Question

the productivity of ecosystems varies
the energy entering ecosystems is fixed by producers at a rate that depends on limiting factors such as temperature and the availability of light, water, and nutrients such as nitrogen and phosphorus. this limits the gross primary productivity of ecosystems which varies across the globe according to the availability of these factors. the biomass produced per unit time after respiratory needs of producers convert the energy they capture into carbohydrates is the net primary productivity. the most productive terrestrial ecosystems are those with high light and temperature and abundant water and nutrients. the least productive terrestrial ecosystems are those with low light and temperature and limited water and nutrients (such as tundra or desert). globally, the least productive terrestrial ecosystems are those that receive little rainfall (or abundant rainfall but low nitrogen). the primary productivity of oceans is lower overall than terrestrial ecosystems because the open ocean waters are low in nutrients.
the savannas of southern louisiana. the productivity of arid scrubland ecosystems, like this in eastern ethiopia, is limited by lack of water.
2 studying the ecosystem npp graph above:
(a) identify the three most productive ecosystems:
(b) what factors are likely to contribute to this high productivity?
(c) why do deserts have low npp?
(d) why is primary productivity of the open ocean lower than that of most terrestrial ecosystems?
3 estuaries and wetlands (including coastal wetlands) are among the most productive on earth. recall the characteristics of the aquatic biomes you looked at earlier and describe factors that contribute to the high productivity of these systems

Explanation:

(a) By observing the NPP graph, the three most productive ecosystems can be identified. High productivity is associated with factors like abundant sunlight, water, and nutrients.
(b) Tropical rainforests, swamps, and estuaries are highly productive due to warm temperatures, high rainfall, and rich nutrient - rich sediments.
(c) Deserts have low NPP because of limited water availability which restricts plant growth and photosynthesis.
(d) The open ocean has lower primary productivity than most terrestrial ecosystems as sunlight penetration is limited in deeper waters and nutrient availability is often low.
For estuaries and wetlands, they are productive due to the mixing of fresh and saltwater which brings in nutrients, and they also have high light availability and suitable temperatures for plant growth.

Answer:

(a) Tropical rainforest, swamps, estuaries
(b) Warm temperatures, high rainfall, rich nutrients
(c) Limited water availability
(d) Limited sunlight penetration and low nutrient availability

1. Mixing of waters bringing nutrients, high light availability, suitable temperatures