پتانسیل یابی نواحی مناسب کشت زعفران استان لرستان در تغییر اقلیم

Introduction

Climate change is one of the current and future challenges facing agricultural producers, ie it affects the type and amount of products produced and ultimately the income of farmers. Therefore, it should be predicted or simulated in a way using various tools in the field of management of this work, so that according to it, the necessary planning and policy-making can be done, finally, while providing food security for consumption. Maximum welfare of producers should also be provided. Considering the high economic value of saffron crop and recent climate change, the need to provide an alternative cultivation pattern for current crops in our country, especially in Lorestan province, such as saifi and horticulture, which need plenty of water, is felt more than ever. Although Lorestan province ranks first in the country in terms of grain production and in terms of figs, pomegranates and other horticultural products is one of the relatively well-ranked provinces, but the climatic conditions of this province is a good ground for expanding and cultivating more productive and profitable crops. It also has another such as saffron.



materials and methods

The length of the statistical period required for climate analysis is at least 25-30 years. The statistical period from 1990 to 2016 was selected using meteorological data from synoptic stations. For spatial-temporal analysis of indices in the future, first, the average of 2050 statistical periods was calculated for two scenarios: RCP 4.5 and RCP 8.5 for temperature and precipitation indices. Then, each of the means was compared with the statistical period of the current situation. Finally, with Spline geostatistical method in GIS10.5 software, zoning maps of 2050 period were prepared based on two optimistic and pessimistic scenarios and future positive and negative phases were analyzed. Also, after preparing the data, the score of each component The weights of descriptive information of each component were determined according to their importance in saffron cultivation in the region. The weighting range of descriptive information was considered between 1-5. In the last stage, the components were combined with each other in GIS environment according to the score and weight of their inner layers, and the optimal areas of saffron cultivation in the current and future situation were identified based on pessimistic (RCP 8.5) and optimistic (RCP 4.5) scenarios. .



Results and discussion

In the current situation, 15.8% of the province's area is in high priority areas, followed by relatively high and medium with 25.5% and 20.9%, respectively. These areas have different environmental constraints such as soil type, land use and unsuitable temperature. These areas can have saffron cultivation conditions with careful studies and adaptation measures. Relatively low priorities for saffron cultivation include mountainous areas with unsuitable temperature, slope and land restrictions. In the current situation, the most suitable cultivation areas for this crop are concentrated in the western and somewhat central areas of the province. Scattered areas in the northeast and north of the province are also suitable. Inappropriate areas include relatively low and low priorities in the eastern and southeastern areas. It is noteworthy that scattered areas in the southwest and north are also seen in two priorities. Future simulations show that climate change has a significant effect on the spatial change of suitable areas for saffron cultivation. By 2070, in the best conditions, according to the RCP scenario, 4.5 high-potential areas (high priority) will decrease by 1.5 percent, and areas with medium priority will increase by 4.8 and 6.3 percent, respectively. Without considering adaptation strategies and adopting appropriate management approaches in accordance with the RCP 8.5 scenario, saffron yield decreases due to climate change when temperature thresholds increase due to climate change. Suitable areas for its cultivation by 2070, areas with high and relatively high priorities will decrease by about 9 percent and areas with relatively low and low priorities will decrease by about 15.5 percent. With the reduction of these middle class areas, the priorities increase by 24.4% compared to the current situation. Scenario RCP 4.5 shows more balanced conditions than RCP 8.5 and moving from optimal conditions by considering adaptation strategies to create conditions without adopting adaptation strategies in saffron cultivation. In the simulation performed in RCP 4.5 scenario, with increasing temperature thresholds in three reproductive, vegetative and stagnation phenological periods of saffron growth, the desired areas from the west and the center of the province in the current situation have been transferred as a strip from north to southeast. In this scenario, the areas with moderate and relatively low priority are more scattered in the west, center and southeast. And low-priority areas are concentrated in the southwest of the province.

Conclusion

The reproductive period of saffron growth in Lorestan province is October. Spatial variations in the priorities of suitable areas for the reproductive period Saffron growth based on the average temperature in the reproductive period in the current situation is 2% of the total area, which is located in the northern and eastern regions of the province. The growing season of saffron in Lorestan province is from November to May. The area of priorities of suitable areas for the growing period of saffron, based on the average temperature index in the current situation, is the highest area with high priority (66%), followed by medium priorities (26%) and low priorities (8%). The period of stagnation of saffron growth in Lorestan province is from April to September. The area of priorities of suitable areas for the period of stagnation of saffron growth based on the average temperature index is the dominant spatial pattern with low priority and its area is 99%. High priority areas with 1% are scattered in the north and east.