A fragile environment is a biome that is under threat from change, damage or unsustainable use. Most impacts will be long-lasting due to the inability of the area to recover easily due to extreme cold because things never decompose nor grow quickly.
There is no denying whether or not cold environments are vulnerable to interference. The slow rate if of plant growth means that any disruption takes 50 years to correct. There is also low productivity because Bacterial activity is low due to cold temperatures and waterlogged conditions, stopping the recycling of nutrients and decomposition. Drainage is poor due to frozen ground, especially in permafrost zones. Although active layer thaws in summer, sub soil remains frozen. Soil contains angular fragments as a result of freeze thaw and frost heave. Plants therefore have to adapt to meet the needs of these challenges.
The food chain is very short, and species have to also adapt to the harsh conditions, meaning the populations are low. It is very fragile as any interference to a certain species will wipe out many others in the food chain.
However whether they be exploited successfully is the key question. For the reasons above it is crucial that the development of these areas is managed wisely. This is shown by the Trans-Alaskan oil pipeline. In 1968 vast deposits of oil were discovered on the North Slope of Alaska, in an area within Prudhoe Bay. However the extraction of this was a major problem due to the presence of pack ice in seas surrounding it disallowing tankers to manoeuvre in and out of the area. Alternatively a pipeline was installed. It took 5 years to design and 3 years to build costing around 8 billion dollars. The 5 years of design meant it could navigate through Alaska, avoiding interference of Caribou migration pathways. It has been adapted by elevation- heat from the line does not thaw the permafrost leading to no subsidence. Caribou can also pass under the elevated areas. Thick insulation allows the pipeline to pass under the ground so that caribou can travel on top, it also allows for further development as roads can be built on top providing infrastructure.
This shows that the large extent of fragility experienced in Alaska can be overruled by careful engineering allowing expensive but possible development of such areas.