Behaviour of Some Grasslands on the Slopes of the Balkan Mountain
The study includes results of a 20-year (1994-2013) period of use of a number of artificial grasses. They have been established with seeds of local origin and are located in the region of the Central Balkan Mountain. Habitats have different exposure of the slopes to the main cardinal points of the world and a variety of soil gleying. When the grasslands are located on different habitats, the presence of a certain rhythm in the formation of the fodder mass is established. The yields were higher in the odd years (1995, 1997, 1999, 2001) in comparison with the even ones (1996, 1998, 2000). The sequence changed in 2002, 2004, 2006, 2008, 2010. The yields were again higher in the odd years (2011, 2013) than 2012. The behaviour of the grasslands, located on slightly gleyed soils with eastern and southeastern exposure, follow the sequence mentioned above more clearly. Those in other habitats were accompanied by too much variety in their behaviour over the years and variants. New elements are added to the various views and hypotheses on the origin of species, about their evolution and the causes of the behaviour of the grasslands.
