نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشکده زیست شناسی و مرکز قطب تبارزایی موجودات زنده، دانشکدگان علوم، دانشگاه تهران،تهران، ایران
2 دانشکده زیست شناسی و مرکز قطب تبارزایی موجودات زنده، دانشکدگان علوم، دانشگاه تهران،تهران، ایران.
3 گروه باغبانی و حفاظت نباتات، دانشکده کشاورزی، دانشگاه صنعتی شاهرود، شاهرود، ایران.
4 موزه جانورشناسی استاد جلال افشار ، دانشکدگان کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
This study investigates the biodiversity and abundance of short-horned grasshoppers (Orthoptera: Acrididae) in relation to slope aspect and altitude in the Jaghatai mountain range, Khorasan Razavi province, northeastern Iran. Sampling was conducted during summer and autumn over two consecutive years (2021-2022) on the northern and southern slopes. On each slope, two sampling sites were selected at altitudes of 900 m and 1500 m. Sampling was carried out using insect nets along two transects (one transect in the northern slope and one transect in the southern slope) from the four designated stations. Specimens were preserved in Falcon tubes containing 75% ethanol, mounted using standard entomological technique, and identified to species level using valid taxonomic keys. Biodiversity was assessed using the Shannon-Wiener diversity index (H′), Margalef richness index (R), and Pielou evenness index (J′). Statistical analyses were performed using SPSS software, and t-test was employed to examine significant differences. A total of 19 species of short-horned grasshoppers were collected and examined in this study. The Shannon-Wiener diversity index showed no significant difference between the two slopes (p-value = 0.2). Comparing different altitudes, the highest Shannon-Wiener diversity was observed at 1500 m altitude in both northern and southern slopes. Margalef richness index was higher in the southern slope (2.66) compared to the northern slope (2.21), while Pielou evenness index was higher in the northern slope (0.98) than in the southern slope (0.8). Regarding altitudinal comparison, the highest species richness was observed at 1500 m altitude (1.83), and the highest evenness was observed at 900 m altitude in the northern slope (0.9) and at 1500 m altitude in the southern slope (0.8). These findings demonstrate that slope aspect and altitude significantly influence the structure of grasshopper communities. The results provide baseline data for ecological monitoring and conservation planning in montane rangelands of northeastern Iran.
کلیدواژهها [English]
Extended Abstract
Introduction
Biodiversity, particularly at the species level, is a critical indicator of ecosystem structure, function, and health. Ecosystems undergo significant changes due to environmental conditions and anthropogenic pressures such as habitat destruction and overexploitation. Orthopteran insects, especially short-horned grasshoppers (suborder Caelifera), represent an important group for biomonitoring owing to their high diversity, sensitivity to habitat alterations, abundance, and ease of sampling. The family Acrididae is one of the most species-rich groups within Caelifera. In Iran, long-term studies have documented a marked decline in grasshopper diversity and abundance since the 1960s, largely attributed to habitat degradation, agricultural intensification, and overgrazing. Vegetation cover and elevation are key environmental drivers influencing grasshopper distribution, diversity, and abundance, with intermediate elevations often supporting peak richness due to favorable microclimatic conditions and resource availability. Despite numerous faunistic surveys of Iranian Orthoptera, comparative quantitative data on the spatiotemporal patterns of short-horned grasshopper diversity remain limited, particularly in mountainous regions with contrasting slope aspects. Therefore, the present study aimed to investigate the diversity, species richness, evenness, and abundance of short-horned grasshoppers (Caelifera: Acrididae) along elevational gradients on the northern and southern slopes of the Jaghatai Mountains (Khorasan Razavi Province, northeastern Iran) over two consecutive years (2021–2022), and to evaluate the effects of elevation and slope aspect on these community parameters.
Methods
The study was conducted on the northern and southern slopes of the Jaghatai Mountain range, located between Sabzevar and Jovein plains in western Khorasan Razavi Province, northeastern Iran. This northwest–southeast oriented range (approximately 110 km in length) separates the fertile Jovein plain (to the north) from the drier Sabzevar plain (to the south) and experiences a cold semi-arid climate, with the highest peak (Mount Gar) reaching an elevation of 2958 m. Four sampling stations were established along two transects (one per slope), each at two elevations: 1500 m (mid-slope: stations A – north, C – south) and 900 m (lowland/foothill: stations B – north, D – south). Each station covered a 300 m × 100 m plot.
Sampling was conducted 15 times between July and October in 2021 and 2022 (sampling was interrupted in mid-August 2021 due to COVID-19 restriction). All samplings were performed during fixed daytime hours using standard sweep-netting, supplemented by hand collection. Collected specimens were preserved individually in 75% ethanol, subsequently pinned, and identified at the Animal Biosystematics Laboratory, School of Biology, University of Tehran. Identifications followed valid taxonomic keys and monographs including Bei-Bienko & Mishchenko (1963), Hodjat & Tork (2015), and Usmani & Nayeem (2012).
Community diversity was quantified using the Shannon–Wiener index (H′), Margalef’s richness index (d), and Pielou’s evenness index (J′). These indices were calculated as follows:
- Shannon–Wiener index: H′ = –Σ(Pᵢ ln Pᵢ), where Pᵢ represents the proportional abundance of species i.
- Margalef’s richness index: d = (S – 1) / ln N, where S denotes total species number and N represents total individuals.
- Pielou’s evenness index: J′ = H′ / ln S.
Differences in Shannon diversity between slopes and elevations were tested using independent samples t-tests. Variations in abundance patterns were examined using Chi-square tests. All statistical analyses were performed using IBM SPSS Statistics version 22.0.
Results
A total of 235 individuals of short-horned grasshopper belonging to 19 species were collected and identified. The recorded species were as follows: Calliptamus barbarus (Costa, 1836), Oedaleus decorus (Germar, 1825), Oedipoda miniata (Pallas, 1771), Sphingonotus (Sphingonotus) nebulosus (Fischer von Waldheim, 1846), S. (S.) savignyi Saussure, 1884, S. (S.) rubescens (Walker, 1870), S. (S.) minutus Mishchenko, 1937, Brunnerella mirabilis Moritz, 1928 , Helioscirtus moseri Saussure, 1884, Dociostaurus (Kazakia) tartarus Stshelkanovtzev, 1921, Aiolopus puissanti Defaut, 2005, Heteracris litoralis (Rambur, 1838), Mioscirtus wagneri (Eversmann, 1859), Sphingoderus carinatus (Saussure, 1888), Ramburiella (Palaeocesa) turcomana (Fischer von Waldheim, 1833), Truxalis eximia Eichwald, 1830, Notostaurus albicornis (Eversmann, 1848), Acrotylus insubricus (Scopoli, 1786) and Hyalorrhipis turcmena Uvarov, 1926. Notably, nine species (Aiolopus puissanti, Heteracris litoralis, Mioscirtus wagneri, Sphingoderus carinatus, Ramburiella turcomana, Truxalis eximia, Notostaurus albicornis, Acrotylus insubricus and Hyalorrhipis turcmena) represent first provincial records for Khorasan Razavi Province, Iran.
The Shannon–Wiener diversity index was higher on the northern slope than on the southern, but the difference was not statistically significant (t = 0.28, df = 102, p = 0.20). Within slopes, diversity was significantly higher at 1500 m than at 900 m on both the northern (t = 7.43, df = 43, p < 0.001) and southern (t = 1.56, df = 54, p = 0.05) aspects. Overall, Margalef richness index was greater on the southern slope overall (2.66 vs. 2.21 on the northern slope), however, within each slope, richness remained higher at the upper elevation (northern: 1.83 at 1500 m vs. 1.20 at 900 m; southern: 2.61 at 1500 m vs. 1.58 at 900 m). Pielou's evenness index was highest on the northern slope (J′ = 0.98) compared to the southern slope (J′ = 0.8), with mixed patterns across elevations.
Grasshopper abundance was highest at station A (1500 m, north slope), which can be attributed to the richer vegetation, higher precipitation, and minimal human disturbance in this area. In contrast, abundance was lowest at station D (900 m, south slope) due to arid conditions and poor plant cover. Calliptamus barbarus was the dominant species overall (31.91% of all individuals), followed by varying dominant species at each station (e.g., Mioscirtus wagneri at B, Oedipoda miniata at C). Overall, abundance decreased progressively from July to October.
Conclusion
This study documented 19 species of short-horned grasshoppers in the Jaghatai Mountains, including nine new provincial records for Khorasan Razavi Province, highlighting the continued value of montane habitats as refugia for orthopteran diversity in northeastern Iran. Although overall Shannon diversity showed no significant difference between northern and southern slopes, clear elevational patterns were observed: higher elevations (1500 m) consistently supported greater species diversity and richness, a pattern driven by more favorable climatic conditions, denser vegetation, and reduced anthropogenic pressure (e.g., limited grazing and agriculture). The northern slope exhibited greater evenness, while the southern slope showed marginally higher richness. These findings align with several global studies reporting peak orthopteran diversity at intermediate or mid-montane elevations, while they contrast with patterns in some tropical or heavily disturbed systems. The results of this study underscore the sensitivity of grasshopper communities to slope aspect, elevation, and land-use intensity, emphasizing the urgent need for the conservation of relatively undisturbed high-elevation northern habitats to maintain biodiversity and ecosystem stability in the region. Therefore, sustainable management practices, including reduced overgrazing and the protection of montane vegetation, are recommended to preserve orthopteran diversity and the associated ecosystem services in this semi-arid mountainous region.
T.P. and M.S. designed the research; T.P.: collected and identified the specimens, wrote the original draft, performed analysis and data curation, conceptualization; M.S.: Writing – review & editing, Validation, Supervision, Resources, Project administration, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization; M.H., N.K. and M.T.: Re-examined the identified specimens and revised the manuscript.
Data will be available upon request.
The authors gratefully acknowledge the support provided by the College of Science, University of Tehran and the Department of Biology, Hakim Sabzevari University. We would further like to thank the editor and the reviewers for their helpful comments and constructive criticism on previous versions of the manuscript.
Not applicable.
The authors declare that they have no conflict of interest.
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