Timber companies are starting to plant cloned trees in order to increase yield and improve the quality of timber. While the genetic modification of trees is older than written history, many of us prefer selective breeding and hybridization to outright cloning. Be that as it may, cloning trees is a mixed evil at worst.
Trees are usually cloned through a somatic embryogenesis process, in which ordinary plant tissue is forced to bud into genetically identical seedlings. This is not a natural process, but it is not unnatural for certain trees to bud under certain circumstances. We have also been cloning fruit trees (and certain famous trees) for centuries, with largely positive consequences. If there is a grey area in the field of cloning, this is it.
We don't have enough trees. We need paper, lumber, and assorted wood-like products. It would be great if we could reduce our consumption to sustainable levels, but we haven't yet, and aren't likely to do so soon. Deforestation is destroying habitats, increasing levels of atmospheric CO2, and leaving local communities without the ecosystems needed to survive. The need for paper and lumber isn't the only cause of deforestation, but it is one of the biggest. Tree farming is a necessary solution, allowing us to produce multiple crops of trees on the same land. But a 'crop' of trees can take up to 50 years to mature. Anything that can speed up growth benefits us all. Cloned forests are still subject to regulations concerning watershed and wildlife management, and while they are more 'artificial' than natural forests, they serve many of the same functions as natural woodland, and are much better than no forest at all.
While cloned forests give us what we need when we need it (well, more so that non-cloned forests), they reduce genetic variation -- meaning that a single virus could wipe out all the forests planted with a given clone. This would be a major disaster, both economically and ecologically.
One obvious solution to this problem would be genetic modification of the clones -- a technique we are already trying to master in order to save our favorite clone, the banana. This could be the start of a slippery slope, resulting in genetically modified trees hybridizing with natural trees, in much the same way as genetically modified corn has hybridized with unmodified corn populations.
At the same time, local ecosystems often rely on a diverse population of trees; the lack of certain species of trees might mean animal populations can't survive. Any well-managed tree farm would have to include multiple species -- which naturally means cloning more species of tree, right? Responsible forest management and economic concerns might well dictate cloning (and genetically modifying?) every species of tree found in natural woodlands. Bad news for fans of genetic diversity.
Cloned seedlings currently cost more than natural seedlings, and are not yet a major source of seedlings for tree farms. But it is likely that they will come to be a very important part of our economy in the near future -- unless we do something. It's up to us to decide whether we need to do something.