PREFIX tci: <https://data.graphplaza.com/tree-city-inventory/ns#>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
SELECT ?species (COUNT(?t) AS ?n) WHERE {
?t a tci:Tree ; tci:taxon ?tx .
?tx skos:prefLabel ?species
}
GROUP BY ?species ORDER BY DESC(?n) LIMIT 20