Effect of gap size and forest type on mineral nitrogen forms under different soil properties

Gaps play a key role in forest ecosystem development and result from either natural processes or targeted forest management activities. The aim of this study was to investigate the interrelationships of soil properties in each of three forest types and two treatments, and to identify factors that influence levels of soil mineral nitrogen forms. The relation between mineral nitrogen and factors of soil parameters and stand type (European beech, Norway spruce, mixed stand) categories were investigated. The spruce forest type stored significant nitrogen in both mineral forms of nitrogen. Moreover, there was a significant linear dependence between N–NO (nitrate anion) concentrations and cation exchange capacity (CEC) parameters such as base cation contents (S-CEC) and potential ureolytic activities (UreasePot), as well as between N–NH (ammonium cation) concentrations and both hydrolytic acidities (Ha-CEC) and ureolytic activities. The dependence of N–NO concentrations on S-CEC contents and UreasePot was negative, especially in adjacent stand. The dependence of N–NH concentrations on Ha-CEC and UreasePot was week in the beech and mixed forest types while it was significantly positive in the spruce forest type.