Strategy Trade-Off of Predominant Stress Tolerance Relative to Competition and Reproduction Associated with Plant Functional Traits under Karst Forests

The Grime (1974) CSR framework posits that ecological strategies of competition, stress tolerance and ruderal reflect plants' adaptability to their survival environments. Karst forests are crucial for terrestrial ecosystem functions. However, how karst forests regulate plant functional traits in ecological strategy to adapt to infertile habitats remains unclear. Therefore, we surveyed fifty-three karst forest plots and measured plant functional traits involving the plan diameter at breast height (DBH), height, leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf carbon (LC) and nitrogen (LN) and phosphorus (LP) with the leaf water content (LWC). We calculated CSR components on the individual and community levels introduced by community-weighted means (CWM) using the 'StrateFy' calculator. Principal component analysis (PCA) and Mantel's test were used to investigate trait correlations with CSR components. Our results showed that stress tolerance (S) contributed an average 65.88% and 63.63% in individuals and communities, respectively, followed by competition (C) at 25.82% and 29.63%, and the least, ruderal (R), at 8.30% and 6.74%. Different plant functional traits exhibited different variations, coupled with significant correlations between CSR components and PC1 scores (except for CWM- LA, SLA and LDMC). Component S increased with the increase in CWM- LC and C:N ratio, and decreased with the increase in CWM- DBH, Height, LWC, LN, and N:P ratio, while it was the opposite for C and R, highlighting strategic trade-offs associated with plant functional traits. Mantel's test revealed varied key trait combinations for each strategy. In conclusion, the predominant stress tolerance strategy relative to competition and ruderal is a result of trade-offs regulating karst forests, in association with plant functional traits. The disentangled CSR strategies provide insights into theoretically understanding functional maintenance for infertile forest ecosystems as an evolutional regulation mechanism.