Abstract
Functional trait ecology demonstrates the significance of the leaf economics spectrum in understanding plants’ trade-off between acquisitive and conservative resource utilization. However, whether trait variations of different vegetative organs are coordinated and whether the plant economics spectrum is characterized by more than one vegetative organ remain controversial. To gain insights into these questions, within a tropical cloud forest in Hainan Island, a total of 13 functional traits of 84 tree species were analyzed here, including leaf, stem and root traits. By using standardized major axis (SMA) regression and principal components analysis, we examined the trait variations and correlations for deciphering plants’ trade-off pattern. We found decreases of leaf phosphorus content, leaf nitrogen content and specific leaf area and increases of leaf mass per unit area (LMA), wood density and leaf thickness along the first principal component, while there were decreases of specific root length and specific root area and increases of root tissue density along the second principal component. Root phosphorus and nitrogen contents were significantly positively associated with the phosphorus and nitrogen contents of both stem and leaf. Wood density was significantly positively associated with LMA and leaf thickness, but negatively associated with leaf thickness and specific leaf area. Our results indicate that, in the tropical cloud forest, there is a “fast–slow” economic spectrum characterized by leaf and stem. Changes of nutrient trait are coordinated, whereas the relationships of morphological traits varied independently between plant above- and below-ground parts, while root nutrient traits are decoupled from root morphological traits. Our findings can provide an insight into the species coexistence and community assembly in high-altitude tropical forests.
Highlights
Plant functional traits individually or jointly indicate species ecological functions and ecosystem response to environmental changes (Cornelissen et al, 2003)
In contrast to the root economics spectrum (RES) (Reich and Cornelissen, 2014), we found that SRL and RTD poorly correlated with RN and RP (Table 2 and Figure 2), indicating that the trade-off among fine root traits of tropical cloud forest trees is not one-dimensional
In the BWL tropical cloud forest, we found a plant economic spectrum (PES) characterized by leaf and stem, which reflects a tradeoff between acquisitive and conservative resource utilization (Figure 4)
Summary
Plant functional traits individually or jointly indicate species ecological functions and ecosystem response to environmental changes (Cornelissen et al, 2003). The leaf economic spectrum (LES) revealed by Wright shows that the variation and correlation of leaf traits reflect an ecological trade-off in resource utilization, which has been widely confirmed by ecologists (Reich et al, 1998; Enquist et al, 1999; Santiago et al, 2004; Poorter et al, 2008; Cornwell and Ackerly, 2009; Baraloto et al, 2010) It remains controversial whether the stems and roots display such a one-dimensional strategic trade-off (Freschet et al, 2010; Prieto et al, 2015). Such a reality suggests that more attempts should be done for testing whether the tradeoff is one-dimensional
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