What will be the P/R ratio of a climax community and a pioneer community? What explanation could you offer for the changes seen in P/R ratio of a pioneer community and the climax community? 

Explanation

In an autotrophic succession , rates of production (P)are more than rates of respiration (R) in the beginning so in the pioneer community , Primary producers are maximum in number so P/R ratio of a pioneer community is more than one. This increases the biomass. But with progress of succession , biomass of organisms increases and P/R ratio tends to be one (P/R=1) . This indicates stability of ecosystem . But in heterotrophic succession, the situation is different and the rates of respiration is greater than the rates of production because the community is dominated by the heterotrophs so P/R ratio is less than 1.