Yanina Arzamendia

Habitat use by vicuña Vicugna vicugna in Laguna Pozuelos Reserve, Jujuy, Argentina

Vicuna Vicugna vicugna are an emblematic species of one of the major arid ecosystems of the neotropics: the puna or altiplano. Excessive commercial hunting of vicuna for their valuable fleece in the past caused a severe decline in the population, with the vicuna almost becoming extinction by the mid 20th century. Effective protection resulted in the recovery of some populations and, recently, limited vicuna exploi- tation has been allowed. Research is urgently required to underpin the design of the management systems used for this exploitation. We present the result of a 2-year study on habitat utilization of vicuna in Laguna de Pozuelos UNESCO Biosphere Reserve in Argentina. Vicuna did not use the study area homogeneously but preferred vegetation communities dominated by grasses (known locally as pajonal and esporal) and with high overall plant cover. Vicuna were less selective in 2003, when overall habitat quality decreased, than in 2002. This change is predicted by habitat selection theory. We also found that members of family groups spend more time foraging than members of non-reproductive groups. Solitary vicuna spend more time standing up than members of groups, consistent with the observation that herding behaviour is related to protection against predators. Heterogeneous use and habitat selectivity suggest that exploitation of vicuna needs to take spatial behaviour into account in the establishment of the optimal location of capturing sites.

Vicugna habitat use and interactions with domestic ungulates in Jujuy, Northwest Argentina

Abstract Worldwide vicugna numbers are slowly recovering after the implementation of conservation measures in several areas of the Andean Puna. Amongst some communities, vicugnas are sustainably managed through captures, shearing, and release schemes. In this study, we explored habitat use and interactions between vicugnas and domestic livestock in Jujuy, Northwest Argentina. We measured the habitat selectivity of vicugna by evaluating the relationship between the availability and its use of vegetation. We estimated the extent and overlap of habitat niche, as well as the foraging effort of vicugnas on the basis of their individual behaviour. Vicugnas and domestic livestock were highly selective in their use of land. They also had similar foraging preferences, grazing rather on the mixed steppe grasses and grasslands that offered greater grass cover. The distribution of vicugna in relation to domestic animals differed according to species and density. With mean density of llamas, vicugnas showed mixed herds but with any other livestock and greater densities, they were segregated. In mixed grazing, when vicugnas engaged with llamas, no behavioural interaction or competition was observed. The presence of herders with dogs was the main stress factor for vicugnas. Here we discuss the importance of a multi-specific management approach.

Double Sampling Methods in Biomass Estimates of Andean Shrubs and Tussocks

ABSTRACT The natural Andean vegetation environment is the most important resource available to local pastoralist economies. Knowledge of its attributes is vital in assessing ecosystem properties and improves management decision making. However, there is a lack of research on models that estimate species and life-form biomass for the Puna. We developed a series of models that facilitated the estimation of biomass while avoiding the direct harvesting of the most representative Puna steppe plant species in Jujuy, Argentina. The models thus developed are useful tools in the evaluation of changes in ecosystem dynamics through time and space. Allometric equations were developed for the dominant shrubs (Baccharis boliviensis, Fabiana densa, Parastrephia quadrangularis, Tetraglochin cristatum, Ocyroe armata, and Adesmia sp.) and tussock grasses (Jarava ichu, Festuca crysophylla, and Cenchrus chilense). A field record of the maximum diameter, perpendicular diameter, and height of each plant; number of individuals per plot; and tussock grasses and shrub cover across all vegetation communities was undertaken. Linear regressions including plant measures demonstrated a good fit (R2 > 0.7, P < 0.001) to the biomass for individual plants and surface area. The predictive equations developed allow for the rapid and accurate estimation of shrub and tussock biomass. This is essential to monitor the effects of grazing for impact assessment of the different management practices and vegetation dynamics.