Repo to analyse Pheno Sink data

this repo can be used to analyse the data gathered last year.

Scope

Link the carbon sink-source to the leaf senescence.

Data avaible

Several data are available

Model

The models used are most of carbon and energy. Carbon dynamics in the most important model, we may also use the energy model for evapotranspiration and stomata conductance.

Carbon mass balance

The mass of carbon must be balanced, the sum of all sink must be equal to the sum of all source

Eq.

The carbon source of defined by the carbon assimilation. The carbon sink is the sum of these different components

• respiration
• NSC
• storage for next growing season
• Growth, divided in
• leaf
• root
• trunk and branches

We can measure the respiration and NSC.

Storage must be assumed somehow.

The growth is more difficult to measure

• Leaf growth we can assume to be negligible (use the carbon stored)
• root growth we cannot measure and we need to ignore / assume
• tree growth can be estimated by the height and diameter

Energy balance

Energy balance can be used to estimate the evapotransportation and the optimal stomatal conductance.

The delta energy (difference between input and output) is divided into latent and sensible heat. sensible heat is measured and is the temperature difference between the different compartment (leaf, air soil). Latent heat is the energy used by the plant to change phase of water from liquid to gaseous (transpiration).

By calculating the latent heat, we can convert it into transpiration and calculating the stomatal conductance.

Implication of considering the energy balance

By calculating the stomatal conductance in this way, we purposely neglect the negative feedback loop on stomata due to the NSC on leaves. Positive systematic deviation between modeled and observed assimilation at the end of the growing season may indicate an early trigger of leaf senescence before the protein catabolism (browing).