Functional Diversity and Ecological Niches of C₄ Climate-resilient Species to Guide Island Ecosystem Restoration

Vanézia Rocha¹Maria M. Romeiras¹Maria José Vasconcelos¹Maria Cristina Duarte^2*

• ¹Universidade de Lisboa Instituto Superior de Agronomia, Lisbon, Portugal
• ²Faculty of Sciences, University of Lisbon, Lisbon, Portugal

Arid ecosystems impose particularly harsh conditions on plants. To thrive, many species have evolved a range of adaptive traits, among which those with C₄ photosynthesis are recognised for their high efficiency in hot and dry environments. Therefore, these species are considered crucial for the restoration and management of dry tropical ecosystems. However, their ecological and functional roles remain poorly understood on oceanic islands such as Cabo Verde. This study, based on herbarium records, GBIF occurrences, and validated field data, presents an analysis of the functional diversity of 162 C₄ species (4,846 occurrences) recorded in the Cabo Verde Islands, representing about 21.6% of the vascular flora of the archipelago. The species were characterised by their functional traits (including life cycle, habit, salinity tolerance, and photosynthetic subtypes NADP-ME, NAD-ME, and PEP-CK), altitudinal distribution, and climatic preferences for temperature and precipitation. The results reveal marked differences in ecological distribution between C₄ eudicots and monocots: eudicots are more frequent in arid and saline habitats at low elevations, whereas monocots occupy a wider ecological range. C₄ halophytes, in particular, show promise for nature-based solutions such as coastal revegetation and soil restoration in degraded areas. The analysis highlights species with strong potential for revegetation and ecosystem management, especially in insular contexts exposed to water scarcity and climate stress. Salinity-adapted annuals and perennials are especially relevant, along with C₄ lineages linked to photosynthetic subtypes that confer enhanced environmental resilience. This functional and ecological assessment provides a scientific basis for selecting climate-resilient species to support revegetation and sustainable management of fragile dry tropical island ecosystems. Indeed, understanding the functional differences between C₄ monocots and C₄ eudicots is essential for developing climate-smart revegetation strategies. The approach adopted here promotes the conservation of biodiversity through functional perspectives, offering a model of ecological action in vulnerable regions under climate change. The findings underscore the ecological preferences of the C₄ species and highlight their potential contributions to ecosystem function, resilience, and restoration.