A Review on Ecological Causes of Oak Decline Phenomenon in Forests of Iran

In this study, all the papers about oak decline phenomena in forests of Iran have been reviewed. One hundred and twelve papers from 51 journals were reviewed, and the information presented in each paper was analyzed and finally summarized. Eighty seven percent of the papers were about Brant’s oak (Quercus brantii Lindl.). Most of the studies were focused on the pest and desease of oak decline. The relationship between decline and quantitative characteristics of trees has conflicting results. Concerning the relationship between decline and stand characteristics, only in two cases, the results were certain: the clump pattern of delined trees and the direct relationship between stand density and oak decline. The findings were contradictory in most cases about the relationship between the physiographic characteristics and the decline of trees. The certain result about the relation between decline and soil properties was that the decline of trees in shallow soils was more than deep soils. Regarding to climatic research, precipitation reduction and an increase of air temperature, wind speed, solar radiation, evapotranspiration, and dust increased the probability of decline or intensification of the phenomenon. Furthermore, the contribution of local people to confront the oak decline and reinforcing of their economies was emphasized in various studies. According to the literature reviews, the use of crescent-shaped bound with preservation of region, and the sanitation cutting of branches will be more likely to decrease the process of decline in trees. Overall, publishing papers suggest two important features of the oak decline phenomenon, including multidimensionality, complexity and sporadic research. Also, it seems that as time passed, the range of areas affected by this phenomenon has increased and the lack of essential research about this phenomenon is felt.