Great theories of species diversity in space and why they were forgotten: The beginnings of a spatial ecology and the Nordic early 20th‐century botanists

Sometimes, we stumble over literature revealing that well‐known and groundbreaking theories have previously been proposed by earlier researchers. Going back to the 1920s and a group of Nordic botanists, we discovered that they had already accomplished much of what theoretical ecologists and biographers, especially Americans, did half a century later. In order to restore their legacy and understand why the work of the early spatial ecologists in Scandinavia and Finland was forgotten, we examined their publications, recalculated some of their results from their original data and compared these to the more recent independent discoveries of these theories. These Nordic early 20th‐century botanists worked with sample areas (mainlands) as well as island systems, examining spatial patterns and foreseeing or even building probabilistic approaches to species–area relationships (SARs), occupancy‐frequency distributions (OFDs) and species‐to‐genus (S/G) ratios. Many theories in spatial ecology and biogeography are linked to the SAR, such as MacArthur and Wilson's equilibrium theory of island biogeography (based on colonization and extinction), Darlington's rule of thumb, Preston's canonical hypothesis, Diamond's rules of reserve design, and Coleman's random‐placement theory. However, many of the most important SAR‐based theories—as the mathematical shape of both mainland and island SARs as well as rules of thumb, colonization rates on islands, and the random‐placement theory—had already been discovered or discussed in the 1920s by members of the Stockholm group which included the Swedes Gunnar Romell, Olof Arrhenius, Harald Kylin, and The Svedberg, and a Finn, Widar Brenner. The notion of stochastic S/G ratios and the idea that distance affects colonization rates can be traced back to another Finn, Alvar Palmgren. Great theories like these may disappear, if they are, as these, buried in obscure journals or written in languages other than English. There was also almost no audience in the 1920s and 30s, as mathematical theories were less acceptable at that time. Perhaps even more importantly, a devastating dispute (“The Great Polemic”) arose between the Stockholm group of theoretically and mathematically inclined botanists and the Uppsala group of descriptive phytosociologists. The fight, in which the Uppsala group won, was more a political and sociological than an intellectual one. As a result, not only the budding discipline of spatial ecology faded into oblivion but also the researchers were lost to science, at least to spatial ecology and biogeography, and descriptive and taxonomic approaches came to dominate Nordic ecology right up to the 1960s.