Two years earlier I had planted a small bed of macrophytic or higher aquatic plants in the connected biopurification sub-ecosystem and water lilies in the supplemental food chain sub-ecosystem.
(I; had planted; a small bed of macrophytic or higher aquatic plants in the connected biopurification sub-ecosystem and water lilies; in the supplemental food chain sub-ecosystem; T:Two years earlier)
I
had planted
a small bed of macrophytic or higher aquatic plants in the connected biopurification sub-ecosystem and water lilies in the supplemental food chain sub-ecosystem T:Two years earlier