Diverging consequences of past forest management on plant and soil attributes in ancient oak forests of southwestern Iran

Abstract

The oak (Quercus brantii Lindl.) semiarid forests of western Iran are among the oldest and host a remarkable diversity. However, the originally high forests were largely converted to coppices and submitted to a long history of traditional management and human disturbances. We investigated the effect of past management and forest structure on soil properties and vegetation diversity on two forest systems: coppice‐with‐standards stands abandoned after an intense period of exploitation (CWS) and high forest stands (HF) submitted to a low intensity of management. We selected in each system three 1–2 ha stands and sampled 30 plots to measure vegetation diversity, forest structure using structural indices and, main soil factors including bulk density, nutrients, organic carbon and porosity. We found a higher species diversity in HF than in CWS with respectively 7 woody species in the former and only 4 in the latter as well as a higher structural complexity. Plant composition differed also between the two systems and multivariate analyses revealed clear associations between vegetation composition and soil factors in particular soil nutrients, soil porosity for HF and bulk density and texture for CWS. In fact, contents in soil nutrients were higher in HF than in CWS for total nitrogen (0.28 vs 0.15%), available phosphorus (22.82 vs 15.47 ppm), available nitrogen (0.28 vs 0.15 ppm), and organic matter (2.58 vs 1.61%) whereas soils of CWS showed a higher bulk density (1.39 vs 1.29) and a lower porosity (47.66 vs 51.50%). This study thus revealed the legacy of the past forest management actions on the different components of the forest ecosystem. We concluded that the conservative management in high forests was more favourable for the protection of soil and vegetation diversity than in the traditional coppicing system.