Final answer:
Assessing the stability of an ecosystem's equilibrium requires understanding its resilience to disturbances. Upland ecosystems may be more resilient due to their isolation, whereas lowland ecosystems could be less stable. Precise identification of which system is more stable cannot be determined without more context.
Step-by-step explanation:
When considering whether the upland or lowland system is characterized by a stable equilibrium, we must assess the ability of the ecosystem to remain in equilibrium despite disturbances. A system in stable equilibrium will return to its original state after it has been disturbed. The description of the upland and lowland systems does not explicitly state which is more stable, but generally, the upland ecosystems, given their isolation and poor agricultural soils, might have developed resilience mechanisms to cope with disturbances due to fewer resources and accessibility. Meanwhile, lowland ecosystems, typically located in more resource-rich and accessible areas, could potentially be less stable due to greater human interference and resource extraction. Unfortunately, without more context, it is challenging to precisely identify which system is characterized by a stable equilibrium.