Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation

Heydari M, Pothier D, Faramarzi M, Merzaei J. 2014. Short-term abandonment of human disturbances in Zagros Oak forest ecosystems: Effects on secondary succession of soil seed bank and aboveground vegetation. Biodiversitas 15: 147-161. Zagros Oak forests in the west of Iran have been degraded by anthropogenic activities during many years and to fight against this degradation, several management strategies have been implemented. The principal objectives this study were to identify the characteristics of the soil seed bank and the aboveground vegetation that were affected by degradation and short-term abandonment of human disturbances and evaluate the potential of the soil seed bank to restore the degraded types after short-term conservation management. For that, we compared three types of Zagros forest ecosystem with different management regimes: (1) Long term disturbed type as LDT (also used and disturbed at the present), (2) Short-term abandonment of human disturbances as SAD (5 years without human disturbances) and an undisturbed control or C (3). We selected three replicates or stands per type. In the aboveground vegetation (ABV), 115, 72 and 51 species were recorded in C, SAD and LDT types, respectively, whereas in the soil seed bank (SSB) flora, 33, 19 and 12 plant taxa were observed in C, SAD and LDT types, respectively. The percentage of annuals increased in ABV and decreased in SSB with increasing site degradation with human activities such as animal husbandry in the forest edges. The percentage of perennial and biennial herbs decreased in ABV and increased in SSB with increasing site degradation. The Shannon index of the SSB decreased with increasing site degradation. The average seed density in the SAD type was significantly larger than that of the LDT type. DCA analysis showed that the seed bank flora of SAD and LDT types were relatively similar and differed from that of the C type. This indicates that a full recovery of degraded type in the oak forest ecosystem in the Zagros region cannot be based only on the soil seed bank present at the beginning of the protection period while a more complete recovery may require a longer period of protection.