The resilience of heathland ecosystems: A working hypothesis

Ecosystem stability and resilience are vital characteristics for understanding key ecosystem dynamics, conservation management and restoration issues. However, for heathlands and other semi-natural ecosystems investigating stability and resilience demands a different approach from that of more stable ecosystems closer to a successional climax state, since we need to distinguish between 1) disturbances that are needed to maintain the ecosystem in a habitat-characteristic state, and 2) pressures that may perturb the ecosystem away from a characteristic state. Here, we suggest methods to measure and predict resilience in Atlantic dry heathland ecosystems. This will be achieved by outlining a working hypothesis of the most important factors that regulate the stability and resilience of semi-natural heathland ecosystems. At the center of the proposed hypothesis is the amount of nitrogen in the soil that is available for plant growth and how the nitrogen-cycling pathway is formed by dominant species of heathland ecosystems. Furthermore, we will discuss possible ways to quantify semi-natural ecosystem resilience and suggest a research program that would allow us to test the outlined working hypothesis in semi-natural ecosystems and provide quantitative information for making ecological predictions on heathland stability and resilience. This investigation has direct consequences for how heathland conservation may be planned in a way that protects both resilience, structure, function and the characteristic species of heathlands. It could also form an ecological basis for investigating anthropogenic practices and ways to protect its associated culture-historical values.