How much of Earth's forested land is currently protected from logging/deforestation?
How much forested land is currently protected from
  logging/deforestation?



I doubt that could be answered with anything better than a rough guesstimate. We would first need to know how much land is OFFICIALLY/LEGALLY protected. Then we would have to subtract acreage to allow for illegal logging or general environmental destruction. There are also areas that aren't legally protected but nevertheless aren't logged simply because they're very remote, the terrain is too rugged, etc.

In addition, it's a moving target. Various governments around the world continually modify their environmental management policies and practices. A forest that's protected today might fall prey to a bribe from some giant oil company tomorrow.



  How much is currently at risk?



Again, that's very hard to answer. Forest destruction is an ongoing process around the world. Forests in the most remote regions are typically the safest, but they will become more vulnerable as surrounding forests are felled, new roads are built, more people move into these remote areas, etc.

Another factor to consider is war, or political corruption in general. So many governments have been destabilized (primarily by the U.S.), and so many governments are grappling with economic woes or fears of invasion. Not surprisingly, they're going to emphasize security and survival over the environment.

Of course, war itself can take a toll. Consider Vietnam, where the U.S. used Agent Orange indiscriminately. I believe the Soviets similarly wiped out much of Afghanistan's montane forests.



  How do tree plantations compare in overall size?



Are you asking how the land area that is devoted to tree plantations compares to the land area covered with wild forests?

Again, I don't know the answer, but please note that there are vast differences between plantations and wild forests. Plantations may be preferable to barren earth, but they don't begin to compare to "natural forests" in terms of biodiversity. Tree farms are to Nature what fast food is to cuisine.

I fear for Africa more than South America. The Amazon is obviously a cause for concern, but there is some political stability in South America, and there are environmental activists there.

In comparison, Africa appears to be lost. How many acres have been converted to genetically modified food? I've read about thousands of traditional African farmers being replaced by GMO, though there isn't much information on the subject.

Libya's destruction by NATO was an enormous blow for Africa (and the world). And for whatever it's worth, I believe Colonel Gaddafi was generally regarded as an environmentalist, at least in comparison to other African leaders. There have long been predictions that the next cold war will be fought between the U.S. and China over Africa's natural resources. In fact, the U.S. has troops stationed in just about every country in Africa, and I just read that China is building a military base there.

In summary, forest loss is a huge problem in South America, but there is at least some hope. I predict that it will be a much bigger problem in Africa in the long run.


  Furthermore, if the size of forested land on N. America, Asia, and
  Europe remains constant or grows, how much of that is due to tree
  plantations?


Once again I don't have a specific answer, but I can offer a good guess: Most of it. After all, native forests will continue to shrink, while tree farms will continue to multiply.

Sorry to be so negative. I actually believe there is hope, but things aren't going to change without a massive change agent.