The growth of trees is governed by an array of internal and external factors. Trees respond to various environmental changes such as climate and hydrological changes. Comparing the pattern of tree-ring widths among different trees of a region and determining the exact year of ring formation underlie the basis knowledge of dendrochronology. The purpose of this study was to evaluate the effects of climatic and hydrological changes on Hormozgan mangrove ecosystems and Zayandehrood riparian trees using dendrochronology. Accordingly, the study area was divided in two separate parts. The first part comprised of Zayandehrood River Basin in Isfahan and Chaharmahal Bakhtiari Provinces. Plane trees (Platanus orientalis) were sampled based on proximity to hydrometric stations. The second part was taken as of mangrove trees (Avicennia marine) in Hormozgan province. Samples were collected from three mangrove areas, Hara, Minab and Gaz. Tree-ring widths of plane trees were first measured and followed by cross-dating and standardization to do the calibration to compare them with climatic and hydrological data. The relationships between tree-ring width variations were tested according to 113 climate variables including SPI, precipitation, temperature, water discharge and water quality parameters, at annual, seasonal, monthly, and growing season periods. Then, regression analysis was used to estimate the response of tree-ring widths to climatic and hydrological variables. The results showed that in the final model, the sensitivity of tree-ring widths in downstream area of Zayandehrud basin was related to water discharge, and then followed by precipitation. Moreover, the January water discharge and spring precipitation included in the final model. In the midstream, the tree-ring widths showed the highest correlation with April water discharge, February precipitation and water discharge and finally the average January temperature. In the upstream, the tree-ring widths showed the highest correlation with the minimum January temperature, April water discharge, growing season precipitation, minimum autumn temperature, TDS and K, respectively. Then, using a linear regression analysis, we reconstructed the climatic variables based on tree-ring widths. Reconstruction was performed based on the correlation analysis between tree rings widths and climatic and hydrological variables. The best coefficients of determination were obtained as follow: January water discharge in downstream as 0.42, in the Midstream water discharge in April as 0.37 and in upstream, April precipitation 0.33. This study showed that Plane trees at different altitudes and different vegetative conditions differed in response to climatic and hydrological factors. Concerning mangrove trees, the tree growth rates were investigated under the influence of environmental parameters such as sea surface temperature (SST) and sea water salinity. The results of this study showed that environmental conditions such as sea surface temperature (SST) and sea water salinity had a significant effect on the tree growth which was recorded as annual growth rate. To gain more insights into mangrove trees, it remains a gap which needs further studied on the planted trees whose their age is clear. In general, the 121 results of mangrove analysis showed that sea surface temperature (SST) and sea water salinity with coefficients of determination of 0.4 and 0.9, respectively, had significant impacts of the growth of studied mangrove tree. Keywords: Platanus orientalis, Avicennia marina, Dendrochronology, Climatic and Hydrological variables, Zayandehrood River.