Do we have enough trees?
A recent article caught my attention with this one statistic: There are 61 trees for each person on earth. Of course this is only a rough guess, based on satellite imagery of forest cover and estimates of the world's population; however, at first glance it seems like a reassuringly large number. But it begs the question: Is 61 trees per person enough?
Not surprisingly, there is no simple answer. For one thing, ‘enough' depends on what you want the trees for. If the value is in their beauty, then it would be difficult to come up with a good number. However, if the concern is about the number of trees needed to sustainably supply wood, then the following items merit consideration:
We use a lot of wood, for many things. A report from the United Nations FAO states that global consumption of wood for fuel and products was about 3.4 billion cubic meters in 2002, which works out to about 0.6 cubic meters per person per year.
There is a lot of wood in the world. The same FAO report calculates that there are about 380 billion cubic meters of wood in our forests, which works out to about 60 cubic meters per person. So, in very rough numbers, we are using about 1% of our global wood stock per year.
Trees grow. Putting a number to this is tricky, given that it depends on tree species, location, age, management intensity and many other factors. However, a 3% grow rate of trees in a forest is a reasonable estimate for many situations.
Deforestation is taking place . The FAO reports that the global forest area decreased by 0.2% per year from 1990-2000. Deforestation patterns vary a lot by location: the Amazon Basin in Brazil, the Congo Basin in Africa and parts of Indonesia are experiencing major losses of forest; Europe and North America are increasing in forest area. Deforestation is caused mostly by land conversion to agriculture and development – not the harvest of wood – but among the many problems caused by deforestation is the reduced area available to supply the global need for forest products.
Our population in increasing . The number of people on earth is expected to increase 50% by the middle of the century. This will likely increase the need for wood products and will intensify the conversion pressures on forest land.
With the above data we can't determine if we have enough trees. Global averages don't indicate the local situations of supply and demand. Uncertainties about population growth, wood use patterns, deforestation, climate change and other factors make predicting the future impossible. However, wood is a renewable and versatile product of our vast, global forest resource. Do we have enough trees? Maybe!