Nitrogen mineralization in a high altitude ecosystem in the Mediterranean phytogeographical region of Turkey.

ABSTRACT

Interrelations exist in the terrestrial ecosystems between the plant type and characteristics of nutrient uptake. Annual net nitrogen mineralization in soils of different plant communities in the high altitude zone of Spil mountain located in the Mediterranean phytogeographical region of Turkey was investigated throughout one year by field incubation method. Seasonal fluctuations resulting from field incubation were markedly higher in autumn and spring than summer. These are mainly associated with the changes in soil moisture being at minimum in the Mediterranean summer. A significant correlation was developed between the net Nitrate (kg NO3--N ha week-1) production and soil water content (p<0.05; r =0.316 in soil of 0-5 cm; r =0.312 in soil of 5-15 cm). The results showed that the annual productivity of nitrogen mineralization shows different values depending on communities. Annual net ammonium (NH4+-N) production in the soils of each community was negatively estimated. However, annual net nitrate (NO3--N) production (0-15 cm) was higher in grassland (27.8 kg ha y-1) and shrub (25.0 kg ha y-1) than forest (12.4 kg ha y-1) community. While annual net Nmin values were close to each other in grassland (14.5 kg ha y-1) and shrub (14.1 kg ha y-1), but negative in forest community (-3.6 kg ha y-1). The reasons for these differences are discussed.