Impact of weather conditions on seasonal development, population structure and reproductive success on Dactylorhiza traunsteineri (Orchidaceae) in the Komi Republic (Russia)

Abstract

Due to specific biological features, high ornamental value and low resistance to anthropogenic factors, Orchidaceae species belong to the most vulnerable plants. To successfully protect their populations, comprehensive investigations of orchid biology and ecology are necessary. Long-term population studies are the most valuable. The paper presents data of population studies of Dactylorhiza traunsteineri, an orchid species listed in the Red Data Book of the Russian Federation. The field investigations have been conducted in the Komi Republic where the orchid species is located at the northeastern limit of its range. The seasonal development of D. traunsteineri lasts from May to August. We found the weather factors (air temperature, precipitations) impact features of small and big life cycles of this orchid species. The size of plant individuals is influenced by weather conditions of both the current and previous vegetative season. The number of generative (flowering) individuals per population had a positive correlation with the air temperature and humidity in August of the previous vegetative season. The fruit set of D. traunsteineri is high (50.4%). This parameter is negatively correlated with the air temperature at the flowering period, while it is positively correlated with precipitation values. The seed number per capsule (4090 seeds in average) was higher than it is known for other Dactylorhiza species in the Komi Republic. The real seed production is associated with the moisture content level during the vegetative season. The seed production of D. traunsteineri was high, from 88 000 to 199 000 seeds per 1 m2 in different study years. The presence of juvenile individuals (3.5–9.4%) over all study years indicates a successful seed reproduction in this population. This parameter was positively correlated with precipitation, air temperature in August, and seed production at the previous vegetative season.

Keywords

• climate influence
• fruit set
• monitoring
• orchids
• population structure
• seed production