Introduction

The gradient nearest neighbor (GNN) data are multivariate, imputed maps of forest attributes based on 30-m Landsat imagery, Forest Inventory and Analysis data, and other geospatial data products, such as climate and topography. These maps provide a valuable source of data for landscape analysis. This website is the primary method for disseminating these data, accuracy assessment reports, and other information needed for interpretation and application of GNN maps.

GNN maps are the product of the Landscape Ecology Modeling, Mapping & Analysis (LEMMA) group, an inter-institutional research team led by USFS Pacific Northwest Research Station and Oregon State University. Additional support and collaboration has been provided by USFS Rocky Mountain Research Station, USFS Pacific Northwest Region, and the USFS Forest Inventory and Analysis Program.

For additional information regarding GNN, please visit the LEMMA homepage.

Instructions

1. Choose the GNN model series that you would like to download. We currently have two modeling series available:

• GNN.2023.1 which has model years 1986-2021; and
• GNN.2020.1 which has model years 1986-2017

We recommend downloading data from one model series only, especially when analyzing more than one model year.

2. Choose the attribute(s) that you would like to download. You may select multiple attributes (Windows: Ctrl+Click, Mac: Cmd+Click) and then click the 'Add to download list' button. These will be added to the table at the right. You may remove selections from the table by clicking the row's button and the table will update.

There are more GNN attributes and years available for download. In order to receive access to these rasters, we ask that you fill out this form so that we might advise you on appropriate usage across multiple years or for less commonly used attributes. Once approved, we will give you access to these additional data.

3. Next, choose the geographic area that you would like to download from the predefined polygons in the list below. Your downloads are limited to 5.0 GB per request.

4. Finally, add your name, organization, and email address and hit the 'Submit Request' button. Once we've received your request, we will start processing and email you a link to the data once it has completed. You will be redirected to a confirmation page if your order was successful; otherwise you may need to correct errors in your request.