Respiration

Respiration can be included in the simulations either as maintenance respiration only, or as the sum of maintenance and growth respiration as determined by the switch (PlantRespiration). In the former case, maintenance respiration is dependent on the surrounding temperature as:

                                          (5.70)

where k_rc is the respiration rate coefficient and f(T_a) is the temperature response (see Common abiotic functions), which can be calculated in several ways as determined by the switch Resp Temp Response. Analogously, this equation is used to calculate respiration from stems and roots and also from the old carbon pools in perennial plants, by using the respective carbon pools.

If salinity stress is included in the simulation an increase in respiration, the function is modified into:

                (5.71)

where f(π) is the salinity stress response function.

Alternatively, both growth and maintenance respiration can be included in the simulation. Total respiration is in this case calculated as:

                    (5.72)

where k_mrespleaf is the maintenance respiration coefficient for leaves, k_gresp is the growth respiration coefficient, and f(T_a) is the temperature response (see Common abiotic functions), which can be calculated in several ways as determined by the switch Resp Temp Response. The equation calculates respiration from stem, roots and grain by exchanging k_mrespleaf to k_mrespstem, k_mresproot, k_mrespgrain, and using the corresponding storage pools. Respiration from the old carbon pools is estimated with the same maintenance respiration coefficients as for respiration from new carbon pools.

If salinity stress is included in the simulation an increase in respiration, the function is modified into:

(5.73)

where f(π) is the salinity stress response function.