Terminology

Here we present a quick introduction to the main data sets and concepts relevant to the suage of the {mapme.agriculture} package. Note, that these are limited descriptions to the usage of this package and if you would like to learn more make sure to visit the Catalog section at the WaPOR website or read methdological documents of the WaPOR products.

Phenology: The phenology layer (PHE) contains information about the start, length, and end of a season for each pixel. The information is obtained by analysing the NDVI curves of a pixel over the course of a growing season. Depending on the location, a growing season might start in the year before the current observation year and it might as well end in the following year. Additionally, certain pixels might show a double season, that is two vegetation cycles after one another. This is indicated by two different data layers, one for the first and one for the seconds season. The values indicate the decad, i.e. ten consecutive days, the start or end of a season was detected. For any given year, the possible range of values is thus between 1 and 36, that is the first decad in the preceeding year or the last decad in the following year.
Total Biomass Production (TBP): This layer estimates the total amount of produces biomass [kg] in a given pixel for both the first and second season. It is a valuable input to assess how much biomass was produced in a certain location. It also serves as an input to the calculation of water productivity, because here we are interested in how much water was consumed to produce a certain amount of biomass.
Transpiration (T): This data layer indicates the amount of water that transpirated by plants per pixel. It is a single estimate, excluding other sources of evaporating water such as the interception storage and soil evaporation. It this can be used as a measure to calculate how much water was directly consumed by plants to produce a certain amount of biomass.
Gross Biomass Water Productivity (GBWP): This layer is defined as the amount of water (m³) from the interception, plant transpiration and soil evaporation in relation to the produced biomass in a given pixel. It is termed cross because soil evaporation and interception are not directly linked to plant biomass production. Currently, FAO does not provide the net biomass water productivity (NBWP) at 100 meter resoultion, that is why {mapme.agriculture} makes it possible to calculate it based on the total seasonal biomass production (TBP) and the plant transpirations (T) layers.
Net Biomass Water Productivity (NBWP): This layer currently is not available as an analysis-ready dataset at WaPOR, thus the {mapme.agriculture} package allows for the calculation of this parameter based on the aformentioned inputs. Compared to GBWP it is assumed to produce a better estimate of how much water was directly consumed by plants to produce a certain amount of biomass, and indicator which is of special relevane in monitoring the impact of project interventions.
Land Cover Classification: This data layer delivers a broad classification scheme that can be used to focues the analysis on certain types of landscapes. For example, the classification scheme includes three different classes for agriculture. These are rainfed and irrigated agriculture as well as fallow fields. These are the most important classes for the {mapme.agriculture} package, though the functionality can be used to calculated the same indicators also for other classes.

Based on the above mentioned parameters the {mapme.agriculture} packages allows users to calculate a number of indicators that can be used to asses a project’s impact over time. What follows are the definitions of the indicators that are currently supported by the package:

Land Cover Median: The median value of the landcover class per pixel
Land Cover Mode: The mode value of the landcover class per pixel
Land Cover Breakpoint: The index of the year where the landcover class first shows a persistend change
Presence of Double Season: A binary encoding of the presence of two seasons per pixel
Total Biomass Production: Information on the total biomass production (kg)
Gross Biommas Water Productivity: Information on the gross biomass water productivity
Net Biomass Water Productivity: Information on the net biomass water productivity
Land Productivity (global): For all parameters (TBP, GBWP, NBWP) the relation of a pixels productivity compared to the 90%-percentile over the complete timeseries is caluclated. Values <1 indicate that a pixels produced lower values and values >1 indicated pixels that produced higher values than that threshold
Land Productivity (yearly): the same as above except that the 90%-percentile is not calculated globally put a different threshold based on the current year is calculated.
Linear Trends: Linear trends including an estimate of the trend as well as the associated p-value is calculated for all input parameters (TBP, GBWP, NBWP) as well as for both land productivity indicators (global and yearly).

Last modified: 2022-01-30