Functional Traits at a Glance: How Do Alpine Communities Respond to Climate Change?

Featured image caption: A meadow in the French Alps.(Image source: “Jallouvre” by Ymaup is licensed under CC BY-SA 3.0, via Wikimedia Commons.)

Source article: B. Bektaş, G. Rutten, A. Saillard, R. Friaud, C. Arnoldi, J. Renaud, M. Guéguen, A. Foulquier, J. Poulenard, E. Lyautey, J. Clément, W. Thuiller, T. Münkemüller, Traits and functions of alpine plant communities respond strongly but not always sufficiently to in situ climate change. New Phytol.249, 1173–1187 (2025). https://doi.org/10.1111/nph.70503

Ecologists place heavy emphasis on functional traits, which describe how species contribute to their broader ecological communities. Those same traits influence how species and communities tolerate environmental disturbances. 

Because individual traits are not independent, it is combinations of traits that determine fitness in the arena of evolution. So what happens when the environment changes rapidly, and previously viable trait sets no longer work as well?

Pressure mounts on species to adapt quickly, which may involve changing quite a few traits. Or if adaptation is impossible, species perish, and community composition changes.

Axes of Plant Functional Traits

Since species are always working with limited resources, they experience tradeoffs of investment along trait spectra. In plants, a well-described axis exists between “fast” species that grow and reproduce quickly but have shorter lifespans, and “slow” species that are more durable but slow to reproduce.

Initially, this axis was derived from measurements of “aboveground” traits like leaf mass and nitrogen content. More recently, “belowground” traits like the density of root tissue have also been described on the fast-slow axis.

In addition, there is another axis that seems exclusive to roots. Some species follow “do-it-yourself” (DIY) tactics by growing lengthy roots to gather resources. Other species develop “outsourcing” relationships with symbiotic fungi to manage uptake, growing wide roots to accommodate the partner.

When the Climate Changes, Strategies May Shift

How do these functional plant trait axes interact? Bektaş et al. (2025) conceptualize the fast/slow and DIY/outsourcing axes as perpendicular, creating four putative quadrants of functional plant strategies.

Image Source: Figure 1: Conceptual framework for tradeoff axes in plant functional traits and resulting strategies. Adapted from Bektaş et al (2025). https://pmc.ncbi.nlm.nih.gov/articles/PMC12780316/figure/nph70503-fig-0001/

Climate change may drive strategy shifts in alpine plant communities towards one of two specific quadrants. If conditions trend towards warmer and longer growing seasons, species may be incentivized to take advantage by employing fast, DIY strategies (lower left quadrant), increasing community productivity, or the generation of biomass. However, if stochastic events like drought or freezing become more common, species may respond by adopting slow, outsourcing strategies (upper right quadrant), increasing hardiness but lowering productivity.

Bektaş et al. tested their hypothesis on a alpine grassland community in the European Alps, where climate change is projected to cause increased temperatures and more frequent droughts. How can those impacts be estimated in the present? By transplanting the alpine plots to a subalpine location, which is warmer and experiences less snowfall. In other words, the authors literally dug up the ground and reassembled everything at a different place, about 500 meters lower in elevation.

The experimental transplanted plots, as well as sets of control (unmoved) plots in the alpine and subalpine environments, were left alone for five years. Then, the authors returned and measured traits to see how the communities fared.

Simulated Impacts

Initial assessments revealed that most of the variation in traits across the plots resulted from differences along the fast/slow and DIY/outsourcing axes. The transplanted alpine plot became more like the subalpine control over time, with both favoring slow/outsourcing strategies, while the alpine control plot exhibited fast/DIY tendencies. 

The authors postulate that the transplanted plot’s adjustments are likely due to drought. A redundancy analysis, which calculates how much a set of response variables changes in response to a set of explanatory variables, found that soil moisture, followed by temperature, were the largest drivers of changes in the transplanted plots. 

Interestingly, for many of the leaf and root trait measurements, there was little or no “acclimation lag” between the subalpine control and the transplanted alpine communities; that is, the trait values were not significantly different. That implies a relatively rapid transition by the alpine species. 

Sounds promising for their adaptability and longer-term resilience, right?

The catch is whether adaptations enable a community to maintain the productivity it had in prior conditions. The authors detected a significant increase in aboveground productivity, as well as a nonsignificant increase in belowground productivity, in the transplanted plots compared to the alpine control plots. 

However, aboveground productivity showed an acclimation lag, being lower in the transplanted alpine plots than in the subalpine control. A second redundancy analysis determined that changes in climate (meaning the transplantation of plots) explained most of the observed variation in aboveground productivity. That connection implicates the altered climate as a detriment to the transplanted community, at least over the timeline of the study.

Key Takeaways

The two orthogonal axes appear useful for predicting how communities respond to changing climates, as trait measurements fall primarily within the fast/DIY or slow/outsourcing quadrants.

For the alpine communities, climate shifts are likely to induce a movement towards slow/outsourcing strategies, at a cost to productivity. Overall, even if trait transitions in a community are quick and strong, they’re not always sufficient to maintain community health.

Furthermore, as communities change, the links between traits and productivity can become disrupted, which may inhibit our capacity to project future outcomes. These are important lessons to recall in the context of mitigating climate change and protecting global biodiversity.

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