Aggregate habitat statistics tools tutorial

This tutorial shows how to run LUCI's online aggregation tools. Data from the Karnataka district in India is used to illustrate how the tools work.

Download the Karnataka data

Unzip the file when you've downloaded the data, but do not unzip any zip files within this folder as they will be used as they are in this tutorial.

The tools covered in this tutorial are:

When aggregating spatial data, you must choose the areas you are going use to aggregate by. These will typically be grid squares or irregular shaped polygons (i.e. district boundaries).

The Create aggregation grid tool generates a shapefile containing grid squares which can then be used as input to the Calculate aggregate habitat statistics tool. The Create aggregation grid tool does not need to be run if you already have a shapefile of polygons that you want to aggregate data by.

Create Aggregation Grid tool

  1. Open https://model.lucitools.org in a web browser on your computer (the tool is not set up to work on tablets or phones).

    LUCI online homepage
  2. Click on the the Create aggregation grid link.

    Create aggregation grid tool interface A
  3. Click the Choose File button and choose the UTM_Karnataka_stateboundary.zip file. This zip file contains a shapefile showing the boundary of the Karnataka region.
  4. Choose the width of each cell in the aggregation grid. Enter 50 into this text box.
  5. Keep the Grid coverage as Rectangular.
  6. Click the Create aggregation grid button.

The above options will overlay a rectangular grid over the Karnataka region as shown below.

Create aggregation grid results A

You will notice that the rectangular grid overlays areas which are not part of the Karnataka region. If you use this rectangular grid to aggregate data by, it will aggregate data outside of the region.

A way around this is to use the second Grid coverage option in the tool. To do this, follow steps 1 to 4 above. Then,

1. Choose the Grid coverage option: Grid covers area bounded by boundary feature class only'.


Create aggregation grid tool interface

When you choose this option, an additional text box appears which accepts a number from 0 to 100.

  • 100 means that all grid squares will be fully contained within the Karnataka region.
  • 50 means that if a grid square's area is at least 50% Karnataka region then it is included.
  • 0 means that if a grid square covers any of the Karnataka region, it is included.

2. Choose 100 for the percentage.

3. Click the Create aggregation grid button.

The above options overlay a grid on the Karnataka region, with the grid squares all contained within the region as shown below.

Create aggregation grid results

Download this grid by clicking the Download link at the bottom left of the screen. You will use this grid as input to the Aggregate data tool.

Calculate aggregate habitat statistics tool

Aggregate by grid

  1. Open https://model.lucitools.org in a web browser on your computer (again, the tool is not set up to work on tablets or phones).
  2. Click on the the Calculate aggregate habitat statistics link.

    Aggregate data tool interface
  3. Click the first Choose file button. Select the LandCoverKarnataka.zip file. This contains a shapefile showing land cover in the Karnataka region. This data was derived from the LCCCI project (http://maps.elie.ucl.ac.be/CCI/viewer/download.php) in raster form clipped to the region and then converted to polygons.
  4. In the Shapefile attribute table column input box, enter 'gridcode'. This is the column name for the land cover in the above zipped shapefile.
  5. Choose the outputGrid.zip file that you downloaded at the end of the Create Aggregation Grid tool steps.
  6. Click the Aggregate data button.

This tool will take a few minutes to run. Once it has finished, you will see the following aggregated layers:

  • Inverse Simpson
  • Shannon
  • Number of covers
  • Mean patch size

Aggregate data tool results

Click on the WSAggregateData text at the top right of the screen to show these layers. Turn them on and off by clicking on the eye symbol to the left of the layers.

You can download the aggregated data by clicking on the download link at the bottom left.

Aggregate by district

Choosing whether to use a grid or other aggregation units (e.g. districts or states) depends on how the user wants to analyse and present their data. Grids allow for comparison and analysis of regular-sized units (e.g. 1km squares). However, aggregating data by administrative boundaries allows for analysis and comparison between these different administrative units. In this part of the tutorial, the administrative boundaries of districts within Karnatka will be used.

To aggregate the land cover by district rather than by grid squares, follow steps 1 to 4 above. Then,

1. Instead of choosing the outputGrid.zip file, choose the UTM_Karnataka_alldistricts.shp.zip file from the sample data. This zip file contains a shapefile showing the boundaries of the districts within the Karnataka region.

2. Click the Aggregate data button.

Again the tool will take a little time to run. The output layers are the same as before but now show the data aggregated by district instead of by grid squares.

Karnataka inverse simpson

 

End of tutorial