Wojciech Adamowski

Patterns of Genetic Diversity in Platanthera bifolia (Orchidaceae) with Respect to Life History Traits and Recent Range Expansion

For evolutionary and ecological analyses, genetic diversity at different scales needs to be studied in terms of biological properties, habitat, population size and population history. We surveyed Platanthera bifolia populations from six regions in northeastern Poland to determine the impact of the mating system and population history on genetic diversity. Based on variation at allozyme markers, genetic variation was relatively moderate (P = 22.3%, A = 1.48, HO = 0.083, FIS = −0.015) and similar to other Platanthera species. These parameters varied between populations (P = 13.3%–26.6%, A = 1.26–1.66, HO = 0.055–0.111, FIS = −0.262–0.147). The genetic diversity patterns were shaped by different proportions of facilitated selfing and/or outcrossing, resulting in positive and negative FIS values, respectively. No relationship between inbreeding coefficient and population size, however, and no impact of apomixis on the level of genetic diversity of P. bifolia were found. The relatively low level of genetic differentiation among the investigated regions (FCT = 0.002, P > 0.05) and among populations (FST = 0.048, P < 0.001), and the lack of a significant relationship between genetic and geographical distance, are discussed in the context of possible scenaria of postglacial expansion.

FOREST RETURN ON AN ABANDONED FIELD - SECONDARY SUCCESSION UNDER MONITORED CONDITIONS

Forest Return on an Abandoned Field - Secondary Succession Under Monitored Conditions The secondary succession pattern observed on an arable field abandoned since 1974 in Tilio-Carpinetum habitat is described and disscussed. Results obtained during 36 years of study confirm that succession on an abandoned field leads from a typical segetal community to the formation of a juvenile treestand composed of pioneer species. Our study supports the view that succession is a process which is largely dependent on the initial conditions and surrounding vegetation. The results indicate that some species can modify the course of this process, accelerating or slowing it down. Limitations of the method and prognosis of future vegetation development are also discussed.

Impatiens zironiana (Balsaminaceae), a new species from Arunachal Pradesh, Northeastern India

Abstract Impatiens zironiana, a new species of Impatiens from Lower Subansiri district of Arunachal Pradesh, northeast India is described and illustrated. Detailed descriptions, distribution and ecology along with colour photographs are provided.