Environmental and geographical biases in plant specimen data from the Colombian Andes

Specimen records are a major source of species information for biodiversity research. However, specimen records currently available may be geographically or environmentally biased. Detailed knowledge of biases is useful for understanding and accounting for errors they introduce into analyses of biodiversity patterns. Here we study geographical and environmental biases in online records representing the flora of the Colombian Andes and explore their effect on sample completeness at different spatial scales. We found a strong geographical and environmental sampling bias. Plant records were concentrated close to cities where herbaria and researchers are located. The highlands >2000 m are better sampled, whereas mid- and lowlands remain poorly sampled (i.e. montane and lowland forest). Sampling completeness (SC) median across the Colombian Andes is<75% at the scales studied. We explore possible causes of sampling bias, identify critical gaps and priority areas for plant sampling and make recommendations for strategies to increase SC and reduce biases.