Read the passage below:
In plant ecology, the "stress-gradient hypothesis" posits that competitive interactions between plant species predominate under benign environmental conditions, whereas facilitative interactions—where one species enhances the survival or growth of another—become dominant under extreme abiotic stress. Early empirical tests of this model in alpine ecosystems primarily evaluated biomass accumulation across elevational gradients, consistently observing that nurse plants mitigated microclimatic extremes for understory saplings. However, recent investigations into arid soil crust communities reveal a more nuanced dynamic: while physical shading by canopy shrubs undeniably reduces evaporative moisture loss, it simultaneously restricts photosynthetically active radiation reaching shade-intolerant cryptogamic species. Consequently, the net interaction toggles between facilitation and competition depending on micro-topographic variations in cloud cover and daily temperature oscillations. This contextual fluidity suggests that categorizing species interactions along a unidirectional stress continuum oversimplifies ecological realities, as it fails to account for how microhabitats decouple macro-climatic stress from localized resource availability.
Which of the following best describes the function of the sentence beginning with "However, recent investigations" in the context of the passage as a whole?
- It introduces empirical findings that qualify the scope and universal applicability of an established ecological hypothesis.Cevap
- BIt presents definitive experimental proof that invalidates the foundational premises of the stress-gradient hypothesis.
- CIt provides additional evidence supporting the early empirical observations made in alpine ecosystems.
- DIt details a specific example of how abiotic stress directly increases overall biomass accumulation in extreme environments.
- EIt outlines a broad theoretical framework for predicting how macro-climatic factors regulate global vegetation patterns.