Question

Passage:
In plant evolutionary biology, scholars have long debated the ecological mechanisms enabling invasive C4 grass species to displace native C3 perennials in arid grasslands. Early physiological models attributed the dominance of C4 grasses exclusively to their superior water-use efficiency during peak summer temperatures. Because C4 photosynthesis minimizes photorespiration under thermal stress, researchers hypothesized that native C3 species were eliminated primarily through direct physiological desiccation during seasonal droughts.

However, recent multi-year microclimate studies in temperate steppes demonstrate that while C4 grasses do maintain higher photosynthetic rates during midsummer heat waves, their total annual biomass accumulation is heavily dependent on early-spring soil moisture reserves. Crucially, isotopic tracking of soil nitrogen reveals that native C3 perennials absorb the vast majority of bioavailable nitrate during the cool early-spring thaw, well before C4 species initiate active root growth. Despite this early-season nutrient capture by C3 plants, late-season soil analyses indicate that dense stands of C4 grasses severely deplete deeper subsoil water tables by late autumn, preventing C3 roots from establishing the deep reserves necessary to survive winter dormancy.

Consequently, the displacement of native C3 perennials cannot be explained solely by high-temperature photosynthetic efficiency. Rather, competitive exclusion occurs because late-season subsoil moisture depletion by C4 grasses undermines the winter survival of C3 perennials, even though C3 plants successfully monopolize early-spring nitrogen uptake.

Based on the passage, which of the following can be inferred about native C3 perennials in temperate steppes where invasive C4 grasses have established dense stands?