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5ASSESSING THE TAXONOMIC IDENTITY, CONSERVATION STATUS, AND DISTRIBUTION MODELLING OF ENDEMIC AND ENDANGERED COUSINIA SPRYGINII KULT. (ASTERACEAE) IN UZBEKISTAN
1Karimov B., 2Toshtemirov J., 3Azimov B., 4Karimov B., 5Yusupov Z.
1,2,3,4,5Institute of Botany, Academy of Sciences of the Republic of Uzbekistan 2Belgorod State National Research University, Russia https://doi.org/10.5281/zenodo.13627283
Abstract. This study examined the morphological characteristics and conservation status of the endangered endemic plant species Cousinia spryginii. Examination of plant specimens under microscopy generated an illustrated description and enriched written profile of distinguishing morphologicalfeatures. Field surveys from 2022-2024 recorded two small isolated populations totaling approximately 200 individuals, indicating a significant contraction from historical herbarium records. The Extent of Occurrence was estimated at 397 km2 and Area of Occupancy at 36 km2 based on a 3 km grid, meeting IUCN criteria for Endangered status. Demographic monitoring revealed a low proportion of juvenile plants and high percentage of senescent individuals, suggesting poor regeneration andpopulation decline. Major threats include overgrazing, road/rail damage, and prolonged drought exacerbated by climate change. Species distribution modelling projected a 64-92% reduction in highly suitable habitat by 2070 under different climate change scenarios, with shifts in important environmental variables indicating vulnerability to changing precipitation patterns and temperatures. While six nature reserves are located near the historical range, none contain suitable ecological conditions to support C. spryginii populations. Conservation strategies proposed include establishing protected areas, grazing management, habitat restoration, and education programs to ensure the long-term viability of this rare endemic species in Central Asia.
Keywords: cousinia; Pamir-Alay; morphology; conservation; species distribution modelling
Introduction
Cousinia Cass. is one of the largest genera of the Asteraceae family, comprising 670 species (1) distributed only in the deserts of Iran-Turan and the mountain system of the Tien Shan (Northern and Western), Pamir-Alai, Hindu Kush, Caucasus, Iran, and eastern Iraq are the arena of life for this unusually rich in forms of the genus (2). Over 170 species can be found in the Pamir-Alay range in Middle Asia, which is the most significant center for the diversity of the genus Cousinia (3). In Uzbekistan, more than 130 species are distributed (4), and 20 species are included in the Red Book of Uzbekistan (5,6).
Conserving biodiversity requires identifying areas rich in species and prioritizing those with unique species, especially endemics. Endemic species, found only in specific geographic locations, are crucial for preserving biodiversity. Their analysis is key to understanding and addressing conservation concerns (7). Endemics are species confined to a particular region (8). These species typically have small populations and limited ranges, making them especially vulnerable. The degree of endemism in a region reflects the uniqueness of its flora and fauna and
is a vital factor in prioritizing conservation efforts (9). Growing human populations in biodiversity hotspots put immense pressure on these areas (10). Threat categories for species and plant endemism are essential for identifying hotspots that require immediate conservation attention (11). Understanding the distribution of endemic plants is critical for assessing their status and developing effective conservation strategies (12).
Cousinia spryginii Kult. is an endemic biennial plant found exclusively in the foothills of the southwest Pamiro-Alai region spanning Uzbekistan and Turkmenistan. Despite its localized distribution and small population size, there have been no comprehensive studies on the conservation status and potential climate change impacts on this rare taxon. Such information is crucial for developing evidence-based conservation strategies (5).
Here we present results from field surveys, herbarium data analysis, and species distribution modelling to assess the status of C. spryginii and project shifts in suitable habitat under current and future climates. We aimed to evaluate threats to the species, propose an IUCN Red List category, and provide guidance on priority actions needed to safeguard this endemic plant.
Materials and Methods
Field surveys were conducted during 2022-2024 to record population parameters like density, life stages, and threats. Herbarium specimens at the National Herbarium of Uzbekistan dating back to 1916 were also examined (13, 14, 15, 16). Based on geographic range data, we calculated the Extent of Occurrence (EOO) and Area of Occupancy (AOO) using GeoCAT (17, 18). Potential distribution modelling was performed in MaxEnt (19). Model performance was evaluated using the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) plot.
We utilized different sources to obtain the necessary environmental data for our study. Firstly, we retrieved 19 historical global bioclimatic variables from the Worldclim database spanning 1970 to 2000 (20). For future climate projections, specifically for the 2070s under different Representative Concentration Pathways (RCPs) such as RCP2.5, RCP4.5, RCP6, and RCP8.5 specifically for the 2070s, we obtained the data from the Climate Change, Agriculture, and Food Security (CCAFS) portal (https://ccafs-climate.org/data_spatial_downscaling/). Additionally, we retrieved 4 aspect factors and 8 slope factors from the Harmonized World Soil Database (HWSD) version 1.2 (21). To address the issue of complexity and potential overfitting within our model caused by correlations among different environmental factors, which can affect model accuracy, we employed the SDMtoolbox v2.4 tool package within the ArcGIS software. This allowed us to calculate the Pearson coefficient (22). Variables with correlation values (greater than 0.8) were eliminated as it is not recommended to use correlated variables for MaxEnt modelling (23). Ultimately, we selected a total of 9 climatic factors and 13 topographic factors (including 4 aspect factors, 8 slope factors, and elevation) to simulate the suitable habitat for C. spryginii in our study.
To visualize the results of the simulation and classify the habitat suitability, we utilized ArcGIS 10.8 software. The software allowed us to divide the habitat suitability into different categories based on the suitability scores. We defined highly suitable habitat as scores ranging from 0.8 to 0.99, moderately suitable habitat as scores ranging from 0.6 to 0.8, low suitable habitat as scores ranging from 0.4 to 0.6, and unsuitable habitat as scores ranging from 0 to 0.4. To calculate the distribution areas corresponding to each suitability grade, we used the Reclassify tool within ArcGIS 10.8 software. This tool enabled us to assign the appropriate class labels to different
areas based on their suitability scores. It allowed us to analyze the distribution patterns of potentially suitable habitats for C. spryginii.
Results
Description of Cousinia spryginii Kult.
We set out to provide additional details and clarification regarding the morphological features of the species of C. spryginii. To accomplish this, we carefully observed specimens under microscopy in order to create an accurate illustrative representation of its distinguishing physical characteristics. We then took the previous description of its form and structure and built upon it with more precise measurements and notes on attributes that had not been fully documented previously. The end result was both an illustration (Fig. 1) and an enriched written profile containing extra defining morphological information about C. spryginii to aid in its proper identification and classification.
C. spryginii is a biennial plant belonging to section Helianthae Bge. It was first published in Descr. Pl. Nov. Turkestan.: 78 (1916). Stem of 20-40 cm high, erect, arachnoid-hairy, striate-sulcate, branched from base; branches are unicapitulate, leafy. Leaves are finely arachnoid-hairy above, gray-tomentose beneath, prickly-toothed; basal leaves are short-petiolate (petioles broad, winged), oblong-obovate, crenate lobate, lobes are short-acute; lower cauline leaves are like basal but sessile; middle and upper cauline leaves are sessile, oblong-obovate, roundish above with short and thin spine, crenate-toothed, half to two-thirds as long as basal leaves. Capitula is globose, large, 25-35 mm wide (excluding cusps), densely arachnoid-hairy. Involucral bracts acuminate into long, stiff, three-angled spine; outer bracts are slightly decurved, 25 mm long, stiff, carinate; middle bracts squarrose, up to 40 mm long, subulate, carinate; subsequent bracts are somewhat flat, gradually acuminate into spine; inner bracts are coriaceous, linear-lanceolate, acuminate, not exceeding middle bracts. Receptacular bristles are smooth. Flowers are 25-35 mm long. Corolla is pale yellow. Apical anther appendages are long acute, straight in outline. Achenes are obovoid, flat, margins are with broad wings (one-third or one-fourth of achene width), not connivent at apex, grayish-green with dark dots, 4.5- 5 mm long and 3 mm wide. Flowering occurs from May to July, and fruiting from July to August. Bee pollination was found during field research (Fig. 1).
Assessing the conservation status
C. spryginii is a biennial plant that is exclusively found in the southwest region of Pamiro-Alai, specifically in the Kashkadarya and Surkhandarya areas of South Uzbekistan and Turkmenistan, near the border of two regions. The plant can be primarily found along the M39 road between Guzar and Shorab villages and in the foothills of Kelif-Sherabad, which are situated at an altitude of 700-1500 meters above sea level. This vegetation thrives in multi-colored rock formations and gray soils in the foothills alongside Alhagi pseudalhagi (M.Bieb.) Desv. ex Wangerin, Allium griffithianum Boiss., Alyssum turkestanicum Regel & Schmalh., Anemone petiolulosa Juz., Arnebia coerulea Schipcz., Atriplex moneta Bunge ex Boiss., Ziziphora tenuior L., and Zygophyllum atriplicoides Fisch. & C.A. The reproduction of this plant is carried out through seeds.
In 2022-2024, the highest population of C. spryginii was observed along the M39 road from Guzar to Shorab villages, with over 100 mature and 50 immature individuals. Another population of 50 individuals was found near the Aktash village in Kelif-Sherabad. However, this species is limited to a single isolate in locations where it occurs.
There are several threats to the survival of C. spryginii. One of the most significant threats is livestock farming and ranching, which includes nomadic grazing (2.3.1) and small-holder grazing, ranching or farming (2.3.2). The foothills of southwest Pamiro-Alai are used as a pasture for fattening small and large cattle throughout the year, and continuous grazing is causing a substantial decline in the population of C. spryginii.
Fig. 1. Illustration of C. spryginii, a- dried capitula, b-c- flowering capitula, d- seeds, e-involucral bracts, f- pollination of flowers by a bee, g- second year status of general appearance, h- flowers, i- apical anther appendages, j- first-year status of general appearance
Another threat is the use of roads and railroads (4.1), which crosses all the populations of this plant, causing significant damage (Fig. 2). Additionally, the populations of C. spryginii are located in environments that experience long periods of summer drought (11.3), and climate change is expected to exacerbate these conditions, making the environment increasingly inhospitable.
Fig. 2. Potential habitat loss of C. spryginii due to road development. a- general appearance of
the plant in habitat, b-habitat
Based on the historical data (1916-1980) from analyzing herbarium specimens of the National Herbarium of Uzbekistan, the Extent of Occurrence (EOO) and Area of Occupancy (AOO) of C. spryginii were wider compared to the current measurements. This suggests that the species has undergone a reduction in its geographical range and population size over time (Fig. 3).
The extent of occurrence (EOO) of C. spryginii is 397 km2, while the area of occupancy (AOO) is 36 km2, based on a user-defined cell width of 3 km. The species meets the criteria for Endangered status under criterion B due to the following reasons: (a) there are no more than three locations based on the main threat (2.3 Livestock farming & ranching), (b) there is a continuous decline in the extent of occurrence (i), area of occupancy (ii), extent and quality of habitat (iii), number of locations or subpopulations (iv), and number of mature individuals (v).
The demographic structure of the populations of C. spryginii indicates that the elimination of seedlings is occurring due to various reasons, including livestock grazing, transportation, and drought. The low proportion of juvenile plants suggests that the population has regressed in its recovery, while the high percentage of senescent individuals is an indication of a continuous decline in plants. Therefore, the species is assessed as Endangered under categories B1ab(i,ii,iii,iv,v) and B2ab(i,ii,iii,iv,v). C. spryginii is a rare and endemic species that was included in the national Red Book of the Republic of Uzbekistan with category 1 (Critically Endangered) in 2019. The taxon was not evaluated at the global level in IUCN 2024.
Distribution modeling near current and future
The study modeled the potential suitable habitat for the plant species of C. spryginii under near current and four different climate change scenarios (RCP2.6, RCP4.5, RCP6.0, and RCP8.5) projected for the 2070s timeframe (Fig. 4). The results showed that the potential suitable habitat for C. spryginii is expected to undergo significant changes compared to the near current baseline (Table 1). Near current scenario: 1,443 km2 of highly suitable habitat. RCP8.5 scenario (high
emissions): 521 km2 (64% reduction). RCP2.6 scenario (moderate emissions): 364 km2 (75% reduction). RCP6.0 scenario: 258 km2 (82% reduction). RCP4.5 scenario (lower emissions): 112 km2 (92% reduction). Across all future climate scenarios, the analysis indicates that the area of highly suitable habitat for C. spryginii is projected to decrease substantially compared to the near current conditions.
Fig.3. Geographic range and evaluating the conservation status of C. spryginii. (Existing population in red color, historical data in blue)
The most severe reduction, a 92% decline, was estimated under the RCP4.5 scenario. Moreover, the suitable habitats were predicted to exhibit significant fragmentation, becoming more isolated and dispersed rather than contiguous, under the future climate projection.
The study found that the most important variables differed between the current/baseline scenario and future climate change scenarios: For future climate change scenarios (RCP2.6, RCP4.5, RCP6.0, RCP8.5) annual precipitation seasonality (Bio17) is a variable that measures the variation in precipitation throughout the year. It is likely that C. spryginii is more sensitive to changes in precipitation patterns under future climate scenarios than it is to the total amount of precipitation. This could be because changes in seasonality can affect the timing of flowering and seed production, which are crucial for the plant's survival. The slope between 0-15% indicates the steepness of the terrain. It seems C. spryginii prefers to grow in areas with relatively gentle slopes. This preference may be related to factors such as soil moisture, sunlight exposure, and the availability of nutrients. The minimum Temperature of Coldest Month (Bio6) variable measures the minimum temperature during the coldest month of the year. It is likely that C. spryginii is sensitive to cold temperatures, and that its distribution is limited by the minimum temperature that it can tolerate.
Table 1. Unsuitable-high suitable area (km2)
Suitability Near current RCP 2.5 2070s RCP 4.5 2070s RCP 6 2070s RCP 8.5 2070s
Area km 2
High suitable 1443 364 112 258 521
Moderately suitable 3146 1375 566 1034 1506
Lowly suitable 5404 2284 1403 2167 2506
For the current/baseline scenario precipitation of driest period (Bio14) variable measures the total precipitation during the driest period of the year. It seems that C. spryginii is more sensitive to the amount of precipitation during the driest period under current conditions than it is to the overall precipitation pattern. This could be because the plant is more likely to experience drought stress during this period, and its survival may depend on the availability of moisture. The slope is between 0-15% variable remains important, reflecting the species' preference for gentle slopes. The minimum temperature of the coldest month (Bio6) variable remains important, reflecting the species' sensitivity to cold temperatures. C. spryginii is likely to be affected by climate change in several ways. The plant's distribution is likely to shift as precipitation patterns change and temperatures rise. The plant may also become more vulnerable to drought stress as the driest period of the year becomes longer and more intense.
While there are six nature reserves located near the geographical range of the plant species of C. spryginii, none of these protected areas have been definitively identified as suitable habitats that could support populations of this species. The six reserves mentioned are: 1) Surkhan State Reserve, 2) Babatag National Natural Park, 3) Upper Tupalang National Natural Park, 4) Hissar State Reserve, 5) Kitab State Geological Reserve, and 6) Historical and Natural Park Shirkent. To date, environmental assessments of these reserves have not found them to contain the specific soil conditions, terrain, climate, or other ecological factors required for C. spryginii to thrive
Conservation Strategies
Establishing protected areas: Designate protected areas to safeguard the remaining habitat of C. spryginii, including the foothills of Kelif-Sherabad and the M39 road corridor.
Grazing management plans: Implementation of grazing management plans to reduce the pressure of livestock farming and ranching on plant's habitat
## High suitable - unsuitable
Fig.4. Species distribution modelling for C. spryginii, a-protected areas 1.Surkhan State Reserve, 2. Babatag National Natural Park, 3. Upper Tupalang National Natural Park, 4.
Hissar State Reserve 5. Kitab State Geological Reserve, 6. Historical and natural park Shirkent, b-near the current, c-RCP 8.5, d-RCP2.5, e-RCP 6, f-RCP 4.5
Monitoring populations and environmental conditions: Regular monitoring plant's population and environmental conditions to track the effectiveness of conservation efforts and adapt to changing climate conditions.
Climate-resilient habitat restoration: Restoring degraded habitats to make them more resilient to climate change, focusing on areas with gentle slopes, suitable soil moisture, and minimal human disturbance.
Ex-situ conservation: Establish ex-situ conservation facilities, such as seed banks and nurseries, to preserve the plant's genetic material and propagate new individuals for reintroduction into the wild.
Community engagement and education: Engaging local communities in conservation efforts, educating them on the importance of protecting C. spryginii and its habitat. Collaborative research and management: Collaboration with international organizations, research institutions, and local governments to share knowledge, expertise, and resources for the conservation of C. spryginii.
Discussion
The results of this study provide valuable insights into the conservation status of the endemic plant species of C. spryginii and the threats it faces. Analysis of historical herbarium records, field surveys, and species distribution modelling collectively indicate the species meet the criteria to be classified as Endangered at the global level according to IUCN guidelines (18).
Several key findings emerge from the research. Analysis of herbarium specimens from the National Herbarium of Uzbekistan showed C. spryginii previously occupied a wider geographic range and larger population size compared to its currently restricted distribution. This suggests the species has undergone a contraction in its extent of occurrence and area of occupancy over time (13, 14). Field surveys in 2022-2024 observed only two extant populations totalling around 200 individuals, highlighting the small, fragmented nature of the remaining populations.
Demographic monitoring found a low proportion of juvenile plants and the high percentage of senescent individuals, indicating poor regeneration and an aging population structure (24, 25). Together these observations provide strong evidence of an ongoing decline as required to justify the endangered classification according to criteria B of IUCN. The small number of isolated locations and continuous decline in habitat quality and number of mature individuals further support listing C. spryginii as endangered under criteria Blab and B2ab.
Species distribution modelling projected a substantial contraction and fragmentation of suitable habitat for C. spryginii under future climate change scenarios across different emissions pathways. Even under the lower emissions RCP2.6 scenario, a 75% reduction in highly suitable habitat was predicted by 2070 compared to current conditions. The most severe decline of 92% was forecast under RCP4.5, suggesting the species is highly vulnerable to climate change impacts on its limited distribution.
Shifts in the important environmental variables between current and future projections provide insights into the mechanisms (26) by which climate change may affect C. spryginii. Increasing seasonality of precipitation, rising minimum winter temperatures, and a longer driest
period point to potential impacts on flowering/seed production timing, cold tolerance, and drought stress. These changing climatic conditions are likely to reduce environmental suitability across much of species' current range.
Several threats endangering the survival of C. spryginii were also identified. Continuous livestock grazing is causing direct destruction of individuals and degradation of habitat quality through overgrazing. The species occur in a landscape primarily used for livestock rearing, exposing populations to ongoing heavy grazing pressure. Roads and railroads transecting populations also pose a risk of accidental damage. Long-term drought periods exacerbated by climate change may further compromise species' persistence (27)
Notably, the study area containing the remaining C. spryginii populations is not currently protected within any conservation area. While six protected areas exist near the historical range, none contain the specific ecological conditions required by the species. This leaves populations and habitats directly exposed to the identified threats with no formal protection mechanisms. Unprotected threatened species lost significantly more habitat and faced greater extinction risks over recent decades than protected species (28).
Conclusion
Through integrated analyses, this study provides the first comprehensive assessment of Cousinia spryginiis morphology, population status, and climate change vulnerability to support an evidence-based conservation status evaluation. Our findings confirm this endemic plant meets IUCN criteria for Endangered listing due to its small population size and range, ongoing decline, and high projected climate change impacts. Urgent conservation action is needed to protect the remaining individuals and habitats, including establishing formal protected areas, implementing grazing management, and restoring degraded areas. Collaborative research and community engagement will also be important to strengthen understanding and long-term protection of this rare species indigenous to Central Asia.
Acknowledgments
This study was carried out as part of the project "Polymorphic plants of the flora of Uzbekistan - taxonomic revision of families" (FZ-20200929321) at the Institute of Botany. The authors would like to express their gratitude to the institute for providing the resources and support necessary to conduct this research. Additionally, the authors acknowledge the contributions of the network of researchers mapping the flora of Hisar-Darvaz and Panjoldi districts in Surkhandarya region, which was undertaken as part of a state program. This collaborative effort was instrumental in expanding the geographical scope and depth of the current study. The authors would also like to thank all the field researchers, taxonomists, and support staff whose dedication and expertise made this multifaceted project possible.
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