Total ecosystem respiration in savanna ecosystems

Savanna ecosystems, which cover approximately 20% of the Earth’s land surface, play a significant role in the global carbon cycle. One crucial aspect of their carbon dynamics is total ecosystem respiration (TER), which represents the combined respiration of plants, roots, and soil microorganisms. Understanding TER is essential for accurately modeling carbon fluxes and predicting the response of savanna ecosystems to climate change.

Factors Influencing TER in Savannas

Several factors influence TER in savanna ecosystems:

1. Soil moisture: Studies have shown that soil respiration, a major component of TER, is highly sensitive to soil moisture changes. Rewetting of dry soils can trigger rapid increases in respiration rates.

2. Vegetation type: The composition and structure of savanna vegetation, such as the ratio of grasses to woody plants, can affect the amount and quality of organic matter input into the soil, influencing microbial activity and respiration.

3. Rainfall patterns: Savanna ecosystems are characterized by distinct wet and dry seasons. Rainfall pulses during the dry season can stimulate a rapid increase in TER, followed by a gradual decline as soil moisture is depleted.

Estimating TER in Savannas

Researchers have used various methods to estimate TER in savanna ecosystems:

1. Eddy covariance: This technique measures the net exchange of carbon dioxide between the ecosystem and the atmosphere, allowing for the calculation of TER

2. Soil respiration chambers: By measuring the CO2 efflux from the soil surface, researchers can estimate the contribution of soil respiration to TER

3. Modeling: Mathematical models, such as the Rothamsted Carbon model, have been used to simulate the dynamics of soil organic carbon and its relationship to TER in savanna ecosystems.

Importance of TER in the Global Carbon Cycle

Savanna ecosystems account for approximately 30% of the global terrestrial net primary production. The carbon fixed through photosynthesis is partially released back into the atmosphere through TER, with studies estimating that about half of the carbon taken in by savanna ecosystems is released through respiration. Understanding the factors that drive TER in savanna ecosystems is crucial for accurately predicting their response to climate change and for developing sustainable land management strategies. By monitoring TER and its relationship to environmental variables, researchers can better model the global carbon cycle and inform decision-making processes related to savanna conservation and restoration.