Beginnings of wetland science in Britain: Agnes Arber and William H. Pearsall

Abstract

Agnes Arber (1879-1960) and William H. Pearsall (1891-1964) were two of England’s most influential antecedent wetland scientists. Arber was a plant anatomist specializing in monocotyledons, whose only major contribution to wetland science was her 1920 book, Water Plants. It was the first compendium of information on wetland plants in English and summarized the literature on their life histories, anatomies, ecologies, and evolution. It remained the standard reference on wetland plants for decades after its publication. William Pearsall began studying the ecology of wetland plants in the lakes of the English Lake District as a young man. This early research (1913-1920), which he did with the help of his school-teacher father, identified the environmental factors (substrate type, siltation rates, maximum light penetration, wave action, etc.) that determined the distribution of wetland plants and changes in the lake basins over time. In the late 1930s, Pearsall pioneered measuring electrical potential (redox) in soils to characterize their chemical status (oxidizing or reducing). He documented that soil electrical potentials became more negative as soils flooded and increased in organic matter. Pearsall also played a major role in the establishment (1929) and initial research program (Honorary Director, 1931-1937) of the Freshwater Biological Association, Britain’s first research organization dedicated to studying aquatic systems.