IRANIAN JOURNAL OF APPLIED ECOLOGY
Year:2019 | Volume:8 | Issue:1|Papers Count:6

Rainfall erosivity is one of the factors determining the amount of water erosion in the soil. Rainfall erosivity is determined by the total rainstorm energy and the maximum intensity in 30 minutes (I30). Since rainfall erosivity is closely related to the amount and intensity of rainfall, it is expected that the rainfall erosivity would change monthly and seasonally throughout the year. The main objective of this study was the spatial and temporal variation modeling of rainfall erosivity, erosivity density and their impacts on the soil erosion in Menderjan watershed. In this research, by using rainfall data with 1 minute from the rain gauge in the proximity of the basin during the 11-year statistical period (2005-2015), the rainfall erosivity factor (R) was calculated on a monthly average; then it was mapped using geostatistical technologies. Comparison of the monthly, seasonal and annual rainfall erosivity maps showed the highest rainfall erosivity occur in autumn (about 41 percent), while the lowest one was recorded in summer (less than 1%), respectively. According to the results obtained the maximum amount of erosivity was observed in November, which was 65 (MJ. mm. ha-1. h-1. month-1), while the lowest amount was observed in August. This study showed that the highest risk of soil erosion was expected to occur in November, because this month is not only the time of rainfall erosion, but also involves a high erosion density.

Replacement of the usual harvesting sugarcane method (burning field before harvesting) by green harvesting method could be the most important factor contributing to the ecological balance and stable sugarcane production in the Khuzestan region. To evaluate the green harvesting sugarcane method and its effects on the agronomic and physiological characteristics of sugarcane cultivars, a field experiment was conducted in Imam Khomeini Agro Industry during the 2015-2016 period. The experiment was carried out using a split plot design based on complete randomized block with four replications. Cultivars of Sugarcane as the main plots (CP73-21, CP69-1062 and CP69-1062) and five harvesting methods and ratooning as the sub plots were investigated. The results showed green harvesting method had a significant negative effect on nearly all agronomic and physiologic characteristics. Yield was reduced about %12. 5 in the green harvesting methods. On the other hand, the results showed water consumption was substantially decreased (10, 000 m-3) in the green harvesting method. Regarding problems in water supply for agricultural production in Iran, green harvesting of sugarcane could play an important role in ecosystem sustainability and sugarcane production of Khuzestan, aiding the better consumption of natural resources.

The Baluchistan Black Bear (BBB), a critically endangered subspecies (CR), is distributed in the southeastern Iran. Modelling of landscape connectivity of the BBBs among habitat patches can be insightful for the conservation managers working in Iran. Our study was designed to identify the potential corridors among 31 habitat patches of the BBBs in Iran using the circuit theory method. Habitat suitability map was generated in MaxEnt using 101 presence points and nine environmental variables, which were later inversed and used in corridor modeling. By using the circuit theory method, areas of high migration density were compared with four clusters determined in a previous study based on the least-cost model. Three main clusters with the high migration density of BBB were detected. Moreover, we identified eight insular habitat patches of the species that required urgent management actions to connect with other patches in the southeastern Iran. Circuit theory method clearly confirmed the main clusters introduced for the conservation of the BBBs in the southeastern Iran. Results of this study could be, therefore, used as a suitable pattern for the conservation priorities of BBBs habitats in this part of Iran.

Habitat destruction is the most important factor determining species extinction; hence, the management of wildlife populations necessitates the management of habitats. Habitat suitability modeling is one of the best tools used for habitat management. There are several methods for habitat suitability modeling, with each of having some different advantages and disadvantages. In this study, we used 15 modeling methods along with 9 environmental factors including Bio1, Bio2, distance to roads, distance to residential areas, distance to agricultural lands, distance to streams, the percentage of slope, geographic aspect, and NDVI to model the Persian squirrel’ s habitat suitability in the forests of Luristan Province. The AUC of each model was computed and the models with an AUC higher than 0. 9 were selected. Finally, the output maps resulted from the selected models were multiplied by their AUC and the average of them was considered as a combined model. In this study, Maximum Entropy, Boosted Regression Tree, Generalized Linear Model, and Random Forest were the only models with an AUC higher than 0. 9. Based on the combined model, 66% of the forest areas in Luristan Province could be suitable for the Persian squirrel, of which 32. 1%, 18. 4%, and 15. 5% have low, moderate, and high suitability, respectively. Among the 9 environmental factors used in this study, distance to roads, distance to agricultural lands and NDVI showed the highest contribution in the habitat suitability of the Persian squirrel. This study indicated that the combination of high-accuracy models could yield more reliable results, as compared to their separate use.

This study was aimed to predict the potential distribution of Ferula ovina (Boiss) in Feridoonshar, in the western part of Isfahan province, and to produce species response curves in relation to the environmental variables using the Generalized Linear Model (GLM). The presence and absence of the species in 278 sites (including 138 presence sites & 140 absence sites) were collected using random stratified sampling. Digital elevation model was used to produce elevation classes, aspect and slope maps. Seventy soil profiles and 10 climate stations data were used to produce 31 environmental maps including climate and soil maps using kriging methods. According to the results, the presence of Ferula ovina was correlated with silt percent, average annual temperature, elevation, organic matter content, soil saturation percentage and CaCO3 content. The produced species distribution model had high accuracy, as indicated by calculated Kappa coefficient (0. 79) and ROC area under curve plots (0. 83). The result of this study can be, therefore, used in the rehabilitation and restoration of this valuable species in the rangeland ecosystems.

In this study, the quality of groundwater aquifer of Gavkhooni basin was investigated in agriculture. For this purpose, water quality data related to 96 wells prepared by Isfahan Regional Water Authority during the statistical period 2015-2016 were used. In this study, sodium parameters, electrical conductivity, chloride, hydrogen bicarbonate and sodium absorption ratio (SAR) were used. Then, groundwater quality classification across the study area was carried out using agricultural water quality index (IWQI), which is based on the FAO standards. Results of IWQI varied from 40 to 80, corresponding to high and low limitations for agricultural use. It was shown that groundwater quality had declined over years from the upstream to the downstream of the basin. Furthermore, some changes in the quality index in the northern region of the study area were found to be more affected by the climate conditions of the region. In the middle and eastern territories, the surface streamflow of Zayandehroud River and agricultural activities had caused changes in the water quality. In general, in the Gavkhooni area, excessive groundwater exploitation, drought conditions and agricultural activities had reduced the groundwater quality. By reducing groundwater withdrawals and agricultural activities in areas where water is required only through water drainage, groundwater quality can be managed, even in dry years.