Final answer:
While Aldo Leopold does not specifically mention which grass took over the northwestern mountains, analogous scenarios suggest that human activities such as fire suppression and increased grazing can lead to invasions by species like Kentucky Bluegrass or Douglas fir with varied effects on local ecosystems, including soil erosion, loss of biodiversity, and enhanced plant competition.
Step-by-step explanation:
In Aldo Leopold's observations, it was not explicitly mentioned which grass took over the northwestern mountains. However, examining similar cases of vegetation change due to human activities, such as the increase in nitrogen from deposition and runoff leading to the spread of Elymus athericus grass in western Europe and the invasion of Douglas fir in the western United States due to fire suppression and increased grazing, can provide insights. These shifts in vegetation can have various detriments and benefits on local ecosystems.
For instance, invasive grasses like Kentucky Bluegrass could potentially increase soil erosion and decrease biodiversity, while other species like Tall Fescue might improve soil stability and increase wildlife diversity. Conversely, Bermuda Grass could enhance water retention at the expense of reducing native plant diversity, and Blue Grama Grass can lead to declined water availability and enhanced plant competition.
Human activities, including overgrazing, poor land management, and agriculture, can have profound impacts on ecosystems, leading to loss of biodiversity, soil degradation, and the spread of non-native species. In some cases, land use changes can facilitate the invasion of exotic plant species, altering the natural vegetation and animal habitats. Nevertheless, practices such as proper cattle grazing management are argued by UC Davis to potentially help mitigate climate change and contribute positively to soil fertility and ecological function.