# On the Limits of Alpine Plants: A Systematic Review of the Factors Behind Species' Elevational Range Limits

## TL;DR

This review shows that research on alpine plants focuses heavily on upper elevation limits and abiotic factors like temperature, while other important factors remain underexplored.

## Contribution

The paper systematically reviews 107 studies to identify research gaps in factors influencing alpine plant range limits.

## Key findings

- Most studies focus on upper elevational range limits and abiotic factors, especially temperature.
- Inter- and intraspecific factors like herbivory and gene flow are underrepresented in current research.
- Water availability is more commonly studied at lower range limits, but many factors remain poorly researched.

## Abstract

Understanding the factors behind species' range limits is a fundamental objective in ecology. Recent research in alpine plant ecology has moved beyond the classical view that distributions are chiefly shaped by climate and competition. Specifically, broader sets of factors have been taken into account, comprising both biotic factors such as facilitation and herbivory as well as additional abiotic factors such as soil properties. However, an overview of the factors that have been identified and studied as important for elevational range limits of alpine plant species is lacking. In this systematic literature review, we synthesize evidence derived from 107 empirical studies on 226 vascular plant species occurring beyond elevational and latitudinal treelines. We find a persistent research focus on the upper elevational range limit (73% of the studies) and on the role of abiotic factors (54% of the studies), particularly temperature (36% of the studies), whereas research on inter‐ and intraspecific factors (40% and 25%, respectively), such as herbivory or phenology, remained comparatively rare. While temperature was clearly identified as a major factor influencing the upper range limit (29% of the studies), water availability (15% of the studies) was most commonly studied at the lower range limit. Even though a broad set of factors has been investigated, many potentially important factors remain poorly researched, such as the influence of gene flow and connectivity between populations, phenology and light (each only one or two studies). Our findings highlight the need to move beyond temperature and plant–plant interactions as factors influencing the elevational range limits of alpine plants and to integrate intraspecific (such as gene flow and adaptations) and edaphic factors more fully into future research. Improved methodological standardization and transparency and increased attention on lower range limits will be essential for explaining and predicting alpine plant responses under accelerating environmental change.

This systematic review of 107 studies on the factors behind the elevational range limits of alpine vascular plants shows a persistent emphasis on upper limits and abiotic factors, especially temperature, while work at lower limits is more evenly distributed across water availability, plant–plant interactions, and selection/local adaptation. Inter‐ and intraspecific factors remain underrepresented, with major gaps in plant–microbe interactions, phenology and light—underscoring the need to move beyond temperature, with improved methodological specificity, and to devote more attention to lower limits.