Isotopic composition of leaf carbon (δ¹³C) and nitrogen (δ¹⁵N) of deciduous and evergreen understorey trees in two tropical Brazilian Atlantic forests

Abstract

Abstract:Isotopic composition of leaf carbon (δ13C) and nitrogen (δ15N) is determined by biotic and abiotic factors. In order to determine the influence of leaf habit and site on leaf δ13C and δ15N in the understorey of two Atlantic forests in Brazil that differ in annual precipitation (1200 and 1900 mm), we measured these isotopes in the shaded understorey of 38 tropical tree species (20 in the 1200-mm site and 18 in the 1900-mm site). Mean site values for δ15N were significantly lower at the 1200-mm site (−1.4‰) compared with the 1900-mm site (+3.0‰), and δ13C was significantly greater in the 1200-mm site (−30.4‰) than in the 1900-mm site (−31.6‰). Leaf C concentration was greater and leaf N concentration was lower at 1200-mm than at 1900-mm. Leaf δ15N was negatively correlated with δ13C across the two sites. Leaf δ13C and δ15N of evergreen and deciduous species were not significantly different within a site. No significant phylogenetic signal for any traits among the study species was found. Overall, site differences were the main factor distinguishing traits among species, suggesting strong functional convergence to local climate and soils within each site for individuals in the shaded understorey.

Leaf Age Compared to Tree Age Plays a Dominant Role in Leaf δ13C and δ15N of Qinghai Spruce (Picea crassifolia Kom.)

“…N availability in ecosystem, N re-translocation in plants, and N fractionation after plant uptake is known to influence leaf δ 15 N [1,41]. Multiple previous studies have reported that there is a positive relationship between plant δ 15 N and leaf N concentrations at various spatial scales [17]. In our work, leaf δ 15 N was also positively related to leaf N concentrations.…”

“…As a consequence of these effects, an enrichment of 13 C in current-year leaves was observed. During the autotrophic growth stage, carbon was assimilated and exported to other plant organs [17], which was most evident for older leaves [14]. The lighter carbon isotope was preferentially assimilated and used to produce the lipids and lignin, while the heavier carbon isotope was transported as 13 C-enriched sucrose to the young new leaves [13].…”

“…Li et al [10] reported that leaf δ 15 N variations at the community, plant growth form and species levels were significantly reduced with increasing stand age over shorter times and at smaller spatial scales. In addition, Vitoria et al [17] demonstrated that there was no significant difference in leaf δ 13 C and δ 15 N values of evergreen and deciduous species within a site. In addition, despite tremendous progress over the past few decades in investigating what causes variation in plants δ 13 C and δ 15 N values, limited studies have allowed a comprehensive explanation for the relative importance of study variables on carbon and nitrogen compositions [16,17].…”

“…In addition, Vitoria et al [17] demonstrated that there was no significant difference in leaf δ 13 C and δ 15 N values of evergreen and deciduous species within a site. In addition, despite tremendous progress over the past few decades in investigating what causes variation in plants δ 13 C and δ 15 N values, limited studies have allowed a comprehensive explanation for the relative importance of study variables on carbon and nitrogen compositions [16,17]. Therefore, it is necessary to conduct further investigation on the natural abundance of 13 Moreover, there are a variety of other abiotic and biotic factors that control leaf δ 13 C and δ 15 N values during plant development and growth [18,19].…”

Stable Isotopes in Greenhouse Gases from Soil: A Review of Theory and Application

“…Zhang et al [72] recognized that the δ 13 C of soil CO 2 emissions was negatively correlated with temperature after farmland was afforested in central China. According to Vitória et al [73], precipitation and δ 15 N values are negatively correlated until the point of soil waterlogging. Lee et al [71] suggested that changes of δ 13 C in SOM obviously follow those of the plant zone in arid and semiarid central East Asia.…”