Latitudinal decrease in folivory within Nothofagus pumilio forests: dual effect of climate on insect density and leaf traits?
GARIBALDI, L.; THOMAS, KITZBERGER; ADRIANA, RUGGIERO
GLOBAL ECOLOGY AND BIOGEOGRAPHY
Lugar: Oxford; Año: 2011 vol. 20 p. 609 - 619
Aim The strength of consumerplant interactionsmay decrease with latitude. Ourobjectives were to assess the spatial variation in folivory on Nothofagus pumilio andunderstand the influence of climate on folivory patterns as mediated by changes infolivore density and leaf traits.Location Nothofagus pumilio forests, between 38 and 55°S (Argentina).Methods We studied the correlation of leaf damage with latitude on data from 47sampling sites, and evaluated spatial patterns of autocorrelation on latitudinallydetrended data with a principal coordinates of neighbour matrices method. Pathanalysis was used to test the association of temperature and precipitation with leafdamage, mediated by folivore density and leaf traits.We evaluated the adequacy ofthis ecological model by examining the spatial pattern of autocorrelation in theresiduals, and combined spatial and environmental predictors of leaf damage intopartial regression.Results Leaf damage decreased with latitude, which was the only significantspatial predictor. The latitudinal decrease in temperature and precipitation wascorrelated with a decrease in the density of folivores and leaf size, and diminishedleaf damage. Our ecological model adequately explained the spatial autocorrelationin the data: 44% of the variation in leaf damage was explained by the latitudinallystructured component of the environment, whereas local environmental effectsaccounted for another 22%.Main conclusions We conclude that N. pumilio forests show consistent latitudinalpatterns of variation in folivory, folivore density and leaf traits. Our studysuggests that the latitudinal variation in folivory rates is partly driven by theinfluence of climate on both plants and herbivores. This warns us about the potentialsusceptibility of folivory rates to climate warming. We emphasize the value oflarge-scale analyses as complementary to