Fig 1.
Map showing the bounding boxes used to delimit the geographical extent of species occurrence data and bioclimatic data used for model calibration in the training ranges of North and South America, Europe, Africa and Australia; and the bioclimatic data for the projected range in the Indian region.
Table 1.
Environmental variables used for modelling and delineating invasion hotspots.
Fig 2.
Box plot showing distribution of mean AUCtrain and AUCtest values for the selected alien invasive plants in each of the model training continents.
In the figure, the boxes represent 25–75 percent quartiles of the AUC values, and the horizontal line inside the boxes represents the median. The minimal and maximal values are shown with whiskers drawn from the top of the box up to the largest data point less than 1.5 times the box height from the box, and similarly below the box. The circles represent the outlier values, and the stars represent the extreme values.
Table 2.
Consolidated result showing the number of species categorized under various model grades on the basis of species-specific mean AUCtrain and AUCtest values in the respective training ranges.
Grading of model quality was done based on AUC value as: Poor (<0.8), Fair (0.8–0.9), Good (0.9–0.95) and Very good (0.95–1.0).
Fig 3.
Climatic suitability map for diverse alien plant species in India based on continent of origin.
A-E show the model consensus identified by summing up the thresholded model projections for multiple species from—(A) Africa, (B) Australia, (C) Europe, (D) North America, and (E) South America. The figure legend show the model agreements, wherein ‘high’ represents the areas with highest model agreement, and ‘very low’ having the lowest agreements. Higher model agreements represent larger number of alien invasive species while the lower model agreements represent lower number of alien invasives.
Fig 4.
Model consensus classes depicting climatic suitability for diverse IAS in India.
The bar diagram depicts the percentage of total geographical area under various consensus class in different states of India. The climate suitability map was generated by combining 525 thresholded model projections from Africa, Australia, Europe, North America and South America. The legend show the model agreements, wherein 'high' represents the areas with highest range of model agreements, and 'very low' having the lowest range of model agreements. 'High' agreement represent high species richness, while 'low' agreement represent low species richness.
Fig 5.
Invasion hotspots in India delineated through intersection of ecoregions, multi-species ecological niche model consensus, and anthropogenic biomes.
The delineated areas cover >50 percent area of various ecoregions, are climatically suitable for a large number of invasive alien species, and have signature of diverse anthropogenic activities. The boundary files on biodiversity hotspots were overlaid on the modelled invasion hotspots matches to portray the level of threat to these areas from invasive alien species.
Fig 6.
Matrix depicting the 3 components viz. climatic suitability, ecoregions and anthropogenic biomes, used for delineation of invasion hotspots in India.
The identified ecoregions have > 50 percent of its area under the high climatic suitability. The numbers on top of the matrix indicate the major categories of anthropogenic biomes: Croplands: (11) Residential irrigated cropland, (12) Residential rainfed mosaic, (21) Populated irrigated cropland, (22) Populated rainfed cropland, (23) Remote croplands; Forested: (24) Populated forests, (25) Remote forests; Rangelands: (26) Residential rangelands, (31) Populated rangelands, (32) Remote rangelands; Urban: (33) Urban, (34) Dense settlements; Villages: (35) Rice villages, (41) Irrigated villages, (42) Cropped & pastoral villages, (43) Pastoral villages, (51) Rainfed villages, (52) Rainfed mosaic villages; Wild Land: (61) Wild forests, (62) Sparse trees, (63) Barren. Description of the anthropogenic biomes is given in Ellis and Ramankutty (2008), and details on ecoregion-wise information can be viewed at http://www.globalspecies.org/ecoregions. The filled boxes signify representation of the particular anthropobiome in each ecoregion.