Distribution, drivers and restoration priorities of plant invasions in India

Abstract

Biological invasions threaten biodiversity and human wellbeing, with developing tropical countries being more vulnerable. Despite the urgency to reduce impacts of invasions, management interventions are constrained by unavailability of timely information on invasive species occurrence, potential drivers and restoration priorities. Generating this information at biogeographic scales can be costly, unless integrated with multi‐objective biodiversity monitoring. Invasive plant monitoring is integrated with India's national‐scale tiger population assessment, wherein natural areas are sampled at 25 km2 scale to inventory plants. In 2018, a total of 158,979 plots were sampled covering ~358,550 km2. We used 206,393 locations of high concern invasive plants to model their distribution using socio‐ecological covariates and identify potential drivers of invasions. Considering the invasion magnitude and financial constraints in management, we further identified priority restorations sites at national‐scale to maximise biodiversity outcomes. High‐concern invasive plants were recorded from ~254,880 km2 (72% sampled area) and modelled to invade in total ~750,905 km2 (66%) Indian natural systems. While open and deciduous ecosystems were the highest invaded by woody plants, areas with extreme climate and less anthropic pressure were least invaded. Since managing invasions across their range seemed futile due to costly (~13.5 billion USD for one‐time management) and ineffective strategies, restoration priority was assigned to least invaded areas (11% protected areas, 23% multi‐use) to maximise biodiversity returns. Synthesis and applications: India implemented national‐scale invasive plant monitoring by integrating it with the umbrella project on tiger assessment. Embarking on this big data, we show that two‐thirds of India's natural areas are under multiple plant invasions, owing to the legacy of anthropogenic modifications. Our study offers a restoration priority model, empowering policymakers to devise adaptive strategies for restoring invaded biomes and maximizing biodiversity returns.

A nature-positive future with biological invasions: theory, decision support and research needs

“…Decision-making needs to be informed by a prioritization process that identifies where the largest contributions to NPF-BI can be achieved, along with identifying the overarching management objective/goal for priority landscapes [ 78 ]. For example, 66% of India's natural areas are invaded making it impossible to manage the full extent of invaded area for invasions [ 79 ]. Management activities (eradication, control and restoration) are therefore prioritized in areas with guaranteed biodiversity returns [ 79 ].…”

“…For example, 66% of India's natural areas are invaded making it impossible to manage the full extent of invaded area for invasions [ 79 ]. Management activities (eradication, control and restoration) are therefore prioritized in areas with guaranteed biodiversity returns [ 79 ]. For example, the ‘restorative continuum’ from reducing societal impact, through to restoring ecological function (rehabilitation) to recovering native ecosystems (restoration) provides clear direction for the appropriate setting of stewardship goals to achieve a NPF-BI across a range of contexts [ 77 ].…”

Evaluating the potential for reintroducing the endangered wild water buffalo (Bubalus arnee) in Kanha National Park, central India

“…Low forage quality and availability in Banjar grasslands was likely due to high herbivory pressure from the high densities of small‐sized herbivores (Awasthi et al 2016), as well as intensive grassland burning that likely promoted less palatable but fire‐resistant species (Pandey 1982; Pandey & Haradha 2007). Unlike the grasslands in semiarid region in India, which naturally have relatively lower aboveground biomass, mesic savannas support higher aboveground biomass, which is increasingly observed to change from grassy to woody composition (Sankaran & Ratnam 2013; Rastogi et al 2023; Mungi et al 2023 a , 2023 b ). As our study shows the aboveground biomass of the grassland systems of Kanha in the absence of megaherbivores, high densities of small‐sized herbivores and frequent management burning have resulted in being dominated by coarse species with less forage quality.…”

“…Megaherbivores are keystone species as they influence ecosystems by modifying species composition, nutrient cycling, primary productivity, fire, and water regimes (Owen-Smith 1988). Increasingly, research is linking their decline (Smith et al 2018) to a cascade of co-extinctions (Keesing & Young 2014), trophic degradation (Estes et al 2011), altered fire regimes (Rule et al 2012;Karp et al 2021), an increase in invasive species (Mungi et al 2023b), and a lasting anthropogenic impact on the biosphere (Malhi et al 2016;Enquist et al 2020). On the other hand, areas with persistent megaherbivores occurrence and areas where they have recovered showcased biodiversity stewardship amidst global changes, supporting the rationale of their recovery for self-sustained ecosystems and allied services (Svenning et al 2019;Malhi et al 2022).…”