Search

Trait‐based approaches have been extensively used in community ecology to provide a mechanistic understanding of the drivers of community assembly. However, a foundational assumption of the trait framework, traits relate to performance, has been mainly examined through univariate relationships that simplify the complex phenotypic integration of organisms. We evaluate a conceptual framework in which traits are organized hierarchically combining trait information at the individual‐ and species‐level from biomass allocation and organ‐level traits. We focus on photosynthetic traits and predict that the positive effects of increasing plant leaf mass on growth depend on species‐level leaf traits. We modeled growth data on more than 1,500 seedlings from 97 seedling species from a tropical forest in China. We found that seedling growth increases with allocation to leaves (high leaf area ratio and leaf mass fraction) and this effect is accentuated for species with high specific leaf area and leaf area. Also, we found that light has a significant effect on growth, and this effect is additive with leaf allocation traits. Our work offers an approach to gain further understanding of the effects of traits on the whole plant‐level growth via a hierarchical framework including organ‐level and biomass allocation traits at species and individual levels. [ABSTRACT FROM AUTHOR]

Seagrasses are considered one of the most rapidly declining ecosystems in the world. One of the main reasons for this decline is eutrophication during which anthropogenic impacts, including light deprivation and nutrient enrichment often result in cumulative stress for seagrasses. This study aims to investigate the physiological and morphological responses of seagrasses to nutrient enrichment and eutrophication in Hainan, China, to understand the processes leading to seagrass losses from eutrophication. Therefore, we tested how a four-week in situ fertilisation affected traits of a multi-species seagrass community in two seasons with different trophic conditions. The species investigated in this study are Cymodocea serrulata, Cymodocea rotundata, Halodule uninervis and Thalassia Hemprichii. The dry season was characterised by high light availability and low nutrient availability. Enhanced seagrass leaf growth rates and leaf area of all species as a response to fertilisation indicate that seagrass growth is nutrient-limited in the dry season. In contrast, under eutrophic conditions in the wet season, growth and leaf area of all species were lower than in the dry season and fertilisation had no effect. Thalassia hemprichii showed signs of morphological adaption under eutrophic conditions, suggesting a higher species-level phenotypic plasticity and resilience to the stressors involved. As expressed in the fast response under eutrophic conditions, our experiment indicates synergetic adverse effects of light reduction and nutrient enrichment on seagrasses. An improved understanding of species-specific physiological and morphological response mechanisms of seagrasses to eutrophication may help to identify thresholds of exposure to stressors early on, and hence to be able to predict and possibly avoid an upcoming large-scale loss. It also has implications for aquaculture and coastal zone management. [Display omitted] • Effects of in situ nutrient enrichment on seagrass varied among species and seasons. • If nutrient limited, fertilisation enhances seagrass growth and leaf area. • T. hemprichii showed a higher morphological plasticity than the other species. • Its morphological plasticity may be related to its higher resistance to eutrophication. [ABSTRACT FROM AUTHOR]