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

Abstract

AbstractAimEvergreen 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.LocationSubtropical evergreen broadleaved forest (SEBLF) of China.MethodsWe measured seven functional traits of 292 woody plant species in 250 forest plots across five locations in the SEBLF. We quantified functional richness (FRic), functional divergence (FDiv), and functional evenness (FEve) 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.ResultsFunctional richness of evergreen species was higher than that of deciduous species, while FDiv and FEve were lower. FRic of evergreen species decreased while FDiv increased with increasing elevation. For deciduous species, FRic and FDiv decreased with increasing latitude. With the increase of longitude, only FDiv of evergreen species decreased. FEve 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 FRic and FDiv of evergreen species, while FRic of deciduous species was mainly affected by precipitation of the driest quarter. FEve of both leaf habits was mostly affected by soil conditions.Main conclusionsFunctional 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.