Eschen et al Case study 1Inter-annual and spatial patterns in insect diversity. Sheet one (All plots). The first four columns contain information about the sampling location name, the fifth the year of sampling and the remaining columns the number of individuals in each of 13 identified insect taxa. Sheet 2 (18-year continuous). The first four columns contain information about the sampling location name, the fifth the number of insect taxa found over eighteen years of sampling, the sixth column indicates the rate of increase in species number and the remaining seven columns contain data that characterise the plots, their geographic location and average climate.Eschen et al Case study 2Intra-annual patterns in insect diversity. The first column identifies the insect trap, the second the date of collection. The remaining 21 columns contain the number of individuals of different identified taxa, counted on each trap per collection date.Eschen et al Case study 3Spatial patterns in diversity of seed-borne fungi. Sheet 1 (Pinus.ponderosa): The first column identifies the seed lot, the second column the tree species (P. ponderosa only), the third the seed that was put on agar and the fourth column identifies the morphotype obtained from a seed. Sheet 2 (Eight species): The first three columns identify the tree species, seed lot and individual plated seeds. The remaining 188 columns indicate presence or absence (1 or 0) of morphotypes obtained from a seed. The numbering of morphotypes in the different tree species does not correspond to the same morphotypes, i.e. Spp 1 in one tree species is not necessarily the same as in another tree species.Eschen et al Case study 4Spatial and temporal patterns across and within regions, locations and years. The first two columns indicate the replicate of the dataset and the created subsample from each sampling location and occasion in each replicate. The next four columns indicate sampling year, geographic region, sampling week and collection site. The remaining 25 columns indicate the number of adults of each ladybird species found at each sampling location and date.Eschen et al Case study 5Cost vs sampling effort. The first five columns indicate the country where samples were taken, whether the country is in Europe (1) or not (0), the number of sampling locations in the country, the total number of tree species sampled in the country and the average number of species per location. The remaining twelve columns contain estimated costs (in EUR) of various aspects of travel, sampling and detection or identification. “NA” indicates that no value was provided.

Aim: Early warning against potentially harmful organisms of woody plant species can be achieved by sampling sentinel plants in exporting countries. However, it is unclear where sentinel plants can best be located, and how many samples are required and when and how often sampling optimally should take place for the adequate assessment of the biodiversity associated with the target plant species. We aimed to review spatial and temporal factors affecting associate biodiversity of single woody plant species and to develop guidance for the design of global biodiversity sampling studies. Location: Worldwide. Taxon: Insects and Fungi. Methods: Literature about factors affecting the diversity of insects and fungi in association with single plant species on global, regional, local and different temporal scales was reviewed. Case studies of insect and fungal diversity, primarily collected on single plant species, and the cost of collecting and analysing samples from locations around the world were analysed. Results: The review of the literature illustrated various factors affecting diversity, and the case studies allowed quantification of the relative impact of some spatial, temporal and financial aspects on captured biodiversity and, thus, illustrate the need to consider all possible factors that may affect the result of the sampling when deciding on a sampling design. Main conclusions: Our study illustrates the factors that should be considered when deciding on the location and timing of sampling for sentinel plants, which is important because of the trade-off between the number of samples and sampling locations needed to detect many of the species which may be potential pests, and the cost of (repeated) sampling in many locations. Decisions about the sampling design must be based on the objective of the sampling, but our recommendations apply irrespective of the targeted plant species or country.