Hypothesis 3: Milder winters and higher water temperature in May lead to higher functional richness (phenological shift).
The hypothesis that milder winters bring higher functional diversity in May was based on two assumptions or observations: 1) phenological shifts occur with milder winters and the summer-like communities will appear earlier and 2) during the summer the communities are usually functionally more diverse (Richardson 2008). To test H3, functional richness was correlated with winter air temperature and water temperature in May.