It is widely assumed that widespread, generalist plant species have high phenotypic variation, but we know little about how intraspecific trait variation (ITV) relates to species abundance and niche breadth. We tested the hypotheses that species with wide niche breadth would exhibit 1) a high among-site ITV, 2) a strong relationship between trait values and the environment, and 3) a close fit between traits and local environment trait optima, represented by community weighted mean (CWM) trait values. We also determined the contributions of species turnover and intraspecific variation to shifts in community mean trait values across light and soil nitrogen (N) availability gradients. To test our hypotheses, we measured leaf functional traits of saplings in temperate rainforests in southern Chile. We compared the relative abundance of each species with its niche breadth, measured as the range of light and soil N availability. We used the slope of the linear regression of species’ trait-environment relationships to assess the strength and direction of these relationships.
We found that the relative importance of ITV among plots was higher for leaf mass area (46.99% of total variance) and leaf N (56.53%) than for leaf area (21.47%). Species abundance was not significantly related to ITV for any trait. We also found that for some particular trait-environment combinations, wide niche breadth species (especially across soil N gradients) had high among-site ITV and close tracking of local trait optima. Niche breadth was related to total ITV but not to the slope of trait-environment relationships. Finally, mean leaf trait values were related to niche breadth along the soil N gradient but not the light gradient. We conclude that ITV may contribute to the ability of wide-niche breadth species to succeed in different environments, i.e., the jack of all trades is master of none, which has important ecological implications for species and habitat conservation. Under local or global environmental changes, the consideration of species’ abundance, niche breadth and ITV has important consequences for predicting community responses to these important changes, i.e., not all species will respond similarly.