Abstract:

Aims: Plant functional traits reflect species’ survival strategies and patterns of resource allocation under varying environmental conditions. Understanding the elevational patterns of functional traits is crucial for elucidating how plants adapt to mountainous environments. However, comparative studies examining how the functional traits of native and invasive herbaceous plants respond to different elevations remain limited. 

Methods: This study examined the elevational patterns of functional traits of native and invasive herbaceous plants and their climatic drives, based on 49 plots (1 m × 1 m) of herbaceous sampled along a 250–1,050 m elevational gradient at 100 m intervals in the Bawangling National Nature Reserve, Hainan. 

Results: The results showed that across the entire elevation range, invasive herbaceous plants had significantly higher plant height (P < 0.001), leaf width (P < 0.001), and leaf nitrogen content (P = 0.032), but significantly lower leaf length (P = 0.003) and leaf dry weight (P = 0.005) than native herbaceous plants. At low elevations (200–500 m), invasive herbaceous plants were taller than native herbaceous plants (P < 0.001). At middle elevations (500–800 m), invasive herbaceous plants exhibited greater plant height (P = 0.012) and leaf width (P = 0.008) compared to native herbaceous plants, while their leaf length was significantly lower (P = 0.032). At high elevations (800–1,100 m), invasive herbaceous plants showed significantly higher leaf width (P = 0.019) and leaf nitrogen content (P = 0.030) than native herbaceous plants, but lower leaf length (P = 0.011), leaf dry weight (P = 0.006), and leaf fresh weight (P = 0.033) than natives. No significant differences were observed in other traits. In invasive herbaceous plants, plant height (P < 0.001), leaf length (P < 0.001), leaf area (P = 0.021), and leaf dry weight (P = 0.037) were significantly positively correlated with mean annual temperature and negatively with precipitation, whereas leaf nitrogen content exhibited an opposite pattern. Native herbaceous plants, however, only showed significant correlations between leaf width and climatic factors. 

Conclusion: This study suggests that invasive herbaceous plants adopt a “resource-acquisitive” strategy at low elevations (characterized by greater height, larger leaf width, and higher leaf nitrogen content), further expanding their trait advantages at middle elevations (increasing chlorophyll content and leaf moisture). At high elevations, they select for cold-tolerant species with high leaf nitrogen through species turnover. Variance partitioning results revealed that this ecological strategy shift is primarily driven by species turnover, which filters out species with varying functional trait combinations at different elevations. In contrast, native herbaceous plants exhibit a more conservative functional trait strategies, with their elevational variation in functional traits also primarily dominated by species turnover. Results recommended to prioritize invasive species monitoring and control at low and middle elevation areas, while also being aware of the potential risk of invasive herbaceous plants maintaining their competitiveness at high elevations through species turnover.

Key words: plant functional traits, native herbaceous plants, invasive herbaceous plants, elevational pattern, climatic factors