside Vapor Deposition Method
Authors: Tandon Pushkar
Published: November 2005

Optical fibers are often made using a flame hydrolysis deposition process, in which silica and doped silica particles from a soot‐laden flame are deposited on a target rod. The porous preforms thus formed are subsequently sintered into glass blanks and then drawn into optical fiber. We review here various tools that have been developed for better understanding of different processes involved in the making of optical fibers using the outside vapor deposition technique. Fundamental understanding of the different unit operations involved in the optical fiber manufacturing is critical for process optimization and improved product attributes.
Modular Micro Reaction System Including Ceramic Components
Authors: Moritz Tassilo , Lenk Reinhard , Adler Jörg , Zins Michael
Published: November 2005

Micro reaction technology offers the possibility to improve the flexibility, selectivity, and mobility of chemical reactions in the chemical industry, process engineering, or pharmaceutical industry. In comparison with conventional chemical devices, the scale down to a millimeter or micrometer scale will result in remarkable time and cost savings, especially in the area of research and development of smaller‐ and medium‐sized enterprises and at universities. The Fraunhofer Alliance Modular Micro Reaction System (FAMOS), consisting of six Fraunhofer institutes, has developed a software‐based micro reaction toolkit provided with all essential elements of conventional chemical devices, e.g., micro reactors, micro mixers, or analyzing modules. All these elements are arranged on a single platform. Besides modules made of other materials, ceramics play a dominant role in micro reactor components. Their chemical and thermal resistance show a number of advantages for application in micro reaction technology, especially in such cases when aggressive media are combined with high temperatures. For this reason, ceramic micro mixers and reaction modules containing multichannel plates for screening of catalysts or ceramic self‐heating foam structures were developed. This contribution will introduce the modular micro reaction system FAMOS such as different ceramic modules. It will show the development of the modules including construction, shaping, covering, and testing.
Effects of Season and Successional Stage on Leaf Area Index and Spectral Vegetation Indices in Three Mesoamerican Tropical Dry Forests1
Authors: Kalacska Margaret E. R. , Sánchez‐Azofeifa G. Arturo , Calvo‐Alvarado Julio C. , Rivard Benoit , Quesada Mauricio
Published: November 2005

We compared plant area index (PAI) and canopy openness for different successional stages in three tropical dry forest sites: Chamela, Mexico; Santa Rosa, Costa Rica; and Palo Verde, Costa Rica, in the wet and dry seasons. We also compared leaf area index (LAI) for the Costa Rican sites during the wet and dry seasons. In addition, we examined differences in canopy structure to ascertain the most influential factors on PAI/LAI. Subsequently, we explored relationships between spectral vegetation indices derived from Landsat 7 ETM+ satellite imagery and PAI/LAI to create maps of PAI/LAI for the wet season for the three sites. Specific forest structure characteristics with the greatest influence on PAI/LAI varied among the sites and were linked to climatic differences. The differences in PAI/LAI and canopy openness among the sites were explained by both the past land‐use history and forest management practices. For all sites, the best‐fit regression model between the spectral vegetation indices and PAI/LAI was a Lorentzian Cumulative Function. Overall, this study aimed to further research linkages between PAI/LAI and remotely sensed data while exploring unique challenges posed by this ecosystem.
The Utility of Spectral Indices from Landsat ETM+ for Measuring the Structure and Composition of Tropical Dry Forests1
Authors: Feeley Kenneth J. , Gillespie Thomas W. , Terborgh John W.
Published: November 2005

There is a growing emphasis on developing methods for quantifying the structure and composition of tropical forests that can be applied over large landscapes, especially for tropical dry forests that are severely fragmented and have a high conservation priority. This study investigates the relationships between various measures of forest structure (annual woody increment, canopy closure, stand density, stand basal area) and composition (tree species diversity, tree community composition) measured in semi‐deciduous tropical dry forests on islands in Lago Guri, Venezuela and three spectral indices derived from Landsat ETM+: Normalized Difference Vegetation Index (NDVI), Infrared Index (IRI), and Mid‐Infrared Index (MIRI). Even though there were significant autocorrelations among spectral indices, there were significant differences in the relationships between spectral indices and forest attributes. IRI was not significantly correlated with any of the structural variables while MIRI was correlated with canopy closure and NDVI values were correlated with canopy closure as well as annual woody increment. NDVI and MIRI were both related to relative tree diversity and all three indices were associated with aspects of tree species composition. Based on the results of this study, it appears that spectral indices, and in particular NDVI, may be useful indicators of forest attributes in tropical dry forest habitats. Further research needs to be undertaken to identify if the results of this study can be applied to other tropical dry forests at a global spatial scale.
Vegetation Structure, Composition, and Species Richness Across a 56‐year Chronosequence of Dry Tropical Forest on Providencia Island, Colombia1
Authors: Ruiz Jorge , Fandiño Maria C. , Chazdon Robin L.
Published: November 2005

We compared vegetation structure and species richness across a 56‐yr chronosequence of six replicated age classes of dry tropical forest on the island of Providencia, Colombia, in the Southwest Caribbean. Stand age classes were determined using sequential, orthorectified panchromatic aerial photos acquired between 1944 and 1996 and Landsat 7 ETM + satellite imagery from 2000. Along the chronosequence we established 59 plots of 2 × 50 m (0.01 ha) to document changes in species richness, basal area, tree height, stem density, and sprouting ability. All woody trees and shrubs >2.5 cm diameter at breast height (DBH) were censused and measured. Although woody species density reached a peak in stands from 32 to 56 yr old, rarefaction analysis showed that species richness increased linearly with stand age and was highest in stands 56 yr old or greater. Nonparametric, abundance‐based estimators of species richness also showed positive and linear associations with age. Basal area and mean tree height were positively associated with age since abandonment, while sprouting ability showed a negative relationship. Our results indicate rapid recovery of woody species richness and structural characteristics along this tropical dry forest chronosequence.
Tropical Dry Forests of Venezuela: Characterization and Current Conservation Status1
Authors: Fajardo Laurie , González Valois , Nassar Jafet M. , Lacabana Pablo , Portillo Q. Carlos A. , Carrasquel Fabián , Rodríguez Jon Paul
Published: November 2005

Tropical dry forests are located predominantly in the northern portion of Venezuela, above 6°N. Although their potential extent covers ca 400,000 km2 (44% of the land), they currently occupy about 10 percent of this area. The diversity and complexity of Venezuelan dry forests increases from north to south along a gradient of decreasing severity of the dry season. A typical dry forest in Venezuela presents ca 110–170 species of plants from ca 40 to 50 families within an area of approximately 10 ha. Species composition and forest structure, however, are dependent on local landscape conditions (e.g., soil type, topography), and nearby forest types can be very different. Our analysis of five dry forest variants showed a maximum family similarity of 67 percent, although most values fell in the 50–60 percent interval. They are currently considered as one of Venezuela's most threatened ecosystems, but only 5 percent of extant dry forests are included in protected areas; this represents 0.5 percent of their potential extent. It is fundamental to promote the creation of at least 3 or 4 more large protected areas (ca 5000 ha), with different climatic and orographic characteristics, in combination with the recovery of threatened species, the restoration of degraded systems, and the implementation of sustainable development projects. Their apparent high resilience suggests that with the proper management we can restore and maintain the integrity of Venezuelan dry forests.
Diverse Optical and Photosynthetic Properties in a Neotropical Dry Forest during the Dry Season: Implications for Remote Estimation of Photosynthesis1
Authors: Gamon John A. , Kitajima Kaoru , Mulkey Stephen S. , Serrano Lydia , Wright S. Joseph
Published: November 2005

Using optical and photosynthetic assays from a canopy access crane, we examined the photosynthetic performance of tropical dry forest canopies during the dry season in Parque Metropolitano, Panama City, Panama. Photosynthetic gas exchange, chlorophyll fluorescence, and three indices derived from spectral reflectance (the normalized difference vegetation index, the simple ratio, and the photochemical reflectance index) were used as indicators of structural and physiological components of photosynthetic activity. Considerable interspecific variation was evident in structural and physiological behavior in this forest stand, which included varying degrees of foliage loss, altered leaf orientation, stomatal closure, and photosystem II downregulation. The normalized difference vegetation index and the simple ratio were closely related to canopy structure and absorbed radiation for most species, but failed to capture the widely divergent photosynthetic behavior among evergreen species exhibiting various degrees of downregulation. The photochemical reflectance index and chlorophyll fluorescence were related indicators of photosynthetic downregulation, which was not detectable with the normalized difference vegetation index or simple ratio. These results suggest that remote sensing methods that ignore downregulation cannot capture within‐stand variability in actual carbon flux for this diverse forest type. Instead, these findings support a sampling approach that derives photosynthetic fluxes from a consideration of both canopy light absorption (e.g., normalized difference vegetation index) and photosynthetic light‐use efficiency (e.g., photochemical reflectance index). Such sampling should improve our understanding of controls on photosynthetic carbon uptake in diverse tropical forest stands.
Regional‐Scale Variation in Litter Production and Seasonality in Tropical Dry Forests of Southern Mexico1
Authors: Lawrence Deborah
Published: November 2005

Highly seasonal rainfall creates a pulse of litterfall in the southern Yucatan peninsula region, with cascading effects on the timing of essential nutrient fluxes, microbial dynamics, and vegetation growth. I investigated whether forest age or a regional environmental gradient related to rainfall has a greater effect on patterns of litterfall in this increasingly human‐dominated landscape. Litterfall was sampled in 10–13 stands in each of three locations spanning a rainfall gradient of ca 900–1400 mm/yr. Litter was collected monthly from November 1998 through January 2000 in mature forests and in secondary forests aged 2–25 yr. Despite a substantial precipitation gradient, age was the only significant predictor of annual litter mass. Two‐ to five‐yr‐old forests produced significantly less litter than 12–25‐yr‐old secondary forests (4.6 vs. 6.2 Mg/ha/yr), but the difference between older secondary forests and mature forests (9 percent) was not significant. Litter production increased with rainfall, but not significantly so. The pattern of litterfall was similar across locations and age classes, with a peak during late March or early April. However, litterfall seasonality was most pronounced in the old secondary and mature forests. Litterfall was more evenly distributed throughout the year in forests under 10 yr old. Seasonality of litterfall was also less pronounced at the wettest site, with less disparity between peak litterfall and off‐peak months. Seasonality was not related to soil texture. Forest age and rainfall are important drivers of litterfall dynamics; however, both litter mass and degree of seasonality depended more strongly on forest age. Thus, the impact of land‐use change on litter nutrient cycling is as great, if not greater, than the constraint imposed by the major natural environmental factor affecting tropical dry forests.
The Influence of Hurricane Winds on Caribbean Dry Forest Structure and Nutrient Pools1
Authors: Van Bloem Skip J. , Murphy Peter G. , Lugo Ariel E. , Ostertag Rebecca , Costa María Rivera , Bernard Ivelisse Ruiz , Colón Sandra Molina , Mora Miguel Canals
Published: November 2005

In 1998, we measured the effects of Hurricane Georges after it passed over long‐term research sites in Puerto Rican dry forest. Our primary objectives were to quantify hurricane effects on forest structure, to compare effects in a large tract of forest versus a series of nearby forest fragments, to evaluate short‐term response to hurricane disturbance in terms of mortality and sprouting, and to assess the ability of hurricanes to maintain forest structure. We sampled damage from 33 plots (1.3 ha) across a 3000‐ha tract of forest as well as in 19 fragments. For stems with 2.5‐cm minimum diameter, 1004 stems/ha (12.4%) suffered structural damage, while 69 percent of the undamaged stems were at least 50 percent defoliated. Basal area lost to structural damage equaled 4.0 m2/ha (22%) in south‐facing native forests. Structural damage and defoliation increased with stem diameter and were more common in certain dry forest species. South‐facing forests and those on ridgetops incurred more damage than north‐facing forests or those comprised primarily of introduced species. Stem mortality was only 2 percent of all stems after 9 mo. Structural damage did not necessarily result in stem mortality. Hurricane‐induced mortality was not associated with stem height or diameter, but was ten times greater than background mortality. Basal sprouting was proportional to the amount of structural damage incurred in a stand. Forest fragments experienced the same patterns of hurricane effects as the reference forest. The low, dense structure of Caribbean dry forest can be maintained by hurricane damage to larger stems and induction of basal sprouting to generate multistemmed trees.
Seasonal Patterns of Flowering and Fruiting in a Dry Tropical Forest in Jamaica1
Authors: McLaren Kurt P. , McDonald Morag A.
Published: November 2005

Tropical dry forests occupy more area and are more endangered than rainforests, yet their regeneration ecology has received less study and is consequently poorly understood. We recorded the flowering and fruiting phenology of a tropical dry forest in Jamaica over a period of 26 mo within ten 15 × 15‐m plots. Community‐wide recruitment reached a maximum in the wet season, whereas no recruitment occurred during the dry season. We observed a unimodal peak in rainfall and fruit production, and the periodicity and intensity of seed production were significantly correlated with rainfall seasonality (the optimal time for germination). Flowering at the community and system levels lagged behind a significant increase and subsequent decrease in rainfall by 7 and 3 mo, respectively, indicating that the dominant factor controlling flowering periodicity is the passage of the major (4‐mo long) rainy season and changes in soil moisture conditions. Fruiting lagged behind flowering by 2 mo and a significant increase in fruiting occurred 2 mo prior to a significant increase in rainfall. At the population level, a correspondence analysis identified a major dichotomy in the patterns of flowering and fruiting between species and indicated two broad species groups based on their time of peak fruiting and the number of times they were in fruit. These were either individuals which were usually in peak fruit 1–2 mo prior to the start of the major rainy season or those that were in fruit more or less continuously throughout the year with no peak fruiting time. This study supports the view that seasonal variation in rainfall and hence soil water availability constitutes both the proximate and the ultimate cause of flowering periodicity in tropical dry forests.
Phyllostomid Bat Community Structure and Abundance in Two Contrasting Tropical Dry Forests1
Authors: Stoner Kathryn E.
Published: November 2005

Although tropical wet forests are generally more diverse than dry forests for many faunal groups, few studies have compared bat diversity among dry forests. I compared ground level phyllostomid bat community structure between two tropical dry forests with different precipitation regimes. Parque National Palo Verde in northwestern Costa Rica represents one of the wettest tropical dry forests (rainfall 1.5 m/yr), whereas the Chamela‐Cuixmala Biosphere Reserve on the Pacific coast of central Mexico represents one of the driest (750 mm/yr). Mist net sampling was conducted at the two study sites to compare changes in ground level phyllostomid bat community structure between regions and seasons. Palo Verde was more diverse than Chamela and phyllostomid species showed low similarity between sites (Classic Jaccard = 0.263). The distinct phyllostomid communities observed at these two dry forest sites demonstrates that variants of tropical dry forest can be sufficiently different in structure and composition to affect phyllostomid communities. At both dry forest sites, abundance of the two most common foraging guilds (frugivores and nectarivores) differed between seasons, with greatest numbers of individuals captured coinciding with highest chiropterophilic resource abundance.
Aboveground Biomass Accumulation in a Tropical Wet Forest in Nicaragua Following a Catastrophic Hurricane Disturbance1
Authors: Mascaro Joseph , Perfecto Ivette , Barros Oton , Boucher Douglas H. , De La Cerda Iñigo Granzow , Ruiz Javier , Vandermeer John
Published: November 2005

Among their effects on forest structure and carbon dynamics, hurricanes frequently create large‐scale canopy gaps that promote secondary growth. To measure the accumulation of aboveground biomass (AGBM) in a hurricane damaged forest, we established permanent plots 4 mo after the landfall of Hurricane Joan on the Atlantic coast of Nicaragua in October 1988. We quantified AGBM accumulation in these plots by correlating diameter measurements to AGBM values using a published allometric regression equation for tropical wet forests. In the first measurement year following the storm, AGBM in hurricane‐affected plots was quite variable, ranging from 26 to 153 Mg/ha, with a mean of 78 (±15) Mg/ha. AGBM was substantially lower than in two control plots several kilometers outside the hurricane's path (331 ±15 Mg/ha). Biomass accumulation was slow (5.36 ± 0.74 Mg/ha/yr), relative to previous studies of forest regeneration following another hurricane (Hugo) and agricultural activity. We suggest that large‐scale, homogenous canopy damage caused by Hurricane Joan impeded the dispersal and establishment of pioneer trees and led to a secondary forest dominated by late successional species that resprouted and survived the disturbance. With the relatively slow rate of biomass accumulation, any tightening in disturbance interval could reduce the maximum capacity of the living biomass to store carbon.
Aboveground Roots in Amazonian Floodplain Trees1
Authors: Wittmann Florian , Parolin Pia
Published: November 2005

Sediment‐rich rivers seasonally flood central Amazonian várzea forests, leading to periodic anoxic conditions in the rhizosphere and requiring morphological and structural adaptations, such as aboveground root systems. We investigated some possible relationships between root types and environmental factors in forest plots covering 3.1 ha of várzea in the Mamirauá Sustainable Development Reserve, Brazil. Digital elevation models of the study sites were obtained; sedimentation and soil texture were investigated to check relationship between position of trees on the flood gradient, soil conditions, and aboveground root systems. Different types of aboveground roots were closely related to flooding duration and habitat dynamics. Species subjected to higher and more prolonged floods tended to produce more aboveground roots than species subjected to lower and shorter inundations. Plank‐buttressing species increased with decreasing flood height and/or flood duration, and with increasing growth height and basal area. Habitats inundated for long periods were dominated by species with low growth heights and low basal areas, which formed stilt roots and aerial roots. Root system and sediment deposition showed a close relationship, plank buttressing being more common in sites subjected to lower sediment rates. In the disturbed sites close to the main river channel colonized by pioneer species, the occurrence of buttresses was lower than in less disturbed climax stages. No clear relationship was found between root systems and sediment grain sizes.
Tree Phenology in Adjacent Amazonian Flooded and Unflooded Forests1
Authors: Haugaasen Torbjørn , Peres Carlos A.
Published: November 2005

Most phenological studies to date have taken place in upland forest above the maximum flood level of nearby streams and rivers. In this paper, we examine the phenological patterns of tree assemblages in a large Amazonian forest landscape, including both upland (terra firme) and seasonally flooded (várzea and igapó) forest. The abundance of vegetative and reproductive phenophases was very seasonal in all forests types. Both types of flooded forest were more deciduous than terra firme, shedding most of their leaves during the inundation period. Pulses of new leaves occurred mainly during the dry season in terra firme, whereas those in the two floodplain forests were largely restricted to the end of the inundation period. Flowering was concentrated in the dry season in all forest types and was strongly correlated with the decrease in rainfall. The two floodplain forests concentrated their fruiting peaks during the inundation period, whereas trees in terra firme tended to bear fruits at the onset of the wet season. The results suggest that the phenological patterns of all forest types are largely predictable and that the regular and prolonged seasonal flood pulse is a major determinant of phenological patterns in várzea and igapó, whereas rainfall and solar irradiance appear to be important in terra firme. The three forest types provide a mosaic of food resources that has important implications for the conservation and maintenance of wide‐ranging frugivore populations in Amazonian forests.
Factors Influencing Tree Phenology in Taï National Park, Côte d'Ivoire1
Authors: Anderson Dean P. , Nordheim Erik. V. , Moermond Timothy C. , Gone Bi Zoro B. , Boesch Christophe
Published: November 2005

Entrained phenology patterns of tropical trees are expected to be sensitive to short‐term fluctuations in typical rainfall and temperature. We examined 47 mo of data on the flowering, fruiting, and new leaf phenology for 797 trees from 38 species in the Taï National Park, Côte d'Ivoire. We determined the timing of the phenology cycles in relation to seasonal rainfall, temperature, and solar radiation. Regression analysis was used to examine how variations in rainfall and temperature influenced deviations in the peaks and troughs of phenology cycles. We also investigated whether populations that fruit during periods of community‐wide fruit scarcity were those populations with relatively long‐ or short‐fruiting duration. Flower, fruit, and leaf‐flushing phenophases all exhibited 12‐mo cycles. The broad peak in flowering began with the northward zenithal passing in April and ended with the southward zenithal passing in September. Fruiting peaks occurred in the long dry season, and leaf flushing peaked in the long dry season but continued into the wet season. Deviations from phenology cycles were largely attributable to short‐term fluctuations in rainfall and/or temperature. Fruiting durations of species were related to the mean diameter at breast height. Species with long‐ and short‐fruiting durations contributed equally to fruit abundance during periods of community‐wide fruit scarcity.
Geographic Variation and Succession of Arthropod Communities in Inflorescences and Infructescences of Xanthosoma (Araceae)1
Authors: García‐Robledo Carlos , Quintero‐Marín Paulina , Mora‐Kepfer Floria
Published: November 2005

Phytotelmata, small aquatic ecosystems within different structures of terrestrial plants, occur in the inflorescescences and infructescences of Xanthosoma (Araceae). This study reports changes in composition and abundance of arthropods during the anthesis of inflorescences and in the developing infructescences of three species of Xanthosoma at three different geographic locations: (1) X. undipes in a tropical cloud forest of Costa Rica, Central America; (2) X. daguense in a tropical cloud forest in the central Andes of Colombia; and (3) X. poeppigii in the Peruvian Amazonas. All Xanthosoma species displayed similar interactions with the main pollinators, dynastine beetles. We observed a succession from terrestrial to aquatic arthropods as inflorescences aged and set fruit. However, community composition varied among different Xanthosoma species. Some arthropods recorded in Xanthosoma phytotelmata have also been reported as inflorescence visitors of the dynastine‐pollinated terrestrial genus Dieffenbachia and of vines from Philodendon and Syngonium. Further research may elucidate if phytotelmata similar to those described for Xanthosoma could occur among dynastine‐pollinated genera of Araceae, both in the understory and the canopy of Neotropical forests.
Preferences and Food Quality of Fruit‐Feeding Butterflies in Kibale Forest, Uganda1
Authors: Molleman Freerk , Van Alphen Monique E. , Brakefield Paul M. , Zwaan Bas J.
Published: November 2005

Many butterflies in tropical forests feed on fruits that have fallen to the forest floor. This substrate differs in many ways from floral nectar, and therefore fruit‐feeding butterflies are expected to possess adaptations for efficient foraging, choice, and ingestion of their food. Differences in food quality and in spatial and temporal availability are also likely to have led to life history evolution. Here we describe the sugar and nitrogen content of fruits that butterflies feed on in a tropical forest in Uganda, and measure the attractiveness of these fruits to the local butterfly fauna together with the role that decay plays in the attraction. These data are supplemented with feeding observations at fruit falls in the forest. Our results show that (1) fruits contain significant and variable concentrations of sugar and nitrogen, and constitute a nutritious food source for butterflies in tropical forests; (2) fruit‐feeding butterflies use cues from the fruits and fermentation products to locate their food; (3) different classes of fruit‐feeding butterflies may vary in their preferences for certain fruits, and differ in their ability to find preferred food; and (4) fruit choice is not strongly correlated with attractiveness or nutrient content. The results are discussed in the light of the evolution of food searching and life history strategies.
Long Tongues and Loose Niches: Evolution of Euglossine Bees and Their Nectar Flowers1
Authors: Borrell Brendan J.
Published: November 2005

I examined relationships between tongue length of orchid bees (Apidae: Euglossini) and nectar spur length of their flowers in the genera Calathea, Costus, and Dimerocostus using phylogenetically independent contrasts. Long‐tubed flowers have specialized on one or several species of long‐tongued euglossine bees, but long‐tongued bees have not specialized on long‐tubed flowers. Whereas long tongues may have evolved to provide access to a wider variety of nectar resources, long nectar spurs may be a mechanism for flowers to conserve nectar resources while remaining attractive to traplining bee visitors.
Complex Nesting Behavior by Two Neotropical Species of the Ant Genus Stenamma (Hymenoptera: Formicidae)1
Authors: Longino John T.
Published: November 2005

Two Neotropical ant species, Stenamma expolitum Smith and S. alasnew species (described here), exhibit three unusual nesting behaviors: (1) they build architecturally sophisticated nest entrances that elevate the nest opening away from the surface; (2) they maintain multiple identical nests but occupy only one of them; and (3) they keep a round “door pebble” at the nest entrance, with which they plug the opening in response to army ants. Adaptive hypotheses for these behaviors are discussed, including the possibility that there are multiple lines of defense against army ant predation.
Habitat Preferences of Ungulates in Hunted and Nonhunted Areas in the Calakmul Forest, Campeche, Mexico1
Authors: Reyna‐Hurtado Rafael , Tanner George W.
Published: November 2005

We investigated habitat preference in the community of ungulates in the Calakmul Forest of Southern Mexico through systematically counting the tracks of six species in randomly placed transects. Tracks were associated with one of four major forest types according to Pennington and Sarukhan (1998). Forest type availability was estimated through 393 independent points on the same transects. We surveyed 90 transects in three hunted areas and one large nonhunted area, with a total of 206 km walked. A total of 1672 tracks of the six species were found. Brocket deer (Mazama americana and Mazama pandora) preferred low‐dry forest in the nonhunted area and low‐flooded forest in the hunted areas. Collared peccary (Pecari tajacu) was a generalist species in the nonhunted area, whereas in the hunted areas, it preferred the subperennial forest. White‐lipped peccary (Tayassu pecari) was found only in subperennial forest in the nonhunted area and favored low‐flooded forest in the hunted areas. White‐tailed deer (Odocoileus virginianus) preferred low‐flooded forest in the hunted areas, while it was a generalist in the nonhunted area. Tapir (Tapirus bairdii) preferred low‐flooded forest in the hunted areas. The most evident habitat difference among hunted and nonhunted areas was a major use of low‐flooded forest in the hunted areas for the species. Conservation of ungulate species in the Calakmul region requires protection of all major habitat types in hunted and nonhunted areas.