Evapotranspiration (AETI), Land Cover Classification (LCC), Net Primary Productivity (NPP), Precipitation (PCP), Phenology (PHE), Quality layers (QUAL), Reference Evapotranspiration (RET), Soil moisture (RSM), Total Biomass Production (TBP) and Water Productivity (WP)

Total biomass production (TBP) data component

Total Biomass Production (TBP) is defined as the sum of the above-ground dry matter produced during the crop growing season. Hence, TBP steadily increases between the start (SOS) and end of season (EOS).

WaPOR data components

The Total Biomass Production (TBP) represents the total biomass production in a given year or growing season and is delivered on a seasonal basis at levels 2 and 3. The seasonal value represents the total accumulated biomass during one growing season, from SOS to EOS. Calculating TBP requires input from NPP for dekadal biomass production and Phenology for demarcating the growing season.

TBP is a good indicator for crop yield forecasting/estimation because it integrates three important aspects: the current vegetation status (via fAPAR, which is included in NPP computation), the meteorological influences (also via NPP) and the ‘history’ (via the summation over the course of the season). TBP, expressed in kgDM/ha, typically ranges between 0 and 45 on a daily basis, although higher values are possible. As the TBP is an integration of the biomass production over time, its accuracy is closely related to the accuracy of the NPP.

Table x: Overview of TBP data component

Methodology

Total Biomass Production (TBP) is defined as the sum of the above-ground dry matter produced during the growing season. TBP is expressed in kgDM/ha/day, and has thus different biomass units compared to NPP, with 1 gC/m²/day (NPP) = 22.222 kgDM/ha/day (DMP). The required inputs are the dekadal NPP values, as well as information on the start and the end of the growing season , as produced by the WaPOR phenology component. A vegetation check is included to account for vegetated areas where no clear growing season is detected (e.g. evergreen forest). In the absence of a growing season, the annual mean NPP value is used to determine if vegetation is present. If for a given pixel the threshold value of 0.75 gC/m²/day is exceeded, the start- and end of the growing season in that pixel will be set to the start and end of the calendar year.

TBP is then calculated as the sum of NPP, converted into DMP units (kgDM/ha), between the start of the season (SOS) and the end of the season (EOS).

The equation to compute the seasonal TBP for a given pixel thus becomes:

where:
- DMP(i) is the Dry Matter Production at dekad i, expressed in kgDM/ha/day.
- Nd(i) is the number of days within each dekad, varying between 8 (end February) and 11.
- The first term, ∑N_d(i), is needed to obtain the TBP sum in terms of kgDM/ha. Without it, one would obtain the mean.

Challenges

A limitation for the derivation of TBP is the dependency on phenological information, meaning that TBP can only be derived for areas where seasonality is detected. For ecosystems that experience almost no seasonality, such as tropical forests or deserts, the start of season is theoretically set at January 1st and end of season is set at December 31st.

Functions and flowcharts

TBP is produced by combining the information on the growing season with the dekadal NPP information.