Are sprouts the dominant form of regeneration in a lowland Quercus pubescens-Quercus frainetto remnant forest in Northeastern Greece? A regeneration analysis in the context of grazing

摘要

The present study was conducted in a lowland degraded Quercus remnant forest in northeastern Greece. In 2006, ten plots of 50 m x 50 m were randomly selected in two site types. Site type A is covered by Quercus pubescens-Quercus frainetto stands that are under grazing pressure. In Site type B there are Q. pubescens stands and grazing pressure is more intense. Inside these plots 180 subplots of 2 m x 2 m were established in three regeneration environments and the number of sprouts and seedlings was counted. The three regeneration environments were: (a) rather dense groups of trees, (b) areas with bare soil that alternate with areas with grazed herbs and (c) areas covered only from sparse scattered trees. Moreover the regeneration plants were classed as recently grazed and not recently grazed plants. Six years later, 180 regeneration plants having a height equal to or over 20 cm were selected and were classed as seedlings or sprouts. Sprouts were the dominant form in regeneration. The sprouting ability of Q. pubescens and Q. frainetto seems to be an adaption that enables them to endure grazing. Grazing was the main factor that determined the distribution of regeneration. The ecological differences of the two species do not seem to substantially influence their distribution in the different regeneration environments. It seems that intense grazing keeps the regeneration plants in low height. However, regeneration density can be considered adequate for the perpetuation of the studied stands if the grazing stops.