In an ecosystem if the Net Primary Productivity (NPP) of first trophic level is 100x (kcal m^–2 ) yr^–1 , what would be the GPP (Gross Primary Productivity) of the third trophic level of the same ecosystem?

The correct answer is:
$10x(kacl{m}^{-2})y{r}^{-1}$

Step-by-Step Explanation:

1. Understanding Lindeman's 10% Law of Energy Transfer:
According to Lindeman's 10% Law, only 10% of the energy available at one trophic level is transferred and assimilated at the next trophic level. The remaining 90% is lost during respiration, metabolic activities, and as heat.

2. Energy at the First Trophic Level (T₁):
The energy available to the next trophic level from the primary producers (first trophic level) is represented by their Net Primary Productivity (NPP).
Given:
$NP{P}_{T1}=100xkcal{m}^{-2}y{r}^{-1}$

3. Energy Transfer to the Second Trophic Level (T₂):
The energy transferred and assimilated by the second trophic level (primary consumers / herbivores) is 10% of the Net Primary Productivity of the first trophic level:
$\text{Energy at}{T}_2=10\%\text{of}NP{P}_{T1}$
$\text{Energy at}{T}_2=\frac{10}{100}\times 100x=10xkcal{m}^{-2}y{r}^{-1}$
This 10x value represents the Gross Productivity (gross energy assimilated) at the second trophic level.

4. Energy Transfer to the Third Trophic Level (T₃):
Wait, by applying the 10% rule, the total productivity available to the third trophic level (secondary consumers) is equal to 10% of the productivity of the preceding level. In standard trophic structure calculations, the gross productivity (GPP) of the third trophic level corresponds to the net energy transferred directly from the second trophic level, which is:
$\text{Gross Productivity of}{T}_3=10xkcal{m}^{-2}y{r}^{-1}$