Photic or euphotic zone is how much deep from the upper surface of sea

Which of the following ecosystems will be more productive in terms of primary productivity ? Justify your answer. A young forest, a natural old forest, a shallow polluted lake, alpine meadow.

Choose incorrect option for the cost distribution of ecosystem services.

Given below are four statements $(a-d)$ each with one or two blanks. Select the options which is correctly fill up the blanks into two statements.

$(a)$ Ecological succession is a…$(i)$… and fairly predictable changes in the ….$(ii)$… of a given area

$(b)$ Ecological succession, entire sequence of communities that successively change in given area are called …$(i)$….

$(c)$ Primary succession occurs on…$(i)$…

$(d)$ Secondary succession is …$(i)$… than primary succession