Soil Collembola Diversity, Endemism, and Reforestation: A Case Study in the Pyrenees (France)

The diversity of soil Collembola was studied in two sites of the central Pyrenees (France). In each site a seminatural beech forest was compared to a conifer plantation. At the Rille site planted spruce and naturally regenerated beech forest were established on ancient meadows, and at the Carmil site a fir plantation had locally replaced the natural beech forest. Thirty-two soil cores of 250 cm³ were collected in each forest type at each site, and core fauna were extracted with a Berlese-Tullgren funnel. Differences in structure and composition of collembolan communities were observed from original to planted forest, and these changes followed different patterns at the two sites. In both cases, however, the diversity of the fauna was impoverished in the plantation. The endemic component suffered a particularly severe loss in species richness and abundance, whereas non-endemic species were more weakly affected. Endemic biota, which from a conservation perspective represent the most valuable element of the fauna, were its most vulnerable component. Endemic species and endemic areas therefore deserve particular attention when biodiversity fluctuations caused by reforestation are studied. This could lead to reassessment of the potential effects of artificial reforestation on the biodiversity of temperate forests. There is a general need for a systematic inventory and protection of forests with endemic soil biota.     

Flock size,food dispersion,and the feeding behavior of crossbills

Summary Feeding rates of five captive red crossbills (Loxia curvirostra) were measured when they were foraging alone, and in flocks of two or four on three seed dispersion patterns. On the most strongly clumped seed dispersion, individuals had higher mean feeding rates and the smallest probability of starvation when in flocks of two than when alone or in flocks of four. Individuals in flocks of four had higher feeding rates on the weakly clumped seed dispersion than on the uniform and more clumped seed dispersions; there were no food finding benefits gained from flocking on the uniform seed dispersion and aggression increased as food became more clumped. Most recent work has assumed that flocking results in higher feeding rates only because time spent vigilant is reduced. Crossbills, however, did not visit more cones per unit time as flock size increased, as would be expected if less time was spent vigilant. Thus, any reductions in vigilance as flock size increased were countered by increases in other behaviours, such as those related to aggression. Consequently, the higher mean feeding rates of crossbills in flocks than when solitary is not attributable to reduced vigilance. The increase in mean and the decline in variance of feeding rates occurred because crossbills in flocks found good patches earlier, and possible by spending less time assessing poor patches.     

Threatened Status, Rarity, and Diversity as Alternative Selection Measures for Protected Areas: A Test Using Afrotropical Antelopes

A major aim of conservation today is the maintenance of biodiversity. Practically, this pursuit might involve protecting a representative sample of the current biotic diversity (where diversity can have a variety of different meanings as in Vane-Wright et al. 1991), safeguarding species with traits that may be correlated with susceptibility to extinction (see International Council for Bird Preservation 1992), or protecting those species that are currently categorized as under short-term threat of extinction. Priority areas for conservation may vary, however, depending on which of these three approaches is taken. We investigated the designation of priority areas using these different approaches for Afrotropical antelope. Sites were selected on the basis of (1) biotic diversity—simple species richness and taxonomic diversity; (2) uniqueness of the fauna relative to other sites—how geographically restricted the component species were; and (3) degree of endangerment of the fauna. When insufficient sites to represent all the species could be selected, there was little agreement between the priority sites selected using the different methods. Sites selected by each approach were also generally poor at representing the diversity components ranked highly by other approaches. Also, many of the species were represented in only one site in the selected network, which on its own probably does not represent a viable population for the species. Therefore, it is important that the precise aims and consequences of any selection procedure be understood. A combination of different approaches, emphasizing different aspects of biodiversity and implemented sequentially, may be the best compromise for preserving a full range of biotic diversity.     

Toward Meaningful Snag-Management Guidelines for Postfire Salvage Logging in North American Conifer Forests

Abstract:  The bird species in western North America that are most restricted to, and therefore most dependent on, severely burned conifer forests during the first years following a fire event depend heavily on the abundant standing snags for perch sites, nest sites, and food resources. Thus, it is critical to develop and apply appropriate snag-management guidelines to implement postfire timber harvest operations in the same locations. Unfortunately, existing guidelines designed for green-tree forests cannot be applied to postfire salvage sales because the snag needs of snag-dependent species in burned forests are not at all similar to the snag needs of snag-dependent species in green-tree forests. Birds in burned forests have very different snag-retention needs from those cavity-nesting bird species that have served as the focus for the development of existing snag-management guidelines. Specifically, many postfire specialists use standing dead trees not only for nesting purposes but for feeding purposes as well. Woodpeckers, in particular, specialize on wood-boring beetle larvae that are superabundant in fire-killed trees for several years following severe fire. Species such as the Black-backed Woodpecker ( Picoides arcticus ) are nearly restricted in their habitat distribution to severely burned forests. Moreover, existing postfire salvage-logging studies reveal that most postfire specialist species are completely absent from burned forests that have been (even partially) salvage logged. I call for the long-overdue development and use of more meaningful snag-retention guidelines for postfire specialists, and I note that the biology of the most fire-dependent bird species suggests that even a cursory attempt to meet their snag needs would preclude postfire salvage logging in those severely burned conifer forests wherein the maintenance of biological diversity is deemed important.     

Early learning of discrete call variants in red crossbills: implications for reliable signaling

The identification of appropriate companions and mates is essential to both speciation and the maintenance of species through prezygotic isolation. In many birds, social assortment is mediated by vocalizations learned through imitation. When imitative vocal learning occurs throughout life, emergent shared signals reflect current social associations. However, when vocal and genetic variation arises among populations, shared learned signal variants have a potential to reflect cultural or genetic origin and to limit social and reproductive intermixing, provided that signal learning occurs prior to dispersal. The red crossbill (Loxia curvirostra) is a bird species in which discrete contact call variants are associated with morphological variation, raising the possibility that learned calls play a role in limiting intermixing. I examined the process of early call learning to determine if contact call variants have a potential to limit intermixing in crossbills. I conducted a captive playback study to nestlings to evaluate potential learning predispositions. I also cross-fostered nestlings to adoptive adult pairs of either their own or a different call variant than their biological parents to assess the degree of vocal learning plasticity. Results show that young crossbills imitate the call structures of adoptive parents, generating shared family-specific calls, which could facilitate family cohesion. Learning processes that generate family-specific calls could also ensure that discrete call variants are transmitted across generations, making call variants reliable signals of crossbills’ morphological and genetic backgrounds.     

Field bioassays of cerambycid pheromones reveal widespread parsimony of pheromone structures, enhancement by host plant volatiles, and antagonism by components from heterospecifics

Recent research has revealed extensive pheromonal parsimony within the large beetle family Cerambycidae, with closely related species producing the same or very similar pheromone components. This article summarizes research that evaluated attraction of cerambycids to individual pheromone components, blends of pheromone components, and combinations of pheromones with host plant volatiles. Field bioassays were carried out, in collaboration with the Pennsylvania Department of Agriculture and the USDA Cooperative Agricultural Pest Survey program, in 10–25 counties of Pennsylvania over 3 years. A total of 15,438 cerambycids of 134 species were captured, including two exotic species. Semiochemical lures attracted significant numbers of beetles in species of the subfamilies Cerambycinae, Lamiinae, and Spondylidinae, but were not attractive to species in the Lepturinae, Parandrinae, and Prioninae. These experiments reconfirmed the behavioral roles of semiochemicals for a number of species that have been studied previously, and yielded new information about semiochemistry of several species. The host plant volatile α-pinene enhanced attraction of species that were conifer specialists, whereas ethanol enhanced attraction of some species of hardwood specialists. The data suggest that species which share dominant pheromone components avoid cross attraction by differing in seasonal activity period, and by antagonistic effects of minor pheromone components on attraction of heterospecifics. This study further supports the concept that with careful choice of components, multiple pheromones can be deployed as single blends, and paired with host plant volatiles, to maximize the number and taxonomic diversity of cerambycid beetles that are attracted to a single lure, so that the number of different lures that must be deployed can be minimized.     

Scale-dependent variation in coral community similarity across sites, islands, and island groups

Community similarity is the proportion of species richness in a region that is shared on average among communities within that region. The slope of local richness (alpha diversity) regressed on regional richness (gamma diversity) can serve as an index of community similarity across regions with different regional richness. We examined community similarity in corals at three spatial scales (among transects at a site, sites on an island, and islands within an island group) across a 10 000-km longitudinal diversity gradient in the west-central Pacific Ocean. When alpha diversity was regressed on gamma diversity, the slopes, and thus community similarity, increased with scale (0.085, 0.261, and 0.407, respectively) because a greater proportion of gamma diversity was subsumed within alpha diversity as scale increased. Using standard randomization methods, we also examined how community similarity differed between observed and randomized assemblages and how this difference was affected by spatial separation of species within habitat types and specialization of species to three habitat types (reef flats, crests, and slopes). If spatial separation within habitat types and/or habitat specialization (i.e., underdispersion) occurs, fewer species are shared among assemblages than the random expectation. When the locations of individual coral colonies were randomized within and among habitat types, community similarity was 46-47% higher than that for observed assemblages at all three scales. We predicted that spatial separation of coral species within habitat types should increase with scale due to dispersal/extinction dynamics in this insular system, but that specialization of species to different habitat types should not change because habitat differences do not change with scale. However, neither habitat specialization nor spatial separation within habitat types differed among scales. At the two larger scales, each accounted for 22-24% of the difference in community similarity between observed and randomized assemblages. At the smallest scale (transect-site), neither spatial separation within habitat types nor habitat specialization had significant effects on community similarity, probably due to the small size of transect samples. The results suggest that coral species can disperse among islands in an island group as easily as they can among sites on an island over time scales that are relevant to their establishment and persistence on reefs.     

Conservation of Stream Fishes: Patterns of Diversity, Rarity, and Risk

Abstract: North America has a rich fauna of freshwater fishes which attains greatest diversity in the central and southeastern United States. Many stream fishes have limited ranges and are locally rare and patchily distributed. Local diversity increases downstream and total diversity follows typical species-area relationships. Drainages linked with the large Mississippi system support more species than those of comparable area flowing directly to the sea and rivers isolated by falls have notably few species. The between-drainage component of diversity is large. Threats to this fauna, which are not addressed by management focused on threatened species, include fragmentation of drainage networks by impoundments and homogenization of faunas by interbasin connections and introductions. Conservation efforts require a biogeographic perspective; they should focus on streams of intermediate size (orders 4–6) plus the upstream portion of each drainage and should attempt to maintain total diversity and, inclusively, populations of rare or threatened species.     

Diversity and community structure of butterfly of Arignar Anna Zoological Park, Chennai, Tamil Nadu

Investigation was carried out on the diversity of butterfly fauna in selected localities of conservation and breeding center of Arignar Anna Zoological Park (AAZP), Chennai, Tamil Nadu. Atotal of 56 species were recorded, 15 of them belonged to Pieridae, 12 Nymphalidae, 9 Satyridae, 8 Papilionidae, 7 Danaidae, 3 Lycaenidae and 1 species each belonged to the families Acraeidae and Hesperidae. Qualitatively and quantitatively Pieridae family were comparatively dominant than that of other families. The notable addition to the 25 more species listed during this observation were compared to previous field survey. Comparison of butterfly species distribution between the different localities revealed that butterfly species richness was higher at mountain region with 52 species and lowest of 25 species at public visiting areas. Visitor's activities may be that reason for effects on butterfly distribution and lack of vegetation. Each five endemic and protected species (i.e. endangered) listed under the Wildlife (Protection)Act were highlighted greater conservation importances of the AAZP. It is suggest that butterfly species diversity generally increase with increase in vegetation and declines with the increase in disturbance.     

Species richness and stand stability in conifer forests of the Sierra Nevada

Theoretical and empirical studies have long suggested that stability and complexity are intimately related, but evidence from long-lived systems at large scales is lacking. Stability can either be driven by complex species interactions, or it can be driven by the presence/absence and abundance of a species best able to perform a specific ecosystem function. We use 64 years of stand productivity measures in forest systems composed of four dominant conifer tree species to contrast the effect of species richness and abundance on three stability measures. To perform this contrast, we measured the annual growth increments of > 900 trees in mixed and pure forest stands to test three hypotheses: increased species richness will (1) decrease stand variance, (2) increase stand resistance to drought events, and (3) increase stand resilience to drought events. In each case, the alternate hypothesis was that species richness had no effect, but that species composition and abundance within a stand drove variance, resistance, and resilience. In pure stands, the four species demonstrated significant differences in productivity, and in their resistance and resilience to drought events. The two pine species were the most drought resistant and resilient, whereas mountain hemlock was the least resistant and resilient, and red fir was intermediate. For community measures we found a moderately significant (P = 0.08) increase in the community coefficient of variation and a significant (P = 0.03) increase in resilience with increased species richness, but no significant relationship between species richness and community resistance, though the variance in community resistance to drought decreased with species richness. Community resistance to drought was significantly (P = 0.001) correlated to the relative abundance of lodgepole pine, the most resistant species. We propose that resistance is driven by competition for a single limiting resource, with negative diversity effects. In contrast resilience measures the capacity of communities to partition resources in the absence of a single limiting resource, demonstrating positive diversity effects.     

Hotspots of Epiphytic Lichen Diversity in Two Young Managed Forests

Understanding within-stand variation in diversity of epiphytes will provide an improved basis for producing timber while conserving biological diversity. Two 80-ha, 50–year–old managed stands of conifers were surveyed to locate 0.4 ha putative "diversity" plots, the areas appearing most diverse in lichen epiphytes. These plots were generally located in areas made heterogeneous by canopy gaps, wolf trees (trees with large-diameter lower branches), and old-growth remnant trees. "Matrix" plots, in contrast, were chosen at random from the remaining, more homogenous forest. Diversity plots hosted from 25% to 40% more epiphytic lichen species than matrix plots in both stands. The strongest within-stand gradients in species composition were correlated with percentage of plot occupied by gaps and wolf trees. Percentage of the plot in gaps was correlated with species richness (r = 0.79). In the more structurally diverse stand, diversity and abundance of nitrogen-fixing "cyanolichens" were correlated with percentage of the plot occupied by gaps (0.5 < r < 0.9), and alectorioid lichens were correlated with percentage of the plot occupied by old-growth remnant trees (0.5 < r < 0.6). In the stand with more homogenous structure, percentage of the plot under gaps was correlated with regionally common species that were otherwise absent or sparse in the matrix. Protecting gaps, hardwoods, wolf trees, and old-growth remnant trees during thinning or other partial cutting is likely to promote the majority of epiphytic macrolichens in young conifer forests. Because these features are easily recognized on aerial photos and on the ground by land managers, it is practical to manage for forest structures that would promote lichen diversity.     

A direct comparison of the consequences of plant genotypic and species diversity on communities and ecosystem function

Biodiversity loss is proceeding at an unprecedented rate, yet we lack a thorough understanding of the consequences of losing diversity at different scales. While species diversity is known to impact community and ecosystem processes, genotypic diversity is assumed to have relatively smaller effects. Nonetheless, a few recent studies suggest that genotypic diversity may have quantitatively similar ecological consequences compared to species diversity. Here we show that increasing either genotypic diversity of common evening primrose (Oenothera biennis) or species diversity of old-field plant species resulted in nearly equivalent increases (approximately 17%) in aboveground primary production. The predominant mechanism explaining this effect, niche complementarity, was similar for each type of diversity. Arthropod species richness also increased with both types of plant diversity, but the mechanisms leading to this effect differed: abundance-driven accumulation of arthropod species was important in plant genotypic polycultures, whereas resource specialization was important in plant species polycultures. Thus, similar increases in primary productivity differentially impacted higher trophic levels in response to each type of plant diversity. These results highlight important ecological similarities and differences between genotypic and species diversity and suggest that genotypic diversity may play a larger role in community and ecosystem processes than previously realized.     

Trade-offs, temporal variation, and species coexistence in communities with intraguild predation

Intraguild predation/parasitism (IGP: competing species preying on or parasitizing each other) is widespread in nature, but the mechanisms by which intraguild prey and predators coexist remain elusive. Theory predicts that a trade-off between resource competition and IGP should allow local niche partitioning, but such trade-offs are expressed only at intermediate resource productivity and cannot explain observations of stable coexistence at high productivity. Coexistence must therefore involve additional mechanisms beside the trade-off, but very little is known about the operation of such mechanisms in nature. Here I present the first experimental test of multiple coexistence mechanisms in a natural community exhibiting IGP. The results suggest that, when resource productivity constrains the competition-IGP trade-off, a temporal refuge for the intraguild prey can not only promote coexistence, but also change species abundances to a pattern qualitatively different from that expected based on the trade-off or a refuge alone. This is the first empirical study to demonstrate a mechanism for why communities with IGP do not lose species diversity in highly productive environments. These results have implications for diversity maintenance in multi-trophic communities, and the use of multiple natural enemies in biological control.     

Nitrogen spatial heterogeneity influences diversity following restoration in a ponderosa pine forest, Montana.

The resource heterogeneity hypothesis (RHH) is frequently cited in the ecological literature as an important mechanism for maintaining species diversity. The RHH has rarely been evaluated in the context of restoration ecology in which a commonly cited goal is to restore diversity. In this study we focused on the spatial heterogeneity of total inorganic nitrogen (TIN) following restoration treatments in a ponderosa pine (Pinus ponderosa)/Douglas-fir (Pseudotsuga menziesii) forest in western Montana, USA. Our objective was to evaluate relationships between understory species richness and TIN heterogeneity following mechanical thinning (thin-only), prescribed burning (burn-only), and mechanical thinning with prescribed burning (thin/burn) to discern the ecological and management implications of these restoration approaches. We employed a randomized block design, with three 9-ha replicates of each treatment and an untreated control. Within each treatment, we randomly established a 20 x 50 m (1000 m2) plot in which we measured species richness across the entire plot and in 12 1-m(2) quadrats randomly placed within each larger plot. Additionally, we measured TIN from a grid consisting of 112 soil samples (0-5 cm) in each plot and computed standard deviations as a measure of heterogeneity. We found a correlation between the net increase in species richness and the TIN standard deviations one and two years following restoration treatments, supporting RHH. Using nonmetric multidimensional scaling ordination and chi-squared analysis, we found that high and low TIN quadrats contained different understory communities in 2003 and 2004, further supporting RHH. A comparison of restoration treatments demonstrated that thin/burn and burn-only treatments created higher N heterogeneity relative to the control. We also found that within prescribed burn treatments, TIN heterogeneity was positively correlated with fine-fuel consumption, a variable reflecting burn severity. These findings may lead to more informed restoration decisions that consider treatment effects on understory diversity in ponderosa pine/Douglas-fir ecosystems.     

Disturbance influences oyster community richness and evenness, but not diversity

Foundation species in space-limited systems can increase diversity by creating habitat, but they may also reduce diversity by excluding primary space competitors. These contrasting forces of increasing associate diversity and suppressing competitor diversity have rarely been examined experimentally with respect to disturbance. In a benthic marine community in central California, where native oysters are a foundation species, we tested how disturbance influenced overall species richness, evenness, and diversity. Surprisingly, overall diversity did not peak across a disturbance gradient because, as disturbance decreased, decreases in overall species evenness opposed increases in overall species richness. Decreasing disturbance intensity (high oyster abundance) led to increasing species richness of sessile and mobile species combined. This increase was due to the facilitation of secondary sessile and mobile species in the presence of oysters. In contrast, decreasing disturbance intensity and high oyster abundance decreased the evenness of sessile and mobile species. Three factors likely contributed to this decreased evenness: oysters reduced abundances of primary sessile species due to space competition; oysters supported more rare mobile species; and oysters disproportionately increased the relative abundance of a few common mobile species. Our results highlight the need for further studies on how disturbance can differentially affect the evenness and richness of different functional groups, and ultimately how these differences affect the relationship between overall diversity and ecosystem function.     

Community composition of aquatic birds in lakes of Bangalore, India

Observations were made on the occurrence, abundance, richness, and diversity of waterbirds in 15 major lakes in Bangalore city during 2008 - 2009. During the study period 35 species of aquatic birds were recorded. The number of aquatic bird species recorded at various lakes ranged from 23 to 35. The percent abundance of waterbirds recorded in the study lakes ranged from 2.46 to 21.49 and itwas significantly different (p < 0.05). The diversity and species evenness of waterbirds in the lakes ranged from 2.07 to 3.16 and 0.32 to 0.76, respectively. There was a significant difference (p < 0.05) in the diversity and species evenness of waterbirds among different lakes. Species richness of the bird population ranged from 2.89 to 4.01 in the different study lakes and it was not significantly different (p > 0.05). There was a variation in number of waterbird species recorded during summer, monsoon and winter seasons. Of the 35 waterbird species, Bubulcus ibis showed cent percent frequency, whereas less frequently (4.44%) observed species was Anas platyrhynchos. Among various waterbird species, Bubulcus ibis, Fulica atra, Tringa hypoleucos, Motacilla maderaspatensis, Phalacrocorax niger Egretta garzetta, Charadrius dubius, Ardeola grayji, Halcyon smymensis and Motacilla alba were frequently encountered in most of the study lakes.     

Ecological problems of tree species in protected ecosystems of Orissa, India

The tree layer vegetation of two protected ecosystems i.e. Similipal Biosphere Reserve (SBR) and Bhitarkanika National Park (BNP) of eastern ghat was analysed for structure, composition and diversity. With respect to the tree species composition the two protected ecosystems were differed from each other at the family, genera and species level. About 117 tree species representing 85 genera and 42 families were recorded in SBR. The average number of species per hectare was 32.5. However, a total of 29 tree species representing 22 genera and 16 families were recorded in BNP with an average number of species per hectare of 24.17. Species dominancy of the two protected areas was also different due to their difference in habitat condition. In SBR Shorea robusta was the most dominant species while in BNP Excoecaria agallocha was the most dominant species. Shannon-Wiener species diversity was 3.15 for Similipal and 2.314 for Bhitarkanika indicating that Similipal was highly diverse than Bhitarkanika. In general both the protected ecosystems of Orissa are highly rich in biodiversity and are characteristics of good ecological wealth of eastern ghat. Thus conservation and management practices are essential for the sustainability of their biodiversity.     

Invasion patterns inferred from cytochrome oxidase I sequences in three bryozoans, Bugula neritina, Watersipora subtorquata, and Watersipora arcuata

Nucleotide variation in cytochrome c oxidase subunit I (COI) was used to examine population structure in three invasive bryozoans: Bugula neritina (Linnaeus, 1758), Watersipora subtorquata (d’Orbigny, 1852), and W. arcuata (Banta, 1969). These species are found on ship hulls and have a short (≤2 days) larval phase. Samples were collected from 1998–2001 at multiple sites in Australia, and in Hong Kong, New Zealand, Hawaii, California, Curaçao, and England. B. neritina is known to include three cryptic species, including species Type S (Davidson and Haygood in Biol Bull 196:273–280, 1999) which occurs on the east and west coasts of the USA. One haplotype recorded previously in the USA, S1, was found to be widespread, occurring throughout Australia and in Hong Kong, Curaçao, Hawaii, and England. W. subtorquata, a Caribbean–Atlantic species which has invaded southern Australia, New Zealand, and California, had low nucleotide diversity in these areas (π=0.0016±0.0014), consisting of three haplotypes connected by one or two nucleotide mutations. W. arcuata, an Eastern-Pacific native, had comparatively high diversity (π=0.0221±0.0115) in introduced populations from Australia and Hawaii. In each species, identical haplotypes were identified on separate coastlines providing evidence of widespread, rather than genetically independent, introductions. The major contrast in nucleotide diversity suggests that different propagule-source models explain introductions.     

Local Species Richness of Leaf-Chewing Insects Feeding on Woody Plants from One Hectare of a Lowland Rainforest

Abstract:  Local species diversity of insect herbivores feeding on rainforest vegetation remains poorly known. This ignorance limits evaluation of species extinction patterns following various deforestation scenarios. We studied leaf-chewing insects feeding on 59 species of woody plants from 39 genera and 18 families in a lowland rainforest in Papua New Guinea and surveyed all plants with a stem diameter at breast height of ≥5 cm in a 1-ha plot within the same area. We used two extrapolation methods, based on randomized species-accumulation curves, to combine these two data sets and estimate the number of species of leaf-chewing herbivores feeding on woody plants from the 1-ha area. We recorded 58,483 feeding individuals from 940 species of leaf-chewing insects. The extrapolation estimated that there were 1567–2559 species of leaf-chewing herbivores feeding on the 152 plant species from 97 genera and 45 families found in 1 ha of the forest. Most of the herbivore diversity was associated with plant diversity on the familial and generic levels. We predicted that, on average, the selection of 45 plant species each representing a different family supported 39% of all herbivore species, the 52 plant species each representing a different additional genus from these families supported another 39% of herbivore species, and the remaining 55 plant species from these genera supported 22% of herbivore species. Lepidoptera was the most speciose taxon in the local fauna, followed by Coleoptera and orthopteroids (Orthoptera and Phasmatodea). The ratio of herbivore to plant species and the estimated relative species richness of the Lepidoptera, Coleoptera, and orthopteroids remained constant on the spatial scale from 0.25 to 1 ha. However, the utility of local taxon-to-taxon species ratios for extrapolations to geographic scales requires further study.     

Evaluation of Central North American Prairie Management Based on Species Diversity, Life Form, and Individual Species Metrics

Abstract:  Reintroduction of fire and grazing, alone or in combination, has increasingly been recognized as central to the restoration of North American mixed-grass and tallgrass prairies. Although ecological studies of these systems are abundant, they have generally been observational, or if experimental, have focused on plant species diversity. Species diversity measures alone are not sufficient to inform management, which often has goals associated with life-form groups and individual species. We examined the effects of prescribed fire, light cattle grazing, and a combination of fire and grazing on three vegetation components: species diversity, groups of species categorized by life-form, and individual species. We evaluated how successful these three treatments were in achieving specific management goals for prairies in the Iowa Loess Hills (U.S.A.). The grazing treatment promoted the greatest overall species richness, whereas grazing and burning and grazing treatments resulted in the lowest cover by woody species. Burning alone best achieved the management goals of increasing the cover and diversity of native species and reducing exotic forb and (predominantly exotic) cool-season grass cover. Species-specific responses to treatments appeared idiosyncratic (i.e., within each treatment there existed a set of species attaining their highest frequency) and nearly half of uncommon species were present in only one treatment. Because all management goals were not achieved by any one treatment, we conclude that management in this region may need refining. We suggest that a mosaic of burning and grazing (alone and in combination) may provide the greatest landscape-level species richness; however, this strategy would also likely promote the persistence of exotic species. Our results support the need to consider multiple measures, including species-specific responses, when planning and evaluating management .