Whenever I see someone claim a given problem is due to a combination of factors, I get a bit suspicious. First, this seems like a way to say "I don't really know the actual cause." Second, in the real world in situations like these, there is almost always one overwhelming factor that accounts for >60% of total influence. I really do wonder what that is because I like insects!
> in the real world in situations like these, there is almost always one overwhelming factor that accounts for >60% of total influence
That may be true when you're optimising a program, but is very much not true in ecology. The parent comment is generally correct with its list of drivers of biodiversity loss (compare the IPBES global summary: https://ipbes.net/global-assessment).
A key feature of ecology is its extreme complexity and the myriad factors at play in any given situation. Of course, there will be individual situations in which one factor is indeed dominant. Those cases actually often end up as textbook examples precisely because they are so rare, like the snowshoe hare/lynx Lotka-Volterra cycles. In most situations, researchers have to resort to some pretty advanced statistics to try and figure out what the most important factors are. There are almost always several, and getting any one factor to explain 60% of the variance is very rare. (That's why principle component analyses -PCAs- are so popular in ecological research papers.)
I studied ecology for a while, and have published a paper in the field. It works exactly the same way as any complex system. If you can't pinpoint a single factor, you're probably failing somewhere. To blame everything on "it's a complex system" is usually a cop out from lack of knowledge, whether the system is genuinely complex or not.
