Aquatic quillworts, Isoëtes echinospora and I. lacustris under acidic stress – a review from a temperate refuge

Quillworts (Isoëtes) represent highly specialised flora of softwater lakes, i.e., freshwater ecosystems potentially sensitive to acidification. In this paper, we combine a review of previous studies and our new results to address unrecognised reproduction strategies of quillworts to overcome long-term environmental stresses. These strategies play an important role in the plant’s ability to overcome atmospheric acidification of freshwaters, protecting the plants until their environment can recover. Environmental drivers of recovery of Isoëtes echinospora and I. lacustris were studied in two acidified lakes in the Bohemian Forest (Central Europe). Both populations survived more than 50 years of severe acidification although they failed to recruit new sporelings. Their survival depended entirely on the resistance of long-living adult plants because the quillworts do not grow clonally. During the past two decades, a renewal of the I. echinospora population inhabiting Plešné Lake has been ob..., ,