Climate warming drives Himalayan alpine plant growth and recruitment dynamics

Abstract

Understanding how climate influences plant reproduction and growth at contrasting range limits is crucial for predicting how species' ranges may shift in response to ongoing climate change. Trees and shrubs have shown warming‐induced increases in performance at upper elevation limits but reduced performance at lower distributional limits due to warming‐driven drought limitation. Whether these differential responses are also valid for alpine forbs exposed to accelerated warming remains largely unknown. We examined climate signal recorded in annual growth and recruitment over the past 60 years in the alpine forb Potentilla pamirica in Western Himalayas, and tested whether the responses to recent climate warming differ between dry steppe, wet alpine and cold subnival zone within the species 5,250–5,900 m elevation range. We reconstructed recruitment and growth chronologies from 1,019 individuals spanning 1–73 years, and more than 21,500 annual growth rings. We identified contrasting climatic controls of recruitment and growth at opposite elevation range margins, as well as contrasting demographic trends identified from age distributions. In lower‐elevation steppes, recruitment increased with high late‐winter snowfall and decreased with high summer temperatures, while growth increased with high summer precipitation. Conversely, warm winters and summers in higher‐elevation alpine and subnival zones support growth and recruitment, while snowy winters reduce them, especially at their upper elevation limit. The age distribution revealed greater numbers of younger individuals, indicating healthy growing populations, in the alpine habitat, while evidence of ageing plant populations was observed in steppe and subnival zones. Accelerated warming since the 1990s reduced growth and recruitment in dry steppes while supporting plant performance in the alpine habitat. The recruitment in the subnival zone did not peak during the past warmest decade due to concomitant extreme snowfall events. Synthesis. Our results provide novel information on population‐specific climate dependency of plant recruitment, growth and population dynamics, suggesting the high vulnerability of high‐elevation Himalayan ecosystems to climate change. This is partly balanced by high species longevity and slow radial growth securing a long‐term population persistence. Continuing trends of extreme snowfall events at higher elevations and droughts at lower elevations may lead to species range contraction.

Contrasting biomass allocation responses across ontogeny and stress gradients reveal plant adaptations to drought and cold

“…Microscopic images of these sections were taken using Olympus BX53 microscope, Olympus DP73 camera and cellSense Entry 1.9 software. This enabled us both count the consecutive number of rings and measure the annual radial growth increments (Dolezal et al., 2020).…”

“…Data available from the Dryad Digital Repository https://doi.org/10.5061/dryad.ksn02v72k (Dolezal et al., 2020).…”

“…Given the overall small plant size and short path length for water transport from roots to leaves, the stomatal conductance limitation is less likely to explain the relative root prioritization in large alpine and subnival P. pamirica plants. Instead, there is probably additional mechanical stability gained from investing in roots to help reduce the risk of plant damage caused by frost heave and solifluction from repeated cycles of soil freezing and thawing (Neuner & Hacker, 2012), which poses a major challenge for larger plants in alpine and especially subnival zone (Dolezal et al, 2016(Dolezal et al, , 2020. We assume that both constant leaf fraction and root prioritization in large plants can significantly contribute to P. pamirica's long life span.…”

Climate fluctuations drive the recruitment and growth of temperate grassland plants

“…However, little is known about the species-specific responses of plants to environmental change drivers, such as recent accelerated warming and frequent summer droughts (Brun et al, 2020; Dolezal et al, 2020). Moreover, while responses to current climate change are extensively documented in trees and shrubs (Francon et al, 2020; Altman et al, 2020), comprehensive assessments of long-term regeneration and growth responses to climate change are still rare in herbs, yet they encompass a vast majority of the plant species globally (Dee & Stambaugh, 2019; Dolezal et al, 2021).…”

“…This makes it possible to directly trace past impacts of environmental fluctuations on plant performance several decades back (Büntgen et al, 2015). Nevertheless, to our knowledge, most research so far has focused on tree species, while only a few studies explored the potential of perennial dicot herbs in capturing the effects of environmental changes and extreme events on plant recruitment and growth dynamics (Dolezal et al, 2021).…”