Question

Briefly describe how patterns of NPP and decomposition vary globally. What similarities and differences are there? What factors ultimately drive these patterns?

Answer 1

• Net Primary Production or NPP may be describe as:

Photosynthesis – respiration (for all autotrophs in the ecosystem).

• NPP is also dependent on NEP and GPP, which relates to autotrophs and heterotrophs respirations.
• NPP is varies due to nutrient availability (like carbon, nitrogen phosphorus in many cases).
• Nutrient may be added as abiotic component to the ecosystem, in form of fertilizers or other additives.
• However, the variation in NPP or a persistence of Nutrient limitation is associated with transient nature of biologically available forms of Nutrient.
• The biological available form of nitrogen/ carbon enters the ecosystem from the atmospheric or geological form, or through recycling of soil by microorganisms. Aquatic NPP also varies due to nutrient availability.
• Thus, the biological processes that might result in various patterns of NPP, is nutrient recycling through ecological cycles.
• Thus, the varying ecosystem and type of microbial activity in different ecosystem, causes different nutrient availability to autotrophs and alters the global NPP.
• The types and age of the plants also dictates the NPP variation in each global ecosystem.
• Global NPP rates also varies due to human activities, like change in atmospheric carbon dioxide.
• The varying climate also governs the change in NPP and decomposition rates. Like temperatures and annual precipitation of the area.
• The type of are also changes the net productivity in terms of available sunlight, like in rain forests.

Factors:

• Nutrient recycling
• Temperature. Higher temperature- faster decomposition.
• Primary and secondary productivity.
• Moisture, annual rainfall.
• Availability of light- NPP decreases on decrease in light.