Global Climatic Niches of Vascular Plants Across Growth and Life Forms

Abstract

Climate niches define species’ adaptive boundaries, forming a fundamental basis for understanding global patterns of plant diversity. However, existing assessments remain scale-limited or geographically confounded, leaving the complete picture of plant climate niches poorly understood. Here, we systematically evaluate the climate niches of 314,625 extant vascular plant species across a two-dimensional, orthogonal climate space defined by thermal and hydrological gradients, comparing how these niches diverge across plant growth and life forms. Our findings reveal that species richness peaks in warmer, central-to-right regions of climate space, whereas peripheral areas support far fewer species, indicating that few taxa adapt to extreme climatic conditions. Globally, most species exhibit intermediate niche breadths, with very few extreme specialists or broad generalists. Furthermore, both climatic niche breadth and positioning vary substantially across strategies. Across vegetative strategies, self-supporting woody taxa (trees and shrubs) as well as climbers and epiphytes generally maintain broader niches than herbs and subshrubs. In terms of niche positioning, herbs and subshrubs occupy cooler niches and, together with shrubs, show a general shift toward drier environments. Among life forms, annual therophytes and phanerophytes occupy the broadest climate spaces through different strategies. Specifically, phanerophytes and nanophanerophytes dominate warm and humid macroclimates, cold-tolerant hemicryptophytes shift heavily into colder climate space, and annual therophytes display strong drought adaptation by overwhelmingly occupying hyper-arid zones. These marked niche divergences among plant strategies advance our understanding of life-history adaptations and provide a crucial theoretical framework for predicting species vulnerability and guiding biodiversity conservation under future climate change.