Forests have long been understood as arenas where light competition dictates survival—taller trees block sunlight, often killing shorter neighbors in a process called stem exclusion. Yet scientists have observed that in old-growth forests, trees of different heights coexist successfully, suggesting that canopy dominance is not the only path to survival.
This finding challenges traditional ecological models, which emphasize that taller trees inevitably outcompete shorter ones. The persistence of size diversity in mature forests hints at more complex dynamics at play, including possible niche partitioning or cooperative interactions.
The research, published in a recent study, highlights the role of forest succession stages. During stem exclusion, shorter trees typically die, but in old-growth systems, some shorter trees endure by exploiting different light spectrums or relying on below-ground resources.