Tougher leaves under global urbanization

We investigated intraspecific variation of 10 leaf functional traits in this study. There were 4 leaf morphological traits: SLA, leaf area (LA), leaf length (LL) and leaf thickness (LT); 3 chemical traits: leaf nitrogen concentration (LN), leaf phosphorous concentration (LP) and LDMC; 3 gas-exchange-related traits: photosynthetic rate under saturating light (Asat); chlorophyll content (Chl), relative water content (RWC). A literature search was performed using the Web of Science and CNKI databases (as of September 15, 2023), combining different keywords based on the research questions. To search for literature on the impact of urbanization on plant traits, we used the keywords ["urban" OR "city" OR "cities" OR "town"] AND ["SLA" OR "photosynthesis" OR "photosynthetic rate" OR "leaf size" OR "specific leaf area" OR "leaf dry matter" OR "leaf nitrogen" OR "leaf phosphorus" OR "leaf N" OR "leaves traits" OR "leaf trait" OR "leaf traits"]. This resulted in a sample of 1,788 publications.