When Dr. Helena Vance surveyed the dense stands of *Polystichum munitum* carpeting the floor of the Blackwood Glen, she noted the unusual regularity of their distribution. Unlike the sporadic patches typical of undisturbed old-growth forests, these ferns clustered in precise, concentric rings around slightly elevated mounds of compressed earth. Standard ecological models attributed the proliferation of this species in the region to recent shifts in annual rainfall. However, Helena cleared away the thick layer of leaf litter on one of the mounds, exposing a compacted layer of charcoal fragments and vitrified soil—the unmistakable footprint of a historic kiln. For two centuries, local colliers had harvested timber to fuel these earthen ovens, baking wood in low-oxygen environments to produce charcoal. As Helena examined the surrounding vegetation, she realized that the soil chemistry, altered by the alkaline ash and carbon residue left behind by the colliers, created a localized microhabitat. The ferns were not expanding outward due to a changing climate, but rather colonizing the nutrient-rich, well-drained outlines of an industry that had vanished before the turn of the twentieth century.
Based on the passage, which of the following best describes the implicit relationship between the historical charcoal-burning industry and the modern distribution of ferns in Blackwood Glen?
- Athe colliers chose to build their earthen kilns in areas where the ferns were already densely populated.
- the activities of the colliers created localized soil conditions that continue to determine where the ferns thrive.Answer
- Cthe ferns' expansion over the mounds was the direct cause of the local colliers abandoning their kilns.
- Drecent changes in rainfall patterns have dissolved the old kilns, dispersing the ferns throughout the glen.