Final answer:
Species distributions on a global scale are primarily controlled by temperature and rainfall changes, which can cause shifts in plant species ranges. Aside from abiotic factors, species' dispersal abilities and geographical constraints influence distributions. Conservation measures must consider these dynamics and the dependence of species on broad-scale ecological processes.
Step-by-step explanation:
The primary control on species distributions at continental and global scales is largely determined by changes in temperature and rainfall, which are expected to drive shifts in plant species distributions. These changes can lead to range contractions at the equator-side boundaries and expansions towards poles or higher elevations. The species distribution models (SDM) have shown potential for large range contractions and significant shifts in native species assemblages under scenarios of climate change. Moreover, the ability of species to disperse and establish in new regions is a critical factor determining their range shifts. This is not only true for native species but also for invasive species, which are also expected to experience range shifts and may not necessarily benefit from climate change despite their broader native distributions. Geographical constraints also play a role in limiting species distributions, as regions like high latitudes and peninsulas naturally harbor fewer species.
At more local scales, temperature and rainfall significantly influence demographic processes such as seedling survival and reproduction rates. Furthermore, broader ecological processes are crucial for conservation, indicating that extensive conservation actions need to account for the dependency of many species on these processes.