DOI: 10.6084/m9.figshare.23657391
title: Cassava field perimeters survey in Uganda and Côte d'Ivoire, 2018

description: Cassava surveys were conducted to gather information on cassava cultivation in Côte d’Ivoire and Uganda during four weeks between February and January 2018. A total of 69 locations in Côte d’Ivoire and 96 locations in Uganda were included in the surveys. To facilitate the measurement of the survey locations, a predefined fishnet grid of 100 x 100 square meters was established using the ArcGIS Collector app. The selection of survey locations was randomised, with approximately 15-20 kilometre intervals along major motorable roads in each country.At each selected sampling location, the survey team assessed an area of approximately 200 x 200 square meters, divided into four predefined quadrants measuring 100 meters by 100 meters each. The team recorded various aspects related to cassava fields within the study area, including the perimeter of all cassava fields, the size of smaller cassava patches, and the number of individual plants outside of the main field patch. Additional attributes of the fields and patches were documented, such as whether cassava was intercropped, the age of the cassava plants, and the density of each field (categorized as high, medium, or low density). In the case of intercropped fields, the other crops present were also noted.To ensure complete coverage of the surveyed area, the surveyors had the option to activate a tracking function in the ArcGIS Collector app. This function automatically marked the route followed by the survey team on the screen. In certain areas where access was challenging or safety concerns arose, such as suburban regions, only one or two 100 x 100 square meter quadrants were selected for practical reasons.The data collected during the surveys were exported and saved as polygons and points representing the surveyed locations. These data underwent post-processing to determine the proportion of the study area covered by cassava fields. The area of cassava fields was calculated based on the field and patch perimeters, while for individual plants, a 0.5-meter radius was assumed around each plant.<b>Civ_study_area_poly</b> and <b>Uga_study_area_poly</b>: these files relate to the actual study sites and the geographical limits in the shape of observed quadrants. Please note they could vary in size. Typically, we were sampling 4 ~100x100m quadrants, however, in some areas (esp. urban sites), we limited this to two or one ~100x100m quadrant. ‘field_id’ is the unique key identifying study site number in this and following files.<b>Civ_cassava_fields_poly</b> and <b>Uga_cassava_fields_poly: </b>contain polygons with cassava fields perimeters and properties for Côte d'Ivoire (Civ) and Uganda (Uga). Notes: Some polygons in this dataset may be overlapping due to two reasons: two teams were doing the surveys, and on occasions, they may have been surveying a field overlapping two quadrants. As a result, two teams could overlap two fields. The second reason is that the GPS accuracy was poor in some locations. Again this may have led to two teams overlapping their observations. As a solution, the intersecting areas of the polygons were converted into new polygons. These areas have polygons with ‘_Merged’ suffixes.The associated data stored in tabular format are available in the csv files. In tabular format, merged fields were separated into a series of non-overlapping unique entries in order to maintain the consistency of individual field attributes from each of the original polygons. The field size was split equally between the separated fields.<b>‘field_id’</b> is the unique key identifying study site number in this and following files. I have imported to those polygons information that we collected about the study site at the start of the survey.<b>Uga_individual_plants_poly</b> and <b>Civ_individual_plants_poly</b>– this is information related to scattered individual plants that we were mapping in our study areas. I assumed a 1-metre buffer around each plant was assumed and calculated areas were calculated based on those buffers. You will find this area calculated in ‘area_m2’ column. Link to study site is in ‘field_id’ column.<br>