For some types of ecosystems, such as deserts, tundra, and croplands, so little is known that the valuation columns under nearly every ecological service remain blank [7] .
(so little; is known; ) Context(so little is known,List([70, 88))):(the valuation columns under nearly every ecological service; remain; blank)
so little is known,List([70, 88))
so little the valuation columns under nearly every ecological service
is known remain
blank