How many tree species are listed when the total plant species is 258?
CREATE TABLE "list_of_protected_forests" (
  "central_forest_reserve" text,
  "size_in_km" real,
  "total_plant_species" real,
  "tree_species" real,
  "endemic" real,
  "threatened_cr_vu_en" real
);
SELECT "tree_species" FROM "list_of_protected_forests" WHERE "total_plant_species"=258;