Population Structure, Morphological Integration and Regional Differentiation of Dactylorhiza fuchsii (Druce) Soó in the Central Highlands of Kazakhstan

Dactylorhiza fuchsii (Druce) Soó is an ecologically sensitive terrestrial orchid and an important indicator of habitat condition, yet its population structure and morphological variability remain poorly studied in the Central Kazakh Uplands. This study evaluated the population size, density, ontogenetic structure, and morphometric differentiation of 21 coenopopulations in Kokshetau, Burabay, and Karkaraly National Parks. Ontogenetic stages were classified as juvenile, immature, virginal, and generative. Twenty-two quantitative traits were measured in 420 generative individuals and analysed using Pearson correlation, principal component analysis (PCA), the Mann–Whitney U test with Bonferroni correction, and PERMANOVA. Generative individuals predominated in most coenopopulations. In Burabay National Park, they comprised 71–100% of all individuals, virginal plants were absent from five of six coenopopulations, and population density was lower than in the other study regions. Balanced ontogenetic spectra were recorded in Kokshetau (CP4, CP6) and Karkaraly (CP1–CP3). Morphometric traits exhibited strong integration, with plant height strongly correlated with lip width (r = 0.723) and median lobe length (r = 0.684), whereas several floral traits varied more independently. The first three principal components explained 86.5% of the total variance, and PERMANOVA revealed significant regional differentiation among the three study regions (p < 0.001). This study provides the first comprehensive assessment of the population structure and morphometric variability of D. fuchsii in the Central Kazakh Uplands and establishes a baseline for long-term population monitoring and conservation planning.