Resilience

During time things grow and develop into an interrelated structure. Humans make communities, big cities countries and empires. Nature is the same, forests, wetlands, seas, mountains and even deserts. Given enough time they interact with each other and maturate. But there are disturbances. War, outbreak of diseases, flood and earthquake are some of disturbances for human and for nature, fire, pollution, human interference, invasive species are considered as some of hazards that can happen.

What happens after the incident? Whether the system returns to its initial condition or not, does it go to another structure, destroys completely. These questions are addressed in concept of resiliency.

Systems are like a ball in a bowl and disturbances move the ball, if the walls of bowl are tall enough they can hold the ball inside itself but if the disturbance is too strong ball goes out of the bowl. Sometimes there are adjacent bowls and systems adapt themselves to that but they might fall totally and no remaining of them may survive.

Forests are different systems in northern part they are combination of some few types of wide leave trees and some needle leaves. Pine and spruce are from needle leaves and birch and aspen are from wide leaves. One of major disturbances in Canadian forests is fire, cause by nature or human. Needle leaves provide good fuel for fire and in summers they can cause lots of problems. Existence of pine beetle may have severed the situation by killing and drying more trees.

So it could be said that forest resilience is the capacity of a forest to withstand (absorb) external pressures and return, over time, to its pre-disturbance state. When viewed over an appropriate time span, a resilient forest ecosystem is able to maintain its ‘identity’ in terms of taxonomic composition, structure, ecological functions, and process rates

The resilience of a forest ecosystem to changing environmental conditions is determined by its biological and ecological resources, in particular (i) the diversity of species, including micro-organisms, (ii) the genetic variability within species (i.e., the diversity of genetic traits within populations of species), and (iii) the regional pool of species and ecosystems. Resilience is also influenced by the size of forest ecosystems (generally, the larger and less fragmented, the better), and by the condition and character of the surrounding landscape.

Primary forests are generally more resilient (and stable, resistant, and adaptive) than modified natural forests or plantations. Therefore, policies and measures that promote their protection yield both biodiversity conservation and climate change mitigation benefits, in addition to a full array of ecosystem services. Nevertheless, it must be recognized that certain degraded forests, especially those with invasive alien species, may be stable and resilient, and these forests can become serious management challenges if attempts are made to re-establish the natural ecosystem to recover original goods and services.

Some forest ecosystems with naturally low species diversity nevertheless have a high degree of resilience, such as boreal pine forests. These forests, however, are highly adapted to severe disturbances, and their dominant tree species have a broad genetic variability that allows tolerance to a wide range of environmental conditions.

The topic was not relevant to my thesis subject by in some part that was talking about human disturbances could have been used as examples.

It might be relevant to say that during thousands of years almost all forest areas could have experienced fire and maybe today’s condition is a post fire condition, so maybe Canadian forests have the potential to host many other species other than existing ones.