Some sources in Swedish: https://www.naturskyddsforeningen.se/igenvaxning-gifter-hot https://www.naturskyddsforeningen.se/igenvaxning-gifter-hot and https://www

Some sources in Swedish: https://www.naturskyddsforeningen.se/igenvaxning-gifter-hot https://www.naturskyddsforeningen.se/igenvaxning-gifter-hot and https://www2.jordbruksverket.se/webdav/files/SJV/trycksaker/Pdf_ovrigt/ovr3_29.pdf https://www2.jordbruksverket.se/webdav/files/SJV/trycksaker/... Biodiversity depend on diversity in environment, and as I understand it, more so in colder climate zones. In the last 100 years the decrease in farm land, grazing areas, and gardens is the primary cause why about 1 300 species is marked as endangered here in Sweden. When small plot of open land in the middle of spruce forest (European spruce) get overgrown here in Sweden, the result is first a stage of small and thick bushes until later the trees reclaim the once open area. Spruce is the dominating tree in the southern part of Sweden. If you are asking why spruce is so dominating you would have to ask a botanist, but I would suspect the temperature, the soil and access to water as being the usual suspects for why one type of tree can dominate an area. I should make it clear that what I describing is the situation in Sweden. Rain forests are unlikely to have the same need for diversity throigh multiple small biomes in the same area. The US is pretty large area so I can't really say if any of its area suffers similar to Sweden, but I would suspect that Canada do. The above linked sources (and references research in those) also point that diversity in how farming is done is also a key part of the decrease biodiversity. High yield farming of the same plant year in and year out is directly harmful to diversity. To enable this kind of farming people adds pesticides and fertilizer, both which links to a decrease in bio diversity through multiple factors. The redirection of water to more concentrated areas also pile on the problems for biodiversity. The more uniform and concentrated the farming become, and the more spill over of pesticides and fertilizer, the more damage we do to nature. Those aspects is true not only for Sweden but globally.