Effects of irrigation and landscape heterogeneity on butterfly diversity in Mediterranean farmlands

Irrigation effects on biodiversity are poorly known, particularly in Mediterranean agroecosystems. In this study we analyzed irrigation effects on butterfly species richness, abundance and diversity as well as on species composition in a farmed landscape under Mediterranean climate. The study area consisted of four contiguous agricultural sub-areas with a decreasing degree of intensification: irrigated, mixed (dry and irrigated), dry and environmentally protected (i.e. Special Protection Area, SPA) dry farmland. Forty 1km-transects (ten per sub-area) were searched for butterflies in 2008 and 2009. Contrary to expectations, species richness (alfa, beta and gamma diversity) was highest in both years in the most intensified sub-area (i.e. irrigated) followed by SPA, dry and mixed sub-areas. Landscape characteristics accounted for most of the between-subareas differences in species richness. Species richness was negatively related to mean field size at the landscape level and positively related to the number of trees and large shrubs along transects. Therefore, the higher number of butterfly species recorded in the irrigated farmland could be due to a more complex landscape. In contrast, butterfly abundance was highest in cereal steppes (i.e. dry and SPA sub-areas), with abundance being negatively affected by mean field size. Inter-annual change in butterfly abundance was much sharper in rainfed (i.e. dry and SPA) than in irrigated (i.e. irrigated and mixed) sub-areas. Irrigated farmland may provide more favorable conditions for butterflies by buffering the (year-to-year and summer) drought periods characterising Mediterranean climate. Species composition differed among sub-areas, with differences being partly explained by field size and number of trees and shrubs along transects. Our study suggest an important role of landscape characteristics in boosting butterfly biodiversity in intensively managed irrigated croplands and emphasizes the importance of encouraging studies on farmland butterfly diversity in different (bioclimatic) regions allowing the design of region-specific agri-environmental schemes.

Understanding and identifying butterfly species in various land uses serves a crucial eco-logical function in protecting biodiversity and improving environmental policy decisions. However, such a study on the diversity of butterflies from different land use types in and around Chebera Churchura Na-tional Park, southwestern Ethiopia, is extremely lacking. Thus, the present study aimed to quantify the species richness and abundance of butterflies in the Chebera Churchura National Park and its surroundings, which are prioritized for their conservation. Data was collected from January 2021 to June 2021 following the line transect method in the three habitat types using a standard insect net. In total, 2118 individuals representing 79 species and 38 genera belonging to five families were recorded. The Nymphalidae were the most dominant butterfly family, accounting for 45 species (57%) of the total butterflies observed, while the Heaspariidae contributed the least. Among the 79 species, 9 were very common, 32 were common, 37 were rare, and 1 was very rare. Based on butterfly species richness and composition, riverine forest had the greatest diversity and abundance with 65 species and 1028 individuals, and the least species composition was recorded in mosaic habitat with 26 species and 350 individuals, and the difference in diversity was significant. The study region was generally found to be rich in the diversity and abundance of butterflies in all three forms of land use. However, the study area is currently becoming an investment hub, and many road development projects are being planned. Ongoing human activities will devastate and harm the richness, abundance, and diversity of butterfly species. As a result, such human-induced activities need to be carefully studied to protect biodiversity.

BackgroundMany species inhabiting Kihansi gorge ecosystem in Southern Udzungwa Mountains, Tanzania are threatened with extinction due to habitat loss caused by constructed hydropower plant that diverted over 90% the water off the Kihansi River. Understanding ecological correlates and structure of an animal community in perturbed ecosystems is an important way to enhancing species conservation particularly in this system, where several species are already threatened with extinction. This study assessed influences of local habitat characteristics on the butterfly abundance, species richness and diversity and examined how the butterfly community structures across three structurally heterogeneous habitats in the Kihansi gorge forest. Butterfly abundance data were collected using baited traps and measured environmental variables in the field, where trapping occurred. To understand the diversity and butterfly richness, these parameters were computed under Primer software. Non-metric multidimensional scaling and analysis of community similarity were used to analyse the butterfly community structure. Furthermore, the generalized linear models (GLM) were used to assess how the measured variables explained observed species diversity, abundance, and richness.ResultsIn total, 72 species of butterfly in five families were recorded. Butterfly species diversity and richness did not vary across the habitat types or elevation gradient but showed strong correlation with some habitat characteristics. In addition, there was evidence of butterfly communities structuring into distinct groups that showed greater separation associated with the habitat characteristics they utilise. Furthermore, across the study area, butterfly species diversity increased significantly in high canopy and in trees with smaller DBH and at lower ground cover. Similarly, abundance significantly increased in the woodland and wooded grassland habitats, where there was high canopy and where tree density was high. Furthermore, butterfly species richness was strongly positively associated with high canopy cover and mostly increased in sites closer to water source.ConclusionFirst, this study shows strong positive correlation between the habitat characteristics and butterfly species and community structure, suggesting strongly that maintaining habitat quality should be a priority in conserving the butterfly communities in Kihansi. Second, conservation of environmental disturbance indicator butterfly taxa which are also endemic and rare is worthy of concern under the ongoing human-induced threats in the area. It is appropriate time that the Tanzania government should declare the Kihansi gorge forest among existing protected areas to secure effective conservation of biological diversity in this threatened ecosystem. Third, the ants–butterfly symbionts and their links to the potential lichen depletion are still unclear, and thus future research should explore the trophic cascades of depleting habitat quality on the endemic and rare butterfly species in the Kihansi gorge.

Within the BiodiverCity project in Malmö (Sweden), green structure elements were implemented aiming to support biodiversity and enhancing amenity in denser parts of the city. In this study, bumblebee and butterfly abundances and species richness were studied in 20 green structure elements in three areas in Malmö. The investigated green structure elements consisted of objects established within the BiodiverCity project and other green structure elements in their surroundings (e.g. road verges, lawns and flowerbeds). Observed bumblebee and butterfly abundances and species richness was generally low. In total, 528 bumblebees of eight species were recorded, with 97% of all bumblebees belonging to two species, Bombus lapidarius and B. terrestris/lucorum. A total of 154 butterflies from 10 species were detected, most commonly Pieris species. There were no significant differences in mean individual or species numbers (bumblebees and butterflies) between green structure elements designed to support biodiversity and conventional ones. Bumblebee species richness and abundance were positively correlated with mean cover of flowering vegetation and mean number of flowering plant species. Butterfly species richness and abundance were positively correlated with mean number of flowering plant species and size of the green structure. Observations of flower visits showed that the two groups of insects had different preferences. The results of this study show that enhancing bumblebee and butterfly diversity and abundances in densely built city areas can be challenging. To support bumblebees and butterflies more successfully, the habitat requirements of these insect groups need to be better considered from the beginning in the design of green structure elements.

A survey was conducted on the species composition, richness and abundance of Papilionoidea (excluding Lycaenidae) butterfly fauna in habitats with various degrees of disturbance and altitudes in tropical forests at Tam Dao National Park, northern Vietnam in 2001. The transect method was used to collect data in the survey. Six transects representing different habitat types at two sites, one site located at a low elevation of 200–250 m a.s.l., and the other located at a high elevation of 950–1000 m a.s.l., were chosen: three transects for each site, with a length of 500 m for each transect. A total of 3594 individuals of 127 species in 240 sets of data were recorded from various habitats. The differences in butterfly composition, species richness, abundance and diversity in different habitat types and altitudes were analyzed. The results showed significant differences of butterfly diversity among the different habitat types and between the low and high altitude sites. The butterfly diversity, species richness and species abundance in the low elevation habitats were higher than in the high elevation habitats. The highest diversity of butterflies occurred in the mixed habitats of agriculture, scrub and clearing lands of high disturbance. However, butterflies most important for conservation are associated with undisturbed or moderately disturbed forests only.

Butterflies are among the most effective bioindicators of climate change; however, their diversity in many rural areas of the Central Himalayas remains understudied. This study provides an assessment of butterfly diversity in the foothills of Bhorletar, Madhya Nepal Municipality, Lamjung District, Nepal, within an elevation range of 420-600 m. Conducted between July 2019 and January 2021, the survey involved opportunistic observations and photography of adult butterflies in their natural habitats, with sampling occurring six times each month. The study aimed to investigate the species composition, richness, and abundance of butterflies across the survey period and identify seasonal changes in species composition and richness. A total of 94,009 individuals across 226 species, 129 genera, and six families were documented. During this study, Halpe arcuata Evans, 1937 and Hasora taminatus bhavara Fruhstorfer, 1911 were recorded for the first time in Nepal. Additionally, Halpe filda Evans, 1949 and Ctenoptilum vasava vasava (Moore, [1866]) were recorded for only the second and third times, respectively, in Nepal, following a gap of approximately three decades. The most abundant species was Pieris canidia indica Evans, 1926 (Relative Abundance [RA] 2.55%), followed by Pseudozizeeria maha maha (Kollar, [1844]) (RA 2.13%). Species richness showed an annual bimodal distribution, peaking in April (180 species) and August (161 species), while the lowest richness was observed in January and February, with 68 and 75 species, respectively. Diversity indices included a Shannon-Wiener index of 4.71, Pielou's J index of 0.87, an effective number of species of 111.24, and Margalef's richness index of 19.65, indicating high species diversity with a well-balanced mix of species evenness and richness. This study offers the first peer-reviewed checklist of butterflies from Bhorletar, providing crucial baseline data for future research and conservation efforts, and highlights the remarkable seasonal and species diversity within the region.

We used butterfly assemblages to evaluate the ecological value of habitat mosaics within garrigue ecosystems in Cyprus. To understand the importance of the local plant communities for Cypriot butterflies, five plots in each of two habitat types (grass-dominated or shrub-dominated) were surveyed weekly for a period of five months in order to assess the abundance, species richness and diversity of butterflies. A total of 810 butterflies of 16 species were recorded. Indices of butterfly diversity, calculated across the whole season, were similar between grassland and shrubland dominated mosaics. However, species richness of all butterflies was consistently higher in grassland dominated mosaics throughout the whole season. The peak abundance of all butterfly species occurred during mid-season (late April - early May), with similar numbers observed in both habitat types. However, a greater abundance was observed during early and late season in grassland patches. The abundance of endemic species (Maniola cypricola, Hipparchia cypriensis, Glaucopsyche paphos) peaked earlier in the season in shrubland patches, but was higher in grassland patches in late season. This difference in seasonal timing of endemic abundance was dominated by the seasonal dynamics of M. cypricola. These results suggest that, while garrigue is characterised by its shrub flora, management to maintain a mosaic of grassland and shrubland could act to maximise the abundance and richness of indicator species groups of conservation importance.

The joint effect of forest edge (FE) heterogeneity and management intensity of the adjacent farmland on FE insect communities is still poorly understood. In this study, a pairwise design was established, consisting of 36 Western European lowland FEs, with each of the 18 FE pairs containing one improved and one nearby non-improved FE. Half of the FE pairs were situated along extensively used and half along intensively used meadows, leading to gradual contrast patterns. Butterflies were selected as the survey group because they contain widely recognized flagship species and are meaningful indicators of landscape quality and resource availability. The main outcomes were as follows: (i) FE improvements led to higher overall FE heterogeneity scores, calculated on the basis of 16 floristic and structural indicator values. (ii) Overall butterfly species richness and butterfly abundance both benefited from higher FE heterogeneity. (iii) Butterfly species richness was higher on improved FEs, irrespective of adjacent meadows’ use intensity. (iv) Butterfly abundance was higher on improved FEs, mainly due to high contrast situations between improved FEs and adjacent intensively used meadows. (v) FE improvements resulted in higher butterfly indicator species richness and abundance. The strategy of the canton of Aargau in Switzerland, where this study was conducted, to ecologically improve around 200 km of additional FEs in the longer term is believed to further promote butterfly diversity in the transition zone between closed forest and open landscape.

The role of power line rights-of-way as an alternative habitat for declined mire butterflies

In this study we investigate the environmental factors influencing butterfly communities and evaluate the Natura 2000 network’s effectiveness in representing butterfly species richness and abundance, taking as a case study the island of Cyprus. We sampled butterflies and 11 environmental factors in 60 randomly selected sites across four 500-m elevation zones, representing seven habitat types. Rural mosaics and riverine vegetation were the habitats with the highest diversity of butterflies. Within habitats, the number of flower heads was the most important factor favouring butterfly species richness and abundance and endemic butterfly richness, while soil humidity had a positive effect on species richness and abundance. Although the Natura 2000 network succeeds in including the majority of butterfly species and all Cyprian endemics, the transects sampled within the network did not support more butterfly species than those outside it, and were significantly poorer in terms of butterfly abundance and endemic butterfly species richness and abundance. We found a similar pattern for the Habitats Directive priority habitats, which held poorer overall and endemic butterfly communities than the other habitats. The effectiveness of existing protected area networks may need to be reassessed in regions such as the South East Mediterranean, to ensure that regionally important components of biological diversity are adequately protected. To this aim, our results suggest that new European and national policies as well as further inclusion of rural mosaics and riverine habitats in protected area networks are needed for effective butterfly conservation in Cyprus.

This study compares the variation of richness, abundance, and diversity of butterfly species for vegetation communities along an elevational gradient and during different seasons in the Priority Region for Conservation of Biodiversity, Sierra Chiquita, located in the northeast of Mexico. We also analyze the influence of environmental variables on the abundance and richness of butterfly species. Seven sampling sites were established based on criteria of vegetation distribution per altitudinal gradient. Sampling was on a monthly basis and carried out in six permanent plots at each site, using an aerial entomological net during November 2015 to October 2016. A total of 38,011 specimens, representing six families and 195 species, were collected. All parameter values showed significant differences across sites, except between thorn forest and gallery forest. Seasonality effect was absent on richness and diversity species; however, for species abundance, the differences between dry season and rainy season were significantly different in each site except for the comparison of thorn forest and gallery forest. The association between the environmental variables and butterfly communities in the elevational gradient was significant, being the dew point, the solar radiation, the canopy leaf area, and the number of flowering plants the most important variables. The present work represents an important contribution of the vegetation communities variation in richness, abundance, and diversity of butterflies in the northeast of Mexico. These results highlight the importance of the conservation of this heterogeneous habitat and establish reference data for the diurnal Lepidoptera fauna of the region.

Road verges can support high densities of flowers and could therefore provide new opportunities for the conservation of flower‐visiting insects. One way of optimizing road verges for vascular plant diversity is to adjust mowing regimes, but to date it is unclear how this affects flower‐visiting insects. Furthermore, for mobile organisms like wild bees and butterflies, there is a risk that the benefit of increased habitat quality in road verges is limited by the proximity to traffic, but this is poorly studied. In a crossed study design, we separated mowing time and frequency (early summer and autumn, or only late summer) from road verge habitat classification (valuable for biodiversity according to transport authority, or regular). We did so along a gradient of traffic intensity, to investigate if a mowing regime designed to enhance plant diversity can also benefit wild bees and butterflies, and if traffic limits the conservation potential of road verges. Road verges that were mown only in late summer had higher flower densities, and there was a positive relationship between flower density and wild bee abundance and species richness. Butterfly abundance and species richness only benefitted from a late summer mowing in valuable but not in regular road verges. Traffic intensity had a substantial negative impact on abundance and species richness of wild bees and butterflies. Higher traffic intensities limited the positive relationship between plant and butterfly species richness that we observed at lower traffic intensities. Increasing width of the road verges buffered negative effects of the traffic on wild bee as well as butterfly abundances, and on wild bee species richness. Synthesis and applications. Road verges can play a valuable role for the conservation of wild bees and butterflies, but there is a need to consider both traffic intensity and resource availability when implementing management strategies. To support wild bee and butterfly diversity, we recommend actions to enhance plant species richness and flower resource availability, and to focus these conservation efforts on roads with low traffic intensity, or on wide road verges.

Understanding wild biodiversity of agroecosystems and other human dominated landscapes are crucial for the management and conservation of biological resources. Here, we studied the diversity, abundance, similarity and functionality of butterflies in different human modified ecosystems in southern Sikkim, the Eastern Himalaya. The study was conducted from January 2015 to May 2015 by covering three habitat types namely, farm-based agroforestry, large cardamom-based agroforestry and adjacent natural forest ecosystem. We followed point count method along the transect to collect data on butterflies in the study area. A total of 911 individual butterflies representing six families and 44 species were recorded during the present study in southern Sikkim. Species richness and abundances of butterflies were significantly different among the systems. While diversity and abundance were higher in forest patches, each system harbored unique species assemblages with low similarity between habitats. The information on larval host plants were available for 41 butterfly species which depended on 128 plant species belonging to 27 families. The butterfly community was dominated by oligophagous II (19 species) followed by polyphagous (11 species), monophagous (8 species) and oligophagous I (3 species). Similarly, generalist feeders had higher species and abundance compared to specialist feeders. Specialist species were confined to forest habitat, whereas generalist species were mostly restricted to cultivated systems. The findings of the study highlighted the need for conservation of traditionally managed agroecosystems in order to conserve butterflies and other associated biodiversity.

Abandoned land management threatens the maintenance of the diversity of flower‐visiting insects and flowering plants. In recent years, cattle grazing on abandoned land has been practiced in Japan to utilize the abandoned land and reduce cattle feed costs. It is important to elucidate the restoration effects that cattle grazing has on the biodiversity of abandoned lands in warm, humid climate regions, such as Japan. However, there are limited case studies that examine the restoration effects on flower‐visiting insects and flowering plants in Japan. In this study, we examined the effects of Tajima cattle grazing on the species richness and abundance of butterflies and flowering plants in abandoned lands in Muraoka‐ku, Kami Town, Hyogo Prefecture, Japan. Our results revealed that the vegetation height was lower and species richness and abundance of butterflies and flowering plants was higher in the grazing lands. However, the abandoned lands had a higher vegetation height and significantly lower species richness and abundance of butterfly and flowering plant. Grazing pressure positively and significantly affected the species richness and abundance of butterfly and flowering plant. These results indicate that grazing increased the species richness and abundance of butterfly and flowering plant. There was no significant difference in the species composition between the grazing and abandoned lands, and no significant indicator species were detected in the abandoned lands. We conclude that Tajima cattle grazing systems on abandoned lands can restore the species richness and abundance of butterfly as well as flowering plants.

Summary1. Environmental changes may not always result in rapid changes in species distributions, abundances or diversity. In order to estimate the effects of, for example, land‐use changes caused by agri‐environment schemes (AES) on biodiversity and ecosystem services, information on the time‐lag between the application of the scheme and the responses of organisms is essential.2. We examined the effects of time since transition (TST) to organic farming on plant species richness and butterfly species richness and abundance. Surveys were conducted in cereal fields and adjacent field margins on 60 farms, 20 conventional and 40 organic, in two regions in Sweden. The organic farms were transferred from conventional management between 1 and 25 years before the survey took place. The farms were selected along a gradient of landscape complexity, indicated by the proportion of arable land, so that farms with similar TST were represented in all landscape types. Organism responses were assessed using model averaging.3. Plant and butterfly species richness was c. 20% higher on organic farms and butterfly abundance was about 60% higher, compared with conventional farms. Time since transition affected butterfly abundance gradually over the 25‐year period, resulting in a 100% increase. In contrast, no TST effect on plant or butterfly species richness was found, indicating that the main effect took place immediately after the transition to organic farming.4. Increasing landscape complexity had a positive effect on butterfly species richness, but not on butterfly abundance or plant species richness. There was no indication that the speed of response to organic farming was affected by landscape complexity.5. Synthesis and applications. The effect of organic farming on diversity was rapid for plant and butterfly species richness, whereas butterfly abundance increased gradually with time since transition. If time‐lags in responses to AESs turn out to be common, long‐term effects would need to be included in management recommendations and policy to capture the full potential of such schemes.