Fig 1.
The geographical locations of the investigated sites (Dashed lines) based on the highest cropland area in Iran.
The percentage of sites studied in any climatic types are shown in the legend of the figure. Dashed lines indicate Urban boundaries. Köppen-Geiger climate classification map obtained from Forest, Range and Watershed Managment organization (http://www.frw.ir). This maps was realised with ArcGIS 10.8 (http://www.esri.com/arcgis) using the georeferenced shapefiles obtained from the National Geographical Organization of Iran and National Cartographic Center (https://www.ncc.gov.ir/en/) at a scale of 1:11,000,000.
Fig 2.
Area of 7 major crops and other crops and vegetables in total (A), rainfed (B) and irrigated (C) cropland in Iran between 1983 and 2018.
Fig 3.
Spatial distribution of Shannon diversity index (H’) trends and tendencies in total (A, B), rainfed (C, D) and irrigated cropland (E, F) in Iran between 1991 and 2018. Significant positive and negative trends are shown by (▲) and (▼) and insignificant upward and downward trends are depicted by (△) and (▽), respectively. White circle (○) also indicates the lack of rainfed cultivation in the site. Besides, the numbers next to the triangle and circle indicate the average rate of change (slope) (B, D and F) and standard deviation (STDV) (A, C and E) in the variable, respectively. Complete time series are shown in S2 Fig. Also, the root-mean-square error (RMSE) of the interpolated values based on the inverse distance weighting method (IDW) to actual data values was specified at the bottom of each figure. Figures were realised with ArcGIS 10.8 (http://www.esri.com/arcgis) using the shapefile of the map of Iran obtained from NCC (https://www.ncc.gov.ir/en/) and Kendall R-package.
Fig 4.
Spatial distribution of Simpson diversity index trends and tendencies in total (A, B), rainfed (C, D) and irrigated cropland (E, F) in Iran between 1991 and 2018. Significant positive and negative trends are shown by (▲) and (▼) and insignificant upward and downward trends are depicted by (△) and (▽), respectively. White circle (○) also indicates the lack of rainfed cultivation in the site. Besides, the numbers next to the triangle and circle indicate the average rate of change (slope) (B, D and F) and standard deviation (STDV) (A, C and E) in the variable, respectively. Complete time series are shown in S3 Fig. Also, the root-mean-square error (RMSE) of the interpolated values based on the inverse distance weighting method (IDW) to actual data values was specified at the bottom of each figure. Figures were realised with ArcGIS 10.8 (http://www.esri.com/arcgis) using the shapefile of the map of Iran obtained from NCC (https://www.ncc.gov.ir/en/) and Kendall R-package.
Fig 5.
Spatial distribution of Simpson evenness index trends and tendencies in total (A, B), rainfed (C, D) and irrigated cropland (E, F) Iran between 1991 and 2018. Significant positive and negative trends are shown by (▲) and (▼) and insignificant upward and downward trends are depicted by (△) and (▽), respectively. White circle (○) also indicates the lack of rainfed cultivation in the site. Besides, the numbers next to the triangle and circle indicate the average rate of change (slope) (B, D and F) and standard deviation (STDV) (A, C and E) in the variable, respectively. Complete time series are shown in S4 Fig. Also, the root-mean-square error (RMSE) of the interpolated values based on the inverse distance weighting method (IDW) to actual data values was specified at the bottom of each figure. Figures were realised with ArcGIS 10.8 (http://www.esri.com/arcgis) using the shapefile of the map of Iran obtained from NCC (https://www.ncc.gov.ir/en/) and Kendall R-package.
Fig 6.
Spatial distribution of Species richness index (S) trends and tendencies in total (A, B), rainfed (C, D) and irrigated cropland (E, F) in Iran between 1991 and 2018. Significant positive and negative trends are shown by (▲) and (▼) and insignificant upward and downward trends are depicted by (△) and (▽), respectively. White circle (○) also indicates the lack of rainfed cultivation in the site. Besides, the numbers next to the triangle and circle indicate the average rate of change (slope) (B, D and F) and standard deviation (STDV) (A, C and E) in the variable, respectively. Complete time series are shown in S5 Fig. Also, the root-mean-square error (RMSE) of the interpolated values based on the inverse distance weighting method (IDW) to actual data values was specified at the bottom of each figure. Figures were realised with ArcGIS 10.8 (http://www.esri.com/arcgis) using the shapefile of the map of Iran obtained from NCC (https://www.ncc.gov.ir/en/) and Kendall R-package.
Fig 7.
The relationship among Shannon diversity index (H’) (A), Simpson diversity index (B) and Species richness index (S) (C) in Iran between 1991 and 2018. The solid line is the polynomial (A) and linear (B, C) regression fit to the points (n = 1748). Significant trends (p ≤ 0.01) shown by **. Created using ggplot2 R-package.
Fig 8.
The trend of Shannon diversity index (H’) (A, B) and area under wheat (A) and barley (B) cultivation in Iran between 1991 and 2018. The relationship between Shannon diversity index (H’) and area under wheat (C) and barley (D) cultivation in Iran between 1991 and 2018. The solid line is the linear regression fit to the blue points (n = 28). Significant trends (p ≤ 0.01) shown by **. Created using ggplot2 R-package.
Fig 9.
List of crops and the frequency distribution of sites under their cultivation in Iran.
Created using ggplot2 R-package.
Fig 10.
The box-plot of Shannon diversity index (H’) (A), Simpson diversity index (C), Simpson evenness index (E) and Species richness index (S) (G) in different climate and cultivation types of Iran, and the trend of the diversity (B, D) and evenness (F) indices and Species richness index (H) in different cultivation types of Iran between 1991 and 2018. The solid line is the linear regression fit to the points (n = 27) and 95% confidence interval shown by light-gray shading. Significant trends (p ≤ 0.01 and 0.05) shown by ** and *, respectively. Created using ggplot2 R-package.