|Restoration of biogeomorphic landscapes by creating ‘windows of opportunity’|
Coastal and arid ‘biogeomorphic’ ecosystems are harsh environments where physical disturbances constantly destroy colonizing vegetation by remobilizing and overturning the sediment. These forces can be impeded by dense stands of vegetation, whose canopy slows the flow of wind and water, and whose roots constrict and immobilize the sediment. But in order for vegetation to take control of these processes, young pioneer plants must first somehow survive the initially extreme environment. How is that possible?The ‘window of opportunity’ concept suggests an answer to this question: the occasionally successful establishment of pioneer vegetation in hostile environments occurs because the state of the environment is non-constant. In periods of unusually calm conditions, establishing organisms can develop the tolerances required to survive once disturbances reappear. This conceptual framework identifies three key parameters that determine how likely an environmental is to experience a ‘window’ between disturbances that will be sufficient to facilitate pioneer establishment. These are: (1) the intensity of disturbances, (2) the interval of calm conditions between disturbances, (3) and the rate at which an organism develops tolerance to disturbances. Based on this premise, the brief manipulation of any of these three parameters should create opportunities for pioneer establishment.In this thesis, we first study how observed natural establishment events fit within the ‘window-of-opportunity’ framework. Then, using this knowledge, we develop restoration tools that recreate the conditions observed in natural establishment events to artificially provoke pioneer recruitment.