bluuebunny/crossref_metadata_2025 huggingface dataset:
Fishery Stability, Local Extinctions, and Shifts in Community Structure in Skates
Authors: Dulvy Nicholas K. , Metcalfe Julian D. , Glanville Jamie , Pawson Mike G. , Reynolds John D.
Published: March 2003

Abstract:Skates are arguably the most vulnerable of exploited marine fishes. Their vulnerability is often assessed by examining fisheries catch trends, but these data are not generally recorded on a species basis except in France. Aggregated skate catch statistics tend to exhibit more stable trends than those of other elasmobranch fisheries. We tested whether such apparent stability in aggregated catch trends could mask population declines of individual species. We examined two time series of species‐specific surveys of a relatively stable skate fishery in the northeast Atlantic. These surveys revealed the disappearance of two skate species, long‐nose skate (  Dipturus oxyrhinchus) and white skate (  Rostroraja alba) and confirmed a previously documented decline of the common skate (  D. batis). Of the remaining five skate species, the three larger ones have declined, whereas two smaller species have increased in abundance. The increase in abundance and biomass of the smaller species has resulted in the stability of the aggregated catch trends. Because there is significant dietary overlap among species, we suggest the increase in abundance of the smaller species may be due to competitive release as the larger species declined. A consequence of this kind of stability is that declining species cannot be detected without species‐specific data, especially in taxa exhibiting competitive interactions. This may explain why previously documented disappearances of two species of skates went unnoticed for so long. The conservation of skates and other elasmobranchs requires species‐specific monitoring and special attention to larger species.
Improving the Evaluation of Conservation Programs
Authors: Kleiman Devra G. , Reading Richard P. , Miller Brian J. , Clark Tim W. , Scott J. Michael , Robinson John , Wallace Richard L. , Cabin Robert J. , Felleman Fred
Published: March 2003

Abstract:The evaluation of conservation programs is rare but increasingly important in improving their effectiveness. Regular evaluations of conservation programs and the implementation of recommendations resulting from such assessments are infrequent because of resistance by participants and lack of funding. Evaluations may be internal or external, depending on the purpose of the review and how broadly it is focused. We strongly recommend external peer review of long‐term complex conservation programs every 5 years, supported by more frequent (annual) internal reviews. Criteria for success must encompass both biological and social measures and include learning and the application of new knowledge to management. Evaluations must also go beyond monitoring to assess the value of the program. We emphasize the need to include the organization and function of a conservation program (the process) in any evaluation in addition to substantive criteria for success, which usually involve biological measures (numbers). A dysfunctional program organization and process can as effectively cripple a conservation effort as can a major biological catastrophe. We provide examples of different types of conservation program evaluations, including moderated workshops and case‐study analysis, and provide advice on the logistics and organization of the review, emphasizing the importance of the evaluation process itself to a successful outcome. One important aspect of an evaluation is having an individual with leadership ability and considerable expertise to organize the format and oversee the review process itself. Second, it is essential at the outset to ensure agreement among the program participants and the review committee on the goals and objectives of the conservation program, what is to be evaluated, and the criteria for defining success. Finally, the best evaluations are inclusive and involve all participants and stakeholders.
Effects of Long‐Term Ungulate Exclusion and Recent Alien Species Control on the Preservation and Restoration of a Hawaiian Tropical Dry Forest
Authors: Cabin Robert J. , Weller Stephen G. , Lorence David H. , Flynn Tim W. , Sakai Ann K. , Sandquist Darren , Hadway Lisa J.
Published: March 2003

Abstract: Although the destruction of tropical rain forests receives much attention, tropical dry forests are in general far more threatened and endangered. Eliminating grazing ungulates is often considered a key first step toward protecting these ecosystems, but few studies have investigated the long‐term effects of this technique. We examined the effects of ungulate exclusion from a 2.3‐ha native dry‐forest preserve on the island of Hawaii by comparing its present flora to the flora of an adjacent area subjected to continuous grazing since the preserve was fenced over 40 years ago. Relative to this adjacent area, the fenced preserve contained a more diverse flora with substantially greater coverage of native overstory and understory species. Until recently, however, regeneration of native canopy trees within the preserve appears to have been thwarted by a dominant herbaceous cover of alien fountain grass (  Pennisetum setaceum) and predation by alien rodent species. Our results indicate that although ungulate exclusion may be a necessary and critical first step, it is not sufficient to adequately preserve and maintain Hawaii's remaining tropical dry forest remnants. Our recent efforts to control the dominant alien species within the fenced preserve suggest that this practice may facilitate both the regeneration of native species and the colonization and potential invasion of new alien plants. Comparisons of seedlings of the dominant native canopy tree Diospyros sandwicensis growing in sites both dominated by and free of fountain grass suggested that fountain grass inhibits Diospyros seedling growth and photosynthesis but may increase survival if seedlings are protected from ungulates.
Obligate Cave Fauna of the 48 Contiguous United States
Authors: Culver David C. , Master Lawrence L. , Christman Mary C. , Hobbs Horton H.
Published: March 2003

Abstract: We assembled a list of obligate cave‐dwelling species and subspecies, their county distribution, and their provisional global conservation rank. A total of 927 species and 46 additional subspecies in 96 families exclusively from cave and associated subterranean habitats have been described in the 48 contiguous states of the United States. The terrestrial (troglobitic) species are concentrated in northeast Alabama (especially Jackson County), with other concentrations in Kentucky, Texas, Virginia, and West Virginia. Only 23 counties, comprising less than 1% of the land area of the 48 contiguous states, account for over 50% of the terrestrial species and subspecies. The aquatic (stygobitic) species are concentrated in Hays County, Texas, with other concentrations in Florida, Oklahoma, Texas, Virginia, and West Virginia. Only 18 counties, comprising less than 1% of the land area, account for over 50% of the aquatic species and subspecies. Endemism is high, with 54% of the species known from a single county. Approximately 95% of the species are listed by The Nature Conservancy as vulnerable or imperiled in the United States. These cave species comprise 50% of all vulnerable or imperiled species listed in databases of the Natural Heritage Program. Less than 4% of these subterranean species have federal status. Conservation can best be accomplished through habitat protection, which must include protection of the associated surface habitat.
Mitigating Human Effects on European Biodiversity through Traditional Animal Husbandry
Authors: Pykälä Juha
Published: March 2003

Abstract:Livestock grazing (without modern fertilizers), mowing, and other traditional methods of animal husbandry are used in Europe for managing human‐made habitats such as seminatural grasslands. From a review of essential literature, I hypothesize that traditional animal husbandry partially compensates for the loss of natural processes that have been suppressed by humans. There is indirect evidence that livestock grazing and mowing have made possible the continued existence of many species threatened by the human overkill of megaherbivores and other large herbivores. Many species that were dependent on natural fires and floods may have benefited from grazing and mowing, which also may be effective tools for mitigating the negative effects of eutrophication. As partial surrogates, traditional grazing and mowing have obscured the importance of natural disturbances to European biodiversity. Thus, the end of traditional animal husbandry, together with the suppression of natural disturbances, may cause even more adverse effects to biodiversity than is generally recognized.
Patch Occupancy and Potential Metapopulation Dynamics of Three Forest Mammals in Fragmented Afromontane Forest in South Africa
Authors: Lawes Michael J. , Mealin Peter E. , Piper Steven E.
Published: March 2003

Abstract: We investigated the persistence of three medium‐sized (2–9 kg), rare forest mammals in the fragmented mist‐belt Podocarpus forests of the midlands of KwaZulu‐Natal Province, South Africa. We recorded patch occupancy of blue duiker (  Philantomba monticola), tree hyrax (  Dendrohyrax arboreus), and samango monkey (Cercopithecus mitis labiatus) in 199 forest patches. Their rarity is ascribed to the fragmentation and destruction of their forest habitat. Incidence functions, derived from presence and absence data, were formulated as generalized linear models, and environmental effects were included in the fitted logistic models. The small and mostly solitary hyrax and duiker persisted in smaller patches than the large and social monkey. Although this result follows expectations based on relative home‐range sizes of each species, the incidence probability of the samango monkey was invariant with increasing isolation, whereas a gradual decrease with increasing isolation was observed for the hyrax and duiker. Group dynamics may inhibit dispersal and increase the isolation effect in social species such as samango monkeys. A mainland‐island metapopulation model adequately describes patterns of patch occupancy by the hyrax and duiker, but the monkeys' poor dispersal ability and obvious area‐dependent extirpation suggest that they exist in transient, nonequilibrium (declining) metapopulations. Through identification of large forest patches for careful protection and management, the survival of all three species—especially the monkey—could be prolonged. Because no functional metapopulation may exist for the monkey, however, this is an emergency measure. For the duiker and hyrax, larger patches should form part of a network of smaller and closer patches in a natural matrix.
A Hierarchical Ecological Approach to Conserving Marine Biodiversity
Authors: Zacharias Mark A. , Roff John C.
Published: March 2003

Abstract: A number of ecological models have been developed to provide an understanding of the various biotic and abiotic components required to conserve biodiversity and to reconcile objectives and methods between those interested in the conservation of species (e.g., population management) and those advocating the conservation of spaces (e.g., protected areas). One of the better known efforts—pioneered in the Pacific Northwest of the United States—is a hierarchical ecological framework that separates biodiversity into compositional, structural, and functional attributes at the genetic, population, community‐ecosystem, and landscape levels of organization. We present an adaptation of this terrestrial framework consistent with the ecological function of marine environments. Our adaptation differs in its treatment of the community and ecosystem levels of organization. In our marine framework, the community level denotes predominantly the biotic community components of biodiversity, and the ecosystem level—consistent with marine terminology—denotes predominantly physical and chemical components. The community and ecosystem levels are further separated into those attributes based on ecological structures such as depth or species richness and those based on ecological processes such as water motion or succession. The distinction between the biotic (genetic, population, and community) and abiotic (ecosystem) is required because the biological components of biodiversity such as competition or predation are often more difficult to observe than the abiotic components such as upwellings, substratum, or temperature. As a result, efforts to conserve marine biodiversity are often dependent on the observable abiotic (ecosystem) components, which can be used as surrogates for the identification and monitoring of biotic (community) components. We used our hierarchical framework to identify and suggest how conservation strategies could be implemented in marine environments depending on whether existing data are to be used or new data are to be collected.
Genetic Diversity and Tests of the Hybrid Origin of the Endangered Yellow Larkspur
Authors: Koontz Jason A. , Soltis Pamela S. , Brunsfeld Steven J.
Published: March 2003

Abstract:Delphinium luteum( Ranunculaceae), an endangered larkspur, is restricted to two wild populations near Bodega Bay, California. The total number of individuals in these two populations is estimated to be <100. We used allozyme and random amplified polymorphic DNA ( RAPD) markers to (1) assess levels and patterns of genetic diversity in one wild population and two cultivated populations and (2) test the hypothesis thatD. luteumis of hybrid origin betweenD. decorumandD. nudicaule. These data will be used to aid in developing a management plan to conserve the species. The wild population maintains high levels of genetic diversity. Genetic data indicate that both cultivated populations, especially the north Sonoma population, have several allozymes and RAPD markers not found in the wild population and could be used to establish new populations ofD. luteumor to enhance the diversity and size of the wild population. The allozyme data did not reveal any fixed differences betweenD. decorumandD. nudicaule, although allele frequencies of the putative parental populations differed. At these loci,D. luteumresembledD. nudicaulemore thanD. decorum . Many unique RAPD markers distinguish each of the three species. The diagnostic markers from populations ofD. nudicauleandD. decorumwere not additive in the putative hybrid, and these data indicate thatD. luteumis not of recent hybrid origin. Conservation of the yellow larkspur should include strategies that use the cultivated populations ofD. luteum, but hybridizingD. decorumandD. nudicauleto “recreate”D. luteumis not recommended.
Comparison of Two Types of Metapopulation Models in Real and Artificial Landscapes
Authors: Hokit D. Grant , Stith Bradley M. , Branch Lyn C.
Published: March 2003

Abstract:Application of metapopulation models is becoming increasingly widespread in the conservation of species in fragmented landscapes. We provide one of the first detailed comparisons of two of the most common modeling techniques, incidence function models and stage‐based matrix models, and test their accuracy in predicting patch occupancy for a real metapopulation. We measured patch occupancies and demographic rates for regional populations of the Florida scrub lizard (  Sceloporus woodi) and compared the observed occupancies with those predicted by each model. Both modeling strategies predicted patch occupancies with good accuracy ( 77–80%) and gave similar results when we compared hypothetical management scenarios involving removal of key habitat patches and degradation of habitat quality. To compare the two modeling approaches over a broader set of conditions, we simulated metapopulation dynamics for 150 artificial landscapes composed of equal‐sized patches (2–1024 ha) spaced at equal distances (50–750 m). Differences in predicted patch occupancy were small to moderate (<20%) for about 74% of all simulations, but 22% of the landscapes had differences openface> 50%. Incidence function models and stage‐based matrix models differ in their approaches, assumptions, and requirements for empirical data, and our findings provide evidence that the two models can produce different results. We encourage researchers to use both techniques and further examine potential differences in model output. The feasibility of obtaining data for population modeling varies widely among species and limits the modeling approaches appropriate for each species. Understanding different modeling approaches will become increasingly important as conservation programs undertake the challenge of managing for multiple species in a landscape context.
Reserve Size, Local Human Density, and Mammalian Extinctions in U.S. Protected Areas
Authors: Parks S. A. , Harcourt A. H.
Published: March 2003

Abstract: We examined quantitatively the interaction of reserve size and surrounding local human density in the United States and their relative effect on extinction of large mammals in 13 national parks of the western United States. Data on reserve size and human density were obtained from publicly available sources. Local human density was calculated as the mean density in the 50‐ or 100‐km zone surrounding the reserves' borders. Reliable extinction data are extraordinarily hard to find. Using a variety of definitions of extinct, we collated information on extinctions of large mammals (>5 kg) that spanned the size of U.S. national parks as a whole. Human density surrounding reserves varies considerably. Overall, small reserves were in areas of higher human density than were large reserves (p < 0.0001, r 2  =  −0.24, n  =  864; excluding Hawaii), and many of the small reserves were at higher local density than the mean for the contiguous United States. Extinction rates of large mammals correlate significantly with local human density, but not with park area. These findings together emphasize that (1) processes occurring outside of a reserve's boundary may unexpectedly strongly affect species within the reserve; (2) small reserves might suffer the double jeopardy of not only their size but also their situation in especially adverse surrounds; and thus (3) small reserves might suffer more intense edge effects and be more isolated than large reserves. If so, conservation workers need to incorporate the relationship into their models and management decisions.
Effects of Forest Fragmentation on Seed Production of the Understory Herb Trillium camschatcense
Authors: Tomimatsu Hiroshi , Ohara Masashi
Published: March 2003

Abstract: We investigated the effects of forest fragmentation on reproduction of a common understory perennial, Trillium camschatcense, in Hokkaido, Japan. We measured seed production of 12 (1998) and 14 (1999) populations, and we explored the relationships of seed production to the number of flowering plants (  population size) and to the surrounding landscape condition (  landscape type). We discriminated between two landscape types, isolated and continuous, to describe the quantity and distribution of forests around T. camschatcense populations. Population size may be correlated with attractiveness to pollinators and the availability of compatible mates, whereas landscape condition can affect the abundance of pollinators. The number of seeds per flower was related to population size in 1999, but not in 1998. In both years, small populations of <50 flowering plants produced few seeds. Although the effect of landscape type was not significant, continuous populations with abundant forest series in their neighborhood tended to produce a higher number of seeds than isolated populations located in small, isolated forest. We attribute the decrease in seed production to pollen limitation because the stigmatic pollen load had a positive relationship to seed production and addition of pollen by hand increased seed production. Variation in population structure (   four stage classes) among populations was better explained by population size than number of seeds produced, suggesting the relative importance of population size for the demography of T. camschatcense. Larger populations had a higher proportion of seedlings, possibly because large populations had fewer edge effects, which reduce seedling recruitment and survival. Small populations with 220 flowering plants or less showed almost no seedling recruitment. The data on seed production and population structure suggest that continuous populations with at least 1000 flowering plants may be required to avoid the effects of fragmentation.
Incorporating Uncertainty into Demographic Modeling: Application to Shark Populations and Their Conservation
Authors: Cortés Enric
Published: March 2003

Abstract: I explored the effect of uncertainty in demographic traits on demographic analyses of sharks, an approach not used before for this taxon. I used age‐structured life tables and Leslie matrices based on a prebreeding survey and a yearly time step applied only to females to model the demography of 41 populations from 38 species of sharks representing four orders and nine families. I used Monte Carlo simulation to reflect uncertainty in the estimates of demographic traits and to calculate population statistics and elasticities for these populations; I used correlation analysis to identify the demographic traits that explained most of the variation in population growth rates ( λ ). The populations I examined fell along a continuum of life‐history characteristics that can be linked to elasticity patterns. Sharks characterized by early age at maturity, short lifespan, and large litter size had high λ values and short generation times, whereas sharks that mature late and have long lifespans and small litters have low λ values and long generation times. Sharks at the “fast” end of the spectrum tended to have comparable adult and juvenile survival elasticities, whereas sharks at the “slow” end of the continuum had high juvenile survival elasticity and low age–zero survival ( or fertility ) elasticity. Ratios of adult survival to fertility elasticities and juvenile survival to fertility elasticities suggest that many of the populations studied do not possess the biological attributes necessary to restore λ to its original level after moderate levels of exploitation. Elasticity analysis suggests that changes in juvenile survival would have the greatest effect on λ, and correlation analysis indicates that variation in juvenile survival, age at maturity, and reproduction account for most of the variation in λ. In general, combined results from elasticity and correlation analyses suggest that research, conservation, and management efforts should focus on these demographic traits.
The Case for Genetic Engineering of Native and Landscape Trees against Introduced Pests and Diseases
Authors: Adams Jonathan M. , Piovesan Gianluca , Strauss Steve , Brown Sandra
Published: March 2003

Abstract: Many important native forest trees and familiar landscape trees of the northern temperate zone have been devastated by introduced pests and diseases. Without human intervention, many of these trees will become extinct or endangered. As trade and travel increase, it is likely that further devastating epidemics will occur. To undo the damage that has been done, we suggest limited, cautious transfer of resistance genes from the original host species in the source region of the pest or disease. The transgenic trees can then be replanted in forests or countryside to resume their original ecological niche. This method could have some advantages over tree‐breeding techniques, including introgression. For instance, fewer tree generations would be required and fewer unnecessary genes of the non‐native tree species would be introduced. Furthermore, once the technique is perfected it would be possible to separately add resistance genes to local land races of trees, for reintroduction to their original habitats, without relying on intensive and lengthy local introgression programs. Practical problems with identifying and transferring resistance genes do exist, however, and somaclonal errors might lead to genetically engineered trees that do not resemble their parent in growth form. Nevertheless, we believe that, with further work, this approach may offer a preferable alternative to introgression with non‐native trees.
Unexpected Ecological Effects of Distributing the Exotic Weevil, Larinus planus (F.), for the Biological Control of Canada Thistle
Authors: Louda Sváa M. , O'Brien Charles W.
Published: March 2003

Abstract: Rhinocyllus conicus, a weevil introduced for biological control of exotic weeds, has had major nontarget ecological effects on native thistles. Some practitioners have argued that this is an isolated case. We report, however, that another Eurasian weevil (   Larinus planus), currently being distributed in North America for the control of Canada thistle (Cirsium arvense), is significantly reducing seed production by a native thistle ( Tracy's thistle, Cirsium undulatum var. tracyi) in Colorado. In 1999 we discovered L. planus feeding in flower heads of Tracy's thistle near a 1992–1993 biocontrol release site. Of the heads collected, 74% had evidence of L. planus, and these heads produced only 1.1 viable seeds on average, compared with 45.9 in heads without this weevil. In 2000 we investigated whether L. planus feeding persisted on Tracy's thistle and whether this feeding affected seed production significantly. Feeding by L. planus occurred on 80% of the plants and in 76% of all the main heads of Tracy's thistle. Flower heads with L. planus averaged 1.4 viable seeds, compared with 44.5 in uninfested heads. Feeding by L. planus decreased the average number of viable seeds produced per plant by over 51%. In contrast, L. planus had less effect on its targeted exotic host, Canada thistle than it did on Tracy's thistle. The high‐frequency and high‐level feeding of L. planus on the native species, coupled with the lack of evidence of its effectively limiting the seed production or density of Canada thistle suggest that the deliberate distribution of this weevil entails a high risk‐to‐benefit ratio and should be discontinued. Our findings challenge the general assumption that biological control with exotic insects is consistent with conservation goals of weed management in natural areas. Effective, a priori quantitative evaluation of the potential effects on both target and nontarget species and better regulatory oversight are required.
Ecosystem Decay of Amazonian Forest Fragments: a 22‐Year Investigation
Authors: Laurance William F. , Lovejoy Thomas E. , Vasconcelos Heraldo L. , Bruna Emilio M. , Didham Raphael K. , Stouffer Philip C. , Gascon Claude , Bierregaard Richard O. , Laurance Susan G. , Sampaio Erica
Published: March 2003

Abstract: We synthesized key findings from the Biological Dynamics of Forest Fragments Project, the world's largest and longest‐running experimental study of habitat fragmentation. Although initially designed to assess the influence of fragment area on Amazonian biotas, the project has yielded insights that go far beyond the original scope of the study. Results suggest that edge effects play a key role in fragment dynamics, that the matrix has a major influence on fragment connectivity and functioning, and that many Amazonian species avoid even small (<100‐m–wide) clearings. The effects of fragmentation are highly eclectic, altering species richness and abundances, species invasions, forest dynamics, the trophic structure of communities, and a variety of ecological and ecosystem processes. Moreover, forest fragmentation appears to interact synergistically with ecological changes such as hunting, fires, and logging, collectively posing an even greater threat to the rainforest biota.
Large‐Scale Conversion of Forest to Agriculture in the Boreal Plains of Saskatchewan
Authors: Hobson Keith A. , Bayne Erin M. , Van Wilgenburg Steve L.
Published: March 2003

Abstract: Despite widespread recognition of the importance of forest loss and fragmentation on biodiversity, the extent and rate of forest loss even in temperate regions remains poorly understood. We documented forest loss and assessed whether road density, rural developments, land quality for agriculture, and land ownership influenced the distribution and rate of change in forest cover for the entire boreal transition zone (49,846 km2) of Saskatchewan, Canada. We used landscape data taken from the Canadian Land Inventory database in forest cover (1996) and Landsat thematic mapper data (1994) to study changes between 1966 and 1994. Forest covered 17,873 km2 of the study area in 1966 and 13,504 km2 in 1994. This represents an overall conversion of 73% of the boreal transition zone in Saskatchewan to agriculture since European settlement and an annual deforestation rate of 0.89% over the last 28 years, a rate approximately three times the world average. Mixed‐regressive, spatially autoregressive models explained a considerable portion of the variation in forest cover (r 2 = 0.83) remaining on the landscape and suggested that less forest remained on lands that (1) were privately owned, (2) had soils with high suitability for agriculture, (3) had high road density, and (4) were in the southern portions of the study area. Strong spatial autocorrelation in the data indicated that areas of remaining forest tended to be spatially clustered. Our ability to predict where deforestation occurred between 1966 and 1994 was poor when we excluded the spatial autocorrelation terms from our model, but it was clear that deforestation was more likely to occur on privately owned lands than on those managed by the provincial government. Despite dramatic changes to forested areas in the boreal transition zone, and despite the importance of this area to a wide variety of forest‐dwelling wildlife, no programs are in place to slow or halt deforestation.
Influence of Exotic Earthworms on the Soil Organic Horizon and the Rare Fern Botrychium mormo
Authors: Gundale Michael J.
Published: March 2003

Abstract: Forests north of the last glacial extent have no native earthworms. Exotic earthworms are now colonizing forests that are naturally free of earthworms. It is currently unknown how these exotic earthworms might affect rare plants. To determine whether there is an association between the presence of an exotic earthworm species and extirpation of the rare fern Botrychium mormo, I surveyed 28 populations documented and counted previously. I estimated current population sizes of B. mormo, soil horizon thickness, earthworm species present, and carbon content, nitrogen content, and pH of the A soil horizon. Two earthworm species were abundant, Lumbricus rubellus and Dendrobaena octaedra. Dendrobaena octaedra had no significant association with any soil variable or with B. mormo extirpation. Lumbricus rubellus was significantly associated with B. mormo extirpation and a mull humus type. Where L. rubellus was present, O1 and O2 horizons were significantly thinner. I conducted a laboratory microcosm experiment to determine whether L. rubellus could create the conditions it was associated with in the field. Microcosms with L. rubellus resulted in a significant reduction in the thickness of the O1 and O2 horizon and a significant increase in the thickness of the A horizon. This experiment suggests that L. rubellus created the conditions with which it was associated in the field. The intrinsic rate of increase (r) of B. mormo was best explained by the O2 depth, which implies that this soil layer supplies a critical resource. My results support the idea that exotic earthworms alter the forest floor, leading to negative changes in native vegetation.
Habitat Fragmentation and the Demographic Structure of an Amazonian Understory Herb (Heliconia acuminata)
Authors: Bruna Emilio M. , Kress W. John
Published: March 2003

Abstract:Little is known about the demographic consequences of fragmentation for plant populations. By assessing the population structure of a common herb (   Heliconia acuminata) in an experimentally fragmented landscape in the central Amazon, we tested the predictions that fragmentation could reduce population density, alter population structure, and reduce reproductive effort. Population density in continuous forest varied six‐fold, some areas having high density and others low density. Population density in small fragments and on the edges of large fragments was often low, but it was within the range of densities found in continuous forest, and the difference between locations was not significant.Heliconiapopulations in forest fragments were skewed toward smaller demographic size classes, however. Because reproduction inH. acuminatais positively correlated with plant size, these shifts were predicted to result in fewer flowering plants in forest fragments. The proportion of the population flowering in forest fragments and continuous forest was not significantly different, although there was a trend toward proportionately greater flowering in continuous forest. For plants that did flower, per‐individual reproductive success (measured as developing fruit set) was the same in forest fragments and continuous forests. Our results suggest that per‐individual and population‐level reproduction by understory herbs in tropical forest fragments may be resistant to the detrimental consequences of fragment isolation. Our study also highlights the need to consider how fragmentation influences aspects of population structure and demography beyond abundance and fruit production, because these alternative measures of population structure can be modified in forest fragments in subtle, unexpected ways.
Effects of Habitat Fragmentation on Pollinator Diversity and Plant Reproductive Success in Renosterveld Shrublands of South Africa
Authors: Donaldson John , Nänni Ingrid , Zachariades Costas , Kemper Jessica
Published: March 2003

Abstract: We examined the effects of habitat fragmentation on the pollinator diversity and reproductive success of seven perennial plant species in renosterveld shrublands in South Africa. We sampled pollinators in small (0.5–2 ha), medium (3–10 ha), and large (>30 ha) habitat fragments during the peak flowering period in spring and summer. We also compared fruit set and seed set in the seven plant species on different‐sized fragments. Hand‐pollinated controls were used to determine pollination deficits in three species. Seed‐germination studies were done on two species to determine the effect of reduced seed set on reproductive output. Overall, the species richness of bees, flies, and butterflies did not vary significantly among different‐sized fragments. However, the abundance of particular species of bees and monkey beetles (Scarabaeidae: Hopliini) was significantly affected by fragment size, together with other factors such as vegetation cover and the ratio of grass to shrubs. Fragment size and distance to large remnants of vegetation had a significant influence on seed or fruit set in four of the seven plant species examined. One species failed to set any seed in small‐ and medium‐sized fragments. Comparisons of fruit and seed set among hand‐pollinated and naturally pollinated plants confirmed that seed set was pollinator‐limited in the orchid Pterygodium catholicum. Our results suggest that perennial plant species respond in different ways to fragmentation, and that populations on small fragments do not always experience pollination deficits. Existing classifications of pollination systems, in relation to their vulnerability to fragmentation, do not adequately explain our results. We argue that there needs to be a greater focus on the habitat requirements of pollinators to predict the effects of habitat fragmentation on pollination systems and plant reproductive success.
Effects of Forest Fragmentation and Flowering Phenology on the Reproductive Success and Mating Patterns of the Tropical Dry Forest Tree Pachira quinata
Authors: Fuchs Eric J. , Lobo Jorge A. , Quesada Mauricio
Published: March 2003

Abstract: The results of several studies suggest that forest fragmentation affects the mating patterns and reproductive success of tropical tree species by reducing pollinator activity, pollen deposition, and outcrossing levels. The flowering synchrony of trees has also been proposed as an additional factor in controlling fruit set and regulating levels of outcrossing, particularly in disturbed habitats. We examined the effects of forest fragmentation and flowering phenology on the reproductive success and genetic structure of the progeny produced by the tropical tree Pachira quinata. We conducted our study in the dry forest of Costa Rica and compared trees in two density and environmental conditions: ( 1 ) isolated trees separated by 500 m from other adult conspecifics and located in disturbed sites and ( 2 ) trees from continuous populations of groups of 20 or more reproductive individuals per hectare surrounded by undisturbed mature forest. Our study was conducted in the Guanacaste Conservation Area, Costa Rica, and surrounding areas. To evaluate flowering phenology, trees were classified as having synchronous or asynchronous flowering. The phenological stage of individuals was classified according to the proximity of the peak flowering date of each tree with respect to the mean peak flowering of the rest of the population. Six percent of the flowers produced a fruit in trees from continuous populations, whereas in isolated trees only 3% of the flowers did so. Fruit set was not affected by the flowering phenology of trees but was influenced mainly by factors associated with forest fragmentation. Seed production per fruit was not affected by forest fragmentation or flowering phenology. Overall, total fruit production per tree was not affected by forest fragmentation, because isolated trees tended to produce more flowers than trees from continuous populations. Genetic analysis revealed that the progeny of trees from continuous populations experienced lower levels of relatedness, a tendency for higher levels of outcrossing, and/or more sires than isolated trees. Our results suggest that forest fragmentation can have an effect on the mating patterns of P. quinata, reducing the number of outcross sires represented in the progeny of isolated trees.
Trophically Transmitted Parasites and the Conservation of Small Populations: Raccoon Roundworm and the Imperiled Allegheny Woodrat
Authors: Logiudice Kathleen
Published: March 2003

Abstract:Disease threats to endangered species are most commonly caused by exotic microparasites accidentally introduced into naïve populations by humans. The case of raccoon roundworm (   Baylisascaris procyonis ) and the Allegheny woodrat (  Neotoma magister ) is an exception to this general rule and, as such, may be useful in the identification of other macroparasite disease threats in the future.B. procyonisis an intestinal nematode of raccoons (  Procyon lotor ) that is highly pathogenic in intermediate hosts. It is hypothesized to have caused or contributed to the extirpation of the Allegheny woodrat from the northern parts of its range. I tested this hypothesis by reintroducing Allegheny woodrats into four historically occupied sites with varying natural levels of environmental contamination withB. procyoniseggs. Populations were monitored via radiotelemetry and trapping for 22 months. Woodrat populations in less contaminated release sites survived significantly longer than populations in highly contaminated sites, and there was a strong negative correlation between the number of raccoon latrines and woodrat population persistence. This case demonstrates several points relevant to the conservation of small populations: trophically transmitted parasites (  in which prey species serve as intermediate hosts to the parasites of their predators ) can be significant sources of mortality in intermediate host populations; native parasites should not be ignored as potential disease threats; and parasites of human‐adapted wild animals are likely to threaten rare and endangered species. This case also illustrates a previously unrecognized route through which host density can be decoupled from disease dynamics and provides evidence of apparent competition in nature.
Countryside Biogeography of Tropical Butterflies
Authors: Horner‐Devine M. Claire , Daily Gretchen C. , Ehrlich Paul R. , Boggs Carol L.
Published: March 2003

Abstract: Although most conservation efforts focus on preserving biodiversity in relatively pristine ecosystems, we investigated possible conservation opportunities in human‐dominated landscapes. We evaluated butterfly diversity in a tropical countryside that was converted about four decades ago from continuous forest to a mosaic of coffee farms, pasture, and forest fragments. We compared the butterfly fauna in coffee plantations with that in a forest remnant, the Las Cruces Reserve (227 ha). We used coffee plantation sites located “near” (<2.5 km) and “far” (>6 km) from the large forest remnant to test the effects of distance from the remnant on butterfly diversity. We also tested the effects of immediately adjacent habitat by selecting coffee plantation sites that were either contiguous with “small” (2.5–9.5 ha) forest fragments (coffee/forest) or lacking adjacent forest (coffee). Both coffee/forest and coffee habitats near the Las Cruces Reserve differed from those far from the reserve in species composition but not in species richness. Overall, coffee/forest habitats had significantly higher mean species richness and higher mean abundance of species than coffee and reserve sites. Further, butterflies with narrow geographic ranges were less likely to be found in coffee plantations than were those with larger geographic ranges. Area of forest cover within a radius of 50 to 100 m of the sampling site was significantly correlated with species richness of frugivorous butterflies during the dry season but was not correlated with richness of frugivorous butterflies in the wet season or of nonfrugivorous butterflies in either season. Nonetheless, species richness of frugivorous and nonfrugivorous butterflies was positively correlated overall; thus, frugivorous butterflies may be good indicators of the status of the entire butterfly community in a region. Our work suggests that small, isolated forest fragments may help retain butterfly diversity in the tropical countryside and increase the conservation value of agricultural landscapes. Relatively large tracts of forest remain important, however, because they maintain rare and endemic species.
Early Postpartum Discharge and Subsequent Breastfeeding
Authors: Janson Staffan , Rydberg Britta ,   Staffan Janson and Britta Rydberg are in the Department of Pediatrics and Adolescent Medicine, Central Hospital, Karlstad, Sweden.
Published: March 2003

Background:
Early postpartum discharge of babies was gradually introduced in Sweden in the 1980s on ideological grounds, based on the premise that maternity wards were unnatural settings for mothers and babies and hampered breastfeeding. From about 1990, early discharge was used as a means to reduce costs. The purpose of this study was to examine if mandated early discharge at Central Hospital of Karlstad, Sweden, influenced subsequent breastfeeding.
Method:
Breastfeeding outcomes of infants up to six months of age of all births in 1993 (n= 3231) were compared with the outcome of newborns in 1990 (n= 1462).Results:Breastfeeding at six months postpartum continued to increase during the early 1990s for both healthy and sick infants, irrespective of whether or not they were discharged early. In infants born in 1995 the breastfeeding rate at six months was 64 percent for healthy newborns and 53 percent for sick newborns.Conclusion:Factors other than the time of discharge, most likely a positive change of attitude in society and vigorous introduction of the Baby Friendly Hospital Initiative, seem to have been more important for successful breastfeeding. (BIRTH 25:4 December 1998)
The Experience of Stress Incontinence After Childbirth
Authors: Mason Linda , Glenn Sheila , Walton Irene , Appleton Carol
Published: March 2003

Background:
Epidemiological studies have reported prevalence of stress incontinence ranging from 23 to 67 percent during pregnancy and 6 to 29 percent after childbirth, but little is known about how the condition affects women at this time. The purpose of this study was to examine the effects of stress incontinence on women in their childbearing years.
Methods:
Interviews were conducted with 42 women who experienced stress incontinence at 8 weeks postpartum and 15 women who reported symptoms one year after delivery. Analysis of the qualitative data involved exploring themes and patterns, relationships and connections, contradictions and contrasts, and the language used within individual accounts and across the spectrum of narratives.
Results:
The results are presented within a framework that the women themselves adopted: day‐to‐day activities, putting the condition in some form of perspective, and feelings and emotions. For some women, stress incontinence had a great impact on their lives in terms of both their daily routine and psychologically, but others described it as a minor inconvenience that rarely disturbed their routine. Major concerns comprised the restrictions placed on the women, the worry or continual awareness stemming from the condition, and feelings of embarrassment associated with it. Twelve months after childbirth the effects appeared to have lessened, but a few women were still significantly affected, both physically and psychologically.
Conclusions:
Although many women experience physical and psychological symptoms of stress incontinence after delivery, this study demonstrated that few sought professional care or advice for their symptoms. Health professionals should be aware of the prevalence, and women's responses to, stress incontinence so that they can initiate appropriate support and care. Further research on stress incontinence on childbearing women is necessary.
Fathers' Coping Style, Antenatal Preparation, and Experiences of Labor and the Postpartum
Authors: Greenhalgh Rebecca , Slade Pauline , Spiby Helen
Published: March 2003

Background:
In recent years the trend for fathers in Western postindustrial countries to attend childbirth has increased. This study examined the interaction between fathers' information‐seeking coping predispositions and their level of attendance at antenatal classes with respect to their experiences of attending childbirth. Associations between fathers' childbirth experiences, their relationship with their baby, and level of depressive symptomatology at 6 weeks postpartum were also examined.
Methods:
A quantitative methodology was employed in which 78 fathers completed several questionnaires, some within 6 days of childbirth and others at 6 weeks postpartum.
Results:
Fathers who were characterized as high blunters (avoiders) of threat information, from antenatal classes reported that experiencing childbirth was less fulfilling than fathers with similar coping styles who did not attend classes. Fathers' reports of fulfillment and delight while attending childbirth were negatively related to their level of depressive symptomatology at 6 weeks postpartum. Levels of distress were associated with subsequent depressive symptoms, but their effect was removed when preexisting depressive symptoms were partialled out. Fathers whose children were born by cesarean delivery used significantly more negative adjectives to describe their baby at 6 weeks postpartum compared with those born by vaginal delivery. More married fathers attended antenatal classes and reported lower levels of depressive symptomatology than unmarried fathers.
Conclusions:
Although fathers' attendance at antenatal classes may have positive consequences for them and their partner, for some fathers, attendance at classes may be associated with less positive reports of experiencing childbirth. The way in which men experience childbirth may have some influence on their subsequent emotional well‐being.