Environmental constraints and species adaptive strategies drive plant
longevity in Himalayan high-mountain plants
Abstract
Plant lifespan has important evolutionary, physiological, and ecological
implications related to population persistence, community stability, and
resilience to ongoing environmental change impacts. Although biologists
have long puzzled over the extraordinary variation in plant lifespan and
its causes, our understanding of interspecific variability in plant
lifespan and the key internal and external factors influencing longevity
remains limited. Here, we demonstrate the concurrent impacts of
environmental, morphological, physiological, and anatomical constraints
on interspecific variation in longevity among >300 vascular
dicot plant species naturally occurring at an elevation gradient
(2800-6150 m) in the western Himalayas. First, we show that plant
longevity is largely related to species’ habitat preferences.
Ecologically stressful habitats such as alpine and subnival host
long-lived species, while productive ruderal and wetland habitats
contain a higher proportion of short-lived species. Second, longevity is
influenced by growth form. Small-statured cushion plants with compact
canopies and deep roots, most found on cold and infertile alpine and
subnival soils, had a higher chance of achieving longevity. Third, plant
traits reflecting plant adaptations to stress and disturbance modulate
interspecific differences in plant longevity. Importantly, we show that
longevity and growth are negatively correlated. Slow-growing plants are
those that have a higher chance of reaching a maximum age. Finally,
changes in plant carbon, nitrogen, and phosphorus content in root and
leaf tissue were significantly associated with variations in longevity.
We discuss the link between the longevity and productivity and stability
of studied Himalayan ecosystems and the intrinsic growth dynamics and
physiological constraints under increasing environmental pressure.