From the Illegal Logging Portal: http://www.illegal-logging.info/topics/what-illegal-logging
The term ‘illegal logging’ is often used as short-hand to describe illegal practices related to the harvesting, processing and trade in wood. Thus, the law may have been broken at any point along the supply chain, for example: logging with an illegally acquired license or in protected areas; harvesting over allowed quotas; processing of logs without the necessary licenses; non-payment of taxes; or exporting products without paying export duties.
There are various causes of illegal logging but often it is a symptom of wider governance problems, such as inappropriate legislation, weak institutions, unclear forest tenure, corruption and a lack of law enforcement.
The impacts of illegal logging also vary widely, depending on both the scale and the type of illegal activity. Thus, it may take place on an industrial scale, or entail small-scale infringements, with minimal or highly localised impacts. The type of illegality is clearly also significant – for example, infringement of harvesting rules will have direct environmental impacts, while financial misdemeanours affect revenues and overall management of the sector. It should be noted that illegality and unsustainability are not synonymous – illegal practices may be sustainable and legal practices unsustainable. Illegal logging can also be an important part of livelihood strategies for rural communities.
The diversity of situations – both with respect to causes and impacts – means that there is no easy solution to illegal logging. Focusing only on enforcement of the law is not usually a solution, as this can reinforce corrupt networks or increase poverty amongst some forest users. Rather, multi-faceted approaches adapted to the particular situation are necessary to help ensure that outcomes are equitable and will be sustained in the long-term.