Llamas (Llama glama) enhance proglacial ecosystem development in Cordillera Blanca, Peru

Abstract

Worldwide, mountain glaciers are shrinking rapidly. Consequently, large areas are becoming available for the development of novel alpine ecosystems. These harsh environments, however, delay primary succession. In this study with a local community, we conducted an inclusion experiment to investigate whether Llama glama influences soils and vegetation primary succession following glacial retreat. At the foot of the Uruashraju glacier in the Cordillera Blanca, Peru (~ 4680 m.a.s.l.), we established four llama inclusion plots and four control plots that we studied from 2019 to 2022, 24-40 years after deglacierization. After three years, the llama plots had significantly increased soil organic carbon and soil nitrogen. In the llama plots, we found a large, significant increase in vascular plant cover (+ 57%) between the second and third years of experimentation, and we identified four new species that were not present in 2019. Our results suggest that Llama glama, through their latrine behavior and role as a seed disperser, enhances the primary succession and novel ecosystem formation in recently deglacierized landscapes. Our study provides scientific support that rewilding of native Andean camelids may favor adaptation to glacier retreat and inform conservation and management strategies in proglacial landscapes.

Figure 1

Location and study site set-up. Map of location with respect to the Santa River watershed (a), and Río Negro sub-watershed (b). Map of the experiment within the Uruashraju glacier foreland (c). The glacier retreat outlines were produced and provided by the ANA (Área de Evaluación de Glaciares y Lagunas, Autoridad Nacional del Agua, Huaraz) based on topographic field surveys of the glacier fronts since 1948, and analysis of photographs. Maps generated by authors with licensed software ArcGIS Pro 3.0.2 (https://www.esri.com/en-us/arcgis/products/arcgis-pro/).

Figure 2

Experimental design and in situ surveys. Design of the experiment (a), Llama glama within a llama plot (b), 1m² vegetation subplot (c), seedling germinated from llama feces found within the experiment in June 2022 (d).

Figure 3

Effects of llamas on soil organic carbon (SOC by LOI) and nitrogen (N) (95% confidence intervals) in 2019 and 2022. Means not sharing any letter are significantly different by Bonferroni tests (p ≤ 0.05).

Figure 4

Effects of llamas on plant cover (95% confidence intervals). Letters represent the significantly different groups according to the post hoc contrasts (p ≤ 0.05).

Figure 5

Effects of llamas on greenery (95% confidence intervals). Letters represent the significantly different groups according to the post hoc contrasts (p ≤ 0.05). Note: December is the wet season.

Figure 6

Seed viability per species found within the llama pellets (n = 266). The percentages expressed are the percentages of viable seeds for each species. For the taxa identified at the species or genus level family names are in brackets.