OC-11.1: Rain Use Efficiency

Definition: Rain use efficiency (RUE) is the ratio of aboveground net primary production (ANPP) to mean annual precipitation (MAP).

Unit of Measure: kg ha^-1 mm^-1

Disaggregated by: Vegetation type, soil type, geographic location (national, sub-national)

Method of Calculation:
Rain use efficiency (RUE) is the ratio of above-ground net primary production (ANPP) to mean annual precipitation (MAP), or simply the ratio of standing biomass to rainfall:
RUE =Aboveground net primary production (ANPP)Mean annual precipitation (MAP)

Data sources: Rangeland and meteorological station.

Data collection method: Field-data collection of ANPP from rangeland and routine recording of MAP from the nearest weather station.

Data collection and reporting responsibility: Program leader, project leader, project M&E focal point person

Data Collection and Reporting Frequency: Annual, bi-annual, baseline, mid-term, end-term.
Please note that above-ground net primary production (ANPP) can be estimated during the peak growing season of primary production which cincides with development of the annual vegetation and carried out in ungrazed sites.

Evidence required:
For internal evaluation or research studies: Study protocol, data collection tools, dataset, report;
For external evaluation or research studies: Request for proposals (RFP) document, final report, dataset

Rationale: Rain use efficiency (RUE) is an important indicator for arid and semi-arid rangeland health, where rainfall is a major limiting factor for plant growth. RUE is a critical indicator for evaluating the response of primary productivity to variability of rainfall in arid and semi-arid ecosystems. Therefore, changes in RUE is an integral measure for evaluating ecosystem health, land degradation and desertification.

Comments and limitations: