Ok, well without getting into specifics deforestation covers a huge swath of territory.
The problem as I see it can be catagorized into two main sections that do overlap. They would be causes due to natural ebb and flow in the ecosystem and problems due to man. Both are found in all forests globally and they interact together.
Natural causes can be broken down further. Deforestation happens due to pest outbreaks and fugus/bacterial outbreaks. Classic examples are bark beetle infestations and Dutch Elm disease. At any time the natural checks and balances within a local ecosystem gets off balance a pest species population can explode causing all sorts of damage. The result can be massive die off of a target species with a lagging bloom in predator species as their food supply becomes abundant.
The catch all to this is in a heterogenous forest you'll have many types of trees and they won't all be targeted by a single pest. This is different of course for tree farms, most noteably in this area is christmas tree farms and pole tree farms.
What compounds natural problems is invasive species. This being the case with Dutch Elm Diesease. It was a biological outbreak but of a forigen bug (can't remember if it was fungal/bacterial/viral) into a population with no resistance. Invasive Speices costs the environment billions of dollars in damages a year. The problem will continue to grow as the world becomes smaller with global trade. This is also the reason the CDC is very worried about southeast asain chicken influenza. Wether you are a forest or a human, the ability for a forgien bug to travel globally is now on an unpresedent scale. I digress.
This leads into man made problems. The first being the aforementioned invasive species carried by man from one local to another. The second in terms of outright deforestation of every tree/plant can come in two forms. Clearcutting for economical purposes and slash 'n burn for subsistance.
First, clearcutting is not a bad harvest method. However, it must be used correctly on the proper scale and is not the #1 method for all locations. Taking into account topography, location to water sources and scale must all be heavily considered. I could write volumes on this issue, but that's not the point.
In my mind the major problem with deforestation is in 3rd world countries and the tropical rain forest. The problem is this: roads. Roads provide vital links between cities/communites and increases trade and general wealth. The downside is it proves access to previous inaccessable land. There were some interesting areial photos taken of the brazilian rainforest when a major highway was cut. Before it was unbroken span of pristen forest. AFter the road went in, squatters used that road to travel into the forest and commence with slash and burn. Over time you could litterally see the forest dissappear along the roadway.
This problem cannot be answered from an ecological standpoint. The problem is poverty in the 3rd world. It is a social issue which is by far much more complicated to solve than simply protecting the forest.
Hopefully this short post will give you leads for areas to reasearch. It is by no means all encompassing. Good luck!
