Butterfly Species Richness Research Articles

Monitoring the Response of Butterfly Communities to Prescribed Fire

Federal land managers in the western United States are interested in the potential of prescribed fire as a tool to decrease fuel loads, increase vegetational heterogeneity, and increase faunal diversity in various ecosystems. I tested whether implementation of a prescribed fire program by the US Forest Service in a watershed in the central Great Basin had significant effects on butterfly species richness and composition. I monitored butterfly communities during the first two years after implementation in five to seven burn units and controls in the watershed. To estimate baseline spatial and temporal variation in butterfly communities in the greater ecosystem, I also monitored butterflies in five untreated canyons outside the project area. Butterfly species richness and butterfly species composition (measured as community similarity) did not differ significantly between burn units and controls. Geographic location had statistically significant effects on species richness. Butterfly species composition of individual locations varied over time, as did the magnitude of that variation. These results emphasize that standardized, repeatable monitoring protocols are vital for evaluating the effects of experimental management treatments and for predicting and assessing the effects of future management strategies and environmental changes.

Geographic distance and the role of island area and habitat diversity in the species–area relationships of four Lesser Antillean faunal groups: a complementary note to Ricklefs & Lovette

Summary 1. Recently, Ricklefs & Lovette (1999) have emphasized the possible confounding effect of habitat diversity on area while studying species–area relationships. They illustrated this problem using four groups of organisms (birds, bats, herptiles, and butterflies) on 19 islands of the Lesser Antilles. Although they referred to the potential for species to migrate between islands, they did not take into account the geographical distances between islands. 2. Here, I reanalyse their data using a multivariate method, based on permutation of distance matrices, which incorporates pairwise geographical distances between islands. The analysis includes as independent variables the geographical distances between pairs of islands, size, maximum elevation, and habitat diversity of each island. The last three variables were obtained from Ricklefs & Lovette (1999). 3. Results of the analysis were similar to those of Ricklefs & Lovette (1999). In addition, however, geographical distances influenced species richness of bats, birds and butterflies. 4. These new results are helpful for investigating the processes that may contribute to the observed pattern of species richness. The level of endemism of the four taxonomic groups is related to the influences of geographical distances among islands, and might be explained by differences in their vagility. 5. Finally, I emphasize the need to incorporate geographical distances among islands, using statistical methods that can manipulate distance matrices.

Patterns in the structure of grassland butterfly communities along a gradient of human disturbance: further analysis based on the generalist/specialist concept

AbstractKitahara and Fujii, in 1994, analyzed the butterfly communities along a gradient of human disturbance by applying the generalist/specialist concept. Butterfly species were classified into generalist or specialist species based on their voltinism (seasonal time dimension) and potential larval resource breadth (food dimension). The community structure and species composition showed the systematic changes along the gradient. To verify the generality of those trends, we monitored five grassland butterfly communities with varying degrees of human disturbance twice a month during 1985 by the line transect method at the foot of Mt. Fuji, central Japan, and analyzed their structure in a manner similar to that employed by Kitahara and Fujii. Most results were consistent with the patterns recognized by Kitahara and Fujii. The route (community) order based on increasing human disturbance was strongly and negatively correlated with butterfly species richness but with neither butterfly species diversity (H′) nor evenness (J′). Also, the degree of human disturbance was significantly and negatively correlated with the number of specialist species, but not with that of generalists, in a community. Butterfly species richness was more strongly correlated with the number of specialist species than with that of generalists. Our analyses also showed that the generalist species were distributed more widely over the communities than were the specialists. However, in contrast to the trend revealed by Kitahara and Fujii, there was no significant difference in the population densities and in the spatial population variability between the two species groups. As a whole, our analyses confirmed the consistency of most community patterns detected by Kitahara and Fujii. The causes of the inconsistencies in some patterns were thought to be mainly the present habitat conditions with a relatively short growing season at high altitudes.

Upsides and downsides: contrasting topographic gradients in species richness and associated scenarios for climate change

AbstractAimWe tested whether montane butterflies exhibit similar responses to elevation in two adjacent mountain ranges in the Great Basin; whether surface water availability, canyon depth and canyon width vary predictably with elevation; and whether those factors act in conjunction with elevation to generate the observed gradients in species richness. These variables might reasonably be expected to affect species richness of butterflies and can be derived readily for most landscapes. We also explored how climate change may affect species distributions in both mountain ranges.LocationField research was conducted in the Toiyabe and Toquima ranges, Lander and Nye counties, Nevada, USA.MethodsWe obtained data for 102 locations in the Toiyabe Range and 49 locations in the Toquima Range. These locations covered an elevational gradient of c.1350 m in the Toiyabe Range and 900 m in the Toquima Range. Species richness data were based upon comprehensive field inventories. Elevation was measured by differentially corrected global positioning systems. Values for the remaining predictive variables were derived using geographic information systems. Availability of surface water was quantified as the distance from the centre of the inventory route to the nearest permanent source of running or standing water.ResultsIn the Toiyabe Range, species richness decreases as elevation increases. Water availability and canyon depth and width vary predictably with elevation, but do not interact with elevation to affect species richness patterns. In the Toquima range, in contrast, species richness increases as elevation increases, and no other predictive variable covaries with elevation.Main conclusionsWe suggest that range‐specific gradients in climatic severity contribute to the distinct elevational gradients in species richness. In the face of climate change, species richness patterns in the Toquima range will likely remain similar. The elevational gradient in species richness in the Toiyabe range may flatten, or the patterns in the two ranges may converge.

Butterfly community structure in fragmented habitats

We analysed effects of habitat fragmentation on the diversity, abundance, and life history traits of butterflies on 33 calcareous grasslands. Diversity of butterflies was positively correlated with habitat area (as was plant diversity), but not with habitat isolation. In contrast to expectations, butterfly densities of polyphagous and oligophagous species declined with habitat area whereas densities of monophagous species increased. The z‐values, i.e. the slope of species–area relationships, increased with food plant specialization, from 0.07 in polyphagous, 0.11 in oligophagous, 0.16 in strongly oligophagous to 0.22 in monophagous species, and were 0.14 in plant species. Significant z‐values were not only found for total species richness, based on a sample size adjusted to fragment area (z = 0.12), but also for the local density of butterfly species richness, based on equal sample size across all habitat fragments (z = 0.06). To our knowledge, this is the first study to show differential responses of monophagous, oligophagous and polyphagous species to area with respect to species richness and population density.

Effects of Selective Logging on the Butterflies of a Bornean Rainforest

Abstract: Selective logging has been the main cause of disturbance to tropical forests in Southeast Asia, so the extent to which biodiversity is maintained in selectively logged forest is of prime conservation importance. We compared the butterfly assemblages of Bornean primary rainforest to those of rainforest selectively logged 6 years previously. We sampled by means of replicated transects stratified into riverine and ridge forests and we included roads in the logged forest. There was a three‐fold variation in species richness and abundance over the 8‐month sampling period. More species and individuals were observed in the logged forest, although between‐replicate variability was high. Rarefied species richness was positively correlated with canopy openness within the range of disturbance levels encountered at our forest sites. Within families, there was no significant difference in the number of species between primary and logged forest. There was a significant difference in the relative abundance of species, but this was due largely to the abundance of one or two species. Community ordination separated the sites along a gradient of disturbance and revealed strong differences between riverine and ridge‐forest butterfly assemblages in primary forest that were obscured in logged forest. There was no evidence that logging has resulted in a change in the composition of the butterfly assemblages from species with a local distribution to more widespread species. We conclude that at a logged forest site in close proximity to primary forest, low intensities of logging do not necessarily reduce the species richness or abundance of butterflies, although assemblage composition is changed.

The diversity and abundance of North American butterflies vary with habitat disturbance and geography

AbstractAimWe used data from the annual Fourth of July Butterfly Count for the years 1989–97 to examine patterns of species richness and total butterfly abundance across North America and within topographically diverse and disturbed landscapes.LocationWe analysed counts from 514 different locations in North America. The counts represent all areas of the USA and southern Canada, with a few Mexican sites as well, although most counts were in the eastern USA.MethodsFirst, we standardized published count data according to the effort expended per count (total party‐hours). Using regression analysis and analysis of variance, we then examined the impact of latitude, longitude, topographical relief, habitat disturbance and different climatic measures on the species richness and total abundance of butterflies per count. We also examined the abundance of exotic species in disturbed landscapes.ResultsOur analyses suggest that: (1) species richness is highest at low latitudes and near Rocky Mountain longitudes; (2) the total abundance of individuals is highest in northern US latitudes and Great Plains longitudes; (3) species richness but not total abundance increases with greater topographical relief; (4) species richness and diversity indices are lower in more disturbed habitats; and (5) the abundance of the introduced Pieris rapae (L.) is greater in more disturbed habitats.Main conclusionsDifferent factors control the abundance and species richness of North American butterflies. Along with geographical location, habitat disturbance and topographical variability affect species richness. Our analysis also shows the value of broad‐based monitoring regimes, such as the North American Fourth of July Butterfly Count.

Conservation of arthropod diversity in montane wetlands: effect of altitude, habitat quality and habitat fragmentation on butterflies and grasshoppers

1. The patterns of arthropod diversity were investigated in 24 montane wetlands in Switzerland. These differed in altitude, management regime (cattle‐grazing vs. mowing), vegetation structure (index combining vegetation height and density) and degree of habitat fragmentation. 2. The general arthropod diversity was determined by net sampling at 10 sampling points per site. The diversity of grasshoppers and butterflies was measured by counting species richness at the site and species density (species richness per unit area) on transects. The species richness of grasshoppers and butterflies was found to be more sensitive to the geographical attributes of the site whereas species density was more affected by the habitat quality. 3. Grasshopper diversity decreased within the observed altitudinal range (800–1400 m) and was higher at grazed sites, whereas butterfly diversity was higher at mown sites. Arthropod diversity but not abundance of arthropods was positively related to the vegetation structure. 4. The species richness of butterflies was negatively influenced by the degree of habitat fragmentation: both the size of habitat as well as the area of wetland habitats within 4 km were related positively to the number of specialist wetland butterflies. 5. Late mowing as well as low‐density cattle‐grazing are appropriate management actions to maintain arthropod diversity in montane wetlands. In order to establish site‐specific management plans, the biology of the present target species as well as the historical context should be considered. 6. We suggest that the best protection for the species examined in this study would be a network of wetland sites managed using a variety of traditional, non‐intensive methods. This can only be achieved by coordinated planning of conservation measures among sites.

AN EMPIRICAL TEST OF RAPOPORT’S RULE: ELEVATIONAL GRADIENTS IN MONTANE BUTTERFLY COMMUNITIES

We examined the response of montane butterflies to a 1300-m elevational gradient in the Toiyabe Range, a mountain range in the central Great Basin. We tested whether elevational ranges of montane butterflies conform to Rapoport’s elevational rule (species at higher elevations have greater elevational ranges). We also tested whether the Rapoport-rescue hypothesis (emigrants from higher elevation populations inflate the species richness of lower-elevation sites) could explain the species richness patterns we observed. In addition, we predicted whether global climate change is likely to perturb current elevational gradients in butterfly species richness. Species presence data were collected from 105 100-m vertical elevational bands in 17 canyons. Elevation and species richness were significantly negatively correlated, although species richness peaked at intermediate elevations, and butterflies in species-rich areas had significantly narrower elevational ranges than species in more depauperate areas. Toiyabe ...

Endemic butterflies on Grande Comore: habitat preferences and conservation priorities

The island of Grande Comore (Comoro Islands, western Indian Ocean) has an endemic butterfly fauna threatened by rapid habitat change. Transect counts were used to assess the abundance and species richness of butterflies in different habitats, and along an elevational gradient. Species richness of non-endemic butterflies was highest in low elevation, man-modified habitats. In contrast, most endemic butterflies were confined to forest habitats, which only remain above 500m elevation. Richness and abundance of endemic butterflies were highest at the lower elevational limits of the remaining forest. Controlling for elevation, the richness of endemic butterflies was highest in mature forest where the gross structure of the forest remained intact, lower in scrubby secondary forest, and lowest in pioneer forest on old lava flows. The survival of the majority of the endemic butterflies may depend on forest conservation measures in the rapidly diminishing areas of mature forest at mid elevations.

Complementarity and the use of indicator groups for reserve selection in Uganda

A major obstacle to conserving tropical biodiversity is the lack of information as to where efforts should be concentrated. One potential solution is to focus on readily assessed indicator groups, whose distribution predicts the overall importance of the biodiversity of candidate areas1,2. Here we test this idea, using the most extensive data set on patterns of diversity assembled so far for any part of the tropics. As in studies of temperate regions2,3,4,5,6,7,8, we found little spatial congruence in the species richness of woody plants, large moths, butterflies, birds and small mammals across 50 Ugandan forests. Despite this lack of congruence, sets of priority forests selected using data on single taxa only often captured species richness in other groups with the same efficiency as using information on all taxa at once. This is because efficient conservation networks incorporate not only species-rich sites, but also those whose biotas best complement those of other areas9,10,11. In Uganda, different taxa exhibit similar biogeography, so priority forests for one taxon collectively represent the important forest types for other taxa as well. Our results highlight the need, when evaluating potential indicators for reserve selection, to consider cross-taxon congruence in complementarity as well as species richness.

Comparison of the Biodiversity of Lepidoptera within Three Forested Ecosystems

Lepidopterans function in the dynamics of forested ecosystems by serving as defoliators, decomposers, prey or hosts to carnivores, and pollinators. The biodiversity of Lepidoptera is thus linked into the ecosystem by influencing nutrient cycling, plant population dynamics, and predator-prey population dynamics. Two important measures of biodiversity are species richness and abundance of individuals. However, values for these measures require an ecosystem context for insightful interpretation of ecological function. We propose that such an ecosystem context is gained by an assessment of host resource requirements; in the case of Lepidoptera, this means larval host plants. The flora that contributes to the biodiversity of Lepidoptera can be grouped into 3 major vegetation types: (1) conifers, (2) hardwood trees and shrubs, and (3) herbs and grasses. We compared the macrolepidopteran biodiversity of 3 forested ecosystems: (1) western Oregon, (2) eastern Oregon, and (3) West Virginia. In respective order of the above locations, totals of 463, 385, and 475 species were found. Conifers supported 9, 10, and 1% of the species richness. By contrast, hardwoods supported 57, 45, and 61% of the species richness, whereas herbs and grasses supported 31, 42, and 31% of the species richness. The patterns in abundance of individual moths were different from species richness of moths and butterflies considered together. Comparisons of moth abundance showed conifers supported 18, 5, and 1%; hardwoods supported 69,39, and 77%; and herbs and grasses supported 11,55, and 8%. Practicesinvolved in the management offorested ecosystems are discussed in the context of how Lepidoptera may be used as an indicator taxon for the assessment of land management practices, and how biodiversity of Lepidoptera could be considered in plans for habitat restoration with a specific focus on food web relationships.

Spatial Modeling of Butterfly Species Richness Using Tiger Beetles (Cicindelidae) as a Bioindicator Taxon

General spatial patterns of species richness can be useful when determining conservation policy. Reliable species distribution data, however, are often rare or limited to a relatively few taxa in many parts of the world, and extensive species inventories tend to be expensive and time consuming. Consequently, the use of a few rigorously selected bioindicator taxa to represent broad-based inventories has been suggested as a viable alternative. Because spatial dependencies (spatial autocorrelations) are likely to exist in species richness data, common statistical techniques that assume independence are inappropriate for making cross-taxa comparisons of species ranges and distributions. We applied geostatistical methods that incorporate spatial dependencies to test the usefulness of a proposed bioindicator, tiger beetles, as a predictor of an unrelated taxon, butterflies, across North America and found a statistically significant relationship. We also showed how the application of statistical procedures that assume independence may be misleading. Finally, we showed how to make spatial predictions of species richness in intermediate areas where no sample species data are available.

Threatened species in a vanishing habitat: plants and invertebrates in calcareous grasslands in the Swiss Jura mountains

We examined the diversity of vascular plants, butterflies, grasshoppers, gastropods and carabid beetles in three calcareous grasslands in the northwestern Swiss Jura mountains, a habitat type that has decreased dramatically during the recent decades. As many as 58 species (ca 22%) of the 266 collected are listed as threatened in northern Switzerland. The number of threatened species ranged from 27 to 49 per site, and 26 species occurred in only one of the three grasslands. The species richness of butterflies and vascular plants correlated positively among the grasslands, while the species richness of other groups did not covary. An index of complementarity indicated that the species compositions (including non-threatened species, and spiders and oribatid mites) of the groups varied greatly among the grasslands. In addition, herbivorous groups were more widely distributed than predators among the three grasslands. Due to this variation in species composition none of the three sites c an substitute for the others, if the biodiversity of these grasslands is to be maintained. Furthermore, the taxonomic groups studied are poor indicators of each others' diversity. Consequently, we support the ‘shopping basket’ approach to conservation evaluation, i.e. measuring species richness, species composition and complementarity of several groups instead of just one.

Species richness and distribution of butterflies (Lepidoptera: Hesperioidea, Papilionoidea) in an agricultural environment in SE Finland

A five-year follow-up study was carried out to assess the species richness, adult flight period and distribution of butterflies in an agricultural environment in southeastern Finland in the years 1991-1995. Butterflies were monitored once a week from early May to late September on a 2.5-km field boundary transect. During 107 counts, a total of 49 species and 6 112 individuals were observed. More than half of all individuals (56%) were observed in July. The results of multivariate analyses indicated that the occurrence of species was related to three habitat types, classified as field margins dividing arable field and coniferous forest, arable field and deciduous forest and two arable fields. Species richness was higher in field margins near forests than in margins between two fields.

The effects of disturbance on forest butterflies using two methods of sampling in Trinidad

The butterfly assemblages of pairs of forest habitats, differing in disturbance level, within the Victoria Mayaro reserve of South-East Trinidad, are described using walk-and-count transects and canopy and understorey fruit traps. The concurrent use of these two butterfly censusing techniques, revealed major but conflicting differences in species accumulation rates under different disturbance conditions. The disturbed evergreen habitat had the significantly highest accumulation rate from walk-and-count data but the significantly lowest from fruit trap data. This reflects the specificity of much of the fruit-feeding guild for closed canopy forest. Disturbed habitats were found to lack a distinct canopy fauna. These results are discussed in light of the intermediate disturbance hypothesis. Within a region of forest, butterflies were found to be more characteristic of a disturbance level than of a particular forest type, lending weight to the belief that butterfly faunas can be used as bioindicators of forest disturbance. Several restricted geographic range species were not adversely affected by forest disturbance, at these levels of disturbance. The butterfly censuses in this study suggest that the optimal strategy for safeguarding butterfly species richness under natural forest management regimes would be to maintain a mosaic of habitats that included areas of undisturbed primary forest and a network of other forest patches, that varied in management regime and level of disturbance.

Butterfly diversity and human land use: Species assemblages along an urban grandient

We examined the distribution and abundance of butterfly species across an urban gradient and concomitant changes in community structure by censusing the butterfly and skipper populations at 48 points within six sites near Palo Alto, California, USA (all former oak woodlands). These sites represent a gradient of urban land use running from relatively undisturbed to highly developed and include a nature preserve, recreational area, golf course, residential neighborhood, office park and business district. The species richness and Shannon diversity of butterflies peaked at moderately disturbed sites while the relative abundance decreased from the natural to the urban areas. Butterfly species thought to be most representative of the original, predevelopment butterfly fauna progressively disappear as the sites become more urban. These patterns are significantly related to shifts in habitat structure that occur along the gradient as determined by canonical correspondence analysis (CCA) using the environmental variables of percent land covered by pavement, buildings, lawn, grasslands, and trees or shrubs. The mechanisms behind these patterns may be related to life history and resource use by the individual butterfly species.

Early succession of butterfly and plant communities on set-aside fields.

Hypotheses on secondary succession of butterfly and plant communities were tested using naturally developed 1- to 4-year-old set-aside fields (n = 16), sown fields (n = 8) and old meadows (n = 4) in 1992 in South Germany. Pioneer successional fields (1st and 2nd year of succession, dominated by annuals) and early successional fields (3rd and 4th year of succession where perennials, especially grasses became dominant) had fewer plant species than mid-successional fields (old meadows). In contrast to established hypotheses, mean number of plant species decreased from 1- to 4-year-old set-aside fields. Species richness of butterfly communities did not change during the first four years of succession, but species composition changed greatly. Pioneer successional fields were characterized by (1) specialized butterflies depending on annual pioneer foodplants (e.g. Issoria lathonia), and (2) species preferring the pioneer successions despite their host plants being more abundant on early and mid-successional fields (e.g. Papilio machaon). The variability in butterfly species richness was best explained by flower abundance which was closely correlated with plant species richness. Species whose abundance was correlated with habitat connectivity were significantly smaller than species which correlated with flower abundance. Numbers of caterpillar species were correlated with numbers of adult butterfly species. Life-history features of butterflies changed significantly from pioneer to early and mid-successional fields. We found decreasing body size and migrational ability, decreasing numbers of species hibernating as imago, decreasing numbers of generations and increasing larval stage duration with age of succession, but, contrary to expectation, host plant specialization, numbers of egg-cluster laying species and egg diameter did not change with successional age.

Importance of historical factors on species richness and composition of butterfly assemblages (Lepidoptera: Rhopalocera) in a northern Iberian mountain range

ABSTRACT. The butterfly assemblages of three vegetation types (pasture, heathland and rocky outcrop with Genista spp.) and two geographical orientations (a northern slope and a sheltered gorge) were studied along an altitudinal gradient in the Picos de Europa in northern Spain. In order to study the effects or historical climatic changes on current butterfly assemblages, it was examined if changes in richness and faunal composition of assemblages were joined with changes in their biogeographical composition. The three vegetation types showed characteristic butterfly assemblages, but no difference in species richness and biogeographical composition was found. Species richness in the sheltered gorge was higher than in the northern slope. Faunal composition also varied between orientations and there were more widespread and Mediterranean species in the sheltered gorge than in the northern slope. Species richness declined with increasing altitude, though a midaltitudinal peak was observed. There was a faunal segregation between high and low localities. Species richness of widespread and Mediterranean butterflies decreased as altitude increased, whereas the reverse was true for montane species. Moreover, biogeographical elements differed in their climatic tolerances measured as altitudinal ranges. Therefore, changes in richness and composition of butterfly assemblages between both slopes and along the altitudinal gradient were joined in part with variation in their biogeographical composition. These results suggest that current species richness and composition of butterfly assemblages in the Picos de Europa might be the consequence of differential colonization of refuges during the past climatic changes.

Nocturnality and species survival.

Surveys of butterfly and moth diversity in tropical forest fragments suggest that nocturnality confers a dispersal, and possibly a survival, advantage. The butterfly faunas of smaller fragments were depauperate; in contrast, the species richness of nocturnal moths was similar in all fragments and even in pasture. The lack of correlation between butterfly and moth species richness among fragments (r2 = 0.005) is best explained by movements of moths at night when ambient conditions in forest and pasture are most similar; butterflies face substantial daytime temperature, humidity, and solar radiation barriers. This interpretation is supported by information on birds, beetles, and bats.