Thresholds of Connectivity

Environmental Thresholds of connectivity refer to the points at which ecological change creates dramatic results. For example, previously integral, continuous landscapes can become fragmented (Monkkonen & Reunanen 1999). The shifts in ecological processes can be dramatic and disastrous especially in certain areas. Nagelkerken (2009) refers specifically to the thresholds of connectivity in tropical coastal ecosystems: including but not limited to wetlands. There are numerous types of ecological processes that are affected potentially by thresholds of connectivity. According to Monkkonen & Reunanen (1999), connectivity is defined in terms of specific species-to-species relationships.

For instance, a foraging animal will respond directly to changes in the flora distributed in its landscape. Changes may promote species migration or local extinctions. The manager of a wildlife area, forest, or park should be well aware of the thresholds of habitat connectivity in order to predict the effects on the animal populations. Distribution of species is another factor that is directly related to thresholds of connectivity. An increase in habitat fragmentation that results from ecological change will impact animal populations.

Because regional planners also contend with park boundaries and other artificial constructions that mean little to animal species, the impact of diminished connectivity on human populations cannot be underestimated. Percolation theory predicts a 60% threshold at which abrupt change occurs in tropical coastal ecosystem behaviors (Nagelkerken, 2009). The number is far lower in terrestrial ecosystems, at which a 30% threshold predicts abrupt change. Population dynamics are the main type of ecological process that is affected by thresholds of connectivity.

Relationships between predator and pray, for example, seriously change when thresholds of connectivity are reached and surpassed. For instance, abundance of specific species of aquatic flora and fauna is affected adversely when the threshold of connectivity is breached or transcended. The availability of seawater plant species may become more sporadic, forcing the dispersion of species. Both shallow and deep-water ecosystems share sensitive thresholds of connectivity. Even when the decline in species abundance or diversity is gradual, the results can be catastrophic.

Species diversity and distribution of food sources impact food chain patterns. Food chain patterns in turn totally alter the means by which flora and fauna move, breed, and contend with predators. Part Two Effective field management and manipulation by human beings depends on understanding the thresholds of connectivity. The thresholds of connectivity will differ from ecosystem to ecosystem, and they may be monitored or predicted using technological tools such as computer simulation software (Nagelkerken 2009).

The critical thresholds usually reflect nonlinear relationships and irregular patterns, which are best visualized using technology (With & Crist 1995). As With & Crist (1995) point out, percolation theory has been used to explain how critical thresholds of connectivity occur and how to predict them. Percolation theory offers calibration data for prediction software used in the field. According to With & Crist (1995), the critical threshold of connectivity develops organically along with or because of the interaction among species.

Thus, managing ecological connectivity might not even be possible; it might not be feasible to manufacture ecological connectivity within a park, wetland, or forest area, for example. Instead, land management specialists must contend with micromanaging at times or alternatively, with radical experimentation. A species determines its own threshold, and humans must learn to work with a high degree of uncertainty with regards to managing properties.

While some thresholds of connectivity can be estimated or predicted using computer software, there are an infinite number of variables that might impact the evolution of a given ecological zone. Much of the scientific data on critical thresholds is actually spurious (Monkkonen & Reunanen 1999). Vegetation maps, digital elevation data, and tracking data all come into play when working with technology tools used to predict thresholds of connectivity and their consequences (Nagelkerken, 2009). Surfaces, whether terrestrial or oceanic, have an indirect and sometimes direct bearing on the thresholds of connectivity.

Geology may take more time to impact the threshold of connectivity.