Climate Suitability, Environmental Heterogeneity and Anthropogenic Factors Jointly Shape the Spatial Patterns of Alien Plant Distributions Across India

Abstract

Aim

Studying the spatially-explicit patterns and predictors of alien species' distributions is crucial in mapping and management of biological invasions. Despite a lot of research progress made so far, there are still wide knowledge gaps from the Global South. Here, we present a curated spatial dataset covering ~1 lakh records on alien plant distributions across India. Leveraging this novel dataset and considering vast environmental and anthropogenic gradients across the country, we employ fine-scale predictors to test three major invasion hypotheses: rich-get-richer, environmental heterogeneity and human disturbance.

Location

India.

Major Taxa Studied

Alien plants.

Methods

We mapped multi-scale spatial patterns of alien plants across 472 (100 × 100 km) grid cells, 51 ecoregions, 19 anthromes, and 614 protected areas of India. We used generalized linear models and hierarchical partitioning to assess the relative influence of climatic, environmental, and anthropogenic variables on the spatial patterns of alien plant species richness across the country.

Results

We found substantial spatial heterogeneity in alien plant distributions across India, with tropical southern and eastern regions supporting substantially higher species richness than the northern and western regions. The alien species richness showed a negative latitudinal trend, peaking ~20° latitude and declining sharply toward northern latitudes. At the anthrome level, alien plant distributions were predominantly associated with human-dominated landscapes. The alien plants were also widespread within the country's protected areas, and worryingly, with much higher richness in their peripheries. Our findings demonstrate that the alien plant distributions in India are jointly shaped by climate suitability, environmental heterogeneity, and anthropogenic gradients, with the human footprint index being the most dominant predictor.

Main Conclusions

Our study, by unravelling spatial patterns and underlying predictors of alien plant distributions, provides empirical support for multiple global invasion hypotheses and furnishes a spatially explicit framework for formulating invasion management strategies in this continental-scale country, with lessons for elsewhere in the Global South.