Evaluation of the diversity and uniqueness of woody plant communities in park forests transformed form forest patches on urban hills

Abstract In the process of urbanization, forest patches on hills are transformed into urban park forests, their functions changing from production to ecological and landscape. The diversity and uniqueness of plant communities support the ecological and landscape functions of parks, but there is a lack of indicators and methods to assess their uniqueness. We propose two evaluation indicators for woody plant community uniqueness in urban parks based on importance value (IV, the average of relative abundance, relative frequency, and relative dominance): the mean non-overlapping IV (MNIV) and the local contribution to beta diversity based on IV (LCBD1). Subsequently, we investigated and evaluated the diversity and uniqueness of woody plant communities in eight hill parks (Parks 1–8) in Qingdao. A total of 101 species were found, with an average of 23.88 ± 5.96 species per park. The Shannon-Wiener and Pielou indices were in the ranges of 1.42–3.13 and 0.48–0.91, respectively. Results from principal coordinate analysis and cluster analysis and the orders of MNIV and LCBD1 suggest that Parks 4 and 8 have the most unique woody plant communities. MNIV was significantly (P < 0.05) positively correlated with Shannon-Wiener and Pielou indexes, while LCBD1 was significantly (P < 0.05) positively correlated with local beta diversity based on species abundance. MNIV and LCBD1 were significantly (P < 0.05) negatively correlated with IV of Pinaceae and significantly (P < 0.05) positively correlated with IVs of Anacardiaceae, Cannabiaceae, and Ginkgoaceae plants. Therefore, diversities of woody plant communities from residual forest patches show great variations. The diversity and IVs of characteristic plants are key factors affecting uniqueness.