Unsustainable Use of Plant Species
Collection of carnivorous pitcher plant (Nepenthes): a practice which can easily become unsustainable if demand is hard and supply poorly managed. Credit: BGCI
The over-exploitation of species by human-kind is the most significant cause of species extinction. A certain amount of species use is sustainable, as plants populations will grow to replenish the stock taken. However, in many cases too much is taken, leaving the resource un-able to regenerate fast enough. Sometimes whole individuals are taken (as when logging for timber) but in other cases just parts of plants are used (when harvesting leaves for a herbal medicine). In both cases over-harvest is possible, but the sustainable level of harvest will depend on the species' life form and biology.
Evidence of human-kind's impacts are all around us, from over-fishing in the oceans, to archeological records of historical mammal extinctions caused by prehistoric man. High levels of exploitation can also affect a species genetic composition. For example, in the Caribbean, the only remaining mahogany trees have non-straight trunks. As mahogany trees take 100 years to reach maturity, sustainable harvesting would only take a small percentage of the standing trees. However, as the straight trees having all been logged for timber, so non-straight trees now are the only ones to reach maturity and reproduce.
There is no evidence that humans have ever acted to conserve and sustain the resources they depend on, but in the past primitive technology and small human populations meant our impact was not so dramatic. Now we have larger populations and better technology, we can harvest plants and their products more quickly, but we also have better understanding of the consequences of our actions. The key is for us to not only understand what a sustainable level of harvest is, but also to actually implement this 'on the ground', where plants are being harvested.
Both the developed and less developed world are responsible for the over-harvest of many of our plant resources. However, when species become rare, it is usually the poorest that suffer most. Also, the poorest people may have no choice but to continue unsustainable practices, if their livelihoods depend on it. Our efforts for sustainable plant use must take human needs into account. It is important that efforts to ensure sustainable use of plant resources are equitable, and where possible link the environment to people's livelihoods. BGCI promotes botanic gardens linking plant diversity with improvements to human well-being.