حرا

Effective mangrove mapping needs reliable indices that can characterize mangroves from other land cover types on remote sensing data. Currently, a variety of vegetation- and mangrove indices are available, while a comparative assessment of their efficiency seems essential. The aim of this study was to evaluate six vegetation indices and seven mangrove indices developed for Sentinel-2 imagery to obtain a robust approach in mangrove mapping within Google Earth Engine (GEE) cloud computing platform. The rasterized indices were classified by support vector machine. The final maps were evaluated by area under curve (AUC) of receiver operating characteristic (ROC) in addition to common accuracy assessment criteria. Results showed that mangrove indices were more reliable than vegetation indices. Amongst the vegetation indices, Modified Chlorophyll Absorption in Reflectance Index (MCARI) (AUCmangrove from 0.91 to 0.92) achieved the highest AUC values, while MFI (Mangrove Forest Index) returned the highest values amongst the mangrove indices (AUCmangrove from 0.93 to 0.95). All in all, results revealed that MFI on Sentinel-2 imagery in GEE was efficient in mangrove mapping within the study sites.

The aim of the study was to investigate the survival and growth of the grey mangrove seedlings (Avecennia marina Forsk) at different planting treatments on tidal zone of a natural mangrove forest at northern coasts of Qeshm Island (Pesian Gulf). The trial was conducted at two sites separately، one on lower tidal zone and the other one on upper tidal zone. At each site the trial was conducted under the statistical design of split plots and randomizaed complete blocks at tree replicates. The treatments consisted of two planting distance as main plots (1×1 and 0. 5×0. 5 m) and two seedling sources (coastal and non-coastalnurseries or irrigated with saline and sweet water). For this purpose، 720 mangrove seedlings of Avicennia marina Forsk were selected from the coastal and non-coastal nurseries and were transported to the plantation sites and were planted on the two upper and lower -tidal zones. the seedlings survival and growth characteristics were recorded during 18 months. ANOVA analysis and Duncan test was applied for data analysis، using SAS computer program. The results showed that 82. 9 percent of the planted grey mangrove seedlings survived 18 months after planting. The survival rate of the saline water irrigated seedlings planted on lower tidal zone with planting distance of 1×1 m، was the highest (92%) whereas the survival rate of the sweet water irrigated seedlings، planted at upper tidal zone with planting distance of 1×1 m and was the lowest (74%). Overall، it might be concluded that the seedlings planted under the protection of natural grey mangrove stands، with planting distanceof 1×1 m on the lower tidal zone، obtained the greatest survival and growth records.