Plant roots are an important part of the ecosystem. Even one hardly can see them, they fulfil many important functions such as:
- Water uptake
- Nutrient uptake
- Plant anchoring in the soil
- Interaction with biotic and abiotic soil environment
- Carbon input to the soil
In this on-line teaching material we will concentrate on the latest point, emphasizing the role of roots in carbon dynamics. Most of the processes occurs in the rhizosphere, defined as a close space around the roots with various biotic and abiotic interactions.
Plant roots are in various interactions with their biotic and abiotic environment and their activities make the rhizosphere an unique living space. This contribution will consider the amount of carbon under ground and will bring it in the context of root architecture. Architecture of the root system is designed to fulfil all major root functions and is closely linked to soil exploration and resource uptake.
Green plants are acquiring their carbon from the atmosphere via photosynthesis and distribute the synthesised carbohydrates to different plant organs. As all other plant parts, roots have to fit in to the overall pay-off of carbon investment. From this viewpoint, the longevity of roots is an important measure regulating plant carbon budget. When the fine roots are shed off and died, they contribute substantially to soil carbon via root litter. Also coarse roots, often deep in the soil provide root litter over the long perspective of tree growth.
The fine roots and their rhizosphere is a living space for complex microbial communities and fungi. They are nursed by the release of carbohydrates from the roots, which is an important carbon input into the soil also contributing to the overall carbon balance of the ecosystem.