Resumen

Climate change represents a major threat to biodiversity and food security. In this study we performed a series of experiments and field measurements to evaluate plant responses to climate change in the Peruvian Andes. In the first experiment, several varieties of potato and maize were planted at different elevations (and thus temperatures) using either the local soil or soil translocated from higher elevations. The rationale was to simulate a “migration” scenario (in which farmers would have to change the location where crops are cultivated to track suitable climates) and a “tolerance” scenario (in which cultivated plants would have to tolerate warmer temperatures and possibly face novel enemies). The second experiment had a similar design, except that it involved a wild plant species (Weinmannia bangii) rather than cultivated plants, and that transplants were performed both at the center and at the limits of the altitudinal distribution of this species. Finally, we evaluated the extent to which the physiological traits of wild plant species (n = 11 species) vary along their altitudinal range. Results from the first experiment show that maize production declined by 21- 29% in response to new soil conditions. The production of maize and potatoes declined by >87% when plants were grown under warmer temperatures, mainly as result of the greater incidence of novel pests. Crop quality and value also declined under simulated migration and warming scenarios. Our estimates indicate that local farmers may experience severe economic losses of up to 2300 US$ ha-1 yr-1. Results from the second experiment indicate that changed soil conditions (migration scenario) did not affect the survival and growth of W. bangii seedlings. However, increased temperatures (tolerance scenario) had a significant negative effect on the survival of seedlings transplanted from the lower limit of their altitudinal range. Results from the third and final measurement, which involved measurements of the maximum quantum yield of photosystem II (Fv/Fm) and leaf chlorophyll content in different plant species, showed substantial interspecific variation in plant physiological traits along elevation. For about half of the species studied, however, there was evidence of greater physiological stress at the lower and upper limit of the altitudinal range of these species. Together, these findings reveal that climate change is a real and imminent threat for both cultivated and wild plants species, and that plant vulnerability is especially great for plants growing at the lower limit of their altitudinal range.