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

To explore the leaf functional traits and leaf economic spectrum patterns of garden shrubs in Xiamen City, and to select shrub species with better adaptability, the study chose 10 commonly used landscaping shrubs in Xiamen, including Rhapis excelsa, Pittosporum tobira, Fagraea ceilanica, Heptapleurum arboricola, Cordyline fruticosa, Rhododendron simsii, Excoecaria cochinchinensis, Loropetalum chinense, Duranta erecta, and Bougainvillea spp, as research subjects. 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）. Redundancy analysis indicates that the structural traits factors that have a significant impact are LA, LWC, and LDMC. Principal component analysis and membership function analysis indicated that the environmental adaptability of the 10 plants could be ranked as Cordyline fruticosa＞Duranta erecta＞Bougainvillea spp＞Fagraea ceilanica＞Heptapleurum arboricola＞Rhapis excelsa＞Excoecaria cochinchinensis＞Loropetalum chinense＞Rhododendron simsii＞Pittosporum tobira. Different shrub species have different leaf functional trait responses to the environment under the same conditions, reflecting different growth adaptation strategies of plants. It can be concluded that the "fast investment-return" growth strategy, characterized by a large SLA, low LDMC, and high LNC, such as Cordyline fruticosa, Duranta erecta, and Bougainvillea spp, show better adaptability to the urban environment of Xiamen and are suitable for use as the main tree species in urban garden planning.