The effect of the shape of gaps on microenvironmental conditions and seedling recruitment in Molinietum caeruleae meadows

Abstract

Cessation of the management of semi-natural habitats such as grasslands and meadows contributes to secondary succession and encroachment of native and alien tall-growing perennials, large tussock grasses, shrubs, and trees. Thus, the formation of gaps in the plant canopy and litter, enabling seedling recruitment, appears to be a very effective method for the restoration of several plant communities. The main objective of the research was to assess the effect of the shape of openings on microenvironmental conditions and seedling recruitment in Molinietum caeruleae patches in various habitat conditions. In all study patches, circular and linear openings, comparable in area, were randomly created through the removal of plant canopy and litter layer. The circular gaps presented greater light availability and lower soil humidity than linear openings, while soil temperature within differently shaped openings was similar. Regardless of differences in microenvironmental conditions, the total number of seedlings in differently shaped gaps did not vary considerably. Three plant categories were found: (i) those recruited mostly in circular openings, (ii) those recruited mostly in linear gaps, (iii) those colonizing circular and linear gaps similarly. The colonizers of circular gaps represented various synecological groups (ruderal, grasslands and meadows, young tree communities) and diverse life forms (therophytes, hemicryptophytes, chamaephytes, phanerophytes), while the colonizers of linear gaps were meadow and grassland hemicryptophytes. The formation of linear openings contributes to increases in the abundance of meadow taxa, while the creation of circular openings may have a negative effect, contributing to the promotion of the secondary succession process.