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Trichomanes speciosum is a threatened species restricted to sheltered, very humid sites. Uniquely amongst European ferns, differing ecological tolerances of the gametophyte and sporophyte generations are manifested as widely differing distributions. The perennial, vegetatively propagating gametophyte persists in drier, colder, darker habitats than the sporophyte. In sites where the gametophyte grows, light availability was found to be 1 µmol m −# s −" for approx. 85% of daylight hours, rarely or (in some sites) never rising above 10 µmol m −# s −" . Much of the time, light was 0.01% of full sunlight. Measurements of gas exchange and chlorophyll fluorescence yield show that these plants have optimal photosynthesis at light intensities c. 5-10 µmol m −# s −" , the highest light to which they are normally exposed to in their natural environment. The absence of any capacity for reversible nonphotochemical fluorescence quenching means that there is little or no protection of the photosynthetic apparatus from light-induced damage. We conclude that these plants are able to create what are essentially monocultures in their extreme environments only because of a combination of low metabolic rate (at low temperatures) and an ability to make efficient use of what little light is available to them by morphological and physiological means.

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Summary Many peatland ecosystems in Europe have become degraded in the last century owing to the effects of drainage, burning, pollution and climate change. There is a need to understand the drivers of peatland degradation because management and restoration interventions are expensive and can affect the natural ecohydrological dynamics of such sensitive environments. However, if given enough time, peatlands may have the ability to recover spontaneously without deliberate action. We use a detailed multiproxy palaeoecological data set from a degraded raised bog in Northern England to examine its ecosystem stability and long‐term dynamics in response to anthropogenic disturbance over a variety of timescales. One feature of many degraded peatlands (including our study site) is the local dominance of Molinia caerulea (purple moor‐grass), which has expanded at the expense of characteristic peatland plants, including sedges and Sphagnum mosses. Our data show that there has been a long history of human impacts at the site which have culminated in its current unfavourable condition. Several distinct episodes of past peat cutting are evident as hiatuses in peat accumulation; however, peat accumulation and plant community structure have subsequently recovered spontaneously. The appearance of M. caerulea occurs coevally with an unprecedented variety of recent anthropogenic impacts, all of which have contributed to providing a suitable environment for its rise to dominance. We have dated the appearance of M. caerulea to the latter half of the twentieth century which corresponds to a number of anthropogenic press disturbances, including the following: dust loading from post‐war expansion of the adjacent quarry; burning; drainage; airborne pollution; and contamination from soil dust and agrochemicals. [Synthesis] Our study demonstrates the importance of palaeoecology for understanding the trajectories of peatland development and ecosystem dynamics, including their resilience and resistance to pulse and press disturbances. We show that peatlands have the capability to recover spontaneously from severe disturbances such as peat cutting, albeit on timescales much longer than those applied to contemporary monitoring of restoration efforts. The implications are relevant for determining whether it is preferable to manage and restore peatlands, or to allow them to recover naturally without human intervention.