Environmental correlates of tree functional diversity with different leaf habits across subtropical evergreen broadleaved forests

Aim: Evergreen and deciduous broadleaved plants have long been considered as different strategies to cope with environmental conditions, which are closely related to the trait syndromes associated with leaf habits. However, there are no assessments of differences in functional diversity among evergreen and deciduous species over a regional scale.Location: Subtropical evergreen broadleaved forest (SEBLF) of China.Methods: We measured seven functional traits of 292 woody plant species in 250 forest plots across five locations in the SEBLF. We quantified functional richness (F-Ric), functional divergence (F-Div), and functional evenness (F-Eve) for evergreen vs deciduous species separately. We compared the patterns of variation of functional diversity for different leaf habits along geographical (latitude, longitude and elevation) and environmental (climate and soil) gradients.Results: Functional richness of evergreen species was higher than that of deciduous species, while F-Div and F-Eve were lower. F-Ric of evergreen species decreased while F-Div increased with increasing elevation. For deciduous species, F-Ric and F-Div decreased with increasing latitude. With the increase of longitude, only F-Div of evergreen species decreased. F-Eve of both leaf habits did not exhibit geographical patterns. Environmental variables explained 9%-38% and 4%-33% of the variation in functional diversity of evergreen and deciduous species respectively. The temperature range was the most important factor affecting F-Ric and F-Div of evergreen species, while F-Ric of deciduous species was mainly affected by precipitation of the driest quarter. F-Eve of both leaf habits was mostly affected by soil conditions.Main conclusions: Functional diversity of subtropical forests in China revealed different geographical patterns across leaf habits. The functional diversity of evergreen species was mainly linked to temperature, while the deciduous species were driven by precipitation. Our study demonstrated that different functional diversity patterns of evergreen and deciduous broadleaved plants in response to environment can result in the coexistence of the two leaf habit types.

Automated summary

This study investigated the functional diversity of evergreen and deciduous broadleaved plants in subtropical forests of China and found that evergreen species had higher functional richness but lower functional divergence and evenness than deciduous species. The functional richness and divergence of evergreen species decreased with increasing elevation, while those of deciduous species decreased with increasing latitude.