Conclusion
There is a paradigm shift from pattern-based hotspot management to
process-based functional approach in biodiversity conservation strategy.
The sustenance of goods and services provided by ecosystems requires not
only the investigation of biodiversity patterns but also the
identification of processes that produce and preserve regional and local
biodiversity. Although community ecologists generally agree that
ecological metacommunity is structured simultaneously by stochastic and
deterministic rules, one assembly rule may be predominant in a given
landscape. In this study, we showed that ecological stochasticity
prevails in natural habitat whereas deterministic processes dominate in
modified environment in a highly dynamic river-floodplain system. In
addition, the patterns of community temporal dynamics are consistent
with ecological stochasticity. The shift in assembly rules in modified
sites are the likely outcomes of the relatively stable environment
created by human interruption to hydrological connectivity. First,
modification alters hydrological regime, which removes the drawdown
phase variability and maintains low water levels to aid production,
thereby removing the stochastic effects of periodic habitat exclusion.
Second, the flattened hydrograph in the high-water phase creates
dispersal barriers, reducing demographic stochasticity such as chance
colonization. Third, modification reduces the topographic heterogeneity,
which minimises benthic structural variability characteristic of the
natural sedge habitats, leading to stronger biotic interactions.