The given table shows the annual Net Primary Productivity (NPP), season length, and Leaf Area Index (LAI) for various ecosystems.

​Which one of the following options represents the correct order of decreasing NPP per day per unit leaf area?​

Correct option is A

To determine the correct order of decreasing NPP per day per unit leaf area, we use the formula:

$$\frac{Annual NPP}{Season length\times total LAI}$$​​

• Annual NPP = Net Primary Productivity per year
• Season Length = Number of growing days in a year
• Total LAI = Leaf Area Index (m² leaf area per m² ground area)

Calculation:

      Tropical Forest =  $$\frac{2482}{365\times 6}$$ = 1.13

     Temperate Forest =  $$\frac{1550}{250\times 6}$$ = 1.03

     Tundra =   $$\frac{180}{100\times 1}$$ = 1.8

      Desert =  $$\frac{250}{100\times 1}$$ = 2.5

Arrange in Descending Order

1. Desert (2.50)
2. Tundra (1.80)
3. Tropical Forest (1.13)
4. Temperate Forest (1.03)

Thus, the correct order is:

$$\mathbf{Desert}>\mathbf{Tundra}>Tropical\; Forest>Temperate\; Forest$$

Information Booster:

1. Net Primary Productivity (NPP)

   • Measures the amount of carbon fixed by plants after respiration.
   • Higher in humid regions (e.g., Tropical Forest) and lower in arid zones (e.g., Desert).

2. Leaf Area Index (LAI)

   • Represents leaf coverage per unit ground area.
   • Higher LAI → More photosynthetic potential but not necessarily higher efficiency per leaf unit