LIFEPLAN: A worldwide biodiversity sampling design

regional and local endemism [35–37], this regional contrast yields insight into the context- dependency of the results achieved–as then validated by global patterns. We chose the Nordic countries and Madagascar for National and Nested scale sampling because they are of comparable area but have very different evolutionary histories. The Nordic countries were colonised after the most recent ice age, while in Madagascar, species have been evolving in isolation for millions of years [35]. Nordic species are very well known, while the enormous biodiversity of Madagascar is still poorly understood [35, 37–39]. The Swedish insect fauna consists of postglacial immigrants and is one of the best known in the world. Mad- agascar is the world’s most important biodiversity hotspot, with a long period of evolution in isolation–as combined with recent, massive deforestation [40]. Many species are critically endangered if not already extinct [41, 42]. By comparison, endemic species in the Nordic countries are next to absent. Given these contrasts, we aim to resolve–among other things— differences in range size between Nordic and Malagasy taxa, patterns of turnover in space and time, and differences in phylogenetic community structure between the respective regions. Beyond providing a general understanding of basic community assembly processes, each of these insights is needed for improved conservation prioritization—thus attesting to the value of large-scale biodiversity survey and biomonitoring programmes. To resolve patterns of community structure and turnover in space and time, we have

invented a hierarchically structured sampling design in Sweden and Madagascar. At the National scale in Madagascar, we have selected 25 sites spanning all major forest types. In the Nordic countries, we selected 18 sites based on their contribution to spatially even coverage of the region. For the Nested scale, we chose an area in southern Sweden and another in Mada- gascar that were accessible enough to be covered by a single sampling team, were covered by forest, and where landowners gave permission to sample. Overall, we will thus achieve site-by-time-by-species tables of fungi as airborne spores and mycelia in soil, insects, birds and mammals, across hierarchically Nested scales. Global design: Natural vs. urban The largest spatial scale in our study design is the Global scale. We initially invited researchers from all over the world to submit proposals for study sites. Of 184 sites proposed for the Global design, we selected 87, of which 14 eventually had to drop out (Fig 1). In the Global design, sites form natural/urban pairs, where the urban location is in or immediately adjacent to a built-up area, and the natural location is in an undisturbed setting with little direct human influence. In other respects, such as altitude and vegetation type, we have aimed to have the two locations be as similar as possible, and separated by 20–50 kilo- metres (Fig 2). We have tried to cover the world map as evenly as possible, and within the selected regions we have asked teams to sample a habitat that is typical for their region. As a

result, we are currently sampling in a wide range of habitats from various forest types to savan- nah, wetlands, desert and tundra. Teams alternate yearly between their natural and urban loca- tions, so that only one location of each pair is sampled at one time. To avoid confounding the effects of urbanisation and sampling year, we have randomised the design so that half of the teams started in the urban location and the other half started in the natural location. In practice, levels of urbanisation vary in different parts of the world so that a “natural” location in a densely populated area such as central Europe may be much more urban than an “urban” location in a sparsely populated area such as Canada. There are many different mea- sures of urbanisation, but using e.g. the Human Footprint Index 2009 [43], we see that for most, but not all, site pairs the “urban” location scores higher than the “natural” (Fig 3B). “Nat- ural” locations also often ended up at higher altitudes, as lower-altitude areas were fully built PLOS ONE LIFEPLAN: A worldwide biodiversity sampling design PLOS ONE | https://doi.org/10.1371/journal.pone.0313353 December 31, 2024 4 / 15