Analysis on Leaf Functional Traits and Leaf Economics Spectrum of 10 Main Garden Shrubs in Xiamen

In order to explore the leaf functional traits and leaf economic spectrum patterns of garden shrubs in Xiamen City, and to select the shrub species with better adaptability, 10 commonly-used landscaping shrubs in Xiamen were selected as the research objects in this study, including Rhapis excelsa, Pittosporum tobira, Fagraea ceilanica, Heptapleurum arboricola, Cordyline fruticosa, Rhododendron simsii, Excoecaria cochinchinensis, Loropetalum chinense, Duranta erecta and Bougainvillea. The leaf functional traits such as leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf water content (LWC), malondialdehyde (MDA), free proline (PRO), catalase (CAT), leaf carbon content (LCC), leaf nitrogen content (LNC), and carbon to nitrogen ratio (C∶N) were measured and analyzed. The results showed that in the correlation analysis, leaf LA was significantly positively correlated with MDA (P＜0.05), as did LA with PRO, SLA with LWC, SLA with PRO, and LCC with C∶N. Leaf LA was extremely significantly positively correlated with LCC (P＜0.01), as did SLA with LNC and CAT with LWC. Leaf SLA was significantly negatively correlated with LDMC (P＜0.05), as did CAI with MDA and CAT with LCC. Leaf LDMC was extremely significantly negatively correlated with LWC, as did LDMC with CAT, C∶N with LNC, and C∶N with SLA (P＜0.01). The redundancy analysis showed that the structural trait factors that had significant effects were LA, LWC and LDMC. The principal component analysis and membership function analysis showed that the environmental adaptability of the 10 plants could be ranked as Cordyline fruticosa＞Duranta erecta＞Bougainvillea＞Fagraea ceilanica＞Heptapleurum arboricola＞Rhapis excelsa＞Excoecaria cochinchinensis＞Loropetalum chinense＞Rhododendron simsii＞Pittosporum tobira. Under the same environmental conditions, the leaf functional traits of different shrub species had different response mechanisms to the environment, reflecting different growth adaptation strategies of plants. The comprehensive analysis showed that Cordyline fruticosa, Duranta erecta and Bougainvillea under the “fast investment-revenue” growth strategy with large leaf SLA, low LDMC and high LNC showed better adaptability to the urban environment of Xiamen, which were suitable for being used as the main tree species in the urban landscape planning.