Carbon and Nitrogen Isotopic Survey of Northern Peruvian Plants: Baselines for Paleodietary and Paleoecological Studies (original) (raw)
Related papers
The application of stable isotopes in ecology, archeology or paleocology highlight the need to understand the variability of the isotopic baselines, as a fundamental step to know the spatio-temporal variability of consumers. The aim of this research is to study the δ 13 C and δ 15 N variability in modern plants along a longitudinal transect − 400 km-in southern Patagonia in order to establish the terrestrial vegetation baseline of the food chains in relation to the climatic and environmental variability of the region. The study area, between 47 • and 49 • south latitude Patagonia Argentina, covered different altitudes, temperatures, vegetation types, and precipitation gradients.δ 13 C and δ 15 N values were obtained for 211 samples from 13 different sampling loci. Vegetation surveys indicated a sharp change from temperate forests in the most humid west of the transect-trees and lichens were only present in the forests-, to steppe, dominated by shrubs and grasses. Stable isotopes of vegetation follow the climate gradient, with higher δ 15 N and δ 13 C values in the more arid steppe than in the forest sites. The lineal best model for each stable isotope, included mean annual precipitation and biological types as explanatory variable, and explained 58.7 % of the variability for δ 15 N, and 45.5 % for δ 13 C. On the broad scale, from the Atlantic coast to the Andes, we can assess the degree of agreement between the isotopic variations recorded in plants and herbivores. In this way, the isotopic variability recorded in both, plants and herbivores, provides unique opportunities to investigate the differential use of space and mobility, both among hunter-gatherer societies and among Patagonian herbivores.
Here we present the within-site, seasonal, and interannual variations of the carbon (δ13C) and nitrogen (δ15N) isotope ratios of leaves, wood, bark and litter from four sites in the Amazon region, Brazil. Samples were collected in Manaus (3° 06′07″ S; 60°01′30″ W), Ji-Paraná (10°53′07″ S; 61°57′06″ W), and Santarém (2°26′35″ S; 54°42′30″ W) with mean annual precipitation of 2207, 2040 and 1909 mm respectively. The overall average for all leaf samples was−32.3 ± 2.5‰ for δ13C and +5.8 ± 1.6‰ for δ15N (n = 756). The leaf δ values at these sites were often but not always statistically distinct from each other. The d13C values varied from−37.8‰ to−25.9‰ Pronounced differences in δ13C values occurred with height associated with differences in forest structure. The δ13C of leaf dry matter showed seasonal variations associated with the length of the dry season, despite the fact that total annual precipitation was similar among the studied sites. Leaf δ15N values ranged from+0.9‰ to a maximum value of+10.9‰, and the Santarém sites showed more enriched values than Manaus and Ji-Paraná sites. No seasonal variation was detected in the δ15N of leaves, but significant differences were observed among sites and with changes in canopy height. The isotope ratio data are consistent with our current understanding of the roles of light, water availability, and recycling of soil-respired CO2 influences on δ13C and consistent with our understanding that an open nitrogen cycle can lead to high δ15N values despite a significant number of legumes in the vegetation.
The signs of maize? A reconsideration of what δ13C values say about palaeodiet in the Andean region
Human Ecology, 2012
Palaeodietary isotope studies have long assumed C4 signals in South American archaeological populations to be due to the consumption of maize (Zea mays), which in turn, underlie interpretations important social processes. We presents δ13C data from wild plants (n=89) from the south coast of Peru, which may have been significant in the diets of humans and animals in the past. A combination of these with previously published results from domesticates of the Andean region (n=144) brings the proportion of C4 species likely to have contributed to the human dietary isotopic signal, whether directly or indirectly, to almost one third. This undermines the widespread assumption that maize is the only plant to contribute a C4 signal to diets. By considering both direct and indirect routes whereby C4 plants may have contributed to the human isotopic signal we show the need for a reassessment of how palaeodietary studies are interpreted in the Andes, and perhaps elsewhere in the Americas.
Isotopic Effects of Fertilization in the Andes: Implications for Dietary Reconstruction
Dietary reconstruction using stable isotopes depends on a thorough understanding of the sources and patterns of isotopic variation in the foods consumed. The potential importance of manured crops has been recognized as a confounding factor in the interpretation of animal protein consumption in Europe due to high plant δ15N values. In the Andes, the practices of fertilization with both llama dung and seabird guano mined from offshore islands is known to have occurred historically, and the high agricultural productivity in regions with low nutrient levels has led some to suggest that the addition of exogenous nitrogen from animal sources was necessary. In the absence of written records, however, the importance these fertilizers have been difficult to determine. This paper presents the results of a series of controlled experiments examining the influence of seabird guano and llama dung on maize. We discuss the implications of this study for the reconstruction of subsistence practices in the prehispanic Andes.