CREATE TABLE table_22897 ("land formation" CLOB, "area ,  km\\u00b2" FLOAT, "of which currently forests ,  km\\u00b2" FLOAT, "% forests" CLOB, "habitat type" CLOB)

When middle prut valley is the land formation what is the highest of which currently forests, km ?
SELECT MAX("of which currently forests, km\u00b2") FROM table_22897 WHERE "land formation" = 'Middle Prut Valley'
SELECT MAX("of which currently forests, km\u00b2") FROM "table_22897" WHERE "land formation" = 'Middle Prut Valley'