Question

Terrestrial net primary production (NPP) is highest in

A. tundra B. boreal forest C. desert rangelands D. tropical rain forests E. eastern deciduous forests

Answer 1

Ans:-D.Tropical rain forests

NPP is the weight of the organic matter stored by the producers in a unit area/volume per unit time.it is given by,NPP=GPP-R,where R is respiration losses and GPP is Gross primary productivity .NPP is utilised by heterotrophs.

Npp is highest in tropical rain forests as it is rich in varieties of plants,regular precipitation occur in this region(60-160inches) every year.NPP is also affected by availability of water,CO2 and nutrients.These factors are consistent in tropical rain forest and resulting in very high GPP (rate of production of organic matter during photosynthesis)and NPP.

Eastern decidious forests fall in the category of moist decidious forests.they receive rainfall between 200 and 100cm.important trees are found in this region like teak,bamboos,mulberry.Biome in this region is 190-380 metric tons per hectare.They have high NPP than tundra,boreal and desert forests but lower than tropicap rain forests because it has lower diversity of consumer component than the tropical rain forests.

Boreal forest has modereate levels of NPP.As the precipitation is quite low in this region and temperature varies frequently which results in lower NPP.

Desert range lands and Tundra have lowest NPP.In desert region rainfall is less than 70cm,natural vegetation consists of thorny trees and bushes.Lower availability of water in desert region results in the most lowest NPP.Tundra region mainly found in ice-covered areas of northern and Southern Hemisphere.This region have most barren landscapes.So,it doesn't have favourable condition for the growth of plants and vegetation resulting in lowest level ot NPP.