# Biomass production from NPP in the Earth Engine

Calculate world wide biomass production from the MODIS NPP.

The NPP can be used to estimate the production of biomass (kgm2). Biomass is the dry matter of vegetation that consists of carbohydrates (CH2O). Total biomass production is calculated by including the molecular masses of hydrogen and oxygen into the equation.

Biomass = NPP * (30/12)

Yearly NPP is downscaled to an 8 daily time-series in this exercise.

Step 1: Open this script

Step 2: Add code below to calculate the biomass

```// calculate the Biomass

var Biomass = function(myimg){
var biomass = myimg.multiply(2.5);
return biomass.copyProperties(myimg,['system:time_start']);
}

// map biomass production
var biomassCollection = npp8Collection.map(Biomass);
```

3. Add the fusion table of the Da basin and one of the Thai Binh province.

``` // import the sub basins as a fusion table
var Da = ee.FeatureCollection('ft:15ytieQkq3UH8DPJPFmB_YnbvhSEhOQLtLIXa6kxA').geometry();
var ThaiBinh = ee.FeatureCollection('ft:1w0nJ-In_Tabrr9zS-C6pdw1sHwuZM1_YS9mxacOf').geometry();

// Set center of map
Map.centerObject(Da, 5);

// show the layer

// create vizualtion settings
var biomass_viz = {min:300.0, max:800, palette:"b27c00,ffff33,58ff33,146003"};

```

4. Plot the temporal changes in a chart.

```// Predefine the chart titles.
var title = {
title: 'Biomass production in Da basin',
hAxis: {title: 'Time'},
vAxis: {title: 'Biomass (kg/m2)'},
};

// create chart
var biomassChartDa = ui.Chart.image.seriesByRegion(biomassCollection,
Da,
ee.Reducer.mean(),
'Gpp',
500,
'system:time_start').setOptions(title);
// plot chart
print(biomassChartDa)

// Predefine the chart titles.
var title = {
title: 'Biomass production in Thai Binh basin',
hAxis: {title: 'Time'},
vAxis: {title: 'Biomass (kg/m2)'},
};

// create chart
var biomassChartBinh = ui.Chart.image.seriesByRegion(biomassCollection,
ThaiBinh,
ee.Reducer.mean(),
'Gpp',
500,
'system:time_start').setOptions(title);
// plot chart
print(biomassChartBinh)
```

Find an example here.

1. Roshni Sanyal says:

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1. nazulamin says:

Sir Kindly share the reference for the biomass formula “”Biomass = NPP * (30/12)”” which is used here.
we will be very thankful to you .

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2. Lilian Guimarães Silva says:

Thank you very much for helping me with this,
Its really usefull !
But, your fusion table, with the countries and cities, doesn’t seem to be open for every one that want to use to understand the potencial of your code.

And, one more question:
For biomass calculate, why you multiple for 2.5?
I don’t understand this!
The formule is “Biomass = NPP * (30/12)”

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3. nazulamin1 says:

Hello sir!
For biomass calculation, why you multiple for 2.5?
If you have any reference please share with us.
Thank you!

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4. nazulamin says:

Thank you!
i mean that Biomass = NPP * (30/12)..do you have any references for this formula from where it is taken?, any article/paper do you have who use it please share! 

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5. nazulamin says:

Sir Kindly share the reference for the biomass formula which is used here.
we will be very thankful to you .

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