Conclusion
Our study provides empirical evidence of variation in species’ vital and population growth rate responses to local-scale heterogeneity in abiotic conditions and plant-plant interactions in a natural system. We illustrate the potential for demographic trade-offs between emergence and subsequent vital rates to counteract the effect of natural variation in shade and soil nutrients on population growth rate. We found a surprising lack of significant effects of neighbours on survival and seed production among species but show the potential of weak vital rate responses to competition to generate strong patterns for population growth rate. We also demonstrate the importance of interactions between different abiotic factors (shade and nutrient availability with water availability) and between abiotic and biotic factors for vital and population growth rates. Linking functional traits to variation in demographic responses is the next aim of this research and will help to generalise our understanding of the mechanisms driving fitness-environment relationships.