bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Species Richness on Resident and Target Species Components in a Prairie Restoration
Authors: Piper Jon K. , Schmidt Emily S. , Janzen Angela J. 
Published: May 2007

Abstract The ecological role of biodiversity in achieving successful restoration has been little explored in restoration ecology. We tested the prediction that we are more likely to create persistent, species‐rich plant communities by increasing the number of species sown, and, to some degree, by varying functional group representation, in experimental prairie plantings. There were 12 treatments consisting of 1‐, 2‐, 3‐, 4‐, 8‐, 12‐, and 16‐species mixtures of native perennials representing four functional groups (C4 grasses, C3 grasses, nitrogen‐fixing species, and late‐flowering composites) that predominate within Central Plains tallgrass prairies. In 2000, species were seeded into square plots (6 × 6 m), with five replicates per treatment, on former agricultural land. Annually, we measured total species richness and evenness, target species richness and cover, and richness and cover of resident species (i.e., those emerging from the seed bank). Both target species richness and rate of establishment of target communities were highest in the most species‐rich mixtures, but there was no additional benefit for treatments that contained more than eight species. Richness of resident species did not vary with target species richness; however, cover by resident species was lower in the higher target species treatments. Our results, indicating that establishment of species‐rich prairie mimics can be enhanced by starting with larger numbers of species at the outset, have implications for grassland restoration in which community biodiversity creation and maintenance are key goals.
Influence of Invasive Tree Kill Rates on Native and Invasive Plant Establishment in a Hawaiian Forest
Authors: Loh Rhonda K. , Daehler Curtis C. 
Published: May 2007

Abstract Fire tree (Morella faya) has invaded extensive areas of wet and mesic forest on the Island of Hawai’i, forming nearly monospecific stands. Our objective was to identify a method of controlling M. faya, which would allow native plants to establish while minimizing establishment by invasive plants. Treatments (logging all trees, trees left standing but girdled, and incremental girdling over 20 months) were selected to kill M. faya stands at different rates, thereby creating different conditions for species establishment. Leaf litter was either removed or left in place; seeds and seedlings of three native pioneer species, three native forest species, and three alien invasive species were then added to determine their ability to establish. Native pioneer species established best in the log and girdle treatments, whereas seedling emergence of native forest species was higher in the girdle and incremental girdle treatments. Seedlings of invasive species emerged faster than the natives, but each of them responded differently to the stand treatments. Leaf litter reduced seedling emergence for all species, with small‐seeded species (<1 mg/seed) affected most under low light conditions. No single method eliminated all invaders, but girdling of M. faya provided suitable conditions for most native species. If combined with selective removal of the most disruptive alien species and native seed additions, girdling could be an effective general strategy for restoring native forests that have been overwhelmed by woody invaders.
Does the Type of Disturbance Matter When Restoring Disturbance‐Dependent Grasslands?
Authors: MacDougall Andrew S. , Turkington Roy 
Published: May 2007

AbstractThe reintroduction of burning is usually viewed as critical for grassland restoration; but its ecological necessity is often untested. On the one hand, fire may be irreplaceable because it suppresses dominant competitors, eliminates litter, and modifies resource availability. On the other hand, its impacts could be mimicked by other disturbances such as mowing or weeding that suppress dominants but without the risks sometimes associated with burning. Using a 5‐year field experiment in a degraded oak savanna, we tested the impacts of fire, cutting and raking, and weeding on two factors critical for restoration: controlling dominant invasive grasses and increasing subordinate native flora. We manipulated the season of treatment application and used sites with different soil depths because both factors influence fire behavior. We found no significant difference among the treatments—all were similarly effective at suppressing exotics and increasing native plant growth. This occurred because light is the primary limiting resource for many native species and each treatment increased its availability. The effectiveness of disturbance for restoration depended more on the timing of application and site factors than on the type of treatment used. Summer disturbances occurred near their reproductive peak of the exotics, so their mortality approached 100%. Positive responses by native species were significantly greater on shallow soils because these areas had higher native diversity prior to treatment. Although likely not applicable to all disturbance‐dependent ecosystems, these results emphasize the importance of testing the effectiveness of alternative restoration treatments prior to their application.
Querying the Obvious: Lessons from a Degraded Stream
Authors: Pohlon Elisabeth , Augspurger Clemens , Risse‐Buhl Ute , Arle Jens , Willkomm Marlene , Halle Stefan , Küsel Kirsten 
Published: May 2007

Abstract A detailed assessment of degradation issues is essential for the development of reasonable restoration strategies. The assessment may be a difficult task when fluxes of organic matter and energy are concerned, which are primarily mediated by microorganisms. In small streams, biofilms are hot spots of trophic interactions. Small weirs cause small‐scale changes of flow velocity, which affects the formation, structure, and function of biofilms. Weirs are superficially considered as disturbing cross barriers that should immediately be removed for the restoration of riparian systems. However, our empirical studies of weirs in the stream Ilm, Germany, and conceptual modeling approaches revealed a rather beneficial effect because weirs compensate the loss of natural retention structures in straightened rivers. Longer processing time of particulate organic matter in the weir reservoirs may have a positive effect on biofilm productivity and nutrient cycling in aquatic ecosystems. This is a striking example of thorough investigations that resulted in a complete and surprising reassessment of a degradation situation, and for a case in which uninformed gut feeling decisions about management plans would have had detrimental effects.
Setting Attainable Goals of Stream Habitat Restoration from a Macroinvertebrate View
Authors: Spänhoff Bernd , Arle Jens 
Published: May 2007

Abstract Many efforts have been undertaken to reduce the impairment of stream ecosystems by wastewaters and other pollution, leading to a remarkable improvement of the water quality in most parts of Central Europe. Actually, the most severe disturbance to stream systems in Central Europe is the structural degradation of stream morphology. Restoration practices increasing the structural heterogeneity of formerly degraded stream sections are necessary to create new habitats at different scales that could provide habitat for a diverse invertebrate community. Increasing biodiversity of aquatic invertebrates strengthens the ecological integrity of streams and is therefore a desirable goal in stream restoration. Nevertheless, recent studies focusing on the effect of structural restoration of stream sections often displayed results that did not really met the preset goal of increasing invertebrate diversity. This might be due to sometimes severe disturbance caused by the restoration practice itself, impairing the established invertebrate community in the restored stream section. Additionally, the potential for immigration of new species into the restored stream section is often limited. Therefore, several important prerequisites must be accounted for in the planning of restoration practices to improve structurally degraded stream sections, when the goal of restoration is increasing invertebrate diversity.
Evaluation of Restoration Practice Based on Environmental Filters
Authors: Nuttle Tim 
Published: May 2007

Abstract Environmental filter models have been proposed as conceptual organizing frameworks for comparing and contrasting restoration practices. I evaluate two such environmental filter models, one proposed by Fattorini and Halle (2004) and the other by Hobbs and Norton (2004). These models were developed by abstracting restoration practice into what the authors viewed as the essential features restoration practitioners target for control or manipulation. In so doing, these conceptual frameworks hope to be able to transfer insights between different kinds of ecosystems. Here, I take the opposite approach: given an environmental filter model, I asked how well its filters could characterize restoration practices reported in the literature. I found that it was easier to characterize specific restoration practice using the more detailed filters described by Hobbs and Norton. I found that manipulation of biotic filters was most common in terrestrial ecosystems, whereas manipulation of abiotic filters was more common in wetland and stream ecosystems. Fattorini and Halle’s model appears most useful for evaluating the current status of degraded ecosystems compared to nondegraded ones, but Hobbs and Norton’s model is better for evaluating what particular restoration activities might be undertaken to move that system from a degraded to a nondegraded state.
The Challenge to Restore Processes in Face of Nonlinear Dynamics—On the Crucial Role of Disturbance Regimes
Authors: Jentsch Anke 
Published: May 2007

Abstract Increasingly, restoration ecologists and managers are challenged to restore ecological processes that lead to self‐sustaining ecosystem dynamics. Due to changing environmental conditions, however, restoration goals need to include novel regimes beyond prior reference conditions or reference dynamics. In face of these fundamental challenges in process‐based restoration ecology, disturbance ecology can offer useful insights. Here, I discuss the contribution of disturbance ecology to understanding assembly rules, ecosystem dynamics, regime shifts, and nonlinear dynamics. Using the patch and multipatch concept, all insights are organized according to two spatial and two temporal categories: “patch–event,”“patch–multievent,”“multipatch–event,” and “multipatch–multievent.” This concept implies the consideration of both spatial patterns and temporal rhythms inside and outside of a restoration site. Emerging issues, such as uncoupling of internal and external dynamics, are considered.
Restoration Ecology to the Future: A Call for New Paradigm
Authors: Choi Young D. 
Published: May 2007

Abstract The discipline of restoration ecology has grown remarkably in the past decades, providing new ideas and opportunities for conserving biological diversity, managing ecosystems, and testing ecological theories. On the other side, its past‐oriented, static, and idealistic approach has been criticized for subjectivity in determining restoration goals, inapplicability to dynamic ecosystems, and inability for restoring certain irreversible losses. Moreover, unpredictable sustainability of the restored ecosystems, which were modeled after its historical fidelity, adds our skepticism under the changing environment. This paper calls for a new paradigm of ecological restoration to the future. A future‐oriented restoration should (1) establish the ecosystems that are able to sustain in the future, not the past, environment; (2) have multiple alternative goals and trajectories for unpredictable endpoints; (3) focus on rehabilitation of ecosystem functions rather than recomposition of species or cosmetics of landscape surface; and (4) acknowledge its identity as a “value‐laden” applied science within economically and socially acceptable framework. Applicability of ecological theories to restoration practice is also discussed in this paper.
Plant phenology and seed predation: interactions between gorses and weevils in Brittany (France)
Authors: Barat Myriam , Tarayre Michèle , Atlan Anne 
Published: May 2007

Abstract Exapion ulicis (Forster) and Exapion lemovicinum (Hoffmann) (Coleoptera: Curculionoidea: Apionidae) are seed predators of the three gorse species occurring in Brittany (France): Ulex europaeus L., Ulex gallii Planch., and Ulex minor Roth.(Fabaceae). Host‐plant phenology plays a major role in the relationship between apionid weevils and their gorse species, because larvae develop within gorse pods and adults have to wait for pod dehiscence to be released. We monitored flowering and fruiting phenology of gorse species, weevil reproductive behaviour, and egg‐laying patterns in six natural populations in the native area of these gorse species. At each site, U. europaeus, which flowers mainly in spring, was sympatric with one of two autumn flowering gorse species, U. gallii and U. minor. We noticed that E. ulicis laid eggs in spring and was restricted to U. europaeus whereas E. lemovicinum laid eggs in autumn and was restricted to the two autumn‐flowering species U. gallii and U. minor. Therefore, host specificity depended on gorse phenology, and not on geographic proximity. In addition, the infested pod content showed that E. ulicis laid several eggs per pod and suggested that females chose pods with the highest numbers of seeds. In contrast, E. lemovicinum laid a single egg per pod and showed no preference for pods with many seeds. Finally, the impact of seed predation by E. ulicis was higher than that of E. lemovicinum.
Evaluation of Napier grass (Pennisetum purpureum) varieties for use as trap plants for the management of African stemborer (Busseola fusca) in a push–pull strategy
Authors: Khan Zeyaur R. , Midega Charles A. O. , Wadhams Lester J. , Pickett John A. , Mumuni Abdulai 
Published: May 2007

AbstractWe evaluated eight Napier grass [Pennisetum purpureum Schumach (Poaceae)] varieties, used in various parts of eastern Africa as fodder, for their potential role as trap plants in the management of the African stemborer, Busseola fusca Füller (Lepidoptera: Noctuidae) through a push–pull strategy. Oviposition preference, larval orientation, settling, arrest and dispersal, feeding, mortality and survival, and development were determined for each of these varieties under laboratory and screen house conditions. Two‐choice tests showed that only two of the varieties tested (cv. Bana and cv. Uganda Hairless) were preferentially chosen by gravid female moths for oviposition over a susceptible maize variety, cv. Western Hybrid 502. Larval preference was, however, highly variable. Larval feeding by first instars on the maize leaves was more intense and significantly more than on leaves of all the Napier grass varieties evaluated. Food consumed and amounts assimilated by the third instars over a 24‐h period were not different among larvae fed on stems of maize and those fed on stems of the various Napier grass varieties. Larval survival was significantly lower on all the Napier grass varieties (below 3%) than on maize (about 44%). Similarly, larval development was about 2–3 weeks longer on majority of the Napier grass varieties. It was concluded that cv. Bana had potential for use as a trap plant in the management of B. fusca because it was more preferred by the moths for oviposition, equally preferred as maize by the larvae for orientation, settling, and arrest, and allowed minimal survival of the larvae. It can thus be used with such ‘push’ plants as Desmodium spp. (Fabaceae) in a ‘push–pull’ strategy, but the effectiveness of such a strategy would strictly depend on proper establishment and management of these companion plants.
Endophyte–grass complexes and the relationship between feeding preference and performance in a grass herbivore
Authors: Bourassa Steeve , Brodeur Jacques , Carrière Yves 
Published: May 2007

AbstractOverseeding non‐endophytic turfgrass lawns with endophytic turfgrass is considered promising for the development of integrated pest management programs in urban landscapes. In this context, a better understanding of the variability in the preference–performance response of insect herbivores exposed to endophytic grasses could be useful to develop efficient practices. Specifically, while endophytic varieties that are strongly toxic and avoided could provide good control of mobile pests, varieties that are toxic but not avoided could be more suitable for the control of sedentary pests. In this laboratory study, we investigated how the infection of 10 grass varieties by Neotyphodium endophytes affected the feeding performance and preference of newly hatched nymphs of the hairy chinch bug, Blissus leucopterus hirtus Montandon (Heteroptera: Lygaeidae), a common turfgrass pest in north‐eastern USA. We found that endophytes generally induced a strong relationship between feeding performance and preference in this herbivore. However, two endophytic varieties did not conform to this relationship, with one variety being highly toxic but not avoided and the other less toxic but highly avoided. These results provide a solid basis to further explore the impacts of endophytic grasses on the dispersal and survival of insect pests in mixed stands of endophytic and non‐endophytic plants.
Bacterial colonization immediately after installation on oral titanium implants
Authors: Fürst Mirjam M. , Salvi Giovanni E. , Lang Niklaus P. , Persson G. Rutger 
Published: May 2007

AbstractBackground: Information on bacterial colonization immediately after dental implant insertion is limited.Aims: (1) To assess the early colonization on titanium implants immediately after placement and throughout the first 12 post‐surgical weeks, (2) to compare the microbiota at interproximal subgingival implant and adjacent tooth sites.Material and methods: Subgingival plaque samples from implant and neighbouring teeth were studied by checkerboard DNA–DNA hybridization before surgery, 30 min after implant placement, and 1, 2, 4, 8, and 12 weeks after surgery.Results: Comparing bacterial loads at implant sites between 30 min after placement with 1‐week data showed that only the levels of Veillonella parvula (P<0.05) differed with higher loads at week 1 post‐surgically. Week 12 data demonstrated significantly higher bacterial loads for 15/40 species at tooth sites compared with pre‐surgery (P‐values varying between 0.05 and 0.01). Between the period immediately after surgery and 12 weeks at implant sites, 29/40 species was more commonly found at 12 weeks. Included among these bacteria at implant sites were Porphyromonas gingivalis (P<0.05), Tannerella forsythia, (P<0.01), and Treponema denticola (P<0.001). Immediately post‐surgery 5.9% of implants, and 26.2% of teeth, and at week 12, 15% of implants, and 39.1% of teeth harbored Staphylococcus aureus. Comparing tooth and implant sites, significantly higher bacterial loads were found at tooth sites for 27/40 species after 30 min following implant placement. This difference increased to 35/40 species at 12 weeks post‐surgically.Conclusions: Bacterial colonization occurred within 30 min after implant placement. Early colonization patterns differed between implant and tooth surfaces.
The Tropical Ant Mosaic in a Primary Bornean Rain Forest
Authors: Davidson Diane W , Lessard Jean‐Philippe , Bernau Christopher R. , Cook Steven C. 
Published: May 2007

ABSTRACTIn primary lowland rain forest in Brunei Darussalam, we studied arboreal ant communities to evaluate whether densities and spacing of spatially territorial taxa along 2.9 km of well‐studied trails are consistent with existence of a continuous mosaic of dominant ants. A median intercolony distance of 24.5 m, about twice or less distances over which colonies of most included species regularly ranged, suggested a relatively continuous mosaic. Despite relying on nesting sites in preformed plant cavities, carpenter ants contributed > 70 percent of mapped colonies. Most belonged to theCamponotus(Colobopsis)cylindricus(COCY) complex, including SE Asia's ‘exploding’ ants. Their lack of aggression against certainPolyrhachisspecies was associated with interspecific territory sharing by members of the two groups, and with a dominance‐discovery trade‐off. Experimental approaches yielded evidence for two putative contributors to positive association. Larger‐bodiedPolyrhachisparasitize food‐finding abilities of smaller, more populousCamponotusworkers, and the two taxa cooperate in territorial defense. Highly territorial and predatory weaver ants (Oecophylla smaragdina) were an important component of the ant mosaic in primary forest, second only to codominant COCY andPolyrhachistaxa. Members of the genusCrematogasterwere significantly associated withOecophyllain baiting censuses and regularly monopolized near‐nest baits to the exclusion of weaver ants. Litter ant abundances differed between territories ofOecophyllaand less predatory COCY species, but direction of difference was inconsistent over time. The densely packed mosaic of spatially territorial, and differentially predatory, taxa in Bornean rain forest likely contributes to spatial variation in ant effects on plant and arthropod communities.
Carrying Capacity and Potential Production of Ungulates for Human Use in a Mexican Tropical Dry Forest
Authors: Mandujano Salvador 
Published: May 2007

ABSTRACTData are provided on the carrying capacity and potential production for sustainable human use of white‐tailed deer (Odocoileus virginianus) and collared peccary (Pecari tajacu) in a protected tropical dry forest at Chamela on the Pacific coast of Mexico. In this paper, the carrying capacity was defined as the equilibrium density plus the number of animals removed by predators. The equilibrium point was estimated from the density dependent relationship between the finite population growth rate and the current density according to a logistic model. Annual density was estimated using the line transect method. Carrying capacity estimates were 16.5 to 17.2 deer/km2 and 9.3–9.5 peccaries/km2, representing a combined biomass of 841–874 kg/km2. A potential production for human use of 2.1 deer/km2 and 4.4 peccaries/km2 was estimated employing the model of Robinson and Redford (1991). The data suggest that, in the protected tropical dry forest of Chamela, the density and biomass of wild ungulates can maintain a similar or greater density and biomass than other Neotropical forests. To obtain an accurate estimation of the maximum sustainable yield (MSY), it is necessary to consider predation. From a management point of view, it is important to consider that carrying capacity varies as a function of the rainfall pattern.