Frost Tolerance Increases With Plant Height Among Co-Occurring Alpine Species in the Central Tibetan Plateau

Frost is a major stressor for alpine plants, and a species' ability to resist it can shape their distribution and diversity. While many studies explore how frost tolerance varies with elevation, research on how co-occurring species differ in their resistance strategies remains limited. We selected twenty-two co-occurring plant species from a single alpine community on the Tibetan Plateau and quantified their frost tolerance (LT₅₀: the lethal temperature at which 50% of tissue died). We also measured six common functional traits (height, specific leaf area (SLA), leaf dry matter content (LDMC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), and the ratio of leaf nitrogen and phosphorus content (NP ratio)) of all species. Overall, we found there was a lot of interspecific variation in the LT₅₀ of alpine plants within the same community. As expected, plant height was the most significant trait associated with LT₅₀. However, unlike patterns observed along elevation gradients, in our study taller plants were more frost tolerant than shorter plants. Overall, short stature together with densely packed small leaves of alpine plants may explain why these species are aerodynamically decoupled from the cold air temperature (avoidance strategy) and do not have to rely as strongly on physiological tolerance to frost (tolerance strategy). Multiple strategies by different species in a single community could facilitate species co-existence under harsh conditions like the Tibetan Plateau. These results can help us to better understand the high diversity of alpine plant communities.